Neural progenitor cells promote corticospinal axon growth in organotypic co-cultures.

The CNS is limited in regeneration following injury in adult mammals. Recent studies show that the transplantation of the neuronal progenitor cells is useful in promoting regeneration. However, the mechanisms of action of the transplanted neural progenitor cells have not been clarified. In this study, we used organotypic co-cultures with neonatal brain cortex and spinal cord as an in vitro assay system for assessing the factors that regulate corticospinal axonal growth. Our results show that the transplantation of neural progenitor cells enhanced corticospinal axon growth in these co-cultures. In addition, neural progenitor cell conditioned medium also significantly promoted axonal growth. These findings strongly suggest that factors derived from neural progenitor cells participate in the effect on axonal growth.