Pluripotent stem cells engrafted into the normal or lesioned adult rat spinal cord are restricted to a glial lineage

Proliferating populations of undifferentiated neural stem cells were isolat ed from the embryonic day 14 rat cerebral cortex or the adult rat subventri cular zone. These cells were pluripotent through multiple passages, retaini ng the ability to differentiate in vitro into neurons, astrocytes, and olig odendrocytes. Two weeks to 2 months after engraftment of undifferentiated, BrdU-labeled stem cells into the normal adult spinal cord, large numbers of surviving cells were seen. The majority of the cells differentiated with a strocytic phenotype, although some oligodendrocytes and undifferentiated, n estin-positive cells were detected; NeuN-positive neurons were not seen. La beled cells were also engrafted into the contused adult rat spinal cord (mo derate NYU Impactor injury), either into the lesion cavity or into the whit e or gray matter both rostral and caudal to the injury epicenter. Up to 2 m onths postgrafting, the majority of cells either differentiated into GFAP-p ositive astrocytes or remained nestin positive. No BrdU-positive neurons or oligodendrocytes were observed. These results show robust survival of engr afted stem cells, but a differentiated phenotype restricted to glial lineag es. We suggest that in vitro induction prior to transplantation will be nec essary for these cells to differentiate into neurons or large numbers of ol igodendrocytes. (C) 2001 Academic Press.