Human dental pulp stem cells differentiate towards peripheral glial cells

Objectives: In the peripheral nervous system, Schwann cells (SCs) are responsible for the formation and preservation of myelin sheaths around axons. Also, SCs play an important role in the regeneration of peripheral nerves after Wallerian degeneration. However, for the treatment of peripheral nerve injury, an alternative cell source is needed since SCs are difficult to obtain and the clinical applications are difficult. Recently, it has been described that dental pulp stem cells (DPSC) are capable of differentiating into glial and neuronal cells and are able to produce neurotrophic factors like BDNF, GDNF and NGF. Since DPSC already express glial markers like S100 and NGFRp75, it is interesting to further investigate their potential to differentiate into glial cells of the peripheral nervous system, like SCs. Methods: DPSC were isolated from human dental pulp tissue and cultured via the explant method. When confluency was reached, cells were subcultured and media was changed every 3-4 days. In vitro, DPSC were stimulated to differentiate into SC-like cells via a mix of growth factors. After 21 days in culture, the differentiation of DPSC towards SCs was analyzed. Via immunocytochemistry, the expression of SC markers GFAP, S100 and NGFRp75 was evaluated. To further elucidate the differentiation into SC-like cells, reverse-transcriptase PCR, cytokine array, and transmission electron microscopy was performed. Results: At the mRNA level, transcripts of GFAP, p75 and S100 were observed in SC differentiated DPSC. These results were confirmed by immunocytochemical analysis. Furthermore, an increased production of neurotrophic factors like BDNF, GDNF, NCAM-1, NT-3 and TGF-Beta1 was found. Ultrastructural analysis showed a Schwann cell morphology. Conclusions: The results of this study indicate that DPSC are capable of differentiating towards peripheral glial cells, like SCs. Therefore, DPSC could be an alternative cell source for future stem cell treatment of peripheral nerve injuries.