Experimental Study On The Transplantation Of A Composite Skin Graft Composed Of Cultured Human Keratinocytes And Fibroblasts And A Chitosan-Collagen Matrix

Experimental Study on the Transplantation of a Composite Skin Graft Composed of Cultured Human Keratinocytes and Fibroblasts and a Chitosan-Collagen Matrix In clinic, it is one of the basic and imperious problems to close various skin wounds fast and effectively, especially to close full-thickness skin injuries from extensive burns and severe trauma. However, for many cases, a limited number of donor sites available for skin grafts prevent early, effective and permanent wound closure. Some methods now widely used in clinic which lack of dermis, such as small stamps of auto-grafting, mesh-grafting, patch-grafting, intermingled transplantation of auto-allografting, micro-skin-grafting and cultured autogeneic keratinocyte-sheets, can't resolve the problems regarding the cosmetic and function satisfactorily. Grafting of epidermal sheets on fat, fascia, or granulation tissue, however, does not provide and immediate dermal replacement and results in problems, such as wound contraction, ulceration, blister and grafting fragility. A dermal layer may be crucial for skin replacements. With split-thickness grafts a minimum critical thickness of dermis is required to control contraction and hypertrophic scar formation. Dermis, historically considered a passive support system, plays a key role in controlling growth, differentiation, and attachment of epidermis. Epidermal growth and differentiation is accelerated when viable fibroblasts are present in a dermal replacement layer, and mesenchymal tissue may induce basement membrane formation. Epidermal sheets transplanted without dermis seldom reform organized epidermal structure, although epidermis that reforms in combination with viable dermis is thicker and contains more layers of stratified cells. Therefore, merely occluding wounds is not enough. Rational measure, such as implantation of composite grafts including dermal, is taken to improve the quality of healing wound. Tissue engineering technique has been a new method to provide adequate skin grafts to improve wound healing quality. Preparing the dermal replacement and reconstituting composite skins in vitro are the main aspects of skintissue engineering. Now, various dermal analogs such as Integra, Alloderm, Dermograft, et al have been developed and used as dermal template to cover full-thickness, chronic ulcer, scar plastic successfully. The dermal replacement grafted with thin autogeneic skin could shorten healing time of donor sites. The recipient sites have improved cosmesis and function with less pigmentation, wound contraction and better durability. However, these dermal substitutes derived from allogeneic skin have limited sources as well as slow vascularization or poor survival grafted simultaneously with autografts. Many researchers have paid attention to developing two-layer composite skin next to normal skin so as to repair full-thickness one step. Now, parts of the composite skins recombined in vitro have been commercial products, for instance, Apligraf. This two-layer material is composed of a dermis of bovine collagen containing fibroblasts from human neonatal foreskin, and an epidermis of stratified human epithelium. This combination of cells and extracellular matrix materials makes it one of the first true skin substitutes. Apligraf has been evaluated for treating wound caused by surgical removal of skin cancers and venous ulcers. Moreover, accompanying more clinical application, its defects were gradually exposed, such as, susceptible to microbial destruction on the excised wound and to enzymatic digestion, toughness weakly to suture difficultly. Therefore, while introducing these products into our country selectively, development of economical dermal replacement with better quality and the composite skin recombined in vitro are significance to solve skin resource insufficiency of full-thickness skin injuries from extensive burns and severe trauma. For ten years, we have investigated chitin and its certain derivatives uses in medical field with help of the nation natural science funds. Me...