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Vol 17 – 1/2016 Immune system fighting malignancy Antigen-specific naive and memory T cells Direct phenotypic and functional characterization p. 11 Evaluation of metastatic burden Recovery of human metastatic cells from mouse model p. 17 DC vaccination Designing a DC-based therapy for primary liver cancer p. 20 CONTENTS Editorial 3 News Commercial-scale manufacture of genetically modified T cells – challenges and approaches 4 Reports Dendritic cells pulsed with PepTivator® Ovalbumin induce both OVA-specific CD4+ and CD8+ T cells and cause antitumor effects in a mouse model of lymphoma 7 Kenji Miki, Koji Nagaoka, Hermann Bohnenkamp, Takayuki Yoshimoto, Ryuji Maekawa, and Takashi Kamigaki Detection, enrichment, and direct phenotypic and functional characterization of antigen-specific naive and memory T cell subsets 11 Petra Bacher and Alexander Scheffold Evaluation of metastatic burden and recovery of human metastatic cells from a mouse model 17 Lorena Landuzzi, Arianna Palladini, Marianna Lucia Ianzano, Roberta Laranga, Giulia D’Intino, Patrizia Nanni, and Pierluigi Lollini Perspectives Designing a dendritic cell–based therapy for primary liver cancer 20 Stuart M. Curbishley, Miroslava Blahova, and David H. Adams Engineering human cells with lentiviral vectors: Making an impact on human disease 25 Rimas Orentas 2 MACS & more Vol 17 • 1/2016 miltenyibiotec.com EDITORIAL Dear Researcher, The immune system with its vast array of different cell types has a myriad of ways to protect the body against malignant disease. Researchers and clinicians worldwide explore the potential of these cells in their quest for novel cellular therapies. In this MACS&more issue, scientists from around the world share their research results and experience on the way to translating basic research into clinical application. With the development of new strategies for cellular therapy, the scientific community has gained enormous momentum in the fight against malignancy. Particularly, genetically engineered T cells expressing a chimeric antigen receptor (CAR) show great promise and – in the future – might provide the basis for the treatment of diseases that are currently considered incurable. On p. 25 Rimas Orentas provides an exciting perspective on lentiviral technology, which is one of the cornerstones of successful CAR T cell manufacture, and on future directions for CAR T cell engineering. Another very promising immunotherapy approach is the vaccination with tumor antigen–presenting dendritic cells (DCs), which can initiate an effective anti-cancer immune response in the body. Using a mouse model of lymphoma, Kenji Miki et al. showed that DCs pulsed with a PepTivator® Peptide Pool induced both CD4+ and CD8+ T cells to proliferate and release cytokines. Ultimately, the DCs inhibited tumor growth (p. 7). Stuart Curbishley gives thorough insight into the process of designing a randomized phase II clinical trial utilizing DCs as vaccines for hepatocellular carcinoma (p. 20). Aim of the study is to evaluate whether vaccination with DCs provides an additional benefit compared to cyclophosphamide pre-conditioning and transarterial chemoembolization alone. Throughout the entire DC manufacturing workflow, S. Curbishley and his colleagues rely on a wide range of products from Miltenyi Biotec. miltenyibiotec.com Petra Bacher and Alexander Scheffold (p. 11) established a technique based on MACS® Technology to increase the sensitivity for flow cytometry analysis of rare antigen-specific T cells. The authors also set up a multicolor panel using numerous MACS Antibodies. The so-called ARTE (antigen-reactive T cell enrichment) together with multicolor flow cytometry will be an excellent tool for research into various immune-related diseases and the development of immunotherapies. The spread of malignant cells in the body is an important topic of cancer research as metastases are the major cause of death in cancer-related diseases. Lorena Landuzzi et al. describe a method that allows the recovery and quantification of human metastatic cells in a mouse model and enables enrichment of these cells for in vitro analyses (p. 17). These are just a few examples of how Miltenyi Biotec’s comprehensive, integrated portfolio has supported researchers on the journey towards novel cellular therapies against malignant disease. We hope you enjoy reading this MACS&more issue! Your MACS&more team Vol 17 • 1/2016 MACS & more 3 NEWS Commercial-scale manufacture of genetically modified T cells – challenges and approaches Adoptive transfer of genetically modified T cells holds great promise for cancer therapy. The manufacture of these cells however is complex, labor-intensive, and comprises many different handling steps – a challenge for the conversion from small-scale clinical trials into larger commercial-scale treatments. The CAR T cell manufacturing process – complex and challenging T cells play a pivotal role in the immune response against cancer. Accordingly, the capacity of T cells to fight malignant diseases provides exciting perspectives with regard to novel, widely applicable cell therapy options. In fact, the adoptive transfer of T cells expressing genetically engineered chimeric antigen receptors (CARs)¹ has shown great promise in clinical studies addressing chronic or acute lymphocytic leukemia²,³. However, the preparation of CAR T cells for clinical application is quite complex and comprises numerous handling steps, including i) enrichment of the T cells, ii) T cell activation, iii) transduction, iv) expansion, and finally v) cell formulation (fig. 1). In the context of a small-scale clinical trial, all these steps can be performed reasonably according to GMP guidelines in a semi-automated manner using several devices and a multitude of liquid handling steps. However, the transformation of such manufacturing methods into a largescale setting has some pitfalls. The complex procedure includes a number of processes that are usually performed in an open environment, thus entailing high demands on the clean room infrastructure and on skill and time for the personnel. Currently, only few institutions would be able to fulfill these requirements, which limits the number of cellular products that can be manufactured or prepared within a specified time. Ultimately, this also narrows the number of patients who could benefit from such therapies. To make cell–based therapy available for many patients, cell manufacture processes need to be adapted and optimized to a commercial scale. 4 MACS & more Vol 17 • 1/2016 Donor/ patient Cryo-preservation Blood leukapheresis T cell selection Activation Transduction Enrichment of modified T cells Cryo-preservation Expansion Final formulation Administration to patient Figure 1 Workflow for the production of genetically engineered T cells. There are quite a few needs that a process for manufacturing a cellular therapy product has to fulfill. First and foremost, the resulting cellular product must be safe and clinically effective (meaning the cells must meet certain functional requirements). Moreover, the GMP-compliant manufacturing process has to be reliable and robust to yield a product with consistent quality, which can be easily validated. For commercial-scale manufacture, it is also necessary to optimize the process with regard to labor intensity, simplification of the workflow, and scalability of production. clean room requirements. Importantly, all cell processing steps are automated, which not only makes for a highly reproducible, standardized, and robust manufacturing process, it also reduces labor intensity. The CliniMACS Prodigy® – enabling robust end-to-end GMP-compliant manufacture of CAR T cells Miltenyi Biotec has developed the CliniMACS Prodigy® as an all-in-one solution for cell processing in a closed GMP-compliant system.⁴ An automated process specifically developed and optimized for the manufacture of CAR T cells will be available soon. With this process, the entire workflow for the manufacture of CAR T cells, from T cell selection through to cell formulation, can be performed in a single-use tubing set. This closed system greatly reduces Figure 2: The CliniMACS Prodigy enables complex automated cell manufacturing workflows in a closed system. miltenyibiotec.com NEWS GMP-compliant cell processing in a closed system – opening up new dimensions of scalability Most of the current concepts for CAR T cell therapies are based on autologous cells, which means that each cellular product is manufactured in a single batch in small scale for a single patient. If the products were to be processed in an open production line, each single batch would almost require its own dedicated clean room. In contrast, the CliniMACS Prodigy, with its closed system, enables GMP-compliant cell processing in itself. For a future CAR T cell–based therapy, multiple cellular products could be manufactured in parallel in a single clean room. This would increase the number of cellular products that can be produced within a specified time, and thus the number of patients that could benefit from the therapy. Thanks to the robust, automated, and standardized processes, the CliniMACS Prodigy could also enable cell manufacture close to the patient. This would greatly simplify logistics and avoid issues arising from transportation of the sensitive cellular material. The Miltenyi Biotec portfolio – supporting the complete workflow of cell manufacture Besides the CliniMACS Prodigy, Miltenyi Biotec also offers a broad range of GMPcompliant products for CAR T cell processing – starting with the CliniMACS® Reagents for the isolation of CD4+ or CD8+ T cells or the isolation of T cell subsets via CD62L, the MACS® GMP TransAct™ CD3/CD28 Kit for the activation and expansion of T cells, through to the TexMACS™ GMP Medium optimized for culturing T cells, and MACS GMP Cytokines including IL-2, IL-7, IL-15, and IL-21. Moreover, the team from Lentigen Technology Inc., who joined Miltenyi Biotec in 2014, has a strong expertise in the development and manufacturing of clinicalgrade lentiviral vectors used to genetically engineer CAR T cells. miltenyibiotec.com The broad range of flow cytometry tools including MACSQuant® Flow Cytometers and hundreds of MACS Antibodies allows for a detailed analysis of the cellular products. With its comprehensive portfolio, Miltenyi Biotec not only provides the basis for the development of innovative CAR T cell–based therapies, but also provides a strong foundation for a future implementation of commercialscale manufacture – all with the goal to open up the possibility of making innovative therapies available to many patients. References 1. Abken, H. (2015) MACS&more 16: 32–36. 2. Kalos, M. et al. (2011) Sci. Transl. Med. 3: 95ra73. 3. Maus, M. V. et al. (2014) Blood 123: 2625–2635. 4. Apel, M. et al. (2013) Chemie Ingenieur Technik 85: 103–110. Unless otherwise specifically indicated, Miltenyi Biotec products and services are for research use only and not for therapeutic or diagnostic use. The CliniMACS® System components, including Reagents, Tubing Sets, Instruments, and PBS/EDTA Buffer, are manufactured and controlled under an ISO 13485–certified quality system. In the EU, the CliniMACS System components are available as CE-marked medical devices. In the US, the CliniMACS CD34 Reagent System, including the CliniMACS Plus Instrument, CliniMACS CD34 Reagent, CliniMACS Tubing Sets TS and LS, and the CliniMACS PBS/EDTA Buffer, is FDA approved; all other products of the CliniMACS Product Line are available for use only under an approved Investigational New Drug (IND) application or Investigational Device Exemption (IDE). CliniMACS MicroBeads are for research use only and not for human therapeutic or diagnostic use. MACS® GMP Products are for research use and ex vivo cell culture processing only, and are not intended for human in vivo applications. For regulatory status in the USA, please contact your local representative. MACS GMP Products are manufactured and tested under a quality management system (ISO 13485) and are in compliance with relevant GMP guidelines. They are designed following the recommendations of USP <1043> on ancillary materials. No animal- or human-derived materials were used for manufacture of these products. Vol 17 • 1/2016 MACS & more 5 REPORT Dendritic cells pulsed with PepTivator® Ovalbumin induce both OVA-specific CD4+ and CD8+ T cells and cause antitumor effects in a mouse model of lymphoma Kenji Miki¹, Koji Nagaoka¹, Hermann Bohnenkamp², Takayuki Yoshimoto³, Ryuji Maekawa¹*, and Takashi Kamigaki⁴ ¹ Medinet Medical Institute, MEDINET Co., Ltd., Tokyo, Japan ² Miltenyi Biotec GmbH, Bergisch Gladbach, Germany ³ Institute of Medical Science, Tokyo Medical University, Tokyo, Japan ⁴ Seta Clinic Group, Shin-Yokohama, Japan * not shown Introduction Dendritic cell (DC)-based vaccines hold great promise for cancer immunotherapy. DCs are pulsed with peptides and subsequently used as antigen-presenting cells to induce an antitumor response in vivo through the activation of T cells. Thus far, mostly epitope-specific peptides with 8–10 amino acids in length have been used to generate DC vaccines, which however activate only CD8+ T cells. Moreover, available single epitope-specific peptides are restricted to MHCI or MHCII and therefore activate either CD8+ or CD4+ T cells. Here we used a PepTivator® Peptide Pool, which consists mainly of 15-mer peptides covering the complete sequence of the target antigen, in this case ovalbumin (OVA), with an 11–amino acid overlap. We show that DCs pulsed with this peptide pool induced both OVA-specific CD8+ and CD4+ T cell responses and caused strong antitumor effects in a mouse model of lymphoma. Material and methods DC generation and antigen loading DCs were generated from mouse (C57BL/6) bone marrow cells cultured in the presence of miltenyibiotec.com specific T cell receptor (TCR). CD4+ and CD8+ T cells were isolated with the CD4+ T Cell Isolation Kit, mouse and the CD8a+ T Cell Isolation Kit, mouse, respectively (both from Miltenyi Biotec). 