Derivation of Schwann cells from mammalian skin and bone marrow for use in axonal regeneration

Abstract

We aimed to use mammalian skin and bone marrow as sources of neural crest-derived cells in differentiation programs towards Schwann cells so that the latter may be used to assist axonal regrowth and nerve regeneration. Cells that grew as floating spheres in serum-free medium supplemented with epidermal growth factor and fibroblast growth factor were selected. The primary and secondary spheres expressed nestin, a marker for neural precursors. The cells were subjected to a differentiation program involving the use of forskolin and neuregulin-1β. About 30 % of the cells expressed the two Schwann cell markers, S100β and p75 neutrophin receptor. After a maturation program involving coculture with dorsal root ganglion neurons, >90% of the cells expressed the Schwann cell phenotype. These cells were seeded with Matrigel™ into chitosan conduits for nerve bridge experiments into adult Sprague-Dawley rats. Control groups included phosphate-buffered saline (PBS), heparan sulphate, Matrigel™ only. At 12 weeks post-surgery, the animals were assessed for electromyographic signals at the target gastrocnemius muscle for computation of conduction velocity along the bridged nerve. Preliminary results indicated that the bridge filled with derived Schwann cells and Matrigel™ showed higher conduction velocity as compared to the group with Matrigel™ only. However, they did not show significant improvement compared to the PBS control. This study promises to develop the methodology for deriving autologous Schwann-like cells for use as grafts in the bridging of severed nerves.