Patients with progressive multiple sclerosis (MS) experience a steady worsening of neurologic function attributed to chronic demyelination and axonal loss. A novel regenerative therapy utilizing autologous mesenchymal stem cell-derived neural progenitors (MSC-NP) is currently under clinical investigation in

patients with progressive MS. Recent results from a phase I trial demonstrated reversal of established disability after repeated intrathecal MSC-NP injections. Pre-clinical studies suggest that the mechanism of action of MSC-NPs occurs through the paracrine release of trophic and immunomodulatory factors.

MSC-NPs were derived from bone marrow of MS patients according to previously described protocol. To test paracrine effects on microglial activation, GM-CSF/IFN-γ/LPS-stimulated BV-2 cells were cultured with either MSC-NP cells or conditioned media, and activation markers were tested by quantitative PCR, ELISA, or Luminex assay. To test the paracrine effects on oligodendroglial differentiation, rat neural stem cells (rNSC) were differentiated by growth factor withdrawal along with either MSC-NP cells or conditioned media (CM). Oligodendrocyte differentiation was tested by quantitative PCR and immunocytochemistry.

We observed that co-culture with MSC-NP cells resulted in a decrease in activated microglia markers in stimulated BV-2 cells, including a reduction in chemokines CCL-2 and CCL-8. These effects could be mediated via paracrine mechanisms through the addition of MSC-NP CM. The reduction in pro-inflammatory chemokines correlated with an increased release of IL-10. In addition, we found a significant increase in the degree of spontaneous oligodendrocyte differentiation from rNSCs in the presence of MSC-NP cells or CM, which correlated with an increase in mature oligodendrocyte markers including PLP, along with an increase in pro-myelinating factors.

These results suggest that MSC-NPs promote a beneficial shift in activation and differentiation of glial cells with relevance to MS.