The fate of proliferating cells in the injured adult spinal cord.

Endogenous cell proliferation and gliogenesis have been extensively documented in spinal cord injury, particularly in terms of proliferating oligodendrocyte progenitor cells. Despite the characterization of different proliferating cell types in the intact and injured spinal cord, the exact sources of new glial cells have remained elusive. Most studies on cell fate within the spinal cord have focused on following the progeny of one specific population of dividing cells, thus making it difficult to understand the relative contributions of each mitotic cell population to the formation of new glia after spinal cord injury. A recent study from the Frisen laboratory is the first to quantitatively and qualitatively characterize the response of ependymal cells, oligodendrocyte progenitors, and astrocytes in parallel by using transgenic reporter mice corresponding to each cell type. The investigators characterize the distribution and phenotype of progeny, along with the quantitative contributions of each progenitor type to newly formed cells. Their findings provide valuable insight into the endogenous cell replacement response to spinal cord injury, thus paving the way for advances in modulating specific populations of progenitor cells with the goal of promoting structural and functional recovery after spinal cord injury.