Neural Stem Cells notes for module 2 Stem Cells ~ Small minority of cells which can maintain an entire organ or tissue for an extended period of time, contributing to recovery after perturbation ~ An undifferentiated cell which retains the capacity to: a) Proliferate b) Self-renew over an extended period of time c) Multi-potent d) Regenerate Tissue following Injury (Differentiation and Regeneration) e) A flexibility of use in these options ~ Multi-potent stem cells are found in different places over time » Classic idea – Hematopoetic system A) Proliferation ~ Process that involves a sequential pattern of cyclic changes in gene expression that ultimately leads to division of the cells ~ Essentially, entails progression through cell cycle with concurrent alteration in a number of gene products ~ Many stem cells undergo proliferation at a very slow rate, often stalling at the G-phase (Quinescent), but able to re-enter the cycle B) Self-renewal/Self-maintenance ~ Over an extended period of time to keep at an existing state or level ~ If not self-renewing, eventually lose population of progenitor/stem cells C) Multi-potent ~ Generate a large family of different progeny ~ Totipotent Pluripotent Multi-potent Bi-potent  Uni-potent (aka blast cell) » Less potent = more committed D) Differentiation