Preparation Of Heterogeneous (Porcine) Skin Substitute And Its Use In Deep Burn Wound

The burn wound is the foundation of causing the pathophysiological change in the body. Now, it has been generally accepted that early excision and grafting in patients with extensive deep burns played a vital role in the survival of the patients. The present method to cover deep burn wounds is the transplantation of thin, split-thickness skin graft(STSG). Although this procedure accomplishes wound closure, it is often associated with scarring and contracture of the wound site due to the thinning of the dermis. An additional trauma results from the generation of a wound at the donor site, and harvesting a thicker STSG results in a increased morbidity at the donor site. And the application of this technique is limited in the case of patients with deep and extensive burns. The patients with major burn underwent a surgical excision, and the resultant wounds were closed with micro-autograft and allo-skin graft. The grafted areas seldom expand as well as normal skin and late contracture may require release. Therefore, the development of permanent skin substitute has an enormous impact on the care of the patients with deep and extensive burns.ObjectiveFor the past few years, various skin substitutes were prepared along with the development of tissue engineering. The main advantages of the porcine skin are (1) a much cheaper price, (2) a much more extensive source , (3) a much higher tissue homogeneity. Therefore, the purpose of this study was to prepare selective acellular porcine skin in order to close the burn wound and toinvestgate the wound healing quality of PADM with auto-skin graft , and to observe the deep burn wound were covered with PADM with combination of auto-microskin and allo-skin graft on improving wound healing quality. The other purpose was to observe the transformation of heterogeneous (porcine) acellular dermal matrix in vivo.Materials and Methods1. The preparation of porcine skin dressing1.1 The preparation of selective acellular porcine skin dressing(SAPS)The SAPS was prepared in formaldehyde, trypsin and TritonX-100 in turn. Treated in formaldehyde, the epidermal could lose vitality and increase the jounction of epidermis and dermis. Treated in trypsin, the casein was dissocated. Continuously shocked in TritonX-100, all of the cells in dermis were removed almostly.1.2 The preparation of heterogeneous (porcine) acellular dermal matrix(PADM) The PADM was prepared by removing cells from the skin with 0.25%trypsin for 30 minutes and 0.5% TritonX-100 for 24 hours. At last, it was cross-linked in 0.5% glutaraldehyde for 10 minutes. 2.Animal experiments2.1 The full-thickness skin defect on the back of Sprague-Dawley rats was covered with auto- microskin, then covered with SAPS, Allo-skin, glutaraldehyde skin and Paraffin gauze dressing, respectively. The histological changes and also transplantation results were observed in 1, 2, 4 weeks post-transplantation.2.2 The full-thickness skin defect was covered with PADM together with auto-microskin and allo-skin graft in test group I, the test group II with PADM andsplit-thickness autoskin and the control group with auto- microskin and allo-skin graft. The transplantation results of composite skin and histological examination were observed.2.3 The PADM was embedded beneath the SD rat's skin. General change and histological change was observed inl, 2, 4, 6, 8, 12, 16, 20, 30 weeks post-transplantation. 3.Clinical observationAt the base of consent of patients, PADM +split-thickness skin or PADM + auto-microskin +Allo-skin was used to cover the deep bum wound, granulation wound or cicatricle. The transplantation results was observed periodically.Results and Conclusions1. Confirmed by histology and immunohistochemistry, -the processing technique results in SAPS with intact epidermis and basement membrane and regular collagen and without any cellular components. The result of wound healing in SAPS groups was different from Allo-skin grafting groups slightly but better than the other groups distincti...