Recruiting new neurons from the subventricular zone to the rat postnatal cortex: an organotypic slice culture model.

The neurogenic subventricular zone (SVZ) of the lateral ventricle is a potential source for neuronal replacement in the postnatal or adult neocortex after injury. Here we present a novel model system to directly explore the cellular mechanisms of this process. In order to visualize directed migration from the SVZ towards the cortex, we transplanted green fluorescent protein-labeled progenitor/stem cells into the SVZ of newborn rats. At 2 days after transplantation, we generated organotypic slice cultures and applied fluorescent time-lapse imaging to explore directly the migration and integration of donor cells into the host tissue for up to 2 weeks. Our studies revealed that subventricular grafts provide a significant number of immature neurons to neocortical regions. In the cortex, immature neurons first migrate radially towards the pial surface and then differentiate into GABAergic interneurons. We conclude that our model system presents a novel and effective experimental paradigm to evaluate the recruitment of SVZ-derived neurons into the postnatal cortex, a phenomenon that may represent a potential route for cortical repair.