20 ng/mL GM-CSF for 10 days. Subsequently, DCs were maturated in the presence of 10 ng/ mL GM-CSF, 10 ng/mL IL-4, and 1 µg/mL LPS. DCs were loaded with antigen by pulsing with PepTivator Ovalbumin peptide pool (Miltenyi Biotec) for 4 hours. Ovalbumin (OVA) peptides with I-Ab (MHCII)-restricted (OVA323–339) and H-2Kb (MHCI)-restricted (OVA257–264) epitopes were used as positive controls. All peptides were used at the final concentration of 2 µg/mL. Following the incubation, cells were washed with medium to remove excess peptides. T cell priming capacity of DCs To test the capacity of DCs to induce T cell proliferation, the DCs pulsed with PepTivator Ovalbumin or the I-Ab- or H-2Kb-restricted OVA peptides were cocultured with CFSElabeled OT-II CD4+ T cells or OT-I CD8+ T cells. The ratio of DCs to T cells was 1:20. Untreated DCs were used as a negative control. After 1 to 4 days of coculture, T cell proliferation was determined by flow cytometry using absolute T cell isolation T cells were obtained from spleens of OT-II or OT-I mice carrying a transgenic OVA- • No antigen • OVA tetramer assay b • S erum IgG detection DCs • Peptide (I-A ) by ELISA • Peptide (H-2K b) • Peptide (I-Ab + H-2K b) • Measurement • PepTivator Ovalbumin of tumor weight E.G7 C57BL/6 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Figure 1 Timeline for the evaluation of antitumor effects of DCs. Numbers indicate the days after tumor induction with E.G7 cells. Vol 17 • 1/2016 MACS & more 7 REPORT A OVA peptide–pulsed DCs induce CD4+ and CD8+ T cells to proliferate and secrete pro-inflammatory cytokines Mature DCs have the capacity to induce T cell proliferation. To test whether the OVA peptide–pulsed DCs can exert this function, we cocultured the DCs with CD4+ or CD8+ T cells carrying an OVA-specific TCR and measured the numbers of T cells after various time points. 8 MACS & more Vol 17 • 1/2016 2.0 1.0 0 1 2 3 Time (days) 5.0 3.0 2.0 1.0 peptide (I-Ab) 0 1 2 3 Time (days) no antigen PepTivator Ovalbumin B ns 4.0 0.0 4 peptide (H-2K b) no antigen Relative cell number Relative cell number no antigen peptide (I-Ab) PepTivator Ovalbumin 10⁰ 10¹ 4 PepTivator Ovalbumin peptide (H-2K b) PepTivator Ovalbumin 10³ 10² 10⁰ 10¹ 10³ 10² CFSE CFSE IL-2 C OT-II CD4 T cells OT-I CD8+ T cells 12.0 10.0 8.0 6.0 4.0 2.0 0.0 ns No antigen Peptide (I-Ab) IL-2 level (ng/mL) + 25.0 ns 20.0 15.0 10.0 5.0 0.0 No antigen PepTivator Ovalbumin Peptide (H-2K b) PepTivator Ovalbumin IFN-γ OT-II CD4 T cells OT-I CD8+ T cells + 12.0 10.0 8.0 6.0 4.0 2.0 0.0 ns No antigen Peptide (I-Ab) PepTivator Ovalbumin IFN-γ level (ng/mL) Results ns 3.0 no antigen IL-2 level (ng/mL) Evaluation of DC-induced immune responses in a mouse model On day 11, serum from three mice was examined for the presence of OVA-specific IgG by ELISA. Moreover, the numbers of OVAspecific CD8+ cytotoxic T cells were determined by flow cytometry. To this end, resected tumors were dissociated into single-cell suspensions by treatment with collagenase. Subsequently, cells were analyzed by flow cytometry for H-2Kb OVA tetramer+CD8+ T cells. Cell numbers were normalized to the weight of tumors to allow for direct comparison of the individual mice. 5.0 4.0 0.0 IFN-γ level (ng/mL) After 4 days, the mice were injected with 3×10⁵ DCs that were either left untreated or pulsed with PepTivator Ovalbumin or MHCII (I-Ab)restricted or MHCI (H-2Kb)-restricted OVA peptides or both peptides in combination. The tumor volume was measured with a micrometer calliper at various time points until day 14. On day 14, six mice were sacrificed to measure tumor size by weight. OT-I CD8+ T cells 6.0 T cell number (×10⁵) Assessment of antitumor effects of DCs in a mouse model of lymphoma The timeline for tumor induction, immunization with DCs, and evaluation of antitumor effects by DCs is outlined in figure 1. Tumors were induced in C57BL/6 mice on day 0 by subcutaneously injecting 5×10⁵ E.G7-OVA tumor cells. E.G7-OVA cells are derivatives of EL4 mouse lymphoma cells modified to express and secrete OVA constitutively. Therefore, these cells can be recognized by pulsed DCs. OT-II CD4+ T cells 6.0 T cell number (×10⁵) count beads. Moreover, proliferation of T cells was analyzed on day 3 by a CFSE dilution assay. On day 2, concentrations of IL-2 and IFN-γ in the culture supernatants were measured by ELISA. 25.0 ns 20.0 15.0 10.0 5.0 0.0 No antigen Peptide (H-2K b) PepTivator Ovalbumin Figure 2 Capacity of DCs to induce T cell proliferation and secretion of proinflammatory cytokines. DCs loaded with PepTivator Ovalbumin or the MHCII (I-Ab)– or MHCI (H-2Kb)–restricted OVA peptides were cocultured with isolated CD4+ or CD8+ T cells on day 0. T cell numbers were determined by flow cytometry at various time points (A; n = 3; means±SD; Student’s t-test; ns: non-significant at p ≥ 0.05). On day 3, T cell proliferation was assessed by flow cytometric CFSE dilution assay (B). Concentrations of IL-2 and IFN-γ in the supernatant of the coculture were determined on day 2 (C; n = 3; means±SD; Student’s t-test; ns: non-significant at p ≥ 0.05). miltenyibiotec.com REPORT A Tumor volume (mm³) 3000 2000 * 1000 * * 0 4 6 8 10 12 Time after tumor inoculation (days) No antigen Peptide (I-Ab) 14 Peptide (H-2K b) Peptide (I-Ab + H-2K b) PepTivator Ovalbumin Tumor weight (mg) B 3000 * 2000 * * * 1000 0 No antigen Peptide (I-Ab) Peptide (H-2K b) Peptide (I-Ab + H-2K b) PepTivator Ovalbumin Figure 3 Inhibition of tumor growth by OVA-pulsed DCs. C57BL/6 mice were injected with E.G7 cells on day 0. (A) Tumor volume was measured with a micrometer calliper at various time points after immunization with DCs that were loaded with PepTivator Ovalbumin or the MHCII (I-Ab)– and/or MHCI (H-2Kb)– restricted OVA peptides. (B) At day 14 after injection of tumor cells, i.e., day 10 after DC immunization, mice were sacrificed and the tumor size was measured in weight. (A and B; n = 6; means±SD; Student’s t-test; ns: non-significant at p ≥ 0.05; *p < 0.05. DCs loaded with PepTivator Ovalbumin induced an increase in the numbers of both CD4+ and CD8+ T cells from day 2 onward, similarly to the respective MHCII or MHCIrestricted peptides. DCs that were not loaded with any antigen did not induce T cell proliferation (fig. 2A). T cell proliferation was confirmed with the CFSE dilution assay on day 3 (fig. 2B). Likewise, DCs loaded with PepTivator Ovalbumin or the MHCI- or MHCII-restricted OVA peptides induced the secretion of IL-2 and IFN-γ, in contrast to DCs that were not loaded with antigen. Cytokine secretion was measured on day 2 (fig. 2C). miltenyibiotec.com OVA peptide–pulsed DCs inhibit tumor growth in vivo in a mouse model of lymphoma Cells from the OVA-expressing mouse lymphoma cell line E.G7 were injected into C57BL/6 mice on day 0 to induce tumor growth (fig. 3A). After four days the mice were immunized by injection of DCs pulsed with PepTivator Ovalbumin or the MHCI- or MHCII-restricted OVA peptides, or both OVA peptides in combination. As a negative control, mice were injected with untreated DCs. Six days after immunization the DCs pulsed with OVA antigen already caused a slight decrease in tumor size compared to the negative control (fig. 3A). Ten days after immunization there was a significant decrease in tumor volume with all pulsed DCs. DCs pulsed with PepTivator Ovalbumin or the two MHCIand MHCII-restricted OVA peptides led to the largest reduction in tumor size by about 90%, followed by the MHCI-restricted peptide (80% reduction). The inhibitory effect of DCs pulsed with the MHCII-restricted peptide was the smallest, leading to a reduction in tumor size by about 50% (fig. 3A). Similar results were obtained for the tumor weight ten days after immunization (fig. 3B). OVA peptide–pulsed DCs induce immune responses in a mouse model of lymphoma The tumors induced by injection of E.G7 cells were also analyzed for OVA-specific cytotoxic CD8+ T cells (CTLs) with a tetramer assay (fig. 4A). The numbers of CTLs were normalized to the tumor weight, which allows for the direct comparison of the individual mice. DCs pulsed with PepTivator Ovalbumin or the combination of both MHCI- and MHCIIrestricted peptides led to the highest relative numbers of OVA-specific CTLs, whereas the MHCI-restricted peptide resulted in a significantly lower number of OVA-specific CTLs. No OVA-specific CTLs were detectable in tumors from mice treated with control DCs or DCs pulsed with the MHCII-restricted peptide (fig. 4A). We also analyzed the relative titers of OVAspecific IgG in the serum. The results were similar to the results from CTL enumeration, except that DCs pulsed with the MHCIIrestricted peptide also induced IgG production, just like the MHCI-restricted peptide (fig. 4B). Conclusion •PepTivator Ovalbumin–pulsed DCs induced both CD4+ and CD8+ T cell responses in vitro, similar to the MHCII- and MHCIrestricted peptides. • Immunization of mice bearing OVAexpressing tumors with DCs that were previously pulsed with PepTivator Ovalbumin or the MHCI-restricted peptide led to infiltration of OVA-specific CD8+ CTLs into the tumor. In contrast, no CTLs were detectable in the tumors from mice that were treated with DCs pulsed with the MHCII-restricted peptide. This directly reflects the greater inhibition of tumor Vol 17 • 1/2016 MACS & more 9 REPORT Number of intratumor CTLs per mg of tumor A 150 ns 100 ** 50 0 B * * ns Peptide (I-Ab) No antigen Peptide (H-2K b) Peptide (I-Ab + H-2K b) 0.8 ** 0.6 OD 450 PepTivator Ovalbumin ** 0.4 * ns ** 0.2 0.0 No antigen Peptide (I-Ab) Peptide (H-2K b) Peptide (I-Ab + H-2K b) PepTivator Ovalbumin Figure 4 Infiltration of CTLs into tumors and production of OVA-specific IgG by DCs pulsed with OVA peptides. C57BL/6 mice were injected with E.G7 cells on day 0. On day 11, i.e., 7 days after immunization, single-cell suspensions prepared from tumor tissue were analyzed for OVA-specific CTLs by a flow cytometric tetramer assay (A) and the serum was tested for OVA-specific IgG by ELISA (B). CTL numbers were normalized to tumor weight. n = 3; means ± SD; Student’s t-test; ns: non-significant at p ≥ 0.05; *0.01 ≤ p < 0.05; **p < 0.01. growth by the DCs pulsed with PepTivator Ovalbumin or the MHCI-restricted peptide. •PepTivator Ovalbumin–pulsed DCs could induce OVA-specific CD4+ T cell response in vivo, which resulted in the efficient production of OVA-specific IgG. •PepTivator Ovalbumin–pulsed DCs could induce both MHCII- and MHCI-restricted T cell responses in vivo. Therefore, antitumor effect and OVA-specific CTL induction by PepTivator Ovalbumin–pulsed DCs were stronger compared to MHCI- or MHCIIrestricted peptide-pulsed DCs. • Responses elicited by PepTivator Ovalbumin-pulsed DCs may be not restricted to MHCI or MHCII. 