Transcript 01 stem cell

Dr. Abdullah Aldahmash
Stem Cell – Definition
• A cell which has the
ability to
continuously divide
and differentiate
into various other
kinds of
cells/tissues
Classifications of stem cells I
Potency
Description
Totipotent
1-3 days, differentiate into
embryonic and extraembryonic
cell types
Pluripotent
Descendants of totipotent cells
and differentiate into cells of 3
germ layers
Multipotent
Produce cells of a closely related
family of cell (e.g. hematopoietic
stem cells
Oligopotent
Differentiate into ONLY a few
cells, such as lymphoid or myeloid
stem cells
Unipotent
Produce ONLY one cell type (e.g.
muscle stem cells)
Nullpotent
The terminal cell
Classifications of stem
cells II
Adult
Embryonic
(Tissue
Specific)
Cloned
(Somatic Cell
Nuclear
Transfer)
Induced
Adult stem cells
(Tissue Specific Stem
Cell)
Found in specific
mature body tissues
as well as the
umbilical cord and
placenta after birth.
They also can be
isolated of
developing embryos’
different tissues
Embryonic Stem
Cell
Embryonic human stem
cells were first isolated in
1995 by Dr. James
Thomson.
Source of ESC is
Blastocysts (IVF, SCNT)
SCNT
The aim of this procedure is to obtain stem cells
that are genetically matched to the donor
organism.
Not all of the donor cell's genetic information is
transferred, as the donor cell's mitochondria that
contain their own mitochondrial DNA are left
behind
The basis of this technique is cloning animals
(such as the famous Dolly, the sheep).
The importance of SCNT-based stem cell
research has been decreased by the
development and improvement of alternative
methods of generating stem cells.
SCNT
iPS
It occurs by the introduction of a
defined and limited set of
transcription factors and culturing
these cells under ES cells
conditions.
A retroviral-mediate introduced to
four transcription factor (OCT3/4,
SOX2, c-MYC, KLF4) could
induce pluripotency.
This protocols has been applied
to mouse cells and human
somatic cells.
Nishikawa, S et.al., 2008
iPS
Skin cells were
taken from the tail
tip of a sickle-cell
model mouse.
The cells were
differentiated into
hematopoietic cells.
The produced cells
were transfused
back into the sick
mouse
Hanna J. et.al., 2007
+LIF
Self-renewal
differenti
ation
Thomson et al., 1998.
Thomson et al., 1998.
Secrete unknown factors
to the media
Characterization of Human
ESCs
SSEA-4
Sox-2
Sox9
Sox17
Oct-4
Beta-III tubulin
Isolate inner cell mass
(destroys embryo)
Day 5-6
Blastocyst
Inner cells
(forms fetus)
Culture cells
“Special sauce”
(largely unknown)
Beta-cells
Neurons Heart muscle
Heart
repaired
The Promise of Stem Cell
Technology
Replacement of tissues/organs
Repair of defective cell types.
Study cell differentiation
Toxicity testing.
Understanding prevention and
treatment of birth defects.
Study of development and
gene control.
Study of drugs therapeutic
potential.
current advances in Stem Cells
therapy
Tissue engineering
Cell based therapy
Obstacles of Stem Cell Research
How to find the right type of stem cells?
How to put the stem cells into the right place?
Will the stem cells perform the desired function in
the body?
Differentiation protocols for many cell types have
not been developed.