Biomedical cell biology: Stem cells

• cells which are not terminally differentiated
• can divide without limit
• division results in daughter cell having a choice: remain stem cell (self renewal), differentiate

adult stem cell - brain, spinal cord, liver, muscle, bone marrow

cord blood stem cells: purified from umbilical cord

fetal stem cells - early development aborted fetus (5-11 weeks gestation)

embryonic stem cells - embryos (<6 weeks) and blastocysts (<2 weeks) virtually immortal

totipotent - fertilized oocyte (zygote) and progeny of the first two cell divisions - cells able to form the embryo and the trophoblast of the placenta

pluripotent - embryonic stem cells derived from the inner cell mass of pre-implantation blastocysts, capable of producing cells from all three germ layers - but not an embryo

multipotant cells - present in most tissues, produce a limited range of differentiated cell lineages appropriate to their location (hematopoietic stem cells from the bone marrow)

Unipotential cells - generate only one cell type (epidermal cells, liver stem cells)

SEE IMAGE AND REMEMBER!

Embryonic stem cells derived from pre-implantation blastocysts can differentiate once cultured into adipocytes, nerve, blood and pancreatic beta cells

Embryonic stem cell lines

• clonogenic and proliferate without transformation or immortalization
• stable diploid karyotype
• unlimited self renewal and high amplification capacity
• pluripotent - retain ability to participate fully in fetal development when reintroduced into the embryo
• multilineage differentiation in culture - to generate all fetal and adult cell types in vitro
• permissive to genetic manipulation

self renewal vs differentiation SEE IMAGE

LIF - leukemia inhibiting factor

alkaline phosphotase is a marker of pluripotency (ability for a stem cell to differentiate)

Leukemia inhibitory factor, or LIF, is an interleukin 6 class cytokine that affects cell growth by inhibiting differentiation. When LIF levels drop, the cells differentiate

SELF renewal:

Nanog: NANOG (pron. nanOg) is a transcription factor critically involved with self-renewal of undifferentiated embryonic stem cells. In humans, this protein is encoded by the NANOG …