10 MACS & more Vol 17 • 1/2016 MACS Product Order no. PepTivator Ovalbumin – research grade* 130-099-771 CD4+ T Cell Isolation Kit, mouse 130-104-454 CD8a T Cell Isolation Kit, mouse 130-104-075 Mouse GM-CSF – premium grade 130-095-739** Mouse IL-4 – premium grade 130-097-759** + * For additional PepTivator Peptide Pools, visit www.miltenyibiotec.com/peptivator ** Order numbers are provided for 100 μg sizes. For different quality grades and additional package sizes, visit www.miltenyibiotec.com/cytokines Unless otherwise specifically indicated, Miltenyi Biotec products and services are for research use only and not for therapeutic or diagnostic use. miltenyibiotec.com REPORT Detection, enrichment, and direct phenotypic and functional characterization of antigen-specific naive and memory T cell subsets Petra Bacher and Alexander Scheffold Department of Cellular Immunology, Clinic for Rheumatology and Clinical Immunology, Charité – University Medicine Berlin, Berlin, Germany Introduction Infection-related mortality is a considerable clinical challenge in immunocompromised individuals, e.g., after hematopoietic stem cell transplantation or chemotherapy. Pathogenspecific T cells are crucial mediators of immune protection as shown for example by adoptive transfer of antigen-specific T cells. However, for both predicting or diagnosing infectious complications as well as for the development of effective therapies it is crucial to have reliable methods to phenotypically and functionally characterize the antigen-specific T cells. In general, multicolor flow cytometry is a robust technique to enumerate and characterize cells according to a multitude of parameters simultaneously. However, antigen-specific T cells are very rare in the naive compartment of peripheral blood (0.2–60 cells/10⁶ naive T cells; ref. 1 and references therein), and even in the memory compartment their proportion is well below 1%¹. Therefore, the number of naive antigenspecific T cells, for example, is too low for the direct ex vivo characterization by conventional flow cytometry. To overcome these limitations, we developed a straightforward method for the fast and specific antigen-reactive T cell enrichment (ARTE) based on MACS® Technology. This technique greatly increases the sensitivity of detection in flow cytometry, and enables the comprehensive analysis of extremely rare T cell subsets.² The method is based on the immunomagnetic enrichment of activated CD154+ or CD137+ cells. For the detailed flow cytometric analysis of the enriched antigen-specific T cells, we designed comprehensive panels of fluorochromeconjugated antibodies and gating strategies. CD154 (CD40L) is expressed specifically on all antigen-activated conventional CD4+ T cells upon TCR stimulation.³ We detected CD154+ cells after stimulation of PBMCs from healthy individuals with antigens from Aspergillus fumigatus, Candida albicans, cytomegalovirus (CMV), and adenovirus (AdV) and with tetanus toxoid. For cell enrichment and detailed characterization, we focused on A. fumigatus–specific T cells as an example. Regulatory T (Treg) cells contribute to maintaining the balance between pro- and antiinflammatory immune responses. We showed recently that A. fumigatus causes a robust Treg cell response in vivo⁴, counteracting inappropriately strong immune responses in healthy individuals. Six hours after stimulation with antigen, Treg cells express CD137.⁵ Using the ARTE technique to enrich CD137+ and CD154+ cells from PBMCs stimulated with A. fumigatus lysate in vitro, we were able to simultaneously identify CD137–CD154+ conventional (Tcon) T cells and CD137+CD154– Treg cells. ARTE in combination with multicolor flow cytometry will be a valuable tool for sensitive monitoring of antigen-specific Naive T cell subsets Memory T cell subsets Cytokine-producing T cells (panel 1) Cytokine-producing T cells (panel 2) CD154+ Tcon and CD137+ Treg cells CD8/14/20-VioGreen™ CD8/14/20-VioGreen CD8/14/20-VioGreen CD8/14/20-VioGreen CD8/14/20-VioGreen CD4-APC-Vio® 770 CD4-APC-Vio 770 CD4-APC-Vio 770 CD4-APC-Vio 770 CD4-APC-Vio 770 CD154-VioBlue® CD154-VioBlue CD154-VioBlue CD154-VioBlue CD154-PE-Vio 770 CD45RO-PE-Vio 770 CD45RO-PE-Vio 770 CD45RO-PE-Vio 770 CD45RO-PE-Vio 770 CD25-Brilliant Violet 421 CD197 (CCR7)-FITC CD197 (CCR7)-FITC Anti-TNF-α-FITC Anti-IL-17-FITC CD137-PE CD45RA-APC CD27-APC Anti-IL-10-APC Anti-IL-5-APC Anti-FoxP3-APC CD31-PE CD95-PE Anti-IFN-γ-PE Anti-IL-4-PE Anti-Helios-FITC Table 1: Antibody panels for the analysis of naive/memory T cell subsets, cytokine-producing T cells, as well as CD154 Tcon and CD137+ Treg cells. Tandem Signal Enhancer was added to all panels. + miltenyibiotec.com Vol 17 • 1/2016 MACS & more 11 REPORT A. fumigatus 0.00% 0.11% C. albicans CD154-PE 0.17% CD154-PE CD154-PE w/o antigen AdV CMV Tetanus CD154-PE 0.06% CD154-PE 0.03% CD154-PE 0.64% Enrichment of CD154+ and CD137+ antigenspecific T cells After stimulation, the antigen-specific cells were isolated using the CD154 MicroBead Kit alone or in combination with the CD137 MicroBead Kit (both from Miltenyi Biotec) according to the manufacturer’s instructions. Briefly, cells were magnetically labeled with CD154-Biotin/Anti-Biotin MicroBeads or CD137-PE/Anti-PE MicroBeads and isolated using two sequential MS Columns.² CD4-APC-Vio 770 Figure 1: CD154 is a reliable marker for the detection of antigen-specific CD4+ T cells. PBMCs from healthy donors were stimulated with A. fumigatus or C. albicans lysates, CMV or AdV peptide pools, or tetanus toxoid for 7 h. CD154+ expression was analyzed by flow cytometry. Numbers indicate the frequencies of antigen-reactive CD154+ cells among CD4+ T cells. Data originally published in: Bacher et al. (2013) J. Immunol. 190: 3967–3976. Copyright © 2013 The American Association of Immunologists, Inc. 12 MACS & more Vol 17 • 1/2016 CD154-VioBlue Material and methods Stimulation of antigen-specific T cells PBMCs were prepared by density gradient centrifugation from blood obtained from healthy donors. All donors gave their informed consent. PBMCs (1–2×10⁷ cells) from healthy volunteers were stimulated for 7 h in RPMI 1640, supplemented with 5% AB serum, with the following antigens: A. fumigatus lysate (40 μg/mL, Miltenyi Biotec), C. albicans lysate (20 μg/mL, Greer Laboratories), PepTivator® CMV pp65, PepTivator AdV5 Hexon (0.6 nmol/mL; both from Miltenyi Biotec), or tetanus toxoid (10 μg/mL; Statens Serum Institute) in the presence of CD40 pure – functional grade and CD28 pure – functional grade antibodies (1 μg/mL each; both from Miltenyi Biotec). For some experiments, cells were stained intracellularly with anti-cytokine antibodies. In this case, 1 μg/mL of brefeldin A was added to the cells for the last two hours of stimulation.² No enrichment w/o antigen 0.02% 20 A. fumigatus 0.00% 0 0.06% 70 0.04% 46 Anti-TNF-α-PE-Vio 770 Enriched fraction w/o antigen CD154-VioBlue T cells in various important immune-mediated diseases, such as autoimmunity, inflammatory bowel disease, allergy, and tumor immunology as well as for the development of specific immunotherapies. Cell staining and flow cytometry Cells were stained for multiparametric flow cytometry with different panels of fluorochrome-conjugated antibodies (table 1), depending on the subset to be analyzed. All antibodies were from Miltenyi Biotec except CD25-Brilliant Violet™ 421 (BioLegend®). For flow cytometry analysis of cytokinesecreting antigen-specific T cells, the stimulated cells were labeled fluorescently during the enrichment procedure: Cells labeled with MACS MicroBeads were applied to the first MS Column and subsequently stained 5.03% 71 1.22% 18 A. fumigatus 14.4% 821 48.9% 2791 Anti-TNF-α-PE-Vio 770 Figure 2: Enrichment of CD154+ cells allows for highly sensitive enumeration and characterization of rare antigen-specific CD4+ T cells. PBMCs from a healthy donor were stimulated with A. fumigatus lysate or left unstimulated. CD154 expression was assessed among CD4+ T cells without prior enrichment (upper plots) and after CD154+ cell enrichment (lower plots). Bold numbers indicate the total count of CD154+ cells after acquiring 4×10⁵ PBMCs (upper plots) or the enriched fraction obtained from 1.5×10⁷ PBMCs (lower plots). miltenyibiotec.com REPORT CD45RO-PE-Vio 770 22.3% 61.9% CD197 (CCR7)-FITC 31.2% 22.7% RTE CD31-PE Gated on CD45RO– CCR7+ 15.2% Tcm 54.7% Tn 0.2% Tscm CD95-PE 4.7% Tem CD197 (CCR7)-FITC Figure 3: Characterization of naive and memory T cell subsets. A. fumigatus–specific CD154+ T cells were enriched as described and counterstained for phenotypic markers to discriminate between naive and memory T cell subsets. Percentages of the respective cell subsets among all reactive CD154+ T cells are shown. RTE: recent thymic emigrants; CD31– naive cells: peripheral circulating naive T cells; Tn: naive T cells; Tscm: stem cell memory T cells; Tcm: central memory T cells; Tem: effector memory T cells Phenotypic characterization of antigenspecific naive and memory subsets To further dissect the enriched CD154 + A. fumigatus–specific T cell population by flow cytometry, we designed two antibody panels (see material and methods section). The gating Highly sensitive enumeration and strategy illustrated in figure 3 allowed us to characterization of rare antigen-specific easily distinguish naive from memory T cells. CD4+ T cell subsets To enable the sensitive analysis of rare antigen- Moreover, we were able to determine the specific T cell subsets by flow cytometry, we proportions of recent thymic emigrants (RTE, magnetically enriched the activated CD154+ 22.7% of CD154+ cells), peripheral circulating cells after stimulation with A. fumigatus lysate. naive T cells (31.2%), stem cell memory T cells In the example shown in figure 2, only about (Tscm; 0.2%), central memory T cells (Tcm; 120 CD154+ cells were detected after acquiring 15.2%), and effector memory T cells (Tem; 4×10⁵ PBMCs. In contrast, after enrichment 4.7%). These data show that the possibility of of CD154+ cells from 1.5×10⁷ PBMCs and measuring a large number of rare target cells acquisition of the entire positive fraction, more pre-enriched from a large blood sample greatly than 3,600 CD154+ cells were detected among improves the significance of the multiparameter only approx. 5×10⁴ total events, whereas approach, permitting identification of small background levels in the nonstimulated sample cell subsets at high resolution. Small subsets, remained low (<100 cells). These results such as Tscm, would not be detectable without indicate that enrichment of CD154+ T cells prior enrichment of the antigen-specific T cells. prior to flow cytometry greatly increases the signal-to-noise ratio for a sensitive analysis of antigen-specific T cell subsets. miltenyibiotec.com Gated on CD45RO+ CD27-APC Gated on CD45RO– CCR7+ CD197 (CCR7)-FITC Results Detection of antigen-specific CD4+CD154+ T cells The CD154 antigen is a reliable marker for the detection of activated antigen-specific T cells.³ We first determined the proportion of CD154+ T cells in PBMCs from healthy donors, upon stimulation with antigens from A. fumigatus, C. albicans, CMV, and AdV and with tetanus toxoid for 7 h. The percentage of the entire population of activated CD154+ cells among CD4+ cells could be determined reliably (range: 0.03%–0.64%; fig. 1). However, the total number of CD154+ cells in the samples was too low to characterize smaller subpopulations, such as naive and memory T cells, by flow cytometry. CD4 +CD154 + CD45RA-APC on the column with fluorochrome-conjugated antibodies. Cells were eluted for fixation (Inside Stain Kit, Miltenyi Biotec) and subsequently applied to the second MS Column, where they were permeabilized (Inside Stain Kit, Miltenyi Biotec). Intracellular cytokines were stained while the cells were still on the column. The transcription factors FoxP3 and Helios were stained using the respective antibodies in combination with the FoxP3 Staining Buffer Set (Miltenyi Biotec). After elution from the second column, the cells were analyzed by flow cytometry on a MACSQuant® Analyzer 10 with the MACSQuantify™ Software (both from Miltenyi Biotec).² Characterization of cytokine production in antigen-specific naive and memory T cells The high resolution is also important for the analysis of cytokine-producing subsets. We compared the cytokine production capacity of the naive and memory T cell subsets by flow cytometry, based on two antibody panels (see material and methods section). These panels enabled us to determine the percentages of cell subsets producing TNF-α, IFN-γ, IL-10, IL-17, IL-4, or IL-5. In the example shown in figure 4, the majority (70.4%) of naive CD4+CD154+ T cells produced TNF-α, whereas effector cytokines were almost absent (<1%). Likewise, the majority (63.6%) of memory CD4+CD154+ T cells produced TNF-α. More than 10% of the memory subset produced IFN-γ, indicating the presence of Th1 cells. However, only small but still significant proportions of memory but not naive T cells produced IL-10, IL-17, or IL-4. Vol 17 • 1/2016 MACS & more 13 REPORT Gated on naive CD4 + T cells CD154-VioBlue 70.4% Anti-TNF-α-FITC 0.6% Anti-IFN-γ-PE 0.4% Anti-IL-10-APC 0.1% 0.1% Anti-IL-17-FITC 0.1% Anti-IL-4-PE Anti-IL-5-APC Gated on memory CD4 + T cells CD154-VioBlue 63.6% Anti-TNF-α-FITC 11.2% Anti-IFN-γ-PE 4.1% 2.7% Anti-IL-10-APC Anti-IL-17-FITC 3.4% 0.3% Anti-IL-4-PE Anti-IL-5-APC Figure 4: Characterization of cytokine production in antigen-specific naive and memory T cells. A. fumigatus-specific CD154+ T cells were enriched by ARTE and analyzed for cytokine expression within the antigen-specific naive and memory compartments. Cells were gated on CD4+ lymphocytes. Percentages of cytokineexpressing cells among CD154+ T cells are shown. 