Conditioned medium derived from mesenchymal stem cells overexpressing HPV16 E6E7 dramatically improves ischemic limb.

Mesenchymal stem cells (MSCs) have been shown to secrete cytokines and growth factors required for angiogenesis. Previously, we demonstrated that MSCs expressing HPV16 E6E7 mRNA (E6E7-MSCs) increase life span and differentiation potential and maintain without neoplastic transformation. Whether E6E7-MSCs are sources of molecules for enhancing angiogenesis is unknown. We demonstrated that E6E7-MSC-derived conditioned medium (E6E7-CM) enhanced endothelial cell migration and tube formation compared to primary MSC-derived conditioned medium (primary-CM). Moreover, E6E7-MSCs increased AKT activation and enhanced the release of Interleukin-1β (IL-1β) and vascular endothelial growth factor A (VEGFA). Neutralization of E6E7-CM with antibodies against IL-1β or VEGFA abrogated its effect in enhancing endothelial migration and tube formation. Primary-CM, added with IL-1β and VEGFA, enhanced its ability to increase endothelial migration and tube formation. E6E7-CM was shown to increase the ability to improve blood perfusion in a mouse limb ischemia model. Histological analysis revealed that E6E7-CM prohibited muscle loss or fibrosis and increased endothelial cell counts compared to primary-CM. Similarly, the effects of E6E7-CM in improving perfusion in ischemic limb were also contributed by the increase of IL-1β or VEGFA levels. These results suggest that E6E7-MSCs increase the ability to secrete angiogenic factors via AKT activation, and E6E7-CM is abundant in IL-1β and VEGFA levels and thereby increases the ability to improve blood perfusion and prohibit muscle loss or fibrosis in a mouse limb ischemia model.