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Stem cells and its role in medicine Biomaterials II 27th March 2015 Introducing….stem cells!
What are stem cells? ü  The body is made up of about 200 different
kinds of specialised cells such as muscle cells,
nerve cells, fat cells and skin cells
ü  All cells in the body come from stem cells
ü  A stem cell is a cell that is not yet specialised
ü  The process of specialisation is called
differentiation
ü  Once the differentiation pathway of a stem cell
has been decided, it can no longer become
another type of cell on its own
Broad classifica9on of stem cells ü  Embryonic stem cells (ES cells)
ü  Induced pluripotent stem cells (iPS cells)
ü  Adult or tissue stem cells
Why are stem cells special?
Stem cells can:
•  self-renew to make more
stem cells
•  differentiate into a
specialised cell type
Stem cells that can become many
types of cells in the body are
called pluripotent
Embryonic stem cells (pluripotent)
Stem cells that can become
only a few types of cells are
called multipotent
Tissue stem cells (multipotent)
Tissue stem cells
•  often known as adult stem cells
•  also includes stem cells isolated from fetal and cord blood
•  reside in most tissues of the body where they are involved
in repair and replacement
Bone marrow
Kidney
Lung
•  generally very difficult to isolate
•  already used to treat patients (haematological malignancies,
diseases of the immune system)
Where do embryonic stem cells
come from?
•  Donated excess IVF embryos
egg
Day 0
Inner cell mass
fertilised
egg
2-cell
8-cell
blastocyst
Day 1
Day 2
Day 3
Day 6
Images from www.advancedfertility.com
Human embryonic stem cells (hES cells)
human embryonic stem cells
•  derived from donated IVF
embryos
•  can be grown indefinitely in
the laboratory in an
unspecialised state
•  retain ability to specialise into
many different tissue types –
know as pluripotent
•  can restore function in animal
models following
transplantation
TreaGng age-­‐related macular degeneraGon (AMD) using hES cells Human ES cells derived re9nal pigment epithelial cells for the treatment of dry atrophic AMD and Stargardt’s macular dystrophy www.thelancet.com Published online October 15, 2014 h7p://dx.doi.org/10.1016/
S0140-­‐6736(14)61376-­‐3 Human ES cells derived cells that mimic pancrea9c beta cells ü  First clinical trial to treat type 1
diabetes started by ViaCyte in August
2014
ü  They developed engineered cells and
medical device for delivery
Do you approve of the extraction of
stem cells from human embryos for
medical research?
•  Don’t know
•  No
•  Yes
Areas of concern
ü  How come there are excess IVF embryos? ü  Why do the embryos have to be destroyed for stem cell research? Isn’t this the same as taking a life? ü  Wouldn’t it be beNer to donate the excess IVF embryos to other infer9le couples? ü  Could women be forced to sell eggs or embryos for research? ü  Won’t doing therapeu9c cloning lead to cloning humans? ü  Is there any other ways to get such potent cells? What about cloning? Has that got anything to do with
stem cell research?
Somatic Cell Nuclear Transfer – cloning to make
stem cells (therapeutic cloning)
Reproductive Cloning
Dolly the Sheep
Snuppy the Puppy
Cloning There are two VERY different types of cloning: Reproduc9ve cloning Use to make two iden9cal individuals Very difficult to do Illegal to do on humans Molecular cloning gene 1 gene 2 Use to study what a gene does Rou9ne in the biology labs Molecular cloning: Principles
1) Take DNA out of the nucleus gene 1 cell 1 gene 2 cell 2 2) Make a new piece of DNA gene 1 gene 1 gene 2 gene 2 3) Put new DNA into a test cell and grow copies gene 1 gene 2 insert new DNA cell divides Daughter cells contain same DNA: Genes 1 and 2 have been cloned Molecular cloning: Applications
Loss of funcGon Reporter gene Lineage tracing remove a gene to see if anything works differently add a gene that shows us when another gene is working mark a group of cells to see where their daughter cells end up gene is acGve in blue areas only gene is passed on to cells all over the body eye Normal mouse embryo gene A missing gene is involved in giving the eye its colour Oct3/4 c-­‐Myc Klf4 Sox2 INDUCED PLURIPOTENT STEM (IPS) Reprogramming adult cells towards embryonic state Can we turn the clock in other direcGon? Induction of Pluripotent Stem Cells
from Mouse Embryonic and Adult
Fibroblast Cultures by Defined Factors
Kazutoshi Takahashi1 and Shinya Yamanaka1,2,*
1
Department of Stem Cell Biology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
CREST, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
*Contact: [email protected]
DOI 10.1016/j.cell.2006.07.024
2
SUMMARY
Differentiated cells can be reprogrammed to an
embryonic-like state by transfer of nuclear contents into oocytes or by fusion with embryonic
stem (ES) cells. Little is known about factors
that induce this reprogramming. Here, we demonstrate induction of pluripotent stem cells
from mouse embryonic or adult fibroblasts by
introducing four factors, Oct3/4, Sox2, c-Myc,
and Klf4, under ES cell culture conditions.