2665 1.1% Anti-FoxP3-APC 2404 1% 0.1% Anti- Helios-FITC CD137-PE 86.6% Anti-FoxP3-APC Anti-FoxP3-APC Gated on CD137+ T cells CD25-BV421 CD154-PE-Vio 770 Gated on CD4 + T cells Anti-FoxP3-APC CD25-BV421 Gated on CD154 + T cells 29.7% 56.9% Anti-Helios-FITC Gated on CD4 + T cells CD137-PE CD154-PE-Vio 770 Enrichment of CD154+ and CD137+ cells enables identification of antigen-specific Tcon and Treg cells in parallel Using the ARTE technique based on the expression of CD154 and CD137⁴,⁵, we were able to differentiate between CD137–CD154+ Tcon and CD137+CD154– Treg cells⁶. Almost all CD137+ cells co-expressed FoxP3, whereas FoxP3 expression was absent in CD154+ cells (fig. 5, lower dot plots). Around 90% of the CD137+ cells were positive for FoxP3 and CD25, and the majority of FoxP3+ cells coexpressed the transcription factor Helios. In contrast, CD154+ T cells had a conventional T cell phenotype (CD25 –FoxP3 –Helios –). These data are in line with our findings that A. fumigatus induces a significant Treg response in vivo⁴, which can control excessive immune responses, such as allergies. Anti-FoxP3-APC Anti-FoxP3-APC Figure 5: Combined enrichment of CD154+ and CD137+ cells enables parallel identification of antigenspecific Tcon and Treg cells. PBMCs were stimulated with A. fumigatus lysate and reactive CD154+ and CD137+ T cells were enriched by ARTE. Enriched CD154+ and CD137+ were counterstained for typical Treg cell markers CD25, FoxP3, and Helios. 14 MACS & more Vol 17 • 1/2016 miltenyibiotec.com REPORT Conclusion • Enrichment of antigen-reactive T cells, based on MACS Technology, enhances the signal-to-noise ratio for sensitive multicolor flow cytometry. •The collection of large numbers of rare target cells following magnetic preenrichment greatly improves the resolution of downstream multiparameter flow cytometric analyses. • C omprehensive panels of MACS Antibodies enable the detailed phenotypic characterization of the enriched antigenspecific CD154+ T cells for the distinction between naive and memory T cell subsets as well as the analysis of cytokine production in naive and memory T cells. •The parallel enrichment of CD137+ and CD154+ cells and a specific antibody panel allow for the characterization of CD137– CD154+ Tcon cells and CD137+CD154– Treg cells. References 1. Bacher, P. and Scheffold, A. (2013) Cytometry A 83: 692–701. 2. Bacher, P. et al. (2013) J. Immunol. 190: 3967–3976. 3. Frentsch, M. et al. (2005) Nat. Med. 11: 1118–1124. 4. Bacher, P. et al. (2014) Mucosal Immunol. 7: 916–928. 5. Schoenbrunn, A. et al. (2012) J. Immunol. 189: 5985–5994. 6. Bacher, P. et al. (2014) J. Immunol. 193: 3332–3343. MACS Pr oduct Order no. Cell isolation CD154 MicroBead Kit, human 130-092-658 CD137 MicroBead Kit, human 130-093-476 Cell culture and stimulation A. fumigatus Lysate 130-098-170 PepTivator CMV pp65, human 130-093-435 PepTivator AdV5 Hexon 130-093-496 CD28 pure – functional grade, human 130-093-375 CD40 pure – functional grade, human 130-094-133 Flow cytometry MACSQuant Analyzer 10 130-096-343 MACSQuantify Software 130-094-556 Anti-FoxP3-APC, human and mouse (clone: 3G3) 130-093-013 Anti-Helios-FITC, human and mouse (clone: 22F6) 130-104-000 Anti-IFN-γ-PE (clone: 45-15) 130-091-653 Anti-IL-4-PE (clone: 7A3-3) 130-091-647 Anti-IL-5-APC (clone: JES1-39D10) 130-091-834 Anti-IL-10-APC (clone: JES3-9D7) 130-096-042 Anti-IL-17-FITC (clone: CZ8-23G1) 130-094-520 Anti-TNF-α-FITC (clone: cA2) 130-091-650 CD4-APC-Vio 770 (clone: VIT4) 130-096-652 CD8-VioGreen (clone: BW135/80) 130-096-902 CD14-VioGreen (clone: TÜK4) 130-096-875 CD20-VioGreen (clone: LT20) 130-096-904 CD27-APC (clone: LG.3A10) 130-097-218 CD31-PE (clone: AC128) 130-092-653 CD45RA-APC (clone: T6D11) 130-092-249 CD45RO-PE-Vio 770 (clone: UCHL1) 130-096-739 CD95-PE (clone: DX2) 130-092-416 CD137-PE (clone: 4B4-1) 130-093-475 CD154-VioBlue (clone: 5C8) 130-096-217 CD154-PE-Vio 770 (clone: 5C8) 130-096-793 CD197 (CCR7)-FITC, human (clone: REA108) 130-099-172 FoxP3 Staining Buffer Set 130-093-142 Inside Stain Kit 130-090-477 Tandem Signal Enhancer, human 130-099-888 Unless otherwise specifically indicated, Miltenyi Biotec products and services are for research use only and not for therapeutic or diagnostic use. miltenyibiotec.com Vol 17 • 1/2016 MACS & more 15 gentleMACS™ Octo Dissociator with Heaters Start smart with automated tissue dissociation Multiple sample processing Dissociation or homogenization of up to eight samples in one go, controlled independently Walk-away tissue dissociation Integrated heaters for on-instrument enzymatic incubation Flexibility Applicable to virtually any tissue using pre-set or user-defined programs Reliability Fully automated, standardized procedures for highly reproducible results Time-saving Minimal hands-on time, short procedures Safety Sample processing in a closed, sterile system miltenyibiotec.com/gentlemacs Unless otherwise specifically indicated, Miltenyi Biotec products and services are for research use only and not for therapeutic or diagnostic use. REPORT Evaluation of metastatic burden and recovery of human metastatic cells from a mouse model Lorena Landuzzi¹, Arianna Palladini², Marianna Lucia Ianzano², Roberta Laranga², Giulia D’Intino³, Patrizia Nanni², and Pierluigi Lollini² ¹ Laboratory of Experimental Oncology, Rizzoli Orthopedic Institute, Bologna, Italy ² Laboratory of Immunology and Biology of Metastasis, Department of Experimental, Diagnostic, and Specialty Medicine, University of Bologna, Bologna, Italy ³ Miltenyi Biotec S.r.l., Calderara di Reno, Bologna, Italy Here we used the Mouse Cell Depletion Kit (human breast carcinoma cell line expressing Introduction Metastatic dissemination is the major cause (Miltenyi Biotec) to enrich and quantify enhanced green fluorescent protein, EGFP)1 of death in cancer. Xenotransplantation of metastatic human cells, derived from human were added. The brain tissues, spiked with tumor tissue into immunodeficient mice is a breast carcinoma, in a model of brain different amounts of MDA-MB-453 EGFP widespread preclinical technique to study tumor metastases1 in NOD scid gamma (NOD.Cg- cells, were dissociated enzymatically and mechanically into single-cell suspensions, development. However, preclinical studies on the Prkdc scid Il2rg tm1Wjl/SzJ, NSG) mice. using the Tumor Dissociation Kit, human spreading of metastases were so far hampered (5 mL/sample) and the gentleMACS™ Octo by the poor dissemination of malignant human Material and methods Dissociator with Heaters (both from Miltenyi tumors in conventional immunodeficient hosts, Ethics statement like the nude mouse. The development of highly All animal experiments were performed Biotec) with program “37_h_TDK_1”. After immunodeficient knockout mice spurred a according to the European directive dissociation each sample was passed through new wave of metastatic model systems. It was 2010/63/UE and Italian law (DLGS 26/2014). a MACS® SmartStrainer (pore size 70 μm) and recently shown that human HER-2-positive Experimental protocols were reviewed and split into two equal portions, one of which was breast cancer cells, which do not metastasize approved by the Institutional Animal Care and used for flow cytometry analysis. The other half in nude mice, when implanted in knockout Use Committee (“Comitato Etico Scientifico was subjected to treatment with the Mouse Cell mice with severe immunodeficiency, give rise per la Sperimentazione Animale”) of the Depletion Kit from Miltenyi Biotec (20 µL of to multiorgan metastatic patterns resembling University of Bologna, and forwarded to the MicroBeads per sample), which enables the immunomagnetic removal of mouse cells from those observed in human patients1. The growth Italian Ministry of Health. the cell suspension. Subsequently, the samples of metastatic nodules in a variety of locations, including brain, lungs, liver, kidneys, adrenals, Recovery of human tumor cells spiked into were counted in a Neubauer hemocytometer under a fluorescence microscope and used ovaries, and bone marrow, opens up the problem dissected mouse brain tissue of quantifying metastatic burden and recovering Mouse brain was cut into small pieces and split for flow cytometry analysis. HER-2 detection human metastatic cells from mouse organs2 into four equal portions. To each portion, 0 or was performed by means of the PE-antifor cellular and molecular studies in vitro. 0.5×10⁶ or 1×10⁶ MDA-MB-453 EGFP cells huHER-2 monoclonal antibody, clone Neu 24.7 (BD® Biosciences). Mouse tissue Number of MDA-MB-453 EGFP cells added Number of human EGFP+ tumor cells after dissociation and depletion of mouse cells Brain (one eighth) 0.5×10⁶ 0.315×10⁶ (recovery 63%) Brain (one eighth) 0.25×10⁶ 0.165×10⁶ (recovery 66%) Table 1: Recovery of MDA-MB-453 EGFP cells added to dissected mouse brain. MDA-MB-453 cells were added to dissected brain in the indicated proportions. Subsequently, the mixtures were dissociated, and the resulting cell suspensions were depleted of mouse cells. Numbers of EGFP+ human tumor cells were determined microscopically. The recovery of EGFP+ cells (percentage in relation to input cells) is indicated in parentheses. miltenyibiotec.com Induction of metastases in the mouse model For the induction of metastasis 2×10⁶ MDAMB-453 EGFP cells were injected i.v. into two NSG mice1. After approximately 2 months the mice were sacrificed and subjected to accurate necropsy1. The whole mice were analyzed by fluorescence imaging for the presence of EGFP+ cells1. Vol 17 • 1/2016 MACS & more 17 REPORT A 18 MACS & more Vol 17 • 1/2016 RelativeEvents cell number Relative cell number Events MDA-MB-453 EGFP cells only, before mixing Brain + MDA-MB-453 EGFP cells, after dissociation D Brain + MDA-MB-453 EGFP cells, after dissociation and depletion RelativeEvents cell number C 5% human EGFP+ cells FL1 EGFP 74% human EGFP+ cells FL1 EGFP 100% human HER-2+ cells HER-2 HER-2PE F Brain + MDA-MB-453 EGFP cells, after dissociation and depletion RelativeEvents cell number MDA-MB-453 EGFP cells only, before mixing Relative cell number Events E 100% human EGFP+ cells FL1 EGFP FL1 EGFP Results Effective separation of human tumor cells from mouse brain suspensions Xenotransplantation of human tumor tissue is a powerful technique to mimic tumors in mouse models. The tumor-bearing tissue is dissected and the xenograft-derived cells can be analyzed on a cellular or molecular level3-⁵. However, contaminating mouse cells can severely hamper the analysis. In order to avoid erroneous results, it is therefore highly desirable to purify the human cells prior to analysis. We used the Tumor Dissociation Kit, human and the gentleMACS Octo Dissociator with Heaters to dissociate mouse brain tissue with disseminated human tumor cells. The Mouse Cell Depletion Kit was used to enrich the human cells subsequently. In a first experiment, we tested whether the experimental setup would enable us to reenrich EGFP-expressing human tumor cells that were spiked into dissected mouse brain. The purity of EGFP+ cells after depletion of mouse cells amounted to 74% (fig. 1D). Usually, more than 60% of the input tumor cells were recovered (table 1), indicating that the system should also enable us to recover xenografts from mouse models. We also took the opportunity to analyze the surface expression of HER-2, the characteristical oncogene/antigene of these breast cancer cells⁴. Comparison of panels E and F in figure 1 shows that HER-2 expression and detection were not altered by enzymatic/ mechanical tissue dissociation and mouse cell depletion. B Brain only, before mixing RelativeEvents cell number Recovery of human tumor cells from disseminated metastases in mouse brain The brains were dissected and subsequently dissociated using the Tumor Dissociation Kit, human (5 mL/sample) and the gentleMACS Octo Dissociator with Heaters (program “37_h_TDK_1”). After dissociation each sample was split into two portions. One fifth of the brain was used for cell counting and flow cytometry1, and 4/5 of the brain were subjected to treatment with the Mouse Cell Depletion Kit (100 µL of MicroBeads per brain sample). After the depletion of mouse cells, the samples were counted in a Neubauer hemocytometer under a fluorescence microscope and used for flow cytometry analysis. 