Continuing Bonds Through AI: A Hermeneutic Reflection on Thanabots
Stem Cell and its applications in medical sciences.ppt
1. STEM CELL : A MYSTERY CELL
Dr. B.P.DASH
Adjunct Professor in Zoology
Fakir Mohan University
Balasore-756 089,Odisha
Email: bisnu.bbs22@gmail.com
2. • AN ADVANCING KNOWLEDGE ABOUT HOW
DIFFERENT TYPES OF CELLS / TISSUES OR
ORGANS DEVELOP FROM A SINGLE CELL AND
HOW THE HEALTHY CELLS REPLACE THE
DAMAGED CELLS IN ADULT ORGANISMS
• THIS PROMISING AREA OF SCIENCE IS LEADING
THE SCIENTISTS TO INVESTIGATE THE
POSSIBILITY OF CELL-BASED THERAPIES TO
TREAT VARIOUS FATAL DISEASES
• IT IS OFTEN REFERRED TO AS REGENERATIVE
MEDICINE
INTRODUCTION
3. WHAT IS STEM CELL ?
AN
UNDIFFERENTIATED
CELL
THAT POSSESSES
THE ABILITY
TO DIVIDE FOR
INDEFINITE
PERIOD IN CULTURE
AND MAY
GIVE RISE TO HIGHLY
A MOUSE EMBRYONIC STEM CELL
4. Stem Cell Research
(Key events)
• 1960s - Joseph Altman and Gopal Das present evidence of adult
neurogenesis, ongoing stem cell activity in the brain; their reports
contradict Cajal's "no new neurons" dogma and are largely ignored
• 1963 - McCulloch and Till illustrate the presence of self-renewing
cells in mouse bone marrow
• 1978 - Haematopoietic stem cells are discovered in human cord
blood
• 1981 - Mouse embryonic stem cells are derived from the inner cell
mass
• 1992 - Neural stem cells are cultured in vitro as neurospheres
• 1997 - Leukemia is shown to originate from a haematopoietic stem
cell, the first direct evidence for cancer stem cells
• 1998 - James Thomson and coworkers derive the first human
embryonic stem cell line at the University of Wisconsin-Madison.
• 2000s - Several reports of adult stem cell plasticity are published
• 2003 - Dr. Songtao Shi of NIH discovers new source of adult stem
cells in children's primary teeth
• 07 January, 2007 - Scientists at Wake Forest University led by Dr.
Anthony Atala and Harvard University report discovery of a new type
of stem cell in amniotic fluid
7. STEM CELLS HAVE BASICALLY THREE DEFINING PROPERTIES
• DIFFERENTIATION INTO OTHER CELLS
THE ABILITY TO DIFFERENTIATE IS THE POTENTIAL TO DEVELOP
INTO OTHER CELL TYPES UNDER CERTAIN PHYSIOLOGIC OR
EXPERIMENTAL CONDITIONS
• SELF-REGENERATION
SELF-REGENERATION IS THE ABILITY OF STEM CELLS TO DIVIDE
AND PRODUCE MORE STEM CELLS
• IDENTIFY THE SIGNALS
THAT CAUSE STEM CELLS TO BECOME SPECIALIZED CELLS
8.
9. TYPES OF STEM CELL
(BASED ON POTENCY)
Totipotent stem cells are produced from the fusion of an egg and
sperm cell. Cells produced by the first few divisions of the fertilized
egg cell are also totipotent. These cells can differentiate in to any
type of cell without exception
Pluripotent stem cells are the descendants of totipotent cells and
can differentiate into any cell type except for totipotent stem cells
Multipotent stem cells can produce only cells of a closely related
family of cells (e.g. hematopoeietic stem cells differentiate into red
blood cells, white blood cells, platelets etc.)
Unipotent cells can produce only one cell type, but have the property
of self-renewal which distinguishes them from non-stem cells.
