Pathogenetic parallels between native and bioprosthetic aortic valve calcification

There was a suggestion that pathological tissue mineralization is a universal, multifactorial, and cell-mediated process, regulated on genetic, biochemical and hormone levels. Structural deterioration of bioprosthetic heart valves is mainly caused by calcification of chemically modified xenogenic tissues. We performed this study with the aim to define parallels in degenerative strokes of native aortic valves and Ca-mediated primary tissue-insolvency of bioprosthetic aortic valves. We investigated calcified tissue samples of bioprosthetic aortic valves and calcified wings of aortic valves. (eight per each group). Functionally safe xenopericardiac mitral prosthetic heart valve, obtained at autopsy were included to investigate processes with prosthetic wings. Histological examination was carried out by hematoxylin and eosin and van Gieson staining on optical microscope AXIOImager A1. We observed mosaic structural alterations which characterized increasing of calcification process in all specimens. There were interactions between mineral deposits and valve tissues by direct contact with the cells and/or fibers of collagen and elastin. Cell composition in calcified native aortic valves was represented by fibroblasts, macrophages, multinucleated giant cells, lymphocytes, and neutrophils. Bioprosthetic heart valves also contained smooth muscle cells and capillaries. Results of our investigation represents that structures of calcified native and bioprosthetic heart valves are similar. This fact make us able to conclude that there are direct cells-mediated processes of biological material and xenogenic aortic valves degradation. Appearance of structurally safe cells in devitalized xenogenic prosthetic aortic valve caused by their functioning in recipient body. We suggest that the source of these cells can be the pluripotent progenitor cells, circulated in bloodstream and able to differentiate into cells of different phenotypes when they penetrated the collagen matrix of implanted prosthetic aortic valves. Based on the above analysis we can suggest that calcium degeneration of soft tissues is an universal pathologic process the basis of which have different mechanisms and the key one is cell-mediated mineralization.

calcification, aortic valves, bioprosthetic valves, cells