Unexpectedly, Nanog was dispensable. These
cells, which we designated iPS (induced pluripotent stem) cells, exhibit the morphology and
growth properties of ES cells and express ES
cell marker genes. Subcutaneous transplantation of iPS cells into nude mice resulted in
tumors containing a variety of tissues from all
three germ layers. Following injection into blastocysts, iPS cells contributed to mouse embryonic development. These data demonstrate
that pluripotent stem cells can be directly generated from fibroblast cultures by the addition
of only a few defined factors.
or by fusion with ES cells (Cowan et al., 2005; Tada
et al., 2001), indicating that unfertilized eggs and ES cells
contain factors that can confer totipotency or pluripotency
to somatic cells. We hypothesized that the factors that
play important roles in the maintenance of ES cell identity
also play pivotal roles in the induction of pluripotency in
somatic cells.
Several transcription factors, including Oct3/4 (Nichols
et al., 1998; Niwa et al., 2000), Sox2 (Avilion et al., 2003),
and Nanog (Chambers et al., 2003; Mitsui et al., 2003),
function in the maintenance of pluripotency in both early
embryos and ES cells. Several genes that are frequently
upregulated in tumors, such as Stat3 (Matsuda et al.,
1999; Niwa et al., 1998), E-Ras (Takahashi et al., 2003),
c-myc (Cartwright et al., 2005), Klf4 (Li et al., 2005), and
b-catenin (Kielman et al., 2002; Sato et al., 2004), have
been shown to contribute to the long-term maintenance
of the ES cell phenotype and the rapid proliferation of
ES cells in culture. In addition, we have identified several
other genes that are specifically expressed in ES cells
(Maruyama et al., 2005; Mitsui et al., 2003).
In this study, we examined whether these factors could
induce pluripotency in somatic cells. By combining four
selected factors, we were able to generate pluripotent
cells, which we call induced pluripotent stem (iPS) cells,
directly from mouse embryonic or adult fibroblast cultures.
Transcrip9on factors Induced pluripotent stem (iPS) cells
Starting cells from
donor tissue
Induced change in
gene expression
iPS Cells
pluripotent
stem cells
ü  Derived from adult cells in
2006
ü  Can be grown indefinitely in
culture in an undifferentiated
state
ü  Similar properties to
embryonic stem cells as can
differentiate into many
different tissue types –
pluripotent
ü  Can create stem cells directly
from a patient for research
Induced pluripotent stem cells (iPS cells) ‘gene9c reprogramming’ = add certain genes to the cell cell from the body induced pluripotent stem (iPS) cell behaves like an embryonic stem cell differen9a9on culture iPS cells in the lab Advantage: no need for embryos! all possible types of specialized cells Japanese researches ini9ated first clinical trial using iPS cells for AMD Adult or Tissue Stem Cells Where can we find adult/
9ssue stem cells? Tissue stem cells:
Principles of renewing tissues
Stem cell stem cell: -­‐  self renew -­‐  divide rarely -­‐  high potency -­‐  rare commi7ed progenitors: -­‐  “transient amplifying cells” -­‐  mul9potent -­‐  divide rapidly -­‐  no self-­‐renewal specialized cells: -­‐  work -­‐  no division Tissue stem cells:
Haematopoietic stem cells (HSCs)
NK cell T cell B cell dendri9c cell megakaryocyte platelets HSC erythrocytes macrophage neutrophil bone marrow eosinophil basophil commi7ed progenitors specialized cells Tissue stem cells:
Neural stem cells (NSCs)
Neurons Interneurons Oligodendrocytes NSC Type 2 Astrocytes Type 1 Astrocytes brain commi7ed progenitors specialized cells Tissue stem cells:
Mesenchymal stem cells (MSCs)
Since the number of MSC decreases with a person's age, neo-­‐natal sources such as umbilical cord blood (UCB), umbilical cord 9ssue (UC), or placenta are being studied to replace adult ones such as bone marrow (BM), adipose 9ssue (AT) or dental pulp (DP). Stem cells at home:
The stem cell niche
Stem cell niches Niche Microenvironment around stem cells that provides support and signals regula9ng self-­‐renewal and differen9a9on Direct contact
Soluble factors
stem cell niche Intermediate cell
Choice of Material ElasGcity for Specific Tissue Engineering ApplicaGon D. E. Discher, et al. Science 2009, 324, 1673 Stem cells in regeneraGve medicine Rafael Nadal: Stem cell treatment ü Nadal recently had undergone stem cell treatment to solve his back pain problem ü He previously did this for his writ and knee Stem Cell Tourism
A growing concern to the stem cell community
Direct marketing to patients
promising instant results for
incurable diseases