ASSESSMENT OF DIFFERENTIAL CYTOKINE EFFECTS ON ANGIOGENESIS USING AN IN-VIVO MODEL OF CUTANEOUS WOUND REPAIR

Angiogenesis, or new blood vessel formation, has been a subject of int ense investigation in recent years. A major obstacle in this research has been the selection of an appropriate in vivo model with which comp arisons to humans can be made as well as a reliable quantitative metho d. Using the porcine excisional wound healing model, we report a new a nd simple technique for obtaining objective assessments of the microva scular compartment. Factor VIII immunostaining of histological specime ns was utilized for specific identification of endothelium devoid of b ackground interference. This technique was coupled with morphometric a nalysis to quantitate the differential effects of tumor necrosis facto r alpha (TNF alpha), transforming growth factor beta (TGF beta), basic fibroblast growth factor (bFGF), insulin-like growth factor-1 (IGF-1) , and epidermal growth factor (EGF) within healing porcine wounds. All cytokines stimulated angiogenesis, with low dose TNF alpha and bFGF t reatments exhibiting the most profound effects at 7 days postwounding. With increasing levels of TNF alpha (1 ng, 10 ng, 100 ng, and 2.5 mu g), a stepwise decrease in microvascular area was noted. Although no s ignificant dose responsive differences in angiogenesis were noted foll owing bFGF treatments, a profound increase in capillary area was shown . Significant yet less dramatic increases were noted in capillary area following treatment with EGF or IGF-1. Comparison of the angiogenic e ffects of TGF beta at 7 and 10 days postwounding showed a significant decrease in the microvasculature as wounds matured. Our data are consi stent with previous qualitative in vitro and in vivo reports, thereby confirming the validity of this new model. The data furthermore provid e the first quantitative evidence of differential angiogenic responses to cytokines within a clinically relevant model of cutaneous wound re pair. (C) 1995 Academic Press, Inc.