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

随着人口老龄化，对心脏瓣膜和血管移植物等替代心血管装置的需求稳步增加。这些设备的性能和耐用性往往受到所用材料的特性的限制。尽管组织工程学很有前途，但所产生的组织的成分组织和功能特性尚未实现。因此，人们一直在寻找更好的替代材料。传统的方法包括使用合成生物材料和经过处理的动物组织，例如机械和生物人工心脏瓣膜。就动脉而言，只有大直径的合成替代物可用。对于冠状动脉置换，必须使用患者的自体移植物。许多问题都可以追溯到组织和所用材料之间的机械不匹配以及材料的血液相容性不足。在我们实验室对生物相容性水凝胶聚乙烯醇(PVA)和微生物发酵法制备的纳米生物材料细菌纤维素(BC)这两种生物材料的研究中，我们证明了可以制备出具有类似于主动脉组织的各向异性力学性能的PVA。通过添加BC纳米纤维，可以创建各向异性PVA-BC纳米复合材料，其性能可以定制以模拟广泛的心血管组织。我们建议设计各向异性的PVA和PVA-BC生物材料，使其具有目标心血管组织的力学性能。利用这些设计的生物材料作为基质，在组织中赋予血液相容性的内皮细胞可以通过表面反应附着到基质上，提供这些细胞的黏附部位。由此得到的各向异性PVA和PVA-BC生物材料-组织杂化材料与邻近组织具有良好的机械相容性，同时由于与内皮细胞的融合表面覆盖而具有血液相容性。这些生物材料-组织混合体将适合用于广泛的心血管替代装置。

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.