The Experimental Study Of A New Kind Of Composite Skin

The treatment of extensive deep burn wound is mainly by transplantation of razor-thin graft or split-thickness skin autograft in clinic.But the lack of dermis makes the wound heal with scarring and contraction.We can prepare a new kind of acellular dermal matrix (ADM) by the method of NaOH-maceration. First the acellular dermal matrix became vascularized within 3 weeks after implantation into full thickness skin defects in SD rats, then auto-split-thickness skin was overlaid on it. By animal experiments, we observed that the new kind of composite skin can reduce scarring and contraction of transplantation of razor-thin or split-thickness skin autograft.The present study was made up of four sections. Section one the preparation of a new kind of acellular dermal matrix. An acellular dermal matrix was prepared from allogenic skin by removing epidermis with a hyperosmotic salt solution and cross-linking with glutaralaldehyde,then clear away acellular components in dermis with NaOH-maceration.The light and SME observation of the acellular dermal matrix revealed that the epidermis and cellular component in dermis were eliminated. Section two the evaluation of biocompatibility ofthe acellular dermal matrix by the method of cell culture.The new born rat's epdermic cells were cultured with the acellular dermal matrix together as experiment group, while the epdermic cell were cultured simply as control.24 hours later,under the invert microscope,the epidermic cells anchored well and transparent flat cells were observed in both groups.7 days later,both cultured cells were taked out and fixed in 95%ethanol,stained with hematoxylin and were observed under light microscope.Many cleaved cells were observed in both groups.During cell culture,no pathogenic microganism was observed.So we considered the acellular dermal matrix was aseptic and had good biocompatibility.Section three subdermal implantation of the acellular dermal matrix.24 rats were used in the experiments.A piece of acellular dermal matrix(1.5 X 1.5cm2) was implanted beneath the dorsum skin flaps of each rat, 1 week,2 weeks,3 weeks and 4 weeks after implantation,6 pieces of acellular dermal matrix were harvested and the size of implanted acellular dermal matrix were measured,the sections were used for HE staining and observed under light microscope.The result were as folio wing: 1-2 weeks after implantation,the acellular dermal matrix began to adhere to the tissue around and turned red gradually;3-4weeks after implantation,the acellular dermal matrix adhered closely to the tissue around and could be recognized easily, 1-3 weeks after implantation,the size ofimplanted acellular dermal matrix had no statistical difference (P>0.05).4 weeks after implantation implanted acellular dermal matrix contracted(P<0.05).Under light microscope, l-2weeks after implantation, the fibroblast cells infiltrated the acellular dermal matrix and a small amount endothelial cells of vessel and lympho-histiocytic cells infiltrated the acellular dermal matrix.3-4 weeks after implantation, infiltrating blood vessels were evident.So we think that the acellular dermal matrix had low immunological reactions and could induce the infiltration of fibroblast macrophage cell and the endothelial cells of vessel. Section four study on composite graft of acellular dermal matrix with auto-split-thickness skin. 10 SD rats were used in the experiments. In experimental group, the acellular dermal matrix were transplanted to SD rat's full thickness skin defect wounds of dorsothoracic and it's surface is covered with irradiation pigskin. Then split-thickness skin autograft were transplanted on the vascularized acellular dermal matrix. In control group, simple split-thickness skin autografts were transplanted on the rat's full thicknss defect wounds of dorsolumbar. 2 weeks, 3 weeks, and 4 weeks after transplantation ordinary observation and histological observation were employed. In comparison with the control group, the composite transplantation skin had no remarkable contraction and have a fine ex...