2. iPS cell
‘Induced pluripotent stem
cell is a type of pluripotent
stem cell artificially derived
from a non-pluripotent cell -
typically an adult somatic
cell - by inducing a "forced"
expression of specific genes’.
Baker, Monya (2007-12-06). "Adult cells reprogrammed to pluripotency, without
tumors". Nature Reports Stem Cells. doi:10.1038/stemcells.2007.124
4. President of the International Society
for Stem Cell Research (ISSCR).
MBBS
MD (1987)
Ph. D (1993)
Residency in Orthopedic surgery
Post doctoral fellowship in Cardiovascular disease
Professor of anatomy
University of California,
San Francisco, USA
5. Nobel prize awarded for
• Generation of induced pluripotent stem cells from adult mouse
fibroblasts (2006)
• Closedly resembled embryonic stem cells (in vivo equivalent of
blastocyst)
• iPSC were pluripotent – could generate whole iPSC mice
• iPSC cells from human adult fibroblasts for the first time (2007)
• Initially used 24 transcription factors for inducing pluri-potency
• Successful in narrowing down the number of factors to just 4
Sox2, Oct4, Klf 4 and c-Myc
13. How was iPSC possible?
• Reprogramming by nuclear transfer
• Tadpoles from unfertilized eggs that
received nucleus from intestinal cells of
adult frogs (Gurdon J 1962)
• Cloning of Dolly (Wilmut W 1997)
• Adult somatic cells contain all genetic
information
• Oocyte contain factors that can
reprogram somatic cell nuclei, so do ESC
(Tada T 2001)
1Past
14. How was iPSC possible?
• Discovery of transcription factors
– Genes of drosophila coding for antenna could
form legs when ‘antennapeda’ was introduced
(Schneuwly 1987)
– Mammalian fibroblasts converted to myocyte
using MyoD (Davis 1987)
2
15. How was iPSC possible?
• Generation of ESC, mouse (Evans 1981),
human (Thomson 1988) and culture media
• Long term maintenance of pluripotency using
LIF (Smith 1988)
• Optimal cultural conditions with bFGF
3
16. • iPSC : simplicity and reproducibility
• Poor efficacy: success rate 1% (?)
• Integrated vectors used for introducing
transcription factors -> retroviruses, can cause
mutagenesis & other adverse effects
• Use of non-integrated vectors: plasmid, Sendai
virus, adenovirus, synthetic RNA and proteins
• Technology development -> applications
Present
17. Current works focused in
Regenerative medicine
–Parkinson's disease
–Platelet deficiency
–Spinal cord injury
–Macular degeneration
Future
18. Disease models
• Patient derived iPSC used for testing of drugs &
toxins
• Found useful for creating models of late onset
diseases like Parkinson’s, Alzheimer’s,
Schizophrenia
• Analysis of disease mechanisms
19. Use in animals
• Genetic engineering
• Production of deficient proteins e.g.
enzymes
• Preservation or recreation of endangered
or extinct animals
20. Direct reprogramming
• In vivo conversion of exocrine pancreatic cells to
endocrine using 3 transcription factors (Zhou
2008)
• In vitro conversion of adult mature fibroblasts to
neural cells, hepatocyte, cardiomyocyte or
hematopoietic progenitor cells
• Problem: source of cells?
A step ahead
21. iPSC Vs ESC
• Similar and different Source of tissue
– Culture medium
– Source of clone e.g. labs
– Vectors used
– Both are basically artificial cells
22.
23. Dark side
• Variation in
– gene expression
– DNA methylation
– Pluripotent potential
– Somatic mutations
– Copy number variations
– Immunogenicity
24. So is it just another hoax?
DARK SIDE
UNDER ATTACK
FLAWED
TROUBLESOME
GROWING
PAINS
25. Not really
• Genetic defects preexisted
in source cells
• Cloning magnified the
defects
• Immunogenicity is very
weak - its effects nil in
animal experiments
• ESC not gold standard for
comparisons of iPSC
26. Conclusions
• iPSC technology ready for applications
• Necessity of establishment of in-advance
stocks of clones
• Source of tissue: healthy donors, cord blood,
HLA homozygous donors
In this journal club I intend to discuss a review article discussing iPSC, which will broaden our knowledge about contemporary research in anatomy and cell biology.At the end of session one should be able to write at least a short note in iPSC.
To start with…Before we proceed to the article of discussion itself.. A brief note on how how came across this article and why we should know about iPSC .Baker, Monya (2007-12-06). "Adult cells reprogrammed to pluripotency, without tumors". Nature Reports Stem Cells. doi:10.1038/stemcells.2007.124
Chinese? Nepalese? Naaa Japanese. He had a very interesting and unique career.
Born in 1962, Osaka , JapanHe was regarded as a lousy surgeon by his colleagues and was nicknamed "Jamanaka” a Japanese word for ‘obstacle’ after he took more than an hour to remove a benign tumor which usually takes not more than 10 minutes. Interestingly, one reason he was admitted into his first stem cell research because of his can do attitude.
Like anybody else, I was more curious than before and wanted to know more about iPSC. I turned to PubMed.
Within 4-5 years around 5 thousand articles were published on iPSC.
I came across what I was looking for..
A review article written by the master himselfBefore we discuss the article it would be a good idea to go through some terms that we need to understand.
Alexander Maksimov 1908 postulated hematopoetic stem cellsJoseph Altman and Gopal Das1960 Vs CajalTill and McCulloch 1963, hematopoeticSo there was this need for stem cells that were not antigenic and the best candidate for this was stem cell derived from the patient or subject himself.Another term is transcription factor.
These are inserted into cell and then into nucleus using vectors most common of which are retrovirus. Retroviruses remain in cell thereafter (Integrated)With this background, now lets proceed to the article.
First we will discuss the past? What made scientists to think that somatic or terminally differentiated cells could be reverted back to stem cells .There were 3 streams of researches which cumulated into scientists believe that iPSC were possible.
ESC: extra embryonic stem cellsDonar cell taken from mammary gland.Dolly Parton
iPSC are being generated and researched by labs throughout the world owing to its …..but has been criticized for ,,,,due to not very clearly known reasons.
What will the audience be able to do after this training is complete?Briefly describe each objective and how the audience will benefit from this presentation.
If somatic cells can be converted to stem cells why cant one somatic cell type converted to another somatic cell type e.g. hepatocyte to cardiomyocyte?
Use a section header for each of the topics, so there is a clear transition to the audience.