| Neural stem cells (NSCs) are abundant in the developing mammalian central nervous system (CNS), but with time NSCs are progressively lost throughout most of the CNS. The adult spinal cord is thought to be devoid of NSCs, but when dissociated spinal cord tissue is exposed to mitogens in vitro, a subset of cells displays a NSC phenotype---i.e. capable of self-renewal and multipotency. However, without the ability to prospectively isolate these unique cells it is not possible to characterize them in detail, including their in vivo identity. Herein, I describe a strategy to prospectively isolate NSCs from a discrete anatomical region in the adult spinal cord, the central canal, using fluorescence activated cell sorting (FACS). Cells in the central canal of the spinal cord express CD133, PSA-NCAM, and CD24, surface markers that have been used to purify NSCs from the developing and adult CNS. By targeting these three surface proteins, I show that CD133+PSA-NCAM+CD24+ cells are able to produce neurospheres. Furthermore, I show that the CD133+PSA-NCAM+CD24+ cells are negative for LeX, a cell surface carbohydrate that has been used to purify NSCs from the adult subventricular zone (SVZ), a region of ongoing neurogenesis. Co-culturing FAC-sorted CD133+PSA-NCAM+CD24+ cells with astrocytes increases the yield of neurospheres by 2.7-fold. In addition, I show that the neurospheres that form from this population are not due to a circulating stem cell that has transdifferentiated. Unlike in the adult SVZ, where GFAP+ astrocytes are the in vivo NSC, astrocytes do not contribute to neurosphere formation from the CD133+PSA-NCAM+CD24+ population. Lastly, I show that unlike the adult spinal cord, a subpopulation of SVZ neurosphere-forming cells can be characterized as CD133+PSA-NCAM+CD24-, suggesting that a common surface profile is not conserved between NSCs from the adult spinal cord and SVZ. |
