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BioMed Research International
Volume 2015, Article ID 542687, 10 pages
http://dx.doi.org/10.1155/2015/542687
Research Article

Biological Niches within Human Calcified Aortic Valves: Towards Understanding of the Pathological Biomineralization Process

1Department of Earth Sciences, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
2Department of Anatomical, Histological, Legal Medicine and Orthopedics Sciences, Section of Human Anatomy, Electron Microscopy Laboratory “Pietro M. Motta”, Sapienza University of Rome, Via Alfonso Borelli 50, 00161 Rome, Italy
3Department of Earth and Geoambiental Sciences, Aldo Moro University of Bari, Via Orabona 4, 70125 Bari, Italy
4Department of Medical-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Corso della Repubblica 79, 04100 Latina, Italy
5Division of Cardiac Surgery, San Bortolo Hospital, Viale Rodolfi 37, 36100 Vicenza, Italy

Received 19 March 2015; Accepted 7 June 2015

Academic Editor: Umberto Benedetto

Copyright © 2015 Valentina Cottignoli et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Despite recent advances, mineralization site, its microarchitecture, and composition in calcific heart valve remain poorly understood. A multiscale investigation, using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectrometry (EDS), from micrometre up to nanometre, was conducted on human severely calcified aortic and mitral valves, to provide new insights into calcification process. Our aim was to evaluate the spatial relationship existing between bioapatite crystals, their local growing microenvironment, and the presence of a hierarchical architecture. Here we detected the presence of bioapatite crystals in two different mineralization sites that suggest the action of two different growth processes: a pathological crystallization process that occurs in biological niches and is ascribed to a purely physicochemical process and a matrix-mediated mineralized process in which the extracellular matrix acts as the template for a site-directed nanocrystals nucleation. Different shapes of bioapatite crystallization were observed at micrometer scale in each microenvironment but at the nanoscale level crystals appear to be made up by the same subunits.