Molecular Spectroscopic Imaging Offers a Systematic Assessment of Pathological Aortic Valve and Prosthesis Tissue in Biomineralization

Abstract

Pathological ECM remodelling and biomineralization in human aortic valve and bioprosthesis tissue were investigated by Fourier transformed infrared (FT-IR) spectroscopic imaging and multivariate data analysis. Results of histological von Kossa staining to monitor hydroxyapatite biomineralization correlated to the definition of mineralized tissue using FT-IR spectroscopic imaging. Spectra exhibit signals of carbonate and phosphate groups of hydroxyapatite. Proteins could be identified by the amide I and amide II bands. Proteins were detected in the calcified human aortic valve tissue, but no absorption signals of proteins were observed in the mineralized bioprosthesis sample region. A shift of the amide I band from 1654 cm−1 to 1636 cm−1 was assumed to result from β-sheet structures. This band shift was observed in regions where the mineralization process had been identified but also in non-mineralized bioprosthesis tissue independent of prior implantation. The increased occurrence of β-sheet conformation is hypothesized to be a promoter of the biomineralization process. FT-IR spectroscopic imaging offers a wealth of chemical information. For example, slight variations in band position and intensity allow investigation of heterogeneity across aortic valve tissue sections. The exact evaluation of these properties and correlation with conventional histological staining techniques give insights into aortic valve tissue remodelling and calcific pathogenesis.

Multiscale Multimodal Characterization and Simulation of Structural Alterations in Failed Bioprosthetic Heart Valves

“…Despite the growing mechanistic understanding of native heart valve calcification, it remains unclear whether similar mechanisms trigger the development of minerals in bioprosthetic valves. While some studies report shared aetiology (12), different cell types and protein contents associated with the mineral in native versus bioprosthetic valves have been reported (13, 14). Calcification in bioprosthetic valves and subsequent failure have also been widely associated with the pretreatments used prior to implantation, i.e.…”

“…Even though considerable advances have been made, bioprosthetic valvular failure remains a significant and unresolved issue (14). The apparent complexity of the mineralisation mechanisms has highlighted the need for a more in-depth, systematic understanding of the mineral structures present in bioprosthetic tissues.…”

Biominerals: Formation, Function, Properties

“…The characterization of biological apatite is the focus of the contributions of Foley et al [4], Dittfeld et al [5] and Korneev et al [6]. Foley et al investigated, in a suite of 18 archeological human bone samples, the dependence between crystallographic lattice parameters and bone function, physicality and bone chemical composition [4].…”

“…The authors demonstrate systematic variation differences in a-and c-unit cell edge-length with relative bioapatite chemical composition and crystallite size, but not with bone mechanical function and, thus, the position of the bone in the human body. Dittfeld et al could show that, in contrast to results obtained with von Kossa staining techniques, multivariate evaluation of FT-IR spectroscopical data allows for the differentiation between mineralized and nonmineralized human aortic valve tissue [5]. Accordingly, the developed analytical tool (measurements and specific data evaluation) enables the identification of extracellular matrix modification and remodelling when the aortic valve is mineralized pathologically.…”