Roles of Neuregulin 1 Type III in the Ex Vivo Generation of Fate Committed Schwann cells from Bone Marrow Stromal Cells

Abstract

Schwann cell transplantation accelerates functional recovery from nerve injury by promoting axonal regrowth and remyelination. Our group had generated fate committed Schwann cells from bone marrow stromal cells (Shea et. al, 2010). It was also demonstrated that co-culture with dorsal root ganglia (DRG, E14/15 rats) neurons was essential for the fate commitment of bone marrow derived Schwann cell-like cells (SCLCs) (Shea et. al, 2010). Signals from the DRG neurons are therefore thought to direct the switch of SCLCs to fate committed Schwann cells.

The reliance on DRG neuron co-culture for SCLCs fate commitment stands as a major hurdle for the therapeutic application of this finding. Thus, we aim to unravel the mechanisms underlying SCLCs fate commitment in order to develop a DRG neuron-free condition for generating fate committed Schwann cells.

We hypothesised that the switch is brought about by the membrane bound neuregulin (NRG), NRG 1 Type III, but not the other soluble isoforms of neuregulin. As our results show that SCLCs treated with soluble neuregulin did not show significant changes in morphology nor marker expression when compared with untreated SCLCs. NRG 1 Type III expression was observed on purified DRG neurons by immunocytochemistry, Western blot analysis as well as reverse transcription PCR for the mRNA. Mammalian expression constructs for NRG 1 Type III were made by transfection into human embryonic kidney cells, HEK 293T, and mouse embryonic fibroblasts (MEF) with the aim of generating surrogate cell types for co-culture with SCLCs to pursue cell-specific effects of NRG 1 Type III on differentiation of SCLCs. The findings promise a way for generating fate committed Schwann cells for autologous transplantation for recovery after nerve injury.