Tissue repair is accompanied by an ordered and definable sequence of cellular responses and the metabolism of wounded tissue is distinctly different from that of non-wounded tissue. We have proposed that the local metabolic response to injury is a consequence of the cellular responses to injury. It is well known that wounds will heal in patients despite the concurrent existence of other disease, starvation or medication. Therefore, the knowledge that the cellular infiltrate (CI) present within a wound not only directs the process of wound healing, but is also responsible for wound metabolism, may help to explain the independent nature (biological priority) of the wound during its healing process. The studies outlined in this application will attempt to answer the following questions: 1) What is the longitudinal contribution of the entire CI to wound metabolism? 2) What is the contribution of the individual cellular components to the metabolism of the entire CI? Does metabolic cooperativity (i.e., cross-feeding or contact-feeding) occur among the cells involved in wound healing? (The CI) 3) Do growth factors produced within the wound environment affect local substrate metabolism? 4) Do the CI & host tissues cooperate or compete for substrate supply? 5) Do alterations in subsrate metabolism within the cells of the CI result in alterations in the function of these cells? The subpopulations from the wound cellular infiltrate will be isolated and purified with density gradient centrifugation. In vitro incubation methods using specifically radiolabelled substrates will be used to define the metabolic characteristics of the cellular infiltrate and its component cells at various stage of wound repair. Interactions between this cellular infiltrate and host tissue will be determined using coincubation techniques. Incubation of media conditioned with cell products will address the questions of cross-feeding vs. contact feeding (metabolic cooperativity). Growth factor- substrate interactions will be predicted from conditioned media experiments and from the addition of selected growth factors to standard incubates. Finally specific incubation and in vivo studies will define whether the local metabolic response is necessary and sufficient for wound healing by testing if interference with the metabolism of the individual cells or with metabolic cooperativity among cells within the cellular infiltrate alters the function of those cells that are crucial to wound healing.
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