Downregulating Heparanase Induced Vascular Normalization: a New Approach to Increase the Bioavailability of Chemotherapeutics in Solid Tumors.

Downregulating heparanase has been shown to reduce tumor angiogenesis and prevent chemoresistance, and it is becoming an appealing approach to treat solid tumors. However, little attention has been given to its underlying antitumor mechanisms, especially the relationship between heparanase and vascular development in solid tumors, which is not yet fully understood. In this study, we found that downregulating heparanase through orthotopic injection of heparanase small interfering RNA not only could reduce vascular density but, more importantly, lead to vascular normalization in solid tumors. Consequently, this may lead to a more efficient delivery of chemotherapeutic agents. These findings provide the basis for developing new approaches to treat solid tumors with a combination of heparanase inhibitors and chemotherapeutics.