Study On Wound Healing And Expression Of COX-2,VEGF After Transplantation Of Sheepskin Acellular Dermal Matrix Combined With Micro-autograft Of Skin

Objective To investigate an appropriate method for the preparation of sheepskin acellular dermal matrix (ADM), we can observe the expression of cycloxygenase -2( COX -2) .vascular endothelial growth factor (VEGF) by using immunohistochemistry method , and the changes of histological structure on the cograft of auto - microskin and sheepskin acellular dermal matrix(ADM). To explore the survival mechanism of composite skin grafting, we can provide a skin substitute for large area deep burn , which covers wound surface earlier period and improves healing quality later period. Methods Using 0.25% Trypsin and 0.5% TritonX - 100 to prepare sheepskin ADM, The full - thickness skin defects were made to 4cm×3cm in the back of Wistar rats. The 48 wounds were averagely divided into test and control groups. The wounds in test group were grafted with auto - microskin and sheepskin ADM, while the wounds in control group were grafted with auto - microskin. All wounds were coverd with the allo -split -thickness skin. The samples of grafted skin of 2,4,and 6 weeks after operation were prepared with immunohistochemistry examination and observed histological structure with light microscope. Simultaneously the wound healing condition and contraction rate of twogroups were detected. Results①Under light microscopy, we can observe the epidermis completely removed, collagen fibers well - distributed and there were not any cellular component in der-mis.②After transplantation, the two groups wounds generally healed for 6 weeks observation. The contraction rate exhibited obvious difference (P < 0. 05). Compare with contral group, the wounds of test group have lower contraction rate. Simultaneously, it was revealed by histological examation that normal vascular structure could be identified in the grafted skin. The structure of collagen fibres appeared integrated clear with regular arrangement. There were no differences of the expression of COX - 2 and VEGF( P > 0.05). Conclusions sheepskin ADM has not only removed immunognicity cellular composition thoroughly, but preserved tissue of basic structure and complete collagen scaffold . It becomes very low antigenic demis scaffold, and it is a good dermal substitute . Compared with control group , the wounds after auto - microskin and Sheepskin ADM grafted have fewer scar, lower contraction rate, similar normal function and not easy to be damaged. COX -2, VEGF may take part in the process of wound repairing.