Stem cells have the ability to differentiate into specialized cell types and can self-renew to produce more stem cells. There are two main types: embryonic stem cells derived from embryos and adult stem cells found in adult tissues. In 2006, Shinya Yamanaka discovered that introducing four transcription factors (Oct4, Sox2, Klf4, c-Myc) into adult cells could reprogram them into induced pluripotent stem cells (iPSCs), which have properties similar to embryonic stem cells. This breakthrough provided a method to generate patient-specific stem cells for research and potential therapies without ethical concerns. However, iPSC reprogramming still has low efficiency and safety issues related to viral gene delivery that need further improvement

2. Outline
 Brief Introduction of stem cell
 What are stem cells
 Types of stem cell
 Various terminology
 Limitation of using ES cell & Adult stem cell
 Journey toward iPS cell
 Background / History
 Battle between Egg & nucleus for supremacy
 How Reprograming can be achieved
 Potential of iPSCs
 Application of this Technology
 Future of iPSCs
 Limitation/ problem
 Prospectus
 What I Realized

4.  unspecialized
 Can proliferate or self renew
 can be differentiated into
specialized cell

5. •
Discovered actually isolated in 1998
•
Discovered in 1960
SCAN – Stem Cell Action Network

7. eg. Zygot(fertilized egg) , early cleavage 2-3 cell blastomeres
eg. Embryonic stem cells (ES cells)
eg. Neural stem cell , haemopoetic stem cell & so on
eg. Germinal cell spermatogonia & oogonia

8. 1.
2.
3.
4.
5.

9. Phenotypically
Characterised
Adult Stem Cells

11.  Less plasticity (potency)
 Limited potential
 Less abundant
 Isolating is difficult
 As to use Embryonic stem cell
for the purpose either for
Research or clinical technique
one has to destroy the whole
developing embryo to isolate
those ICM
 And it is considered
something immoral so it is
been ethical issue therefore
banned in many countries
However, current research is changing some of these ideas
.

12. Problems with Adult Stem Cells
Mutations can lead to leukemia

13. Why Are Stem Cells Important?
- cell replacement therapy
- drug discovery
- Diseases model
- early human development

14. Dopaminergic Neuron
Parkinson Disease
Neural stem cells
Spinal cord injury
Cardiac cells
Cardiac failure
Pancreatic cells
Diabetics
Hepatic cells
Hepatic failure
Bone cells
Osteoporosis
Muscle cells
Dystrophy
Bone marrow cells
Leukemia
Skin cells
Burn

16. John gurdon
Shinya
yamanka

17. Journey of human start from single cell
zygote(fertilized egg)

18. Robert briggs
(1911-1983)
Thomas J. king
1921-2000
• In 1952, They worked on a frog, Rana pipiens, became the first to successfully
transplant living nuclei in multicellular organisms. They transplanted later embryo
(blastula ) cell nuclei into enucleated eggs, which then developed into normal
embryos.
• They were initiator of using SCNT for first time
• However, the successful transplants that Briggs and King performed were of
undifferentiated nuclei
• Until it was possible to accomplish the same feat with a differentiated nucleus, it
would remain an open question as to whether the genome itself somehow
changed during development

19. Robert briggs
(1911-1983)
Thomas J. king
1921-2000
• If & only nucleus transplanted is from the same species as the egg
cytoplasm then only egg will cleaves and can develop in to a normal
embryo….further to tadpole
• There something happens when the cell get differentiated that make the
nucleus unable to reprogramed or participating in normal development
whether it was loss of Genes or some permanent inactivation
• But that was also not clear

21. Sir John Gurdon
• In 1958, Gurdon, at the University of
Oxford successfully transplanted
intestinal epithelium-cell nuclei
from Xenopus tadpoles into enucleated
frog eggs and managed to produce 10
normal tadpoles: Molly and her fellow
clones
• This work was an important extension of
work of Briggs and King
• It was cleared that all cell have contain
Blueprint of life
The logical consequence of Gurdon's success — that the nuclei of differentiated cells
retain their totipotency — provided a key conceptual advance in developmental
biology.

23. Sir John Gurdon
• Genes were not lost or changed
during cell differentiation — they
were just differentially expressed.
• It was cleared that all cell have
contain same Blueprint of life
• It proved once-and-for-all that the
genome remained intact during
differentiation and that the
epigenetic changes to the somaticcell nucleus were reversible.
Provide the Key

24. Analyses difference between Resistance(repression) & activation state of genes

25. The battle for supremacy
The egg
The nucleus
Designed to
transform sperm
to an embryo
active nucleus
Designed to
maintain the
same pattern of
gene expression
Tries to do the
same for somatic
nuclei
Tries to resist any
change

26. A sperm nucleus is specially designed to yield
normal development
Sperm cell
99%
Embryo cell
35%
Specialized cell
1%
% of normal development after nuclear transfer (to a feeding tadpole)
Images from Dr Kei
Miyamoto

