Effects of chronic wound fluid on the bioactivity of platelet-derived growth factor in serum-free medium and its direct effect on fibroblast growth

The fate of biologically active proteins applied to chronic wounds is almost totally unknown. Growth factors may be degraded by proteases, which are produced by both inflammatory and skin cells and by resident bacteria. However, there has been little work on the effect of chronic wound fluid on the activity of growth factors. A bioassay method has been chosen to examine the effect of incubation of platelet-derived growth factor with chronic wound fluid from leg ulcers on the in vitro growth of human dermal fibroblasts. Human dermal fibroblasts were cultured in serum-free medium, and a dose-response curve for proliferation in response to platelet-derived growth factor was obtained. Wound fluid was collected under occlusive dressings from five patients with chronic leg ulcers. Platelet-derived growth factor was incubated with chronic wound fluid at 37 degrees C for 4 hours, and the reactions arrested by snap freezing. The resultant solutions were tested for their ability to promote fibroblast proliferation. A colorimetric assay was used to monitor changes in the platelet-derived growth factor mitogenicity. The results showed that, in our standard culture conditions, chronic wound fluid always stimulated fibroblast proliferation, and, in most cases, incubation of platelet-derived growth factor with chronic wound fluid increased the stimulation compared with that produced by platelet-derived growth factor or chronic wound fluid alone.