A very brief account of Stem cells .

1. STEM CELLS
Dr. Saji Mariam George
Associate Professor (Retired)
Assumption College Autonomous
Changanacherry

2. STEM CELLS
• Undifferentiated cells of a multicellular organism which have the ability to
divide extensively (proliferate) and can differentiate into specialized cell
types.
Stem cells may be
• Totipotent - Cells produced by the first few divisions of the zygote are
totipotent. Such cells can form a complete viable organism .
or
Pluripotent - They are the descendants of totipotent cells and can
differentiate into nearly all cells types that make up the body - embryonic
stem cells are considered pluripotent.
or
Multipotent - cells can develop into more than one cell type, but are more
limited than pluripotent cells - adult stem cells and cord blood stem cells
are considered multipotent .
or
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., a stem cell that comes from the liver will only make more liver cells).

3. Stem cells
https://commons.wikimedia.org

4. https://www.medicinenet.com

5. Types of Stem cells
1. Embryonic stem cells
• Pluripotent embryonic stem cells originate as
inner cell mass cells within a blastocyst.
( A blastocyst is an early stage embryo
approximately 4 to 5 days old in humans
consisting of 50 – 150 cells ) .
• These stem cells can become any tissue in the
body , excluding a placenta.

6. Sources of human
embryonic stem cells
• Human embryonic stem
cells (hESCs) are extracted
from human embryos
created by in vitro
fertilization in
in vitro fertilization clinics
, which are no longer
needed.
• hESCs are pluripotent cells
– can proliferate
indefinitely in culture –
have the potential to
differentiate to any cell
type in the body.
http://sgugenetics.pbworks.com

7. 2. Amniotic fluid
stem cells
• Stem cells are also
found in amniotic fluid.
• Amniotic stem cells are
multipotent and can
differentiate into cells
of adipogenic,
osteogenic, myogenic,
endothelial, hepatic
and also neuronal lines.
https://www.europeanreview.org

8. 3. Adult stem cells
• The type of stem cells found in developed
organisms .
• Pluripotent adult stem cells are rare and
generally small in number but can be found
in various tissues.
• In adult organisms, stem cells act as a repair
system for the body, replenishing adult
tissues.

9. Sources of adult stem cells
1. Bone marrow
• Bone marrow is the soft spongy tissue that lies
within the hollow interior of long bones. In adults,
marrow in large bones produces new blood cells.
• Stem cells are extracted by drilling into bone.
• Bone marrow has been found to be one of the rich
sources of adult stem cells.
• Marrow in a human femur contain undifferentiated
cells that can replenish various types of blood cells.
These hematopoietic stem cells keep the circulatory
system supplied with lymphocytes, erythrocytes and
platelets.

11. 2. Adipose tissue (Lipid cells )
• Adipose tissue has higher
numbers of Mesenchymal
stem cells (MSCs) .
• Stem cells are extracted by
liposuction.
• MSCs are purified
and cultured.
• They are ‘multipotent’-
can produce more than one
type of specialized cell, but
not all types.
Human Mesenchymal stem cells
(MSCs) .
https://www.sigmaaldrich.com

13. 3. Tooth bud of the mandibular third molar (Wisdom
tooth)
• A source of adult stem cells.
• Dental stem cells are harvested from the dental pulp
within the tooth - Baby teeth and wisdom teeth have
dental stem cells – mesenchymal stem cells .
• These stem cells can form enamel, dentin,
periodontal ligament, blood vessels, dental pulp,
nervous tissues , hepatocytes etc.

14. • Because of extreme ease in collection at 8 – 10
years of age before calcification and minimal to no
morbidity , dental stem cells will probably
constitute a major source of cells for personal
banking for future therapies (Tooth banking) - can
be used to treat diseases, in regenerative medicines
- heal injuries and grow replacement tissues like
bone, cartilage, nerve , skin, blood vessels, muscles
etc. - and research .

15. Dental Stem cells
https://www.thailandmedical.news/news/study-uncovers-stem-cells-for-tooth-repairs

16. Tooth bud of the mandibular third molar
(Wisdom tooth)
• (A) After a tooth was cut
horizontally, the pulp tissue
(arrow) in the pulp chamber was
exposed; this pulp provides dental
pulp stem cells (DPSCs).
• (B) Extracted impacted third
molar (10-year-old , containing the
dental follicle (dotted line) that
provides dental follicle stem cells
(DFSCs). Bar: 5 mm.
• (C) Extracted impacted third molar
(18-year-old ) containing root
apical papillae (asterisks) that are
a source of stem cells from the
apical papilla (SCAP).
Figures - uploaded by Ikiru Atsuta
https://www.researchgate.net/publication/229
151758_Stem_cells_in_dentistry_-
_Part_I_Stem_cell_sources

17. 4. Blood
• Stem cells are extracted by passing blood through a
machine (Apheresis machine) that extracts the stem
cells.
5. Umbilical cord blood
• Stem cells can also be taken from umbilical cord
blood just after birth. These stem cells can be frozen
cryogenically for future medical use (Stem cell
banking) – can be used in the treatment of some
life-threatening diseases.

18. http://nbrpnig.nbrp.jp

19. Cord blood in treatment of diseases
https://www.cryo-cell.com/cord-blood-banking

20. 6. Placenta
• Placental
blood and
tissue also
contain
stem cells.
https://advancedrejuvenationinstitute.com

21. Applications of Stem cells
• The ability of stem cells to self – renew and
to differentiate into different types of tissues
offers great potential for generation of
tissues that can replace diseased and
damaged areas in the body with minimal risk
of rejection and side effects – Great scope in
regenerative and personalized medicine.

22. • Bone marrow transplantation is the only
established use of stem cells. Bone marrow stem
cells have been used in the treatment of Spinal
cord injury , Leukemia, Lymphoma, Liver
Cirrhosis, Endstage heart failure etc.
• Researchers hope that , in future, stem cell
therapy will help to treat cancer, Type 1
Diabetes, Parkinson’s disease, Alzheimer’s
disease, cardiac failure, muscle damage,
neurological disorders etc.

23. https://superstemcell.weebly.com/benefits-of-stem-cells.html

24. Stem cells – Limitations
• A number of stem cell therapies are possible, but
most of them are at experimental stages.
• Currently no approved treatments using embryonic
stem cells (ES cells) .
• ES cells being pluripotent, require specific signals for
correct differentiation – if injected directly into
another body, ES cells may differentiate into different
types of cells, causing teratoma.
• Transplanted stem cells may form tumours and
become cancerous if cell division continues
uncontrollably.

25. • Many nations currently have moratoria on either ES
cell research or the production of new embryonic
stem cell lines.
• Legal, moral and ethical issues and scientific
uncertainty in stem cell research.

26. THANK YOU