Transforming growth factor-beta(1) restores antiplatelet function of endothelial cells exposed to anoxia-reoxygenation injury

Transforming growth factor-beta(1) released from platelet alpha-granules ma y preserve endothelial functions in injured vessels. However, direct eviden ce is lacking regarding how this cytokine modifies the antithrombotic funct ion of injured endothelial cells. We performed an in vitro study to investi gate the effects of transforming growth factor-beta(1) on platelet function s in the presence of cultured endothelial cells exposed to anoxia-reoxygena tion injury. Cultured bovine aorta endothelial cells were placed in an anox ic chamber (0.5% O-2, 5% CO2) for 60 minutes followed by a 90-minute reoxyg enation. Collagen (2 mu g/mL)-induced platelet aggregation (10(8) platelets /mL), as determined by impedance aggregometry, was potently inhibited in th e presence of control endothelial cells (17.4+/-3.3 Ohm) at a concentration of 5x10(4) cells/mL, as compared to their absence (68.2+/-2.2 Ohm). Inhibi tion of platelet aggregation was attenuated in endothelial cells exposed to anoxia-reoxygenation (54.6+/-2.5 Ohm). However, preincubation of endotheli al cells with transforming growth factor-beta(1) (1.0 ng/mL) for 16 hours p artially recovered the inhibitory capability of platelet aggregation by inj ured endothelial cells (40.6+/-3.8 Ohm). Cell viability, confirmed by a try pan blue dye exclusion test, was similar (93-96%), including control, 1.0 n g/mL transforming growth factor-beta(1)- and/or anoxia-reoxygenation-pretre ated cells. The capability of platelet inhibition was restored when the end othelial cells were preincubated for 4 hours or more. Restoration of antipl atelet capacity in endothelial cells by transforming growth factor-beta(1) was suggested to be due to several mechanisms, including an increase in nit ric oxide synthase activity, up-regulation of prostacyclin release, and res toration of adenosine triphosphate diphosphohydrolase activity, which was a ttenuated by anoxia-reoxygenation pretreatment. In summary, transforming gr owth factor-beta(1) released from activated platelets may play a compensato ry role in the preservation of endothelial functions to inhibit platelet ac tivation. (C) 2000 Elsevier Science Ltd. All rights reserved.