27. Cloning of sheep : Dolly by SCNT
1998

29. Human ES cells
hES cell
• In 1998, Thomson’s Lab was the first to
report the successful isolation of human
embryonic stem cells.
• On November 6, 1998, Science published
this research in an article titled "Embryonic
Stem Cell Lines Derived from Human
Blastocysts", results which Science later
featured in its “Scientific Breakthrough of
the Year” article, 1999
Dr. James Thomson, 1998

30. 2006
Dr. Shinya
Yamanaka, PhD
2007
Dr. Kazutoshi
Takahashi, PhD
Human iPSCs

31. induced Pluripotent stem cells (iPSC)
Reprogramming
factor
Using Retrovirus for induction
ES like cell
iPS cell
A combination of several genes can re-program skin fibroblasts into
pluripotent cells

32. Shinya Yamanaka:
James A Thomson
OCT3/4
OCT3/4,
SOX2
SOX2
C-myc
NANOG
Klf4
LIN28
iPSCs were 1st produced in 2007 from human cells by Shinya
Yamanka team at Kyoto University Japan, and by James Thomson's
team at the University of Wisconsin-Madison. independently

33. Potential of Induced Pluripotent Stem Cells

34. Retroviruses
• Randomly inserts DNA into genome of cells
• The host cell then treats the viral DNA as part of its
own genome, translating and transcribing the viral
genes along with the cell's own genes, producing the
proteins required to assemble new copies of the
virus.
• Can make special retroviruses with whatever gene
you want
• Can’t really control how
many copies of genes

35. Takahashi and Yamanaka, Cell, Aug 25, 2006

36. Four Magic Genes
•
•
•
•
Sox2- Self Renewal
Oct4- Differentiation switch
Klf4- p53 pathway, Oncogene
c-Myc- Global Histone Acetylation, Oncogene

37. Reprogramming Factors – Magic Four
24 candidates
expressed in embryonic stem cells
10 candidates
4 candidates
Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. Takahashi and Yamanaka. Cell. 126, 663-676,
2006.

41. Reprogramming Menu

42. Different cells have different efficiency for
reprogramming

43. iPS cell sources
• Cell type effects reprogramming efficency
• Human iPS cells
–
–
–
–
–
Fibroblasts and keratinocytes - most common sources
Neural cells - neural stem cells need only Oct4
WBCs from blood being developed - convient
Amniotic Fluid cells -increased efficency
Melanocytes - increased efficency.

45. Long-Term Applications

46. Applications of Human pluripotent stem Cells
•
•
•
•
•
•
Basic Knowledge of Human Development
Models of Human Disease
Human model for drug screnning
Transplantation-Cell Replacement
Drug Development
Regenerative Medicine / Therapeutic
cloning/ Cell replacement therapy
• Organogenesis

48. In 1962
Cloning in Frog
Gurdon
1997
Cloning in Sheep
Wilmut
2001
ESC fusion
Tada
1987
Weintraub
the transcription factor MyoD
turns fibroblasts into muscle
1981
Mouse ESCs
Evans Martin
2006
iPSCs
Shinya
yamanka
1998
Human ESCs
Thomson

50. ?
Human
iPSC therapy
?
2007
Mouse
iPS therapy
2006
iPSCs
Shinya yamanka
2009
Patient iPSCs
Dalley
Eggan
2008
In vivo direct
Reprogramming
Melton
?
Drug discovery
?
2012 Mouse Therapy by
Direct reprogramming
Srivastava

51. iPSCs has been generated from
Mouse (Yamanaka et al., 2006)
Humans (Yamanaka et al., 2007)
Rhesus monkey (Liu et al., 2008)
Rats (Liao et al., 2009; Li et al., 2009)
Canine (Shimada, H. et al, 2010)
Porcine ( Esteban, M. A. et al., 2009)
Marmoset (Wu, Y. et al., 2010)
Rabbit (Honda, A. et al., 2010)
Equine (Kristina Nagy et al., 2011 )
Avian (Lu et al., 2011)

52. our contributions to iPSC research
Efficiency and Kinetics
•
•
•
Secondary reprogramming system.
Differentiation state of starting cells.
Endogenous level of reprogramming factors.
Safety
• iPSC without viral integration.
• Selection of bonafide iPS clone
based on Imprinting pattern.
Disease Modeling
• Disease specific iPS.
• Differentiation bias due to epigenetic memory.
• Ease in gene targeting in hiPS with murine ES
cell state.

53. iPS cell reprogramming: Problems
• Low efficiency of reprogramming
• As using of retroviruses for induction of
factors can lead to mutations and cancers
• Epigenetic memory
• So many changes in the DNA can be harmful
• Risk of tumour formation
• Efficient differentiation protocols required

54. What I Myself Realize
“ Always Biological science
especially Cell biology is
intricately Designed to the point
where the more We Discover the
more We realize how much there
is to discover it is like Question
which Yield a thousand
Questions”