Divergent routes for derivation of alternative glial cell fate from bone marrow stromal cells of adult rats for remyelination

Abstract

Loss of myelin due either to traumatic injuries or congenital abnormalities impacts severely on neuronal function. Focusing on cell replacement based remyelination therapy for both CNS and PNS, we attempted to direct differentiation of bone marrow stromal cells (BMSCs, adult rats) along the oligodendrocyte and Schwann cell lineage in vitro. BMSCs acquired phenotypes of neural progenitors in non-adherent culture conditions. To foster differentiation along the oligodendroglial lineage, BMSC-derived neural progenitors (BM-NPs) were then maintained in adherent culture supplemented with 3 glial inducing factors: β-heregulin, PDGF-AA and bFGF. Oligodendrocyte precursors positive for markers - NG2, Olig2, PDGFRa and Sox10, were detected within 2 weeks. To derive Schwann cells, BM-NPs were co-cultured with purified dorsal root ganglia (DRG) neurons and simultaneously treated with the 3 glial inducing factors. Schwann cells positive for markers - p75 and S100b, were detected within 2 weeks. DRG neurons prevented the neural progenitors from committing oligodendroglial fate and promoted their differentiation along the Schwann cell lineage. To test for myelination capability, BMSC-derived OPCs (BM-OPCs) and Schwann cells (BM-Schs) were co-culture with purified DRG neurons for 2 weeks, respectively. BM-OPCs matured into oligodendrocytes and extended myelin basic protein (MBP)- positive processes along multiple axons, indicating myelination. BM-Schs lined themselves along axons and were positive for MBP, also indicating myelin formation. Our findings indicate BMSCs as a possible source of both OPCs for and Schwann cells for remyelination therapy.