PREPARATION OF COLLAGEN-SULFONATED CARBOXYMETHYL CHITOSAN/SILICONE MEMBRANE BILAYER DERMAL EQUIVALENT AND ITS APPLICATION IN THE TREATMENT OF SCALDS OF PORCINE SKIN

A dermal equivalent applied in the treatment of scalds has been attracting much attention.We report here the fabrication of a bilayer dermal equivalent(BDE) composed of collagen-sulfonated carboxymethyl chitosan(SCC) porous scaffold and silicone membrane,and its application for accelerating the healing of skin scalds in a Bama miniature pig model.Firstly,the SCC was synthesized,and its chemical structure was characterized by FTIR and ~1H-NMR.Then the effect of the ratio of the SCC on the microstructure of the collagen-SCC porous scaffolds was investigated.Sheet-like structure and bigger pores in the scaffolds appeared gradually along with the increase of the SCC amount.In vitro culture of human fibroblasts proved that the scaffold facilitated the proliferation of cells,confirming that it can function as a physical template with good cytocompatibility.Two kinds of BDEs,i.e.collagen-chitosan/silicone membrane(BDE1) control and collagen-SCC/silicone membrane(BDE2),were used to repair skin scalds of Bama miniature pigs.The healing process of both BDEs was studied by macroscopic observation and HE staining.Immunohistochemical staining of VEGF and CD34 were performed to investigate the angiogenesis ability of these two kinds of BDEs.The results showed that compared to the BDE1,the BDE2 had a stronger ability to enhance the angiogenesis of the skin equivalent and the regeneration of the dermal layer.Transplantation of split-thickness skin graft was further carried out on the regenerated dermal layers.Results showed that only the scalds treated by the BDE2 had the ability to support the restoration of full-thickness skin.All these results demonstrate that the BDE2 with the SCC and collagen as the major component has better effect on accelerating the healing of scalds than that of the BDE1 with collagen and chitosan as the major component.One can also conclude that the sulfonated carboxymethyl chitosan,which is more structurally similar as heparin,should take the main role for the better repair results.