74% human HER-2+ cells HER-2 PE HER-2 Figure 1: Recovery of MDA-MB-453 EGFP cells added to dissected mouse brain tissue. Flow cytometry analysis of cell suspensions of dissociated brain tissue alone (A), MDA-MB-453 EGFP cells alone (B), mixtures of brain tissue (one eighth of total brain) and 0.5×10⁶ MDA-MB-453 EGFP cells after dissociation (C) and after depletion of mouse cells (D). HER-2 expression in MDA-MB-453 cells before mixing (E) and after mixing with mouse brain tissue followed by dissociation and mouse cell depletion (F). Numbers indicate the percentage of EGFP+ cells and HER-2+ cells. In panel E, the open profile represents MDA-MB-453 cells incubated with PE-control isotype antibody. Mouse tissue Number of human EGFP+ tumor cells after tissue dissociation Number of human EGFP+ tumor cells after dissociation and depletion of mouse cells Brain metastases (mouse 1) 9.64×10⁶ 5.9×10⁶ (recovery: 61%) Brain metastases (mouse 2) 11.24×10⁶ 6.94×10⁶ (recovery: 61%) Table 2: Recovery of human metastatic cells from dissociated mouse brains. Dissected mouse brains were dissociated into single-cell suspensions and subsequently depleted of mouse cells. Numbers of EGFP+ human tumor cells were determined microscopically after each procedure The recovery of EGFP+ cells after depletion, i.e., the percentage in relation to EGFP+ cells present before depletion, is indicated in parentheses. miltenyibiotec.com REPORT A Mouse 1, brain after dissociation Relative cell number Events Side scatter Side scatter 256 0 0 Forward scatter 21% human EGFP+ cells FL1 256 EGFP FSC Mouse 2, brain after dissociation Relative cell number Events Side scatter Side scatter 256 0 0 Forward scatter 256 Conclusion 17% human EGFP+ cells FL1 EGFP FSC B Mouse 1, brain after dissociation and mouse cell depletion Relative cell number Events Side scatter Side scatter 256 250 0 0 Forward scatter 256 84% human EGFP+ cells FL1 EGFP FSC Mouse 2, brain after dissociation and mouse cell depletion Relative cell number Events Side scatter Side scatter 256 0 0 Forward scatter 256 92% human EGFP+ cells FL1 EGFP FSC Figure 2: Flow cytometry analysis of EGFP+ tumor cells in cell suspensions from two metastasesbearing mouse brains. After dissection the metastases-bearing brains were enzymatically and mechanically dissociated, and the resulting cell suspensions were depleted of mouse cells. Cells were analyzed after tissue dissociation (A) and after mouse cell depletion (B). Forward scatter and side scatter plots of each sample are shown with gates used to analyze the percentage of EGFP+ cells. Histograms show the percentage of EGFP+ human tumor cells. miltenyibiotec.com Recovery of human metastatic cells from mouse brain metastases We used i.v. injection of MDA-MB-453 EGFP cells into NSG mice to induce metastases1. After approximately 2 months, heavy metastatic burden was observed in the brains of the NSG mice. Using the same basic experimental setup as above, we were able to enrich the human tumor cells effectively. Cells derived from metastases in the brain were enriched to a purity of 84–92% (fig. 2B). The recovery of tumor cells, i.e., the percentage in relation to tumor cells present before depletion of mouse cells, was greater than 60% (table 2) and proportional to the tumor cell burden in the brain. The combination of enzymatic and mechanical tumor dissociation and subsequent depletion of mouse cells enabled us to both quantitate and enrich human tumor cells from brain metastases grown in immunodeficient mice. This is a promising system particularly for the quantification of the metastatic burden in the brain and other organs of mice bearing human tumors. Simultaneously, the human metastatic cells can be enriched for in vitro studies by removing mouse cells. This could be of interest to all researchers involved in the preclinical development of new antimetastatic drugs. References 1. Nanni, P. et al. (2012) PLoS One. 7: e39626. 2. Nanni, P. et al. (2010) Eur. J. Cancer 46: 659–668. 3. De Giovanni, C. et al. (2012) Br. J. Cancer 107: 1302–1309. 4. Menotti, L. et al. (2009) Proc. Natl. Acad. Sci. USA 106: 9039–9044. 5. Nanni, P. et al. (2013) PLoS Pathog. 9:e1003155. Acknowledgments M.L.I. and A.P. are in receipt of a Postdoctoral Fellowship from University of Bologna. R.L. is in receipt of a Ph.D. Fellowship from University of Bologna. The research of the authors is supported by the Italian Association for Cancer Research, AIRC, project n. 15324, Milan, Italy. MACS Product Order no. gentleMACS Octo Dissociator with Heaters 130-096-427 Tumor Dissociation Kit, human 130-095-929 Mouse Cell Depletion Kit 130-104-694 MACS SmartStrainers (70 μm) 130-098-462 Unless otherwise specifically indicated, Miltenyi Biotec products and services are for research use only and not for therapeutic or diagnostic use. Vol 17 • 1/2016 MACS & more 19 PERSPECTIVES Designing a dendritic cell–based therapy for primary liver cancer Stuart M. Curbishley, Miroslava Blahova, and David H. Adams University of Birmingham Medical School, National Institute for Health Research (NIHR) Birmingham Liver Biomedical Research Unit and Centre for Liver Research, Birmingham, UK Hepatocellular carcinoma – an introduction Hepatocellular carcinoma (HCC) is the most common primary hepatic tumour and one of the most prevalent cancers worldwide. It is especially common in Asia and Sub-Saharan Africa. Risk factors for its development worldwide include hepatitis B, hepatitis C, alcohol abuse, aflatoxin exposure, and metabolic liver disease. The incidence of HCC is rising, both in the United States and the United Kingdom, and is likely to be a reflection of the increased prevalence of cirrhosis from three main causes: hepatitis C, fatty liver disease, and alcoholic liver disease (ALD). It is therefore considered to become a major health burden in the UK in the coming years. Current treatment for HCC is limited and 5-year survival for all stages combined is less than 5%. At present, surgery (either tumour resection or liver transplantation) is the only potentially curative treatment for HCC. However, resection is only feasible in less than 10% of patients, as it requires small tumours, limited-stage disease, and good hepatic function. Hence, the majority of patients present with advanced disease that is deemed unresectable. The survival rate is relatively poor, even in those patients who undergo surgical resection, with high recurrence rates and a 5-year survival of about 30–60%. 20 MACS & more Vol 17 • 1/2016 of tumours of various types. For instance alphafetoprotein (AFP) is a serum marker for HCC. For patients with unresectable but localised HCC, local ablative therapy can remain an option. However, for those patients who are unsuitable for surgery or local ablation but with liver-confined disease, palliative benefit may be gained from transarterial chemoembolisation (TACE). Two randomised, controlled trials have shown that TACE performed with doxorubicin¹ or cisplatin² improves survival in selected patients compared to best supportive care. Even so, TACE remains palliative and disease progression is inevitable, such that combination with novel therapies is attractive. Since TACE may liberate an abundance of tumour antigens it may lend itself to combination with immunotherapeutic strategies. Proteins that are specifically or predominantly expressed by tumours are potential targets for immunotherapy. Standard vaccination strategies have had only limited success in stimulating anti-tumour immunity, leading to the use of adoptive therapy with T cells or dendritic cells (DCs) to stimulate more potent immune responses which selectively kill malignant cells expressing specific antigens. Tumour antigens expressed in varying degrees in HCC and thus potential targets for immunotherapy include AFP, MAGE-1 and 3, SSX-1 and 4, TSPY, NY-ESO-1, and Glypican-3.³–⁵ The immunotherapy of malignancy: antigens The immunotherapy of malignancy: DCs As immune-mediated mechanisms play an important role in controlling the growth of some types of cancer, immunotherapy could in theory exploit such responses to generate therapeutic immune responses against tumour antigens. Many tumours have altered gene regulation resulting in expression of specific tumour antigens or overexpression of other proteins. One such category is the cancer/testis antigens, a category of tumour antigens that are normally expressed in male germ cells but not in adult somatic tissues. In malignancy, this gene regulation is disrupted, resulting in cancer/testis antigen expression in a proportion DCs are potent antigen-presenting cells which exist in peripheral tissues where they take up and process antigens. Short peptide fragments of the antigens are then presented on the cell surface in association with the major histocompatibility complex (MHC). Signals released by infected or damaged tissues act through receptors on the DCs to promote their activation and maturation. Maturation is associated with expression of costimulatory molecules that allow the DCs to activate T cells and chemokine receptors that mediate DC migration from peripheral tissue into draining lymph nodes. In the lymph nodes DCs interact miltenyibiotec.com PERSPECTIVES with and activate T cells that recognise the presented epitopes, resulting in the generation of effector T cells that can mount antigenspecific anti-tumour immune responses. Following the demonstration that activated DCs were potent inducers of immune responses when adoptively transferred into animals, the development of techniques to generate large numbers of monocyte-derived DCs (Mo-DCs) from peripheral blood enabled DC-based immunotherapy to be tested in clinical trials. We previously conducted a clinical trial⁶ to assess the safety and efficacy of intravenous vaccination with mature Mo-DCs, pulsed ex vivo with a liver tumour cell line lysate (HepG2), in patients with advanced HCC. Furthermore, we have conducted tracking studies to assess the differential homing of MoDCs delivered intravenously or directly into the liver via the hepatic artery (manuscript in preparation). These studies demonstrated that autologous Mo-DC vaccination in patients with HCC is safe and well tolerated and that increased numbers of Mo-DCs can be retained in the liver when infused via the hepatic artery. Developing the next generation of Mo-DC vaccines in Birmingham Following the successful completion of our previous clinical trials involving Mo-DCs, we looked to develop a new study to extend our understanding of these vaccines in patients with HCC. This led to the development of the ImmunoTACE clinical trial (long title: A randomised phase II clinical trial of conditioning cyclophosphamide and chemoembolisation with or without vaccination with dendritic cells pulsed with HepG2 lysate ex vivo in patients with Hepatocellular Carcinoma; EUDRACT # 2011001690-62). This would combine the standardof-care TACE with a Mo-DC vaccination and the addition of preconditioning in all patients with cyclophosphamide, which at low doses has been shown to selectively deplete regulatory T cells and increase antigen-specific immune responses in patients with HCC⁷. Changes to the regulatory landscape between the closure of our first HCC Mo-DC trial and the development of ImmunoTACE saw the introduction of new guidelines concerning miltenyibiotec.com the manufacture of Advanced Therapeutic Medicinal Products (ATMP). In order to be compliant with these current regulations it was necessary for us to develop our manufacturing process into a “closed” system. Cell enrichment and culture process The initial phase of this work included the use of CD14 MicroBeads from Miltenyi Biotec to isolate monocytes from peripheral blood samples. The CliniMACS® System provides a GMP-compliant platform for the isolation of CD14 monocytes, typically from leukocyterich apheresis. Based around a single-use, closed tubing set, the relative cost of CD14+ cell enrichment using this method is expensive and clearly would not be cost effective when beginning a new process development. With this in mind, we chose to begin the definition of our manufacturing process using CD14+ monocytes that were enriched from single units of whole blood with Miltenyi Biotec’s autoMACS® Pro Separator and GMP-grade CliniMACS MicroBeads. The introduction of this automated step removed any operator bias in the preparation of the starting monocyte population before differentiation into Mo-DCs. As with many previous trials involving Mo-DCs, we chose to differentiate monocytes in the presence of GM-CSF and IL-4 (both 1,000 IU/mL). Here, we used premium-grade cytokines from Miltenyi Biotec which, whilst not certified as GMP grade, are prepared to the same standard and, importantly, are released with a lot-specific activity enabling us to ensure consistent dosing of cells in all experiments. The next stage of our process development required transfer of our cell culture from traditional multi-well plates into a closed bag system. We compared culture bags and media from several manufacturers and found little variability in the quality of Mo-DCs prepared in each. Further development runs were performed in DendriMACS™ GMP Medium (Miltenyi Biotec). Usually a limitation of bag culture vessels is the need for a relatively high medium volume and consequently the requirement of high initial cell numbers. As an alternative to single-chamber bag systems we performed