stem cells

stem cells

unspecialized cells that can develop into many kinds of cell types

embryonic stem cells

• cells removed from a destroyed embryo

• pluripotent—can become any cell type

downsides of embryonic stem cells

• ethical concerns:

  • an embryo must be destroyed to collect stem cells

• immune system may cause rejection, as the cells did not originate in the recipients body

adult stem cells

• can be taken from any tissue, although the bone marrow is the easiest to access

• multipotent—can only be turned into some kinds of cells

why use adult stem cells?

• no worries of rejection; cells are taken from recipient

  • less ethical concern

induced pluripotent stem cells

pluripotent stem cells created from adult cells by reprogramming them back to an embryonic-like state

how are stem cells differentiated into different cell types?

different culture conditions in the lab create specialized responses in the cells which allow them to correctly differentiate

are induced pluripotent stem cells and adult stem cells different?

YES! iPSC’s are pluripotent (can become any cell type), but must be created in a lab; adult stem cells are found naturally in the body, but are only multipotent (can become limited cell types)

ways to induce pluripotency?

• adding genetic material

  • Yu et al. added extra DNA which forced the cells to express four genes that induced pluripotency

• chemical reprogramming

  • Guan et al. treated fibroblasts with a sequence of chemicals that induced pluripotency by targeting certain metabolic pathways

downside of adding genetic material to induce pluripotency?

extra DNA can cause cancer if not monitored closely

What four genes are necessary to induce pluripotency?

OCT4, SOX2, NANOG, and LIN28