Neural progenitors migrate toward VEGF.

Blood vessels and neural stem cells can be led to their targets by the same factor, say Zhang et al. on page 1375. The factor, vascular endothelial growth factor A (VEGF), is known as a major inducer of angiogenesis. Zhang et al. show that it is also a powerful attractant for immature neural progenitor cells. In the developing mammalian brain, it may be used when both neural stem cell migration and blood vessel growth must head for the same brain region.

The authors purified neural progenitors from the subventricular zones of newborn rats, and cultured them in the presence of fibroblast growth factor 2 (FGF-2) to prevent them from differentiating. The progenitor cells migrate up gradients of VEGF, in a chemotactic response specifically mediated by VEGF receptor 2. In cocultures in three-dimensional collagen matrices, the progenitors migrate toward VEGF-secreting cells. Progenitor cells that are allowed to differentiate into neuron- or glia- restricted lineages become insensitive to VEGF.

The data suggest that VEGF links angiogenesis to neurogenesis to establish neurogenic niches within the developing brain. Once the niches are established by immature progenitors, they could act as launching points for migrations by more differentiated cells. VEGF and FGF-2 might be useful in treating brain injuries by directing transplanted progenitor cells to migrate into damaged areas. â–ª