Structural and Biochemical Characterisation of Endothelialization of Aortic Valve Bacterial Nanocellulose (BNC) Bio-Prosthesis in an Ovine Model

Aortic valves consist of specialized cellular components, in which endothelial cells play a critical role by inhibiting thrombosis and preventing the adhesion and infiltration of inflammatory cells. The biofunctionalization of protheses with scaffolds such as bionanocellulose (BNC) requires colonization by cells with specific phenotype that supports optimal valve performance and long-term durability and the presence of a biologically active endothelial monolayer is essential. In this study, we compared the extent of cell colonization and endothelial function of BNC prosthesis removed 6 months after implantation in comparison to ovine native aortic valves. Histological analyses revealed similar mean thickness of the ovine native valve and BNC aortic valve. Functional endothelial cells were present on both external aortic surfaces of native AV, while in BNC valve a continuous layer of endothelial cells was visible only on the aortic side. On the BNC surface, we detected the presence of endothelial nitric oxide synthase (eNOS), visualized by fluorescent antibody staining. In the functional test, the BNC valve showed higher adhesion of blood mononuclear cells compared to the native AV. These results showing partial cellularization of functional endothelium on implanted valve prostheses are not only a significant improvement compared to previous in vitro studies on BNC, but also further support the hypothesis that effective endothelialization of scaffold prostheses represent important element that may preserve their function and durability.