Stem cells, pluripotency, Yamanaka factors, regeneration, organoids, dedifferentiation.
Stem Cells And Development Principles
Stem cell
Undifferentiated cell with dual capacity: self-renewal (divide to produce daughter stem cells) + differentiation into specialised cell…
Embryonic stem cell (ESC)
Pluripotent cell from inner cell mass of blastocyst (Evans-Kaufman-Martin 1981). Can differentiate into all three germ layers; maintained…
Induced pluripotent stem cell (iPSC)
Somatic cell reprogrammed to pluripotency by ectopic Yamanaka factors (Oct4, Sox2, Klf4, c-Myc). Takahashi-Yamanaka 2006 (mouse), 2007…
Yamanaka factors
Core pluripotency transcription factors OSKM: Oct4, Sox2, Klf4, c-Myc. Sufficient to reprogram fibroblasts to iPSCs; c-Myc replaceable…
Adult (tissue) stem cell
Multipotent/unipotent stem cell in adult tissue niche: HSC (blood), satellite cell (muscle), Lgr5+ crypt-base cell (intestine), neural stem…
Organoid
3D self-organising miniature organ grown from stem cells in Matrigel. Recapitulates crypt-villus (intestine), nephron (kidney), cortex…
Tissue regeneration
Restoration of lost/damaged tissue. Epimorphic (blastema formation: salamander limb, zebrafish fin) vs morphallactic (remodelling without…
Hematopoietic stem cell
Bone-marrow self-renewing cell giving rise to all blood lineages. First stem cell characterised (Till & McCulloch 1961). Foundation of BM…
Stem cell niche
Tissue microenvironment maintaining stem-cell self-renewal + quiescence (Schofield 1978). Signals: Wnt, Notch, BMP, direct contact with…
Direct lineage reprogramming
Transdifferentiation: forcing one differentiated cell type into another without iPSC intermediate via transcription-factor cocktails…