2. Stem Cell Basics
• I. Introduction: What are stem cells/ Research
• II.What are the unique properties of all stem cells?
• III. Types of stem cells
• IV.
What are the similarities and differences between embr
• V. What are the potential uses of stem cells?
3. Introduction
• Stem cells are cells that have the remarkable
potential to develop into many different cell
types in the body during early life and growth
• In addition, in many tissues they serve as a
sort of internal repair system, dividing
essentially without limit to replenish other
cells as long as the person or animal is still
alive
4. • When a stem cell divides, each new cell has the
potential either to remain a stem cell or become
another type of cell with a more specialized
function, such as a muscle cell, a red blood cell, or a
brain cell
• Stem cell research.
Reseach on stem cells with a primary goal to
identify how undifferentiated stem cells become
the differentiated cells that form the tissues and
organs
5. • Scientists know that turning genes on and off is
central to this process. Some of the most serious
medical conditions, such as cancer and birth
defects, are due to abnormal cell division and
differentiation.
• A research for more complete understanding of the
genetic and molecular controls of these processes
may yield information about how such diseases
arise and suggest new strategies for therapy
6. Stem cells are distinguished from other cell
types by two important characteristics.
• i. They are unspecialized cells capable of renewing
themselves through cell division, sometimes after
long periods of inactivity
• ii. Under certain conditions, they can be induced to
become tissue- or organ-specific cells with special
functions.
7. • In some organs, such as the gut and bone
marrow, stem cells regularly divide to repair
and replace worn out or damaged tissues
• In other organs, however, such as the
pancreas and the heart, stem cells only divide
under special conditions.
8. II.
What are the unique properties of all stem cells?
• All stem cells—regardless of their source—have
three general properties:
ii. They are capable of dividing and renewing
themselves for long periods
iv.They are unspecialized
vi.They can give rise to specialized cell types.
9. Potency specifies the differentiation potential (the
potential to differentiate into different cell types) of
the stem cell
• Totipotent (a.k.a omnipotent) stem cells can differentiate into embryonic
and extraembryonic cell types. Such cells can construct a complete, viable
organism. These cells are produced from the fusion of an egg and sperm
cell.
• Pluripotent stem cells are the descendants of totipotent cells and can
differentiate into nearly all cells, i.e. cells derived from any of the three
germ layers.
• Multipotent stem cells can differentiate into a number of cells, but only
those of a closely related family of cells.
• Oligopotent stem cells can differentiate into only a few cells, such as
lymphoid or myeloid stem cells.
• Unipotent cells can produce only one cell type, their own,but have the
property of self-renewal which distinguishes them from non-stem cells
(e.g. muscle stem cells).
10. Types of stem cells
• Often based on where in the body or what stage in
development they come from
11. 1. Embryonic Stem Cells
• Embryonic stem cells are derived from very
early embryos and can in theory give rise to all
cell types in the body.
• However, coaxing these cells to become
a particular cell type in the laboratory is not
trivial.
• Furthermore, embryonic stem cells carry the
risk of transforming into cancerous tissue
after transplantation
12. The morula's cells are totipotent, able to become all
tissues and a placenta.
13. 2. Adult Stem Cells or Tissue-specific
Stem Cells
• Many adult tissues contain stem cells that can
replace cells that die or restore tissue after injury.
• Skin, muscle, intestine and bone marrow, for
example, each contain their own stem cells. In the
bone marrow, billions of new blood cells are made
every day from blood-forming stem cells
14. • Adult stem cells are tissue-specific, meaning they
are found in a given tissue in our bodies and
generate the mature cell types within that
particular tissue or organ.
• It is not clear whether all organs, such as the heart,
contain stem cells. The term ‘adult stem cells’ is
often used very broadly and may include fetal and
cord blood stem cells
15. a. Fetal Stem Cells
• As their name suggests, fetal stem cells are
taken from the fetus.
• The developing baby is referred to as a fetus
from approximately 10 weeks of gestation.
• Most tissues in a fetus contain stem cells that
drive the rapid growth and development of the
organs
16. • Like adult stem cells, fetal stem cells are generally
tissue-specific, and generate the mature cell types
within the particular tissue or organ in which they
are found.
17. b. Cord Blood Stem Cells
• At birth the blood in the umbilical cord is rich in
blood-forming stem cells.
• The applications of cord blood are similar to those
of adult bone marrow and are currently used to
treat diseases and conditions of the blood or to
restore the blood system after treatment for
specific cancers.
• Like the stem cells in adult bone marrow, cord
blood stem cells are tissue-specific
18. • To be used in cell transplant treatments the
cells will most likely need to be directed into a
more mature cell type, both to be
therapeutically effective and to minimize risk
that cancers develop.
• There are currently no treatments using
embryonic stem cells accepted by the medical
community.
19. 3. Induced Pluripotent Stem Cells
(iPS cells)
• In 2006, scientists discovered how to “reprogram”
cells with a specialized function (for example, skin
cells) in the laboratory, so that they behave like an
embryonic stem cell.
• These cells, called induced pluripotent cells or iPS
cells, are created by inducing the specialized cells to
express genes that are normally made in embryonic
stem cells and that control how the cell functions.
20. • Shinya Yamanaka and his colleagues at
Kyoto University used the transcription factors
Oct3/4, Sox2, c-Myc, and Klf4 to induce
epithelial cells to be like embryonic stem cells.
21. • Embryonic stem cells and iPS cells share many
characteristics, including the ability become the
cells of all organs and tissues, but they are not
identical and can sometimes behave slightly
differently.
• IPS cells are a powerful method for creating
patient- and disease-specific cell lines for research.
However, the techniques used to make them need
to be carefully refined before they can be used to
generate iPS cells suitable for safe and effective
therapies
22. V. Potential uses of stem cells
• Human stem cells could be used to test new drugs.
For example, new medications could be tested for
safety on differentiated cells generated from
human pluripotent cell lines.
• Generation of cells and tissues that could be used
for cell-based therapies.
e.g Today, donated organs and tissues are often used
to replace ailing or destroyed tissue, but the need
for transplantable tissues and organs far outweighs
the available supply
23. • Stem cells, directed to differentiate into specific cell
types, offer the possibility of a renewable source of
replacement cells and tissues to treat diseases
including, spinal cord injury, burns, heart disease,
diabetes, osteoarthritis, and rheumatoid arthritis.
25. 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.
26. To summarize
• Stem cells offer exciting promise for future
therapies, but significant technical hurdles
remain that will only be overcome through
years of intensive research
