Distal segment extracts of the degenerated rat sciatic nerve induce bone marrow stromal cells to express Schwann cell markers in vitro.

Bone marrow stromal cells (MSCs) have the ability to support nerve regeneration when transplanted into lesion sites, but the mechanism is unclear. We hypothesized that specific factors in the lesioned microenvironment induce the differentiation of transplanted MSCs into functional Schwann-like cells. To test this hypothesis and determine the origin of such factors, we investigated the effects of different extracts from degenerated rat sciatic nerves on MSCs in vitro. After 3 days of degeneration, extracts from the distal segment (Ds) and proximal segment (Ps) of the rat sciatic nerve were used in experiments. After 1 day of treatment, the morphology of MSCs cultured with Ds extracts were spindle shaped, and the cells interconnected with each other, followed by gradual loss of typical morphology during culture. After 7 days of treatment, western blotting and RT-PCR analyses indicated that the cells cultured with Ds extracts had significantly higher expression of glial fibrillary acidic protein (GFAP), Sox10, Oct6, and early growth response 2(Egr2) than that of cells cultured with Ps extracts and the untreated cells. Our study suggests that, in the microenvironments of nerve lesions, specific factors induce MSCs to differentiate into functional Schwann-like cells, which may originate from the Ds of the degenerated nerve. These results may help to elucidate the mechanisms by which MSCs function in peripheral nerve repair.