BACKGROUND: The vascular niche necessary for cancer stem cell maintenance is a potential target for cancer therapy. MATERIALS AND METHODS: Human glioma xenografts were treated with IFN-ß delivered systemically via a liver-targeted, adeno-associated viral vector. The vascular niche was examined with immunofluorescence for glioma stem cells, endothelial cells, and perivascular cells. RESULTS: Although IFN-ß was not directly toxic to glioma stem cells in vitro, IFN-ß decreased tumor size and the number of stem cells recovered in both heterotopic and orthotopic models. Treatment with IFN-ß increased perivascular cells investing the tumor vasculature (6-fold) distancing stem cells from endothelial cells. Additionally, vascular smooth muscle cells co-cultured between stem cells and endothelial cells decreased stem cell recovery. CONCLUSION: Continuous delivery of IFN-ß decreased the number of stem cells in glioma xenografts by disrupting the vascular niche through an increase in perivascular cells, which created a barrier between the glioma stem cells and the endothelial cells.