090 Extracellular Matrix Regulation and Dermal Repair in Burn Wound

To better understand the mechanisms of dermal restoration in burn wound we examined the mRNA expressions, using a porcine secondary-degree burn wound model, of major dermal matrices including type I, III collagens and elastin, basement membrane components of collagen IV and laminins, regulatory Matrix Metalloproteinase MMP 1 and MMP 9, as well as growth factors of bFGF, CTGF, TGFβ, and VEGF. Fresh skin burn wound samples from six pigs were collected at days 0, 1, 4, 7, 10, 14, and 21. Semiquantitative Reverse Transcription and Polymerase Chain Reactions (RT-PCR) were used with gene-specific primers. RT-PCR products were run on ethidium bromide gel and analyzed under UV light with Bio-Rad Gel Document 2000 system. One-way analysis of variance was used for statistical analysis. The results showed:'1) There were increases of all dermal extracellular matrices and growth factors tested; 2) A significant increase of type IV collagen occurred the earliest, while expressions of type I collagen and elastin increased at the latest; 3) A dramatic induction of MMP 1 and MMP 9 was observed shortly after wounding, which lasted through entire experiment; 4) The increased expression of VEGF, which is critical to angiogenesis, occurred early with peak at days 1 and 4, respectively. The expression pattern of bFGF, which has strong promoting effects on both endothelial cells and fibroblasts, is similar to that of VEGF; 5) For growth factors important for matrix deposition, both TGF beta 1 and 3 expressions increased gradually with sustained high level during entire experiment. The expression of CTGF, which is important in matrix production and remodeling, increased in later stage. This study showed the correlation between growth factor expression and dermal matrix deposition, which may have implications in developing strategies to improve burn wound healing. This study was supported by grants from DOD/DARPA and the Dermatology Foundation of South Florida.