Role of mesenchymal stem cells in delivering Newcastle disease virus to glioma cells and glioma stem cells and enhancing the oncolytic effect of the virus by secreting TRAIL.

3100 Background: Newcastle disease virus (NDV), an avian paramyxovirus, is tumor selective and oncolytic by induction of apoptosis. Preclinical and clinical studies in patients with glioblastoma (GBM) using NDV demonstrated occasional clinical benefits with no major side effects. Limitations to the use of NDV as virotherapy of GBM is the inefficient delivery into cancer cells in the brain. Methods: Mesenchymal stromal cells (MSCs) can migrate towards cancer cells. We examined potential delivery of oncolytic effect of NDV (MTH-68/H) against glioma cell lines and glioma stem cells (GSCs) and the ability of MSCs to deliver NDV to glioma cells and GSCs in culture. Results: NDV induced a dose-dependent cell death in the glioma cells U87, A172 and U251 with maximal effects at 10 MOI. In contrast, we found only small level of apoptosis or changes in self-renewal in three GSCs infected with NDV. We found that MSCs derived from bone marrow, adipose tissue and cord were successfully infected by NDV and were able to deliver the virus to co-cultured glioma cells and GSCs. In addition, treatment of glioma cells and GSCs with culture supernatant of infected MSCs increase apoptosis of glioma cells as compared to the effect of direct infection of glioma cells. Moreover, the culture supernatants of the infected MSCs induced cell death in GSCs that were resistant to the oncolytic effect of NDV, suggesting that factor(s) secreted by the infected MSCs sensitized the glioma cells and GSCs to the cytotoxic effects of NDV. Using antibody array and ELISA we identified TRAIL as the factor secreted from infected MSCs. Indeed, treatment of infected glioma cells with TRAIL increased the cytotoxic effect of NDV and sensitized GSCs to the oncolytic effects of NDV. Conclusions: MSCs can be employed to deliver NDV to GBM. In addition, MSCs can also sensitize glioma cells and GSCs to oncolysis by NDV. Considering the resistance of GSCs to chemotherapy and radiation therapy, treatment of GBM with MSC-mediated targeted oncolytic NDV may provide a new clinical tool for treatment of GBM and eradication of GSCs.