Lipid accumulation features in the heart valve epoxy-treated xenograft

Introduction.Xenograft heart valves are prone to structural valve degeneration accompanied by lipid accumulation. Research data suggest that the lipid insudation of bioprosthetic valve is secondary to cellular infiltration, since glycosaminoglycans produced by the recipient's cells are responsible for the lipid storage in the xenograft tissue. The objective of this research was to study the mechanisms of lipid accumulation in the heart valve xenograft, and to test the hypothesis that cells and glycosaminoglycans play a role in this process. Materials and methods.The study included 10 explanted bioprosthetic mitral valves (5 xenoaortic and 5 xenopericardial). We separated the leaflets of these valves from the stent, then the material was fro-zen and transferred to the cryotome for section preparation. The sections were stained with Gill's H&E staining in order to study the cellular infiltration and detect any degenerative changes. To analyze the component composition of the leaflets the sections were stained with Movat's pentachrome, whereas Oil Red O was used to visualize the lipids. We used light microscopy to analyze the stained samples. Results. Lipids and clusters of foam cells were present in all xenoaortic heart valves, but they were not found in the xenopericardial heart valves. Most lipid deposits and cellular infiltrates were not colocalized. Movat’s pentachrome staining revealed an absence of glycosaminoglycans in the leaflets of both types of bioprostheses. Conclusion. The intensity of lipid insudation in the leaflets of bioprosthetic heart valves depends on the xenograft biomaterial. Xenoaortic bioprosthetic heart valves are revealed to be prone to lipid accumulation, unlike xenopericardial bioprostheses. The presence of cell infiltration and glycosaminoglycans in the leaflets is not a determining factor contributing to the accumulation of lipids. Keywords: bioprosthetic heart valves, structural valve degeneration, cell infiltration, blood lipids, glycos-aminoglycans