Low temperature induced de-differentiation of astrocytes.

Radial glial cells are astrocyte precursors, which are transiently present in the developing central nervous system and transform eventually into astrocytes in the cerebral cortex and into Bergmann glia in the cerebellum. Previous reports indicate that the transformation from radial glia to astrocytes can be reversed by diffusible chemical signals derived from embryonic forebrain in vitro and by freezing injury in vivo. But there is no direct evidence proving that mature astrocytes can de-differentiate into radial glial cells. Here we show that purified astrocytes could de-differentiate into radial glial-like cells (RGLCs) in vitro with freeze-thaw stimulation. RGLCs had the expression of markers for radial glia including Nestin and Pax6, and astrocyte markers, the glial fibrillary acidic protein and Vimentin. Cortical neurons, when co-cultured with RGLCs, migrated along the processes of RGLCs at an average speed of 26.26 +/- 3.36 microm/h. Moreover, the proliferation of RGLCs was significantly promoted by epidermal growth factor (EGF) at the concentration of 10-30 ng/ml. These results reveal that low temperature induces astrocytes to de-differentiate into immature RGLCs, which provides an in vitro model to investigate mechanisms of astroglial cells de-differentiation.