Significant angiogenic potential is present in the microenvironment of muscle flaps in humans

The purpose of this study was to determine the presence of growth factors and the quality of angiogenic potential in the wound microenvironment in different types of flaps in humans. The wound exudates from 23 flaps were processed for analysis of transforming growth factor beta1 (TGF-beta1), epidermal growth factor (EGF), interleukin 1alpha (IL-1alpha), platelet-derived growth factor-AB (PDGF-AB), vascular endothelial growth factor (VEGF), and insulin-like growth factor (IGF-1) by enzyme-linked immunosorbent assay (ELISA) or radio immuno assay (RIA). Angiogenic activity of wound fluid from latissimus flaps was determined by thymidine incorporation in porcine microendothelial cells exposed to various concentrations of wound fluid and control media. Angiogenic and matrix growth factors were altered in a linear fashion during the wound-healing process. Regression analysis provided evidence for decreasing levels of PDGF and EGF for latissimus flaps. Also, statistically significant differences of growth factor levels were found for paired comparison of flap types at different times after operation. Growth of in-vitro endothelial cells was stimulated most by 10 percent wound fluid, compared to any of the individual recombinant angiogenic factors or combinations of these factors. The data suggest that vascularized tissue flaps will promote wound healing by providing sufficient sources of growth factors in the wound environment. The particular type of flap, i.e., muscle or fasciocutaneous flap, does not seem to have an impact on growth-factor expression.