13. Types of Stem Cells
(Based on Origin)
Grouped into two types:
Embryonic Stem Cell (ESC)
• Embryonic stem cells are derived
from embryos that develop from
eggs that have been fertilized in
vitro—in an in vitro fertilization
clinic—and then donated for
research purposes with informed
consent of the donors.
• The embryos from which human
embryonic stem cells are derived
are typically four or five days old
and are a hollow microscopic ball
of cells called the blastocyst.
Human Embryonic Stem cell colony
16. Embryonic stem cell lines
• Mouse ES cells are grown on a layer of gelatin and require the
presence of Leukemia Inhibitory Factor (LIF)
• Human ES cells are grown on a feeder layer of mouse
embryonic fibroblasts (MEF's) and require the presence of
basic Fibroblast Growth Factor (bFGF or FGF-2 )
• human embryonic stem cell is also defined by the presence of
several transcription factors and cell surface proteins
• The transcription factors Oct-4, Nanog, and Sox2 form the core
regulatory network which ensures the suppression of genes
that lead to differentiation and the maintenance of pluripotency
• The cell surface proteins most commonly used to identify hES
cells are the glycolipids SSEA3 and SSEA4 and the keratan
sulfate antigens Tra-1-60 and Tra-1-81
18. Embryonic Stem Cell Lines Derived from Human Blastocysts
James A. Thomson, et.al. Science 6 November 1998:
Vol. 282. no. 5391, pp. 1145 - 1147
• Human blastocyst-derived, pluripotent cell lines are described
that have normal karyotypes, express high levels of telomerase
activity, and express cell surface markers that characterize
primate embryonic stem cells but do not characterize other early
lineages. After undifferentiated proliferation in vitro for 4 to
5 months, these cells still maintained the developmental
potential to form trophoblast and derivatives of all three
embryonic germ layers, including gut epithelium (endoderm);
cartilage, bone, smooth muscle, and striated muscle
(mesoderm); and neural epithelium, embryonic ganglia, and
stratified squamous epithelium (ectoderm). These cell lines
should be useful in human developmental biology, drug
discovery, and transplantation medicine.
19. CULTURE PROCEDURE
• Thirty-six fresh or frozen-thawed donated human embryos produced
by IVF were cultured to the blastocyst stage in G1.2 and G2.2
medium
• Fourteen of the 20 blastocysts that developed were selected for ES
cell isolation
• The inner cell masses were isolated by immunosurgery (26), with a
rabbit antiserum to BeWO cells, and plated on irradiated (35 grays
gamma irradiation) mouse embryonic fibroblasts
• Culture medium consisted of 80% Dulbecco's modified Eagle's
medium (no pyruvate, high glucose formulation; Gibco-BRL)
supplemented with 20% fetal bovine serum (Hyclone), 1 mM
glutamine, 0.1 mM -mercaptoethanol (Sigma), and 1% nonessential
amino acid stock (Gibco-BRL)
• After 9 to 15 days, inner cell mass-derived outgrowths were
dissociated into clumps by exposure to Ca2+/Mg2+-free phosphate-
buffered saline with 1 mM EDTA and replated on irradiated mouse
embryonic fibroblasts in fresh medium (Thomson et.al. 1998)
20. Expression of cell surface markers by H9 cells. Scale bar, 100 µm. (A)
Alkaline phosphatase. (B) SSEA-1. Undifferentiated cells failed to stain for
SSEA- 1 (large colony, left). Occasional colonies consisted of nonstained,
central, undifferentiated cells surrounded by a margin of stained,
differentiated, epithelial cells (small colony, right). (C) SSEA-3. Some small
colonies stained uniformly for SSEA-3 (colony left of center), but most
colonies contained a mixture of weakly stained cells and a majority of
nonstained cells (colony right of center). (D) SSEA-4. (E) TRA-1-60. (F)
TRA-1-81. Thomson et.al. 1998.
