Release of bFGF, an endothelial cell survival factor, by osmotic shock.

PURPOSE: To test the effects of osmotic change on basic fibroblast growth factor (bFGF) release from cultured endothelial cells (ECs). METHODS: Bovine aortic and bovine retinal ECs were exposed to hypoosmotic shock for 2 minutes, were allowed to recover for 15 minutes, and had bFGF release assayed. The role of bFGF in cell recovery was assessed by including neutralizing antibody against bFGF or the addition of exogenous bFGF. Cell number and viability were determined under varying conditions. Apoptosis was assessed by immunoperoxidase detection of digoxigenin-labeled DNA. RESULTS: After shock and recovery, both ECs released significantly greater amounts of bFGF than untreated control. bFGF release after shock for 2 minutes was lower than release after shock and recovery. Bovine retinal endothelial (BRE) cell number was reduced at 48 hours after shock, recovery, and removal of released bFGF compared with cells left in the presence of released bFGF. Cell number was significantly lower when BRE cells were shocked and recovered in the presence of a neutralizing anti-bFGF antibody (P<0.05). Exogenous bFGF reversed this effect. Apoptosis was significantly increased in BRE cells shocked and recovered or in the presence of bFGF antibody (P<0.001). CONCLUSIONS: bFGF is released by cultured ECs in response to osmotically induced cell injury. These results support the concept of bFGF as a "wound" hormone and survival factor for ECs. In further compromised tissue, release of bFGF in this manner may play a role in the pathogenesis of disease.