Static magnetic fields increase tumor microvessel leakiness and improve antitumoral efficacy in combination with paclitaxel

•Static magnetic fields increase tumor microvessel permeability without affecting leukocytes.•The effectiveness of small molecular chemotherapy is increased by static magnetic fields.•Static magnetic fields possibly open the blood-tumor-barrier.

Static magnetic fields (SMF) induce an intratumoral edema possibly by increasing microvessel permeability. The aim of this study was to evaluate the effects of SMF on tumor microvessel permeability and on treatment effects of conventional cytotoxic chemotherapy. Using intravital microscopy in skinfold chamber preparations in A-Mel-3-tumor-bearing hamsters, functional tumor microcirculation, microvessel permeability and leukocyte–endothelial cell interactions were measured under SMF-exposure (587 mT). Combining SMF-exposure with paclitaxel-chemotherapy, tumor growth was analyzed.SMF inhibited tumor angiogenesis and increased tumor microvessel permeability significantly. This was not mediated by inflammatory leukocyte–endothelial cell interactions. Further, SMF increased the effectiveness of paclitaxel-chemotherapy significantly.These findings support that SMF possibly open the blood–tumor-barrier to small molecular therapeutics.