Study On The Properties Of Collagen-chitosan/silicone Bilayer Scaffold And Its In Situ Induced Regeneration Of Dermis

The pvirpose of this work is to construct a collagen/chitosan scaffold for dermal equivalent, which has the similar microstructure of extracellular matrix of dermis, good biostability and biocompatibility. Further, mimicking the structures and functions of the human skin, a bilayer artificial skin, collagen-chitosan/silicone bilayer scaffold, is fabricated.The collagen-chitosan/silicone bilayer scaffold is made of collagen-chitosan dermal scaffold and a silicone film, which are adhered together by a kind of good biocompatible glue. Of the two layers, the collagen-chitosan dermal scaffold is equivalent to the dermal extracellular matrix, promoting the regeneration of the damaged dermis in situ;while the silicone film, functions as a temporary epidermis, which can play a role in controlling water loss and inhibiting bacterial entry and so on.For this purpose, a porous scaffold withe controllable pore sizes and internconnected pore structure was prepared by collagen and chitosan by freeze-drying. In order to enhance the mechanical properties and biostability, glutaraldehyde (GA) was added to function as cross-linking bridges. The swelling test indicated that the GA treated collagen/chitosan dermal scaffold had an enough water-absorbing ability for dermal tissue engineering. In vitro fibroblast culture demonstrated that the collagen-chitosan dermal scaffold showed good biocompatibility and bioviability.The silicone film was introduced to form a full-thickness artificial skin. The results showed that the silicone film not only retained the microstructure, biostability and bioviability of the collagen-chitosan dermal scaffold, but also improved themechanical properties and decreased the water permeability of the collagen-chitosan/silicone bilayer scaffold. The biological safety evaluation showed that the collagen-chitosan/silicone bilayer artificial skin scaffold had no cytotoxicity, no remarkable potential irritability and sensitization for skin.Finally, the properties of the collagen-chitosan/silicone bilayer scaffold inducing dermal regeneration in situ were evaluated by transplanting into the backs of the pigs. We explored the transplant methods and designed standard operation procedures, improving the efficiency from 0 to about 94%. The gross views and histological sections showed that the collagen-chitosan/silicone bilayer scaffold can effectively induce fibroblast differentiation and proliferation, promoting the damaged dermis regeneration in situ. However, 28 days later, scaffold still preserved partially, demonstrating its biodegradation behavior would be a long-term process.