our initial culture experiments in Miltenyi Biotec’s MACS GMP Cell Expansion Bags. These have the advantage of multiple chambers that can be used flexibly, according to the required medium volume. This enabled us to begin process development with a bag material that is easily scalable to the next level. The initial monocyte number was set to 3×10⁶ to account for medium additions on days 3 and 5. On day 6 of culture the resulting immature DCs were loaded with antigen (see below) and matured in the presence of the TLR4 ligand monophosphoryl lipid A (MPLA). This maturation step was chosen as the material is available as a cGMP product and a single maturation agent lends itself to a simpler process with fewer interventions and is more cost effective. Furthermore, we have previously demonstrated that maturation via TLR4 ligation leads to potent up-regulation of costimulatory molecules as well as the lymph node homing receptor CCR7. This final maturation and antigen-loading phase continued for 48 hours until Mo-DCs are released on day 8. Preparation of antigen The choice of antigen to be loaded onto Mo-DC vaccines has long been a source of much discussion because tumour antigens are often shared self-antigens and thus elicit a tolerogenic response. As our understanding of tolerance within the immune system increases, the combination of inhibitors of checkpoint molecules such as CTLA-4 and PD-1/PD-L1⁸,⁹ and perturbation of regulatory cells has led to a resurrection of host tumour as an antigen source. The ImmunoTACE clinical trial was developed ahead of these exciting new changes. For this reason, and for pragmatic reasons associated with access to host tumour, we decided to use a cancer cell line lysate as a source of antigen. In our case, the hepatoblastoma cell line HepG2 was chosen, partly due to our previous vaccine trial experience and because this cell line shares some antigens associated with HCC. Typically, preparation of lysates for clinical application makes use of repeated freeze/ thaw cycles to induce cell lysis. This method, whilst simple, often leads to low total protein yields and can result in residual whole-cell contamination. We again chose to make Vol 17 • 1/2016 MACS & more 21 PERSPECTIVES use of a frequently used tool in our research laboratory from the Miltenyi Biotec stable. We have used the gentleMACS™ Dissociator for many years to generate single-cell suspensions from whole tissue and to prepare material for molecular biology protocols. Here, we used gentleMACS M Tubes with the RNA_01.01 protocol to generate a lysate for clinical use. Briefly, HepG2 cells were harvested from Corning® CellStack® – 5 Chambers using a closed bag system (Macopharma) and cGMP trypsin substitute (TrypLE™ Select, Invitrogen™) before being washed in PBS and resuspended in normal saline supplemented with calcium and magnesium. Individually wrapped sterile gentleMACS M Tubes were taken into a grade A processing area and 7 mL of the HepG2 cell suspension (approx. 35×10⁶ cells) were added via injection through the septa to keep the process closed. The lids were then firmly closed and each tube processed on a gentleMACS Dissociator using protocol RNA_01.01, repeated 5 times. Following lysis, 500 IU DNAse I (Pulmozyme®, Roche) was added and the tubes incubated at 37 °C for 10 minutes. The lysate was then recovered using a long needle and syringe via the septa and transferred to a sterile bag and washed in normal saline. Following final resuspension in saline the lysate was aliquoted into 2 mL crimp-sealed vials and stored at –80 °C. A representative sample of the batch produced was removed and tested for sterility, endotoxin contamination, and presence of whole-cell contamination before being released for use in the clinical manufacturing process. Final release and cryopreservation Choosing a suitable assay to define the release of cell therapy products can be a complex process. Parameters such as viability, sterility, and presence of endotoxin can be measured using easily validated tests, whilst surface phenotype is a more complex proposition. In Birmingham, we have integrated a MACSQuant® Flow Cytometer into our ATMP manufacturing facility QC lab as a singleplatform cytometer for the enumeration and phenotypic analysis of monocytes and mature DCs. Following apheresis, total leukocyte count and percentage of monocytes are calculated using the MC CD14 Monocyte Cocktail and “Express mode” on the MACSQuant Analyzer 10 (fig. 1). This requires minimal operator input and gives a rapid determination of key parameters required for enrichment of CD14+ monocytes using the CliniMACS Platform. This same cocktail and protocol are used after enrichment to determine absolute monocyte count and purity before beginning differentiation in culture. Following differentiation of Mo-DC as described previously, an analysis of phenotype is made on day 6, prior to addition of antigen and MPLA. Specifically, we measure the Before separation 10³ Enriched CD14+ cells 10³ P1\P2\P3\P4 23.88% 10² CD14-PE CD14-PE 10² CD14-PE CD14-PE P1\P2\P3\P4 99.09% 10¹ 1 0 -1 -1 0 1 10¹ 10² CD45-VioBlue CD45-VioBlue 10³ 10¹ 1 0 -1 -1 0 1 10¹ 10² 10³ CD45-VioBlue CD45-VioBlue Figure 1 Enrichment of CD14+ monocytes. CD14+ monocytes were enriched from PBMCs using the CliniMACS System. The percentage of monocytes was calculated using the MC CD14 Monocyte Cocktail and “Express mode” on the MACSQuant Analyzer 10. 22 MACS & more Vol 17 • 1/2016 expression of HLA-DR, CD11c, CD86 and CD14 (fig. 2). Final release of the cells is performed on day 8 with samples taken for sterility testing, endotoxin contamination and repeat phenotypic analysis. Our release criteria stipulate an increase in expression of HLADR and CD86 on dual-positive cells between day 6 and day 8, consistently high expression of CD11c, and absence of CD14. Cells that meet these criteria are released in four batches. An initial batch will be delivered directly to the patient for administration via the hepatic artery whilst the remaining three batches are resuspended in an appropriate volume of cryoprotectant (CryoStor® CS10, BioLife Solutions®) before being transferred to individual CryoMACS® Freezing Bags (Miltenyi Biotec). Controlled-rate freezing is carried out according to a previously validated protocol and cells are stored in a –152 °C mechanical freezer until required. Repeat peripheral infusions will be thawed at the patient bedside and delivered via a peripheral vein monthly for 3 months. Transfer to GMP and validation We are currently completing the final phase of validations to begin delivery of this Mo-DC cancer vaccine in the near future. Engineering runs under full GMP conditions are underway using both the CliniMACS Plus Instrument and the CliniMACS Prodigy®, though intention is to use the CliniMACS Prodigy for all cell enrichments. This automation of the enrichment process is a key forward step in the manufacturing of Mo-DC therapies, saving considerable hands-on time and being relatively simple to scale out with the provision of additional machines. Furthermore, as the development of the CliniMACS Prodigy continues, the introduction of a compliant culture process to take patient apheresis samples through to immature Mo-DCs without the need for additional manual manipulations will simplify the delivery of novel cellular therapies. Conclusion In common with many similar facilities throughout the UK, our experience in Birmingham of developing an ATMP manufacturing facility has been challenging. The commitment of a strong team has enabled miltenyibiotec.com PERSPECTIVES This article represents independent research funded by the National Institute for Health Research (NIHR). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, or the Department of Health. Day 6 immature Mo-DCs 52.46% 10² 10¹ 1 0 0.02% -1 -1 0 1 10³ 47.50% CD11c-APC CD11c-APC Anti-HLA-DR-VioBlue Anti-HLA-DR-VioBlue 10³ 0.02% 10¹ 10² 10³ 95.58% 4.38% 10² 10¹ 1 0 0.04% -1 -1 0 1 CD86-PE-Vio 770 CD86-PE-Vio 770 0.00% 10¹ 10² 10³ CD14-VioGreen CD14-VioGreen 10² 10¹ 1 0 0.03% -1 -1 0 1 0.00% 10¹ 10² 10³ CD86-PE-Vio 770 CD86-PE-Vio 770 With a rapidly increasing incidence of liver disease in the UK, the development of novel therapies has never been more pressing. Moreover, as we gather a greater understanding of the interplay between the human immune system and tumour microenvironment we have at our disposal a greater armoury to manipulate the immune response to cancer. For many years cell therapy has promised much, but failed to deliver comprehensively. Combination of improved manufacturing techniques with immunomodulation is moving the field into an exciting era that may finally see us translate some of the early potential into meaningful miltenyibiotec.com CliniMACS Prodigy 200-075-301 CliniMACS CD14 MicroBeads 130-019-101 CliniMACS CD14 Reagent 272-01 autoMACS Pro Separator 130-092-545 Human GM-CSF – premium grade (100 µg) 130-093-866 170-076-302 MACS GMP Cell Expansion Bags 170-076-403 gentleMACS Dissociator 130-093-235 gentleMACS M Tubes 130-096-335 10² MACSQuant Analyzer 10 130-096-343 10¹ Anti-HLA-DR-VioBlue, CD11c-APC, CD86-PE-Vio 770, CD14-VioGreen * CryoMACS Freezing Bags ** 93. 00% 6.87% MC CD14 Monocyte Cocktail, human 130-092-859 1 0 0.13% -1 -1 0 1 0.00% 10¹ 10² 10³ CD14-VioGreen CD14-VioGreen Figure 2 Phenotypic characterization of mature Mo-DCs. Enriched CD14+ cells were differentiated for 6 days and the resulting immature Mo-DCs were matured for two days. Cells were stained with Anti-HLA-DRVioBlue®, CD86-PE-Vio® 770, CD11c-APC, and CD14-VioGreen™ on day 6 and day 8, and analyzed by flow cytometry on the MACSQuant Analyzer 10. us to bring the ImmunoTACE clinical trial into reality and has demonstrated how research laboratory tools can, with careful planning, be integrated into validated manufacturing processes for the preparation of ATMPs. 151-01 DendriMACS GMP Medium 10³ 74.11% CD11c-APC CD11c-APC Anti-HLA-DR-VioBlue Anti-HLA-DR-VioBlue 25.86% Order no. CliniMACS Plus Instrument Human IL-4 – premium grade (100 µg) 130-093-922 Day 8 mature Mo-DCs 10³ MACS Product treatments for the many patients living with the burden of cancer. References 1. Llovet, J. M. et al. (2002) Lancet 359: 1734–1739. 2. Lo, C. M. et al. (2002) Hepatology 35: 1164–1171. 3. Chen, C. H. et al. (2001) Cancer Lett. 164: 189–195. 4. Sideras, K. et al. (2015) Br. J. Cancer 112: 1911–1920. 5. Yin, Y. H. et al. (2005) Br. J. Cancer 93: 458–463. 6. Palmer, D. H. et al. (2009) Hepatology 49: 124–132. 7. Greten, T. F. et al. (2010) J. Immunother. 33: 211–218. 8. Hato, T. et al. (2014) Hepatology 60: 1776–1782. 9. Zitvogel, L. and Kroemer, G. (2012) Oncoimmunology 1: 1223–1225. * Visit www.miltenyibiotec.com/antibodies ** Visit www.miltenyibiotec.com/cryomacs The autoMACS Pro Separator, gentleMACS Dissociator and gentleMACS Tubes, MACS Premium-grade Cytokines, MACSQuant Analyzer 10, MC CD14 Monocyte Cocktail, AntiHLA-DR-VioBlue, CD11c-APC, CD86-PE-Vio 770, and CD14VioGreen are for research use only. The CliniMACS® System components, including Reagents, Tubing Sets, Instruments, and PBS/EDTA Buffer, are manufactured and controlled under an ISO 13485–certified quality system. In the EU, the CliniMACS System components are available as CE-marked medical devices. In the US, the CliniMACS CD34 Reagent System, including the CliniMACS Plus Instrument, CliniMACS CD34 Reagent, CliniMACS Tubing Sets TS and LS, and the CliniMACS PBS/EDTA Buffer, is FDA approved; all other products of the CliniMACS Product Line are available for use only under an approved Investigational New Drug (IND) application or Investigational Device Exemption (IDE). CliniMACS MicroBeads are for research use only and not for human therapeutic or diagnostic use. MACS® GMP Products are for research use and ex vivo cell culture processing only, and are not intended for human in vivo applications. For regulatory status in the USA, please contact your local representative. MACS GMP Products are manufactured and tested under a quality management system (ISO 13485) and are in compliance with relevant GMP guidelines. They are designed following the recommendations of USP <1043> on ancillary materials. No animal- or human-derived materials were used for manufacture of these products. CryoMACS® Freezing Bags are manufactured by Miltenyi Biotec GmbH and controlled under an ISO13485 certified quality system. These products are available in Europe as CE-marked medical devices and are marketed in the USA under FDA 510(k) clearance. Unless otherwise specifically indicated, Miltenyi Biotec products and services are for research use only and not for therapeutic or diagnostic use. Acknowledgments We acknowledge the NIHR for their funding support of this work and the team in the Advanced Therapies Facility at the University of Birmingham, in particular Heather Beard and Savita