Antiangiogenic properties of viscum album extracts are associated with endothelial cytotoxicity.

BACKGROUND Viscum album (VA) extracts are widely used in cancer therapy and are known to be cytotoxic to tumors and endothelial cells. Angiogenesis plays an important role in the growth, sustenance and metastasis of tumors. Inhibition of angiogenesis is now being explored as a new therapeutic avenue for cancer. MATERIALS AND METHODS The cytotoxicity of VA extracts was analyzed by Annexin V labeling and propidium iodide uptake in EA-hy926 endothelial cells. The antiangiogenic effect was studied in vitro by treating the EA-hy926 cells in matrigel and subsequent analysis of vascular formation. Computer-assisted image analysis of vascular formation was analyzed to quantify the in vitro data. In vivo studies were performed by implanting matrigel +/- VA extracts in Balb/C mice that had been subjected to IP treatment with VA extracts. RESULTS The combination of systemic and intra- matrigel treatment with the VA Qu Spez extract caused significant inhibition of angiogenesis. The VA P extract treatment showed insignificant change in vessel formation. CONCLUSION These results may provide novel guidelines towards improved strategies using VA extracts based on the inhibition of angiogenesis of tumors.