Poly (vinyl alcohol) and its bacterial cellulose nanocomposites based tissue hybrid material

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There is a steady increase in the demand for replacement cardiovascular devices such as heart valves and vascular grafts as our population ages. Performance and durability of these devices are often limited by properties of the materials used. Although tissue engineering is promising, organization of components and functional properties of tissues generated are yet to be realized. Therefore there is a continuing search for better replacement materials. Traditional approaches include the use of synthetic biomaterials and treated animal tissues as in the case of mechanical and bioprosthetic heart valves. In the case of arteries, only large diameter synthetic replacements are available. For coronary replacements, autografts from the patient have to be used. Many of the problems have been traced to mechanical mismatch between the tissue and the material used and lack of hemocompatability of the material. In our ongoing study of two biomaterials, poly(vinyl alcohol) (PVA), a biocompatible hydrogel and bacterial cellulose (BC), a nano-biomaterial made by microbial fermentation in our laboratory, we have demonstrated that PVA with anisotropic mechanical properties similar to that of aortic tissue can be prepared. By the addition of the BC nanofibers, anisotropic PVA-BC nanocomposites with properties that can be tailored to mimic a broad range of cardiovascular tissues can be created. We propose to design anisotropic PVA and PVA-BC biomaterials to possess mechanical properties of the target cardiovascular tissue. Using these designed biomaterials as substrate, endothelial cells which impart hemocompatability in tissues can be attached to the substrate via surface reactions to provide adhesion sites of these cells. The resulting biomaterial-tissue hybrids of anisotropic PVA and PVA-BC would have good mechanical compatability with the neighboring tissue and at the sametime hemocompatabile due to confluent surface coverage with endothelial cells. These biomaterial-tissue hybrids would be suitable for use in a broad range of replacement cardiovascular devices.