title: Engineering of bone using bone marrow stromal cells and a silicon-stabilized tricalcium phosphate bioceramic: evidence for a coupling between bone formation and scaffold resorption.
abstract: Resorbable porous ceramic constructs, based on silicon-stabilized tricalcium phosphate, were implanted in critical-size defects of sheep tibias, either alone or after seeding with bone marrow stromal cells (BMSC). Only BMSC-loaded ceramics displayed a progressive scaffold resorption, coincident with new bone deposition. To investigate the coupled mechanisms of bone formation and scaffold resorption, X-ray computed microtomography (muCT) with synchrotron radiation was performed on BMSC-seeded ceramic cubes. These were analyzed before and after implantation in immunodeficient mice for 2 or 6 months. With increasing implantation time, scaffold thickness significantly decreased while bone thickness increased. The muCT data evidenced that all scaffolds showed a uniform density distribution before implantation. Areas of different segregated densities were instead observed, in the same scaffolds, once seeded with cells and implanted in vivo. A detailed muX-ray diffraction analysis revealed that only in the contact areas between deposited bone and scaffold, the TCP component of the biomaterial decreased much faster than the HA component. This event did not occur at areas away from the bone surface, highlighting coupling and cell-dependency of the resorption and matrix deposition mechanisms. Moreover, in scaffolds implanted without cells, both the ceramic density and the TCP:HA ratio remained unchanged with respect to the pre-implantation analysis.
authors.affiliation: Istituto Nazionale per la Ricerca sul Cancro, and Dipartimento di Oncologia, Biologia e Genetica dell Universita di Genova, Largo R. Benzi, 10, 16132, Genova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Mastrogiacomo
authors.forename: A
authors.initials: A
authors.lastname: Papadimitropoulos
authors.forename: A
authors.initials: A
authors.lastname: Cedola
authors.forename: F
authors.initials: F
authors.lastname: Peyrin
authors.forename: P
authors.initials: P
authors.lastname: Giannoni
authors.forename: S G
authors.initials: SG
authors.lastname: Pearce
authors.forename: M
authors.initials: M
authors.lastname: Alini
