Human bone marrow-derived Schwann cells seeded and nanofiber-packed conduit fo rperipheral nerve regeneration

Abstract

For bridging gaps between stumps of severed peripheral nerves, (1) myelinating cells and (2) physical guidance channel are needed. We reported selective expansion of neuro-ectodermal progenitor cells among the human bone marrow stromal cells (BMSCs) for cytokine induction into Schwann cell-like cells and then co-culture with embryonic dorsal root ganglion neurons to accomplish the switch to fate-committed Schwann cells (Cai et al, 2017a). Here we report use of human iPSC-derived sensory neurons (Cai et al., 2017b) as a surrogate for the co-culture to achieve fate-committed human Schwann cells. Following storage under liquid nitrogen for extended periods, the Schwann cells were thawed for use on demand. We seeded the cells into chitosan-based nerve guidance channels for bridging a critical gap in a rat model of sciatic nerve injury; axonal regrowth and remyelination were observable across the gap in two months. Alternatively, we packed genipin-treated, uniaxially aligned chitosan nanofibers into the guidance channel for the critical gap-bridging experiment. In set-ups without Schwann cell-seeding and one month after bridging, the genipin-treated chitosan nanofibers retained structural integrity, showing early function of a nerve bridge in which (1) Schwann cells adhered to and proliferated along the direction of genipin-treated chitosan nanofibers and (2) axons grew into the conduit directionally guided by the nanofibers. We expect our strategy to support translation into a protocol whereby human bone marrow-derived Schwann cells become available for autologous transplantation and the genipin-treated chitosan nanofibers accelerate axonal regrowth and remyelination. (Supported by HMRF 05163296, 06173706, 06172326 and 05163156)