Bacterial particles retard tumor growth as a novel vascular disrupting agent.

Due to hypoxia and poor circulation in the tumor interior, malignant cells in solid tumors are resistant to traditional therapies. In the present study, we reported that bacterial particles (BactPs) functioned effectively in retarding tumor growth as a novel vascular disrupting agent. The BactPs were inactivated intact bacteria. Intravenous administration of BactPs extensively disrupted vessels in the tumor interior, but not in normal organs, and resulted in tumor hemorrhage and necrosis in six hours. We revealed that the extensive disruption of tumor vasculature was due to drastic changes in the inflammatory factors in mice sera and the tumor microenvironments, indicating the critical role of the host immune response to the BactPs. Furthermore, we showed that a combination of six inflammatory cytokines was capable of inducing tumor hemorrhage and necrosis, similar to the effects of the BactPs. Together, these results suggest that BactPs are a novel kind of tumor vascular disruptor with a promising potential for solid tumor treatment.