22. Adult Stem Cell
• An adult stem cell is an undifferentiated cell
found among differentiated cells in a tissue
or organ, can renew itself, and can
differentiate to yield the major specialized
cell types of the tissue or organ
• Some scientists now use the term Somatic
Stem Cell instead of adult stem cell
• the origin of adult stem cells in mature
tissues is unknown.
23. Where are adult stem cells found ?
• There are a very small number of stem cells in
each tissue
• The adult tissues reported to contain stem cells
include brain, bone marrow, peripheral blood,
blood vessels, skeletal muscle, skin and liver
• Stem cells are thought to reside in a specific
area of each tissue where they may remain
quiescent (non-dividing) for many years until
they are activated by disease or tissue injury
24. Tests for identifying adult stem
cells
• Labeling the cells in a living tissue with molecular
markers and then determining the specialized cell
types they generate
• Removing the cells from a living animal, labeling
them in cell culture, and transplanting them back
into another animal to determine whether the cells
repopulate their tissue of origin
• Isolating the cells, growing them in cell culture, and
manipulating them, often by adding growth factors
or introducing new genes, to determine what
differentiated cells types they can become
25. Adult Stem Cell Differentiations
• The bone marrow contains at least two kinds
of stem cells
• One population, called hematopoietic stem
cells, forms all the types of blood cells in the
body. A second population, called bone
marrow stromal cells
• Stromal cells are a mixed cell population
that generates bone, cartilage, fat, and
fibrous connective tissue.
27. Adult stem cell plasticity and
transdifferentiation
• Adult stem cells may also exhibit the ability to form
specialized cell types of other tissues, which is
known as transdifferentiation or plasticity
• Hematopoietic stem cells may differentiate into:
three major types of brain cells (neurons,
oligodendrocytes, and astrocytes); skeletal muscle
cells; cardiac muscle cells; and liver cells
• Bone marrow stromal cells may differentiate into:
cardiac muscle cells and skeletal muscle cells
• Brain stem cells may differentiate into: blood cells
and skeletal muscle cells.
34. What are the similarities and differences
between embryonic and adult stem cells?
• ESC
• can become all cell
types of the body
• easily grown in
culture
• Would be rejected
by the immune
system
• ASC
• differentiating into
different cell types
of their tissue of
origin
• Not so easy
• would not be
rejected by the
immune system
36. Potential uses of human stem cells
• Studies of human embryonic stem cells may yield
information about the complex events that occur
during human development
• Human stem cells could also be used to test new
drugs
• Perhaps the most important potential application of
human stem cells is the generation of cells and
tissues that could be used for cell-based therapies
• A significant hurdle to this use and most uses of
stem cells is that scientists do not yet fully
understand the signals that turn specific genes on
and off to influence the differentiation of the stem
cell.
37. Stem Cell Transplantation
To be useful for transplant purposes, stem cells
must be reproducibly made to:
• Proliferate extensively and generate
sufficient quantities of tissue
• Differentiate into the desired cell type(s)
• Survive in the recipient after transplant
• Integrate into the surrounding tissue after
transplant
• Function appropriately for the duration of the
recipient's life
40. An embryonic pancreas growing in culture, the red cells are insulin-producing beta cells
41. Monitoring Stem Cell Research
• The President's Council on Bioethics
Washington, D.C.
January 2004
www.bioethics.gov
• As with all dividing cells, stem cells are subject to a very small but
definite chance of mutation during DNA replication; thus, prolonged
growth in vitro could introduce genetic heterogeneity into an
originally homogeneous population
• During this process of repeated expansion and preservation, subtle
changes in the growth conditions or other variables may give rise to
“selective pressures” that can increase the heterogeneity in a stem
cell preparation by favoring the multiplication of advantaged cell
variants in the population
• Chances of Chromosome Changes
• Microbial Contamination
• Immune rejection
42. SUMMARY
• It is too soon to attempt to draw any
conclusions about the state of the
stem cell field that is changing very
rapidly.
• Much basic and applied research
remains to be done if human stem cells
are to achieve their promise in
regenerative medicine.
