GROWTH-FACTORS - LOCAL AND SYSTEMIC

Growth factors that are produced locally at the wound site and systemi cally from distant sources may elicit inhibitory or stimulatory respon ses depending on interactions with other factors and the cellular envi ronment into which they are liberated. Growth factors released from ma crophages, neutrophils, lymphocytes, platelets, and fibroblasts bind t o target cells via specific cell-surface receptors inducing cells to m igrate, divide, or produce other factors required for wound healing. S tructural similarities between cell receptors may explain cross-reacti vity between substances. Systemic growth factors, such as growth hormo ne and local epidermal growth factor, fibroblast growth factor, platel et-derived growth factor, and transforming growth factor beta have all been shown to enhance wound healing. Further, growth factors have bee n shown to have a distinct role in catabolic and malnourished patients as well as in patients with cancer. Clinical trials with growth facto rs have demonstrated efficacy, and specific uses for those particular factors may become an accepted mode of therapy producing important dif ferences in outcome.