Stromal injury results invariably in stromal scarring which is a leading cause of blindness in the world. The overall goal of this proposal is to identify and characterize the cellular changes that occur after corneal stromal injury in vitro and in vivo. The PI has evidence that injury in vitro and in vivo alters the synthetic profile of proteoglycans by stromal cells as injury induces an increase in the relative proportion of both dermatan and heparan sulfate. The appearance of heparan sulfate correlates with reports of other investigators that the heparan sulfate containing proteoglycan, perlecan, increases after injury. He has demonstrated also that heparan sulfate can directly modulate growth factor receptor binding and activity, in other cell models. He and other investigators have shown that the receptors for TGF-B and bFGF are present in stromal cells. Furthermore, the PI has observed a transient increase in the expression of TGF-B1 mRNA in response to injury. From these results he predicts that the bioavailability and activity of growth factors may be altered within the wound environment.
The specific aims of this proposal are: 1. Identify regional differences in growth factor and proteoglycan expression with respect to stromal cell injury in vitro. He will define differences in the expression of bFGF, TGF-B (1 and 2), their receptors, and smooth muscle actin mRNA and protein surrounding the would, and we will quantify the changes in proteoglycan synthesis and growth factor binding that occur in response to injury. 2. Quantify the response of stromal fibroblasts to putative would mediators in vitro. Results from the PI laboratory and others have suggested that bFGF, TGF-B and proteoglycans act in concert to modulate the cellular response to injury. In this aim he will evaluate the wound response to stromal cells to purified growth factors, proteoglycans, specific antisense oligonucluotides, and to aqueous humor. 3. Define changes in proteoglycan biochemical profile, growth factor expression and binding induced by trauma in vivo. The PI will quantitate bFGF and TGF-B (1 and 2) expression and binding in the stroma in response to wounds of variable depth (+epithelial injury), and will characterize the biochemical profile of proteoglycans in response to defined would types and would mediators. Ultimately this information could provide important insight towards the development of new therapeutic modalities to enhance the repair of the injured cornea with retention of transparency.
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