ABSTRACT
It is clear that certain proteins (polypeptides) directly regulate many of the processes crucial for normal wound healing, including chemotactic migration of inflammatory cells, mitosis of fibroblasts, keratinocytes, and vascular endothelial cells, neovascularization, and synthesis and degradation of extracellular matrix components (1). These regulatory peptides known as cytokines include such polypeptides as the interleukins, hematopoietic colony-stimulating factors, and tissue necrosis factors (2). They also include the various growth factors. Growth factors are synthesized and secreted by many types of cells involved in tissue repair including platelets, inflammatory cells, fibroblasts, epithelial cells, and vascular endothelial cells (3). They may act on the producer cell (autocrine stimulation), adjacent cells (paracrine stimulation), or distant cells (endocrine stimulation). Substances such as cytokines that are chemotactic to inflammatory cells, such as neutrophils and macrophages, or mitogenic to cells, such as fibroblasts, endothelial cells, and keratinocytes, should benefit wound healing (4). Certainly, the literature is replete with examples of effects of exogenous application of cytokines and/or growth factors for animal models of both acute and chronic wounds (5–7). In all of those animal models, it has been suggested that wound healing would be enhanced by topical application of growth factors.
