Although animal models and in vitro systems have been very useful in the past to gain insight into the cellular, biochemical and molecular events during tissue repair, these systems have limitations when addressing the unique clinical problems associated with human wound healing. The human response encompasses a wide spectrum of healing phenomena with overhealing and fibrosis on one end and chronic ulcer formation on the other end. Animals do not develop excessive scar issue nor do they manifest problems with deficient healing. Therefore, this project is designed to characterize and analyze the normal wound healing response in humans as well as the pathologic responses seen at opposite ends of the spectrum. The human keloid will represent conditions of fibrosis whereas chronic non-healing diabetic ulcers will serve as a model of deficient healing. All studies will be done in humans using the normally available wound exudates, biopsies, and excised tissue following normally scheduled surgical treatments for these patients. In addition, an implantable tube consisting of an expanded form of Teflon, called Impra, has proven to be useful to collect new wound tissue for analysis. This laboratory has now developed and adapted state-of-the-art technologies and methods to study human wound healing. Therefore, these strategies will be employed to analyze inflammation, cytokine production, matrix synthesis and degradation, angiogenesis and contraction in normal human wounds, keloids and chronic non- healing ulcers. The laboratory methods include routine histology, immunostaining, ELISA assays, in situ hybridization, RNase protection assays, a new collagen radiolabeled substrate assay to quantify collagenase and gelatinase activity, HPLC quantitation of hydroxyproline and leucine deposition, and Western blot analysis. These methods have been modified to be applicable to analyze the small amounts of tissue and exudate material that can be obtained from these human sources. These studies will compare and contrast the normal mechanisms responsible for healing in healthy tissue to those mechanisms responsible for overhealing in keloids and underhealing in chronic ulcers.
