Journey to iPS Cell our future


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it gives detail or you can say brief introduction of iPS cells , what are they , how can be obtained , what are the future possibilities of iPS cells what promise it made to upcoming future technology to medical health

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Journey to iPS Cell our future

  1. 1. 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
  2. 2.  unspecialized  Can proliferate or self renew  can be differentiated into specialized cell
  3. 3. • Discovered actually isolated in 1998 • Discovered in 1960 SCAN – Stem Cell Action Network
  4. 4. 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
  5. 5. 1. 2. 3. 4. 5.
  6. 6. Phenotypically Characterised Adult Stem Cells
  7. 7.  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 .
  8. 8. Problems with Adult Stem Cells Mutations can lead to leukemia
  9. 9. Why Are Stem Cells Important? - cell replacement therapy - drug discovery - Diseases model - early human development
  10. 10. 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
  11. 11. John gurdon Shinya yamanka
  12. 12. Journey of human start from single cell zygote(fertilized egg)
  13. 13. 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
  14. 14. 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
  15. 15. 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.
  16. 16. 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
  17. 17. Analyses difference between Resistance(repression) & activation state of genes
  18. 18. 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
  19. 19. 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
  20. 20. Cloning of sheep : Dolly by SCNT 1998
  21. 21. 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
  22. 22. 2006 Dr. Shinya Yamanaka, PhD 2007 Dr. Kazutoshi Takahashi, PhD Human iPSCs
  23. 23. 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
  24. 24. 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
  25. 25. Potential of Induced Pluripotent Stem Cells
  26. 26. 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
  27. 27. Takahashi and Yamanaka, Cell, Aug 25, 2006
  28. 28. Four Magic Genes • • • • Sox2- Self Renewal Oct4- Differentiation switch Klf4- p53 pathway, Oncogene c-Myc- Global Histone Acetylation, Oncogene
  29. 29. 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.
  30. 30. Reprogramming Menu
  31. 31. Different cells have different efficiency for reprogramming
  32. 32. 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.
  33. 33. Long-Term Applications
  34. 34. 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
  35. 35. 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
  36. 36. ? 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
  37. 37. 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)
  38. 38. 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.
  39. 39. 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
  40. 40. 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”