Mehmi for their assistance in validation of release tests. Vol 17 • 1/2016 MACS & more 23 The MACSQuant® Tyto™ The revolution in cell sorting has begun The MACSQuant® Tyto™ is revolutionizing cell sorting. Our patented microchip-based technology opens new possibilities in basic research and clinical settings with high-speed multiparameter flow sorting in the safety of a fully enclosed cartridge. Innovation Sort cells with the world’s fastest mechanical sort valve and 11-parameter fluorescence-based sorting. Safety Samples and operator are kept contamination-free and safe with disposable, fully enclosed cartridges. Viability Cells are gently driven through the microchip with low positive pressure. Less stress means higher yield of viable, functional cells. miltenyibiotec.com/tyto The MACSQuant Tyto is for research use only. Ease of use No droplet delay or laser alignment needed. Simply insert the cartridge, gate on cells, and sort. PERSPECTIVES Engineering human cells with lentiviral vectors: Making an impact on human disease Rimas J. Orentas Translational Research and Development, Lentigen Technology Inc., A Miltenyi Biotec Company Tackling disease with engineered immune cells Advances in science are also advances in human self-understanding. When tragedy such as life-threatening infection or advanced cancer strikes, we look both without, to pharmacologic interventions, and within. Within our own bodies there is a network of systems that govern tissue development and repair, inflammation, and the response to microorganisms. Depending on our own scientific training and the purpose for which we intervene, we approach these largely unknown systems with a particular bias, and often with a desire to meet a pressing medical need. Miltenyi Biotec has been enabling investigators in biomedicine to unravel these mysteries by providing key tissue preparation and cell separation reagents. With these tools investigators can isolate and study stem cell populations, the cell populations that govern inflammation and wound repair, and the various cells that play a role in the immune response to both infectious agents and cancer. Vaccination against viral and bacterial pathogens has been a pillar of public health for decades. However, vaccination works best in disease prevention, as opposed to a direct therapeutic intervention. Standard vaccine approaches to chronic viral infections such as HIV or hepatitis C have not been effective to date. And the same can be said for cancer. In light of this, scientists are working to unravel the mechanisms and principles that define the immune response to vaccines, and have begun to apply them to treating established human miltenyibiotec.com Lentiviral genome Tev Rev LTR Gag Tat Vif Pol Vpr LTR Vpu Env Nef Split packaging & SIN SIN LTR PGKp CAR SIN LTR + Gag Pol Rev + Env Split packaging & SIN & 4-plasmid system SIN LTR PGKp CAR SIN LTR + Gag Pol + Rev + Env Figure 1 Evolution of human lentiviral gene vectors. The identification of HIV was a medical breakthrough that allowed significant advances in treatment to be made. This discovery also introduced us to a powerful tool for introducing synthetic DNA sequences into the human genome. On the top row, the critical genes expressed by the wild-type virus are shown. This virus was transformed (or "gutted") into a non-infectious vector that cannot replicate through a number of steps. First, in order to assemble a lentiviral vector particle (LV) a producer cell is transfected with plasmid DNA that contains the minimal information required to assemble a particle that can bud from the cell and transduce a target cell, without ever being able to reactivate. In the middle row the classic three-plasmid system is depicted. Here the LTR that normally drives gene expression in HIV has been modified such that once it incorporates into the genome it is “self-inactivating” (i.e. a SIN LTR) and no longer functional. This requires a second synthetic promoter, shown here is one from the housekeeping gene PGK, to drive the therapeutic gene of interest. This is the only part of the vector that inserts into the genome. On a second plasmid the gag (group antigens, the virion structural proteins), pol (polymerase, i.e. reverse transcriptase), and the rev element are encoded. The third plasmid encodes env (envelope), which for most LV is derived from vesicular stomatitis virus (VSV-G). An added level of safety was created in the 4-plasmid system, bottom row, where the rev element was removed and is expressed from its own plasmid. To re-create an infectious agent all of these elements would need to re-combine correctly, the SIN promoter would have to be repaired, and a new env provided, which is an essentially impossible event. cancers. It is abundantly clear that vaccination induces and expands activated lymphocyte populations in the body, and that the transfer of vaccine-educated T lymphocytes can transfer protective immunity. In some approaches, native T cell populations are used. The primary example of this would be the expansion ex vivo and subsequent re-infusion of tumor- Vol 17 • 1/2016 MACS & more 25 PERSPECTIVES infiltrating lymphocytes, recently reviewed by Rosenberg and Restifo¹. In other approaches, immune cells are first genetically modified. The ability to genetically modify, or engineer, immune cell populations is central focus for Lentigen Technology, Inc., a Miltenyi Biotec Company. Lentigen produces lentivirus-based gene vectors. These gene vectors are essentially highly modified versions of the HIV virus. Because the modified virus cannot replicate, or make new copies of itself, the term "vector" as opposed to virus or virion is used. This is an important distinction, as it makes clear that we have a very safe and controlled way to introduce new DNA sequences into the human genome, see figure 1. The DNA being introduced into the genome can encode for a native human transcript, such as the alpha and beta chains of the T cell receptor (TCR) for antigen, or can encode for new types of proteins that are a composite of different human transcripts and thus are termed "synthetic" or "chimeric". Although not encoded in toto by the human genome, these are still essentially self-proteins, created from distinct functional protein subdomains. If the individual components were not encoded by the genome, the protein itself would be foreign, and thereby a locus for immune rejection of the cell that expresses it. This would then eliminate any potential therapeutic benefit of the modified cell population. Engineering of T cells with chimeric antigen receptors Contemporary thinking about synthetic biology, in fact the very use of the term, was crystallized by Wacław Szybalski² who envisioned a new biology wherein genetic control circuits could be engineered at the level of the cell and subsequently the entire organism. With regard to proteins associated with immunologic function, Zelig Eschar demonstrated that receptor- or ligandbinding domains, transmembrane sequences, and intracellular signaling motifs could be interchanged between different cell surface glycoproteins³. These patchwork proteins were soon termed "chimeric antigen receptors" or CARs. Putting these advances together, we have now arrived at the current era where control of gene expression with molecularly cloned promoter and enhancer elements, and the creation of novel chimeric proteins (fig. 2), can 26 MACS & more Vol 17 • 1/2016 Synthetic biology CAR shop CAR elements A) Active CARs B) Double CARs C) Subunit CARs D) iCARs αCD22 scFv αCD19 scFv αCD20 scFv Sp6 scFv CD8 linker (w/TM) 2nd gen. CAR, CD137/CD3ζ CD28 TM, signaling Just CD3ζ Just costim. domains E) CID assembled “AND” CARs (GGGGS)x T cell inhibitory domain dimerization agent Figure 2 The chimeric antigen receptor. The expression of a chimeric antigen receptor (CAR) on the surface of a LV-transduced T cell requires a binding domain, scFv, to interact with the tumor-expressed surface antigen on the opposing cell membrane, and a means to link that binding to T cell–specific transmembrane and signaling domains. Here we highlight a subset of the tools that can be assembled for the engineering of a T cell with CAR. Shown on the left are i) different scFv-derived binding domains (anti-CD19, 20, 22, Sp6 control), ii) a linker that has been used to join these domains to T cell signaling domains (CD8 linker with transmembrane domain, TM), iii) two signaling systems that have been used to activate T cells (the second-generation CAR that incorporates the activation domains present in the CD137 and CD3ζ chain molecules or a domain that includes the CD28 transmembrane and activation domains), iv) an amino acid linker sequence (GGGGS) composed of a string of glycines and serines that is multimerized up to 4 times to join individual protein domains, v) a representative inhibitory domain that could be derived from PD-1 or an intracellular phosphatase and vi) a representative chemical dimerization reagent. These subunits can be assembled as A) active CARs, that can lyse tumor cells upon contact, B) double CARs that contain two binding domains, C) subunit CARs that require multiple contacts to give full T cell activation, D) iCARs, inhibitory CARs that turn off T cells upon binding to a target antigen, and E) "AND" CARs that require assembly with a chemically induced dimerization (CID) agent. These next-generation, gated "AND" CARs require both the target and the CID to be present for activity. be introduced together as a unit into human cells in a safe manner and with apparent clinical benefit, (reviewed in ref. 4). Thus the engineering of T cells with CARs is the result of many independent contributions in science that span protein chemistry, cell biology, gene vector biology, and adoptive immunotherapy. In looking to the future, what are the key areas in which synthetic biology will be used to improve immunotherapeutic cell populations? The first will be in the cellular substrate itself. The second will be in better defining target antigens of interest. The third will be in better design of the effector molecule expressed by the engineered cell. The final area we will consider will be the manner in which the transgene and the cell expressing that transgene are controlled (fig. 3). miltenyibiotec.com PERSPECTIVES Initial cell type Engineered T cell Gene vector TSCM Next-generation “gated” CARs TCM X Selected CD4+ and/or CD8+ T cells Transgene expression CARs Virus-specific T cells Soluble factors Target selection X Tumor vs. normal • • • • Genetic control elements CID activation or cell death Expression profiling Next-generation sequencing Proteomic analysis Tumor-specific Abs Figure 3 The engineered T cell. To create an engineered cell we begin with a target cell population that we wish to modify, and a specific antigen that can be targeted. At the top left, several cell types are illustrated from which CAR strategies have been approached (T stem cell memory (Tscm), T central memory (Tcm), T cells that have been selected by surface marker expression, and T cells that are specific for viral antigens, and can be expanded in vitro). At the bottom left, we illustrate the concept that understanding what serves as a suitable target is an essential aspect of CAR therapy. The more restricted to the cancer cell, and the greater the over-expression of a tumor-associated protein, the higher the margin of safety for CAR-based therapy. The engineering of the T cell itself begins with the introduction of a gene vector (such as a LV) that encodes the antitumor effector protein (CAR), as well as other factors that control the biology of the T cell itself. These factors include soluble proteins that enhance T cells or alter the tumor microenvironment, components of a genetic switch, and domains that can induce cell death as a means to provide a safety switch. Though not illustrated, T cell costimulatory domains or agents that block immune checkpoints can also be envisioned. As currently applied, adoptive immunotherapy with engineered T cells is usually performed using unselected lymphocyte populations. However even in these procedures, there is some degree of enrichment for activated T cells. For example, in the creation of CD19-specific CAR T cells for the treatment of pediatric B-ALL, the lymphocyte population (obtained by apheresis) is stimulated with magnetic beads decorated with anti-CD3 and anti-CD28 antibody⁵. During activation and culture, lymphocytes bound to these beads are enriched by adherence to a magnet. In an attempt to standardize this process and improve the T cell populations used for CAR T cell engineering, Sommermeyer et al., described the most active CD4+ and CD8+ T lymphocyte populations miltenyibiotec.com that could be selected and subsequently infused for a consistent therapeutic effect⁶. Thus, immunomagnetic bead