Tumor necrosis factor inhibiting angiogenesis in vitro

The effect of recombinant human tumor necrosis factor (TNF) on the capillary growth was evaluated using an in vitro angiogenesis model recently developed. Sprague-Dawley rat microvessel fragments, from epididymal fat pads, seeded onto the confluent culture of myofibroblastic cells from the same tissue origin, gave rise to microvascular networks on and in the multilayered myofibroblastic cells. In contrast, the capillary growth from the vessel fragments was markedly inhibited in the presence of 10-1,000 U TNF/ml. Monoclonal antibody against TNF completely neutralized the capillary growth inhibitory activity of TNF. The mode of angiogenesis inhibitory action of TNF was also examined by use of bovine capillary endothelial (BCE) cells and rat myofibroblastic cells. TNF exerted growth inhibitory and cytotoxic actions against BCE cells cultivated on the various basement membrane components, such as extracellular matrix secreted by BCE cells, fibronectin, laminin, and type IV collagen. An irreversible damage to most of the BCE cells was observed ultrastructurally after 60 hours' exposure to TNF. TNF, however, did not injure the myofibroblastic cells but rather stimulated their growth. These findings indicate that TNF inhibits in vitro capillary growth by its direct cytostatic and cytotoxic actions to microvascular endothelial cells.