Inhibition of breast tumor growth and abnormal angiogenesis in mice treated with endothelial cells and their progenitor mesenchymal stem cells derived from bone marrow.

Incorporation of endothelial cells or their progenitor cells into newly sprouting blood vessels can contribute to tissue vascularization after ischemic injury. However, the interaction of the stem cells-derived endothelial cells with angiogenesis within tumors is not well understood. The aim of this study was to examine the efficiency of endothelial-like cells derived from MSCs in controlling breast tumor growth associated with abnormal angiogenesis. For this purpose, Balb/c mouse model of breast carcinoma was developed and subjected to intra tumor (I.T)/intra venous (I.V) therapy with undifferentiated MSCs or endothelial cells derived from them. The homing of the stem cells was approved by measuring different markers as well as tracing green fluorescence protein (GFP)-labeled MSCs in the tumors. Tumor growth was measured following cell therapy using a digital caliper. At the end of treatment period (30 days) the angiogenesis markers; VEGFR2 expression as well as micro-vessel density (MVD) using CD31 were estimated in tumor tissues. Stem cell transplantation to mice bearing breast tumors resulted in tumor growth suppression in all experimental groups. The endothelial markers; CD31 and VEGFR2 were down regulated following I.T delivery of the endothelial cells. Accordingly, angiogenesis was suppressed following I.T administration of endothelial cells which was associated with increased focal necrosis in the tumors. In conclusion, data show that endothelial cells directly injected into tumors is more efficient compared to undifferentiated MSCs in controlling tumor-associated angiogenesis and tumor growth.