selection plays a key role in identifying the appropriate T cell population for adoptive transfer. Investigators are also looking to include more naive T cell subsets that appear to be active at lower numbers and which expand and persist to a greater degree once infused into the host⁷. The cells used for adoptive immunotherapy can be engineered to express costimulatory molecules such as CD137L, cytokines, or cytokine receptors, and also microRNA species associated with increased T cell survival and anti-tumor reactivity⁸,⁹. The ability to express multiple transcripts from a lentiviral vector (LV) makes the ability to engineer T cell populations a single-step process. Furthermore, although the ability to augment anti-tumor T cell populations in vivo with antibody-based approaches, such as anti-PD-1 or anti-CTLA-4, has been quite effective, similar effects can be seen through the knockdown of the appropriate receptor on the engineered T cell population¹⁰. Thus, LV-based T cell engineering can not only deliver a payload into the genome, such as a CAR, but also transcripts that will govern the activation, expansion, and persistence of the therapeutic cell population. Identifying appropriate CAR T cell targets How we search for a truly tumor-specific antigen (TAA, tumor-associated antigen), has changed due to the impact of CAR T cell therapy. Traditionally a TAA is a mutated-self or a foreign viral protein that is expressed by a cancer cell. To date, the most effective CAR target, CD19, is a normal self-protein that is overexpressed on the leukemia cell surface. When CAR-modified T cells that recognize CD19 are infused, the normal B cell population that expresses this antigen is also eliminated. This is an "on-target" but "off-tumor" effect. The loss of normal B cells is a survivable event that can be managed with polyclonal immunoglobulin infusions. This may not be the case for other self-antigens, and they will have to be considered on a case-by-case basis. Until this year, the antigen-binding domain of the CAR, the scFv domain, was often not the target of affinity maturation, as is the case for antibody-based therapeutics. Studies by Chmielewski et al. demonstrated that upon reaching a threshold affinity, not much is gained in affinity maturation of the antigen-binding domain of the CAR, as the T cell transduced to expressing the CAR expresses numerous copies of the protein on the plasma membrane, and avidity thus trumps affinity¹¹. However, a very important recent study showed that degrading the scFv affinity to the level where the avidity drives the biology of the CARexpressing T cell, may allow effective targeting of tumor cells that over-express the TAA and spare normal cells that express far fewer copies. This was demonstrated using CARs based on two antibodies specific for EGFR, low-affinity nimotuzumab and high-affinity cetuximab¹². This has invigorated genomic approaches to searching for TAA based on comparing the expression of normal to cancer-associated Vol 17 • 1/2016 MACS & more 27 PERSPECTIVES tissue samples by gene expression profiling or next-generation sequencing methodologies¹³. Switching CAR T cells on and off If the approach to a specific cancer target is still limited by the lack of a safe overexpressed target, this calls for a more complex CAR structure to be developed that requires two specific "hits" for activation, or which is negatively regulated by an antigen that is overexpressed on a vital normal tissue. Neither of these options has been put into practice in the clinic, but experimental results are promising. For negative signals both intracellular phosphatases such as CD45 and the intracellular signaling motifs of the checkpoint molecules PD-1 and CTLA-4 have been proposed¹⁴,¹⁵. Thus a CAR specific for TAA "A", to which an active intracellular domain is spliced, will react to any cell that expresses "A", unless antigen "B" is present, which is targeted by a second CAR expressed by the same T cell, yet to which negative or inhibitory signaling domains are spliced. There also have been numerous "split CAR" approaches, wherein binding to "A" delivers only a partial signal, and full activation to the point of target cell cytolysis requires a second binding event, "C", that is also present on the tumor cell. This process can also be approached pharmacologically, wherein a CAR specific for "A" does not contain any T cell activation signals, but does contain a small-molecule binding domain that can induce protein-protein association. In the same LV a second transcript, "D", is expressed that would contain the dimerization domain linked to the intracellular signaling motifs that would activate a T cell. This small molecule thus becomes an "on switch" and is required for full CAR activity. Chemical inducers of dimerization (CID domains) have been widely developed using the rapamycin/FK506 and FK506-binding protein (FKBP) system. Similar systems have been recently reviewed by Wu et al.¹⁶. The control of CAR T cells to date has employed various mechanisms to immuno-deplete the cells from the body, or to induce apoptotic cell death. Immunodepletion is envisioned by the use of an antibody that has already been approved for therapy and has an established safety profile. Creating a LV that expresses both a CAR of interest and the extracellular domain 28 MACS & more Vol 17 • 1/2016 of CD34, CD20, EGFR, or LNGFR allows for a planned removal of the CAR-transduced cell, should unwanted side-effects develop, by infusion of antibody specific for these domains. The rapidity by which this would occur in the clinic is not yet known, and no reports of clinical depletion of CAR T cells with an antibody have been published. Nevertheless, it may provide some degree of assurance in the case of a risky target. The most effective "off switch" to date is the induction of apoptosis by a CID. In CAR-expressing T cells engineered to express an engineered caspase 9 gene, the small molecule AP109 induces dimerization and rapidly induces cell death through the activation of the endogenous apoptotic cell death pathway, known as the iCasp9 system¹⁷. A molecular "on switch" as envisioned by early synthetic biologists, may require added levels of control to prevent "read-through" transcription. A eukaryotic version of a true genetic switch mechanism, inducible by a small ligand, has already been reported¹⁸. The challenge remains to fully operationalize this system using native human elements and clinically relevant inducer molecules. To date these have all been hormone-like small molecules that can interact with distinct intracellular receptor domains linked to transcriptional transactivators. A bright future for synthetic biology In conclusion, the era of synthetic biology is upon us. The human T cell can be readily engineered with lentiviral gene vectors to express effector proteins and RNA molecules ex vivo, and upon expansion these cells can be re-infused into the body for therapeutic effect. There have been promising reports of children and adults with refractory B-ALL who survived because engineered T cells were made available for their treatment.¹⁹,²⁰ Our vision is to expand this availability to any setting where cell processing can be carried out, and to continuously improve the targets identified for CAR therapy. We hope to support and participate in new technological developments that allow investigators to control the function of CAR proteins at the molecular level and to control the expansion or the elimination of T cells at the cellular level. References 1. Rosenberg, S.A. and Restifo, N.P. (2015) Science 348: 62–68. 2. Szybalski W. and Skalka, A. (1978) Gene 4: 181–182. 3. Stancovski, I. et al. (1993) J. Immunol. 151: 6577–6582. 4. Lee, D. et al. (2012) Clin. Cancer Res. 18: 2780–2790. 5. Lee, D. et al. (2015) Lancet 385: 517–528. 6. Sommermeyer, D. et al. (2015) Leukemia Sep 15: Epub ahead of print. doi: 10.1038/leu.2015.247. 7. Gattinoni, L. et al. (2012) Nat. Rev. Cancer 12: 671–684. 8. Pegram, H. et al. (2012) Blood 119: 4133–4141. 9. Ji, Y. et al. (2015) Proc. Natl. Acad. Sci. USA 112: 476–481. 10.Condomines, M. et al. (2015) PLoS One 10: e0130518. doi: 10.1371/journal.pone.0130518. 11.Chmielewski, M. et al. (2011) Gene Ther. 18: 62–72. 12.Caruso, H. et al. (2015) Cancer Res. 75: 3505–3518. 13.Orentas, R. et al. (2014) Front. Oncol. 4: 134. doi: 10.3389/fonc.2014.00134. 14.James, J.R. and Vale, R.D. (2012) Nature: 487: 64–69. 15.Federov, V. et al. (2013) Sci. Transl. Med. 5: 215ra172. doi: 10.1126/scitranslmed.3006597. 16.Wu, C. et al. (2015) Science 350: aab4077. doi: 10.1126/science.aab4077. 17.Straathof, K. et al. (2005) Blood 105: 4247–4254. 18.Deans, T. et al. (2007) Cell 130: 363–372. 19.Grupp, S.A. et al. (2013) N. Engl. J. Med. 368: 1509–1518. 20.Maude, S.L. et al. (2014) N. Engl. J. Med. 371: 1507–1517. miltenyibiotec.com Automate your manufacturing Your trusted partner in cell and gene therapy • Fully integrated workflows for ex vivo cell processing • Established protocols for gene modification of T cells and stem cells • Design, development, and manufacturing of customized lentiviral vectors • Commercial-scale supply of ancillary materials for manufacturing miltenyibiotec.com/prodigy The CliniMACS® System components, including Reagents, Tubing Sets, Instruments, and PBS/EDTA Buffer, are manufactured and controlled under an ISO 13485–certified quality system. In the EU, the CliniMACS System components are available as CE-marked medical devices. In the US, the CliniMACS CD34 Reagent System, including the CliniMACS Plus Instrument, CliniMACS CD34 Reagent, CliniMACS Tubing Sets TS and LS, and the CliniMACS PBS/EDTA Buffer, is FDA approved; all other products of the CliniMACS Product Line are available for use only under an approved Investigational New Drug (IND) application or Investigational Device Exemption (IDE). CliniMACS MicroBeads are for research use only and not for human therapeutic or diagnostic use. Unless otherwise specifically indicated, Miltenyi Biotec products and services are for research use only and not for therapeutic or diagnostic use. MACS&more (ISSN 1610-4994) is published by Miltenyi Biotec GmbH. Editorial board: Bastian Ackermann, Dirk Balshüsemann, Caroline Blumer-Toti, Hermann Bohnenkamp, Vincent Chu, Steven Dublin, Anja Gaugel, Christoph Hintzen, Jason Jones, Andrew Kaiser, Kalpana Singh, Boris Stoffel, Tim Stolle, Katharina Winnemöller Editor: Ralph Schaloske Graphics & Layout: Miltenyi Biotec GmbH, Graphics team Miltenyi Biotec GmbH Friedrich-Ebert-Straße 68, 51429 Bergisch Gladbach, Germany Phone +49 2204 8306-0 [email protected] The CliniMACS® System components, including Reagents, Tubing Sets, Instruments, and PBS/EDTA Buffer, are manufactured and controlled under an ISO 13485– certified quality system. In the EU, the CliniMACS System components are available as CE-marked medical devices. In the US, the CliniMACS CD34 Reagent System, including the CliniMACS Plus Instrument, CliniMACS CD34 Reagent, CliniMACS Tubing Sets TS and LS, and the CliniMACS PBS/ EDTA Buffer, is FDA approved; all other products of the CliniMACS Product Line are available for use only under an approved Investigational New Drug (IND) application or Investigational Device Exemption (IDE). CliniMACS MicroBeads are for research use only and not for human therapeutic or diagnostic use. MACS® GMP Products are for research use and ex vivo cell culture processing only, and are not intended for human in vivo applications. For regulatory status in the USA, please contact your local representative. MACS GMP Products are manufactured and tested under a quality management system (ISO 13485) and are in compliance with relevant GMP guidelines. They are designed following the Copyright © 2016 Miltenyi Biotec GmbH. All rights reserved. recommendations of USP <1043> on ancillary materials. No animal- or human-derived materials were used for manufacture of these products. CryoMACS® Freezing Bags are manufactured by Miltenyi Biotec GmbH and controlled under an ISO13485 certified quality system. These products are available in Europe as CEmarked medical devices and are marketed in the USA under FDA 510(k) clearance. Unless otherwise specifically indicated, Miltenyi Biotec products and services are for research use only and not for therapeutic or diagnostic use. autoMACS, CliniMACS, CliniMACS Prodigy, CryoMACS, DendriMACS, ExpAct, gentleMACS, MACS, the MACS logo, MACSQuant, MACSQuantify, PepTivator, REAfinity, TexMACS, TransAct, Tyto, Vio, VioBlue, and VioGreen are registered trademarks or trademarks of Miltenyi Biotec GmbH or its affiliates in Germany, the United States, and/ or other countries. All other trademarks mentioned in this document are the property of their respective owners and are used for identification purposes only. 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