سلولهای بنیادی عصبی در گروههای مجزایی در مغز پستانداران بالغ واقع شده اند

Title

Neural Stem Cells Reside in distinct pocket in the adult mammalian brain

English Abstract

It is now clear that new neurons continue to be generated in the adult mammalian brain, and that endogenous neural stem cells (NSCs) provide the basis for replacing those neurons lost due to normal processes, such as ageing, or in response to pathological insults, such as spinal cord injury or stroke. Owing to the absence of a positive marker distinguishing NSCs from other precursor populations, we know little about the activity of endogenous stem cells, and even less about their regulation. A defining characteristic that distinguishes endogenous NSCs from more committed progenitors is their relatively quiescent nature. Here we sought to identify infrequently cycling endogenous NSCs by "pulsing" dividing cells with BrdU for a period of 1 month. This was followed by "chasing" these cells for a period of three months post-injection, over which rapidly cycling cells will have diluted their label leaving only slow cycling or label retaining cells (LRCs). An analysis of the distribution of LRCs along the adult mouse ventricular neuraxis was accomplished by serially sectioning (14 µm) the entire brain (n=5 mice), and counting the number of BrdU-immunoreactive cells that did not colocalize with markers of mature cell types (NeuN, GFAP, S-100, O4). This analysis revealed three distinct regions where high concentrations of LRCs correlated exactly with peaks in the number of neurosphere-forming cells that could be harvested. However, as neurosphere formation is indicative of both stem and progenitor cells, we are currently employing the neural-colony forming cell assay, which can be distinguish stem from progenitor cells based on colony size, to determine what percentage of LRCs are indeed NSCs.

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