Stem Cell Engineering
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stem cell research aims to:
• create tissues/cells for transplantation: bone marrow for leukemia and chemotherapy; nerve cells for PD and AD; heart muscles cells for heart disease; and pancreatic islet cells for diabetes • study cell differentiation (understand prevention and treatment of birth defects) • identify drug targets and test potential therapeutics • toxicity testing
totipotency
ability of a cell to give rise to all cells of an organism, including embryonic and extra-embryonic tissues e.g. zygote
pluripotency
ability of a cell to give rise to all cells of the embryo and subsequently adult tissues e.g. embryonic stem cells
multipotency
ability of a cell to give rise to different cell types of a given lineage e.g. adult stem cells
embryonic stem (ES) cells
develop into different cell types with characteristics appropriate for that site (even germ cells) capable of proliferating indefinitely in culture with unrestricted developmental potential unable to generate a full organism
how to get ES cells
inner cell mass at blastocyst stage can extract ES cells and put back into blastocyst stage of animal and will integrate well with the embryo
ES cells –> adipocyte requires
• retinoic acid 2. insulin and thyroid hormone
ES cells –> neuron requries
retinoic acid
ES cells –> macrophage requires
• macrophage colony-stimulating factor 2. interleukin-3 and 1
ES cells –> smooth muscle cell requires
dibutyryl cAMP and retinoic acid
ES cells –> astrocytes and oligodendrocytes requries
• fibroblast growth factor • fibroblast growth factor 2; epidermal growth factor • fibroblast growth factor 2; derived growth factor
ES cells have to be injected during blastocyte stage, if injected at another time
teratomas (tumors) form due to lack of cues and signals for proper differentiation
high throughput screening
using stem cells to test large amounts of chemical compounds that show promise
somatic cell nuclear transfer (SCeNT)
-combines cloning methods with embryonic stem cell technology to produce cells which are custom-made for patient nucleus taken from somatic cell of patient and injected into oocyte of a donor replacing the oocyte nucleus –> blastocyst generated from this hybrid oocyte and ES cells isolated
what condition is being treated with SCeNT
type I diabetes
what cells can be injected with specific gene regulatory proteins so they form ES-like cells
fibroblasts
Induced Pluripotent Stem Cells (iPSC)
somatic cells (fibroblasts) being reprogrammed to form ES-like cells by exposure to transcription factors (Oct4, Sox2, Kif4, Myc, and Nanog)
What do Oct4, Sox2, Kif4, Myc, and Nanog genes do
• up regulate embryonic stem cell genes • up regulate cell proliferation • loosen chromatin structure • down regulate differentiation genes
main goals of Induced Pluripotent Stem cells (iPSC)
• study treatment of drugs on tissues 2. transplantation of genetically matched healthy cells
challenges for regenerative medicine and transplantation therapy
• production of cell types in pure form • production of sufficient numbers • delivery method • proper integration into tissue/organ • stability of cells in culture • tissue/immune rejection** • genetic and epigenetic changes**
for repair of skin, artificial matrix graft is composed of
matrix of collagen and glycosaminoglycan with thin membrane of silicone rubber on outside
how does cadaver or artificial graft result in healing
fibroblasts and blood capillaries from patient’s tissue migrate towards the artificial skin and reform connective tissue underneath graft while waiting for cultured epidermal cells to be ready