Proliferation of parenchymal neural progenitors in response to injury in the adult rat spinal cord

It has long been believed that the fully developed mammalian central nervou s system (CNS) lacks significant regenerative capacity. Recent advances hav e revealed, however, that many regions of the adult CNS contain neural prog enitors that have the ability to generate new neurons and glia. Although th e periventricular area has been identified as a rich source of these progen itors, their precise location in each region and details of their propertie s in vivo still remain poorly understood. Here we provide evidence that in the adult rat spinal cord, a significant number of neural progenitors are p resent, not only in the periventricular area, but also in other regions of the parenchyma. These progenitors could proliferate in vitro as neurosphere -like cell aggregates in the presence of growth factors and also gave rise to neurons and glia under appropriate conditions. We further demonstrate th at these parenchymal neural progenitors were capable of proliferating in vi vo in response to injury. Immunohistochemical studies suggested that prolif erative progenitors emerged throughout the gray and white matter in the les ioned spinal cord. Consistently, an increased number of neurosphere-forming cells could be isolated from injured tissues, and they were able to differ entiate into neurons in vitro. The widespread occurrence of neural progenit ors in the parenchyma expands the possibility of repairing damaged tissue b y activating the latent regenerative potential of the adult spinal cord. (C ) 2001 Academic Press.