title: Imaging collagen packing dynamics during mineralization of engineered bone tissue.
abstract: The structure and organization of the Type I collagen microfibrils during mineral nanoparticle formation appear as the key factor for a deeper understanding of the biomineralization mechanism and for governing the bone tissue physical properties. In this work we investigated the dynamics of collagen packing during ex-vivo mineralization of ceramic porous hydroxyapatite implant scaffolds using synchrotron high resolution X-ray phase contrast micro-tomography (XPCμT) and synchrotron scanning micro X-ray diffraction (SμXRD). While XPCμT provides the direct 3D image of the collagen fibers network organization with micrometer spatial resolution, SμXRD allows to probe the structural statistical fluctuations of the collagen fibrils at nanoscale. In particular we imaged the lateral spacing and orientation of collagen fibrils during the anisotropic growth of mineral nanocrystals. Beyond throwing light on the bone regeneration multiscale process, this approach can provide important information in the characterization of tissue in health, aging and degeneration conditions.
  
  
  CONCLUSIONS
  BONE grafts are the most common transplants after the blood transfusions. This makes the bone-tissue regeneration research of pressing scientific and social impact. Bone is a complex hierarchical structure, where the interplay of organic and inorganic mineral phases at different length scale (from micron to atomic scale) affect its functionality and health. Thus, the understanding of bone tissue regeneration requires to image its spatial-temporal evolution (i) with high spatial resolution and (ii) at different length scale. We exploited high spatial resolution X-ray Phase Contrast micro Tomography and Scanning micro X-ray Diffraction in order to get new insight on the engineered tissue formation mechanisms. This approach could open novel routes for the early detection of different degenerative conditions of tissue.
authors.affiliation: Institute of Crystallography, CNR, Via Salaria km 29.300, I-00015 Monterotondo, Roma, Italy. Electronic address: gaetano.campi@ic.cnr.it.
authors.forename: G
authors.initials: G
authors.lastname: Campi
authors.affiliation: Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche "Enrico Fermi", Roma, Italy; Dipartimento di Scienze, Università di Roma Tre, Roma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Fratini
authors.affiliation: Institute for Chemical and Physical Process, CNR, c/o Physics Dep. at Sapienza University, P-le A. Moro 5, 00185 Roma, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Bukreeva
authors.affiliation: Istituto di Fisica, Universitá Cattolica SC, L.go Francesco Vito 1, I-00168 Roma, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Ciasca
authors.affiliation: European Synchrotron Radiation Facility, B. P. 220, F-38043 Grenoble Cedex, France.
authors.forename: M
authors.initials: M
authors.lastname: Burghammer
authors.affiliation: Department of Engineering and Architecture, University of Trieste, Via A. Valerio 10, 34127 Trieste Italy.
authors.forename: F
authors.initials: F
authors.lastname: Brun
authors.affiliation: Sincrotrone Trieste SCpA, 34149 Basovizza, Trieste, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Tromba
authors.affiliation: Istituto Nazionale per la Ricerca sul Cancro, and Dipartimento di Medicina Sperimentale dell'Università di Genova & AUO San Martino Istituto Nazionale per la Ricerca sul Cancro, Largo R. Benzi 10, 16132 Genova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Mastrogiacomo
authors.affiliation: Institute for Chemical and Physical Process, CNR, c/o Physics Dep. at Sapienza University, P-le A. Moro 5, 00185 Roma, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Cedola
mesh_terms: D000818:Animals; D001846:Bone Development / Q000502:physiology*; D001842:Bone and Bones / Q000000981:diagnostic imaging* / Q000648:ultrastructure; D002113:Calcification, Physiologic / Q000502:physiology*; D024042:Collagen Type I / Q000502:physiology* / Q000648:ultrastructure*; D003198:Computer Simulation; D008954:Models, Biological; D012756:Sheep; D054457:Tissue Scaffolds; D014057:Tomography, X-Ray Computed / Q000379:methods; D014961:X-Ray Diffraction / Q000379:methods*
chemical_list: D024042:Collagen Type I
keywords: Biomineralization; Collagen; Fluctuations; Scanning X-ray micro-diffraction; Spatial statistics