Biological Niches within Human Calcified Aortic Valves: Towards Understanding of the Pathological Biomineralization Process.
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.
Department of Earth Sciences, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.
Valentina
V
Cottignoli
Department 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.
Michela
M
Relucenti
Department of Earth and Geoambiental Sciences, Aldo Moro University of Bari, Via Orabona 4, 70125 Bari, Italy.
Giovanna
G
Agrosì
Department of Medical-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Corso della Repubblica 79, 04100 Latina, Italy.
Elena
E
Cavarretta
Department 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.
Giuseppe
G
Familiari
Division of Cardiac Surgery, San Bortolo Hospital, Viale Rodolfi 37, 36100 Vicenza, Italy.
Loris
L
Salvador
Department of Earth Sciences, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.
Adriana
A
Maras
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000473:pathology*; D001031:Apatites / Q000737:chemistry; D002114:Calcinosis / Q000473:pathology*; D003461:Crystallography; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology; D053758:Nanoparticles / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission
D001031:Apatites