Stem Cell – Definition A cell that has the ability to continuously divide and differentiate (develop) into various other kind(s) of cells/tissues
Stem Cell Characteristics • ‘Blank cells’ (unspecialized) • Capable of dividing and renewing themselves for long periods of time (proliferation and renewal) • Have the potential to give rise to specialized cell types (differentiation) • once the differentiation pathway of a stem cell has been decided, it can no longer become another type of cell on its own
Importance of Stem Cell Research
What makes stem cells so valuable? Modified from Keller & Snodgrass, Nat Med 1999 Cell Therapy Research New Drugs Pluripotent stem cells Tissue stem cells No one stem cell type fits all applications. Research must continue using all types of stem cells.
Sir John Gurdon and Dr. Shinya Yamanaka, Nobel prize in Medicine (2012) for the discovery that mature cells can be reprogrammed to become stem like Gurdon's research taught us that the nucleus of a mature, specialized cell can be returned to an immature state. The experiment involved the removal of cell nuclei with pipettes followed by their introduction into other cells. Would it ever be possible to turn an intact cell back into a stem cell?
Sir John Gurdon and Dr. Shinya Yamanaka, Nobel prize in Medicine (2012) for the discovery that mature cells can be reprogrammed to become pluripotent Yamanaka tried to find the genes that kept stem cells immature. After identifying several of these genes, he tested whether any of them could reprogram mature cells to become stem cells. He introduced these genes, in different combinations, into mature cells and found a combination that worked, and the recipe was surprisingly simple. By introducing four genes together, they could reprogram their fibroblasts into immature stem cells!
Areas of community concern • Why do the embryos have to be destroyed for stem cell research? Isn’t this the same as taking a life? • Wouldn’t it be better to donate the excess IVF embryos to other infertile couples? • Could women be forced to sell eggs or embryos for research? • Won’t doing therapeutic cloning lead to cloning humans?
Stem Cell Tourism A growing concern to the stem cell community
Using stem cells to conduct medical research and treat disease is acceptable? • Don’t know • No • Yes 3% 5% 92*% Biotechnology Community Attitudes to Biotechnology (2012) * Compares to 70% in 2005 survey But which type of stem cells? - pluripotent stem cells (embryonic, SCNT, iPS stem cells) - tissue stem cells (foetal, cord, adult)
1. gametogenesis 2. fertilization 3. cleavage 4. blastulation 5. gastrulation 6. organogenesis Development of Embryo-7 steps:
Fertilization 1. Sperm contacts the egg 2. Sperm or its nucleus enters the egg, and regulation of sperm entry .
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- Fall '19