Neural stem cell biology took off in 1992 when Brent Reynolds and Samuel Weiss, working at the University of Calgary, discovered that culturing mammalian brain cells in serum-free conditions (in EGF and bFGF), yielded clonally derived colonies of undifferentiated neural cells (neurospheres). This culture system demonstrated that cells within these colonies showed cardinal properties of stem cells: self-renewal and multilineage differentiation.1
That led to the question: If this process worked for isolating stem cell populations from normal brain, could it be used to isolate stem cells from brain tumors? Several groups did exactly this to show that a minority of the cells in a brain tumor could clonally form colonies of cells in vitro that expressed neural precursor markers and that could be replated to reform colonies demonstrating self-renewal, as well as expression of mature neural-lineage markers after differentiation in vitro.2-5 Brain tumors contain a small population of cells that ...
