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Perfusion Chamber with Porous Membrane for Cellular-Level Glaucoma Research Joey Labuz Holly Liske Laura Piechura Kellen Sheedy Donna Peters, PhD Department of Pathology and Laboratory Medicine William Murphy, PhD Department of Biomedical Engineering Overview Project Motivation Design Specifications Design Alternatives and Final Design Design Matrix Expected Budget Future Work Questions Glaucoma 2nd leading cause of blindness 3 million suspected cases in America Progression: Elevated intraocular pressure Optic nerve damage Loss of vision (National Eye Institute) Fluid Outflow Pathways normal glaucoma (Modified from Lewis et al., 1999) Glaucoma Treatment Current Prescription eye drops To decrease production of ocular fluid Dr. Peters’s research Injection of ECM peptides To increase fluid release through the trabecular meshwork Approach to Research Isolate cells of the trabecular meshwork Treat cells with the ECM peptide β-catenin Induce disassembly of the actin cytoskeleton Measure fluid flow across the cell layer Client Motivation Identify peptides as potential glaucoma therapies Cellular-level experimentation Replicates Cost (Johnson and Tschumper, 1987) Problem Statement Cells are more readily available than whole eyes Device to control fluid flow across cells adhered to membrane Variable pressure from above and below cells Secure membrane to membrane holder and pressure device Design Criteria Ability to withstand 30 mmHg above and below Compatibility with various membranes Ability to perform simultaneous replicates Integration with existing equipment Sterile system Alternative Design One Top Chamber To Transducer From Syringe = Membrane Holder Bottom Chamber From Syringe To Transducer Stand Design One Evaluation + Simple design + Interchangeable membrane + No fluid leakage – Difficult to assemble in a sterile setting – Unstable on a laboratory bench Alternative Design Two Upper Pressure Chamber Membrane Holder = Lower Pressure Chamber Alternative Design Two From Syringe To Transducer Plan View of Lower Chamber Design Two Evaluation + Interchangeable membrane + Stable on a laboratory bench + Simple assembly for user – Potential for leakage – Wells cannot be disassembled – Unequal pressure application Final Design Upper Pressure Chamber Membrane Holder = Lower Pressure Chamber Final Design To Transducer Front View of Assembled Device Side View From Syringe Final Design Evaluation + Magnets provide tight membrane seal + Independent pressure chambers + Minimal user interaction – Upper chamber pressure regulation – Coating of membrane holder Design Matrix Criteria Rank Design 1 Design 2 Design 3 Reliability 0.25 2 3 4 User Interaction 0.25 1 3 4 Ease of Use 0.20 3 1 2 Replicate Independence 0.20 4 1 4 Ease of Manufacture 0.10 3 2 5 Total 1.00 2.50 1.74 3.70 Estimated Budget Plexiglas $20 set of 25 Small hardware $20 upper chamber $25 lower chamber Neodymium magnets (www.professionalplastics.com) $30 Total = $95 (www.amazingmagnets.com) Future Work Coating and sterilizing magnets Maintaining a constant back pressure Ordering of materials Construction Testing Fluid flow and measurement Sealing of membrane http://www.omega.com Questions References “Acrylic Sheets: Plexiglas.” Professional Plastics. <http://www.professionalplastics.com> 17 October 2007. “Back Pressure Regulator.” Plastomatic Valves, Inc. <http://www.plastomatic.com> “Glaucoma Resource Guide.” National Eye Institute. <http://www.nei.nih.gov/health> 17 October 2007. Johnson, DH and Tschumper RC. 1987. “Human trabecular meshwork organ culture. A new method.” Investigative Ophthalmology & Visual Science 28: 945-953. Lewis, Peter R., Phillips, Grant T., and Sassani, Joseph W. April 1, 1999. “Topical therapies for glaucoma: What family physicians need to know.” American Family Physician 59. “Miniature Back Pressure Regulators.” Omega Process Measurement and Control. <http://www.omega.com> 17 October 2007. Peters, Donna M. “Use of cell-matrix interactions to treat glaucoma.” PowerPoint presentation. University of Wisconsin-Madison Departments of Pathology and Laboratory Medicine and Opthamology and Visual Sciences. “Rare Earth Neodymium Magnets.” Amazing Magnets. <http://www.amazingmagnets.com> 17 October 2007. The Eye Digest. “Glaucoma Treatment.” University of Illinois Eye & Ear Infirmary. 17 June 2007. <http://www.agingeye net/glaucoma/glaucomadrugtreatment.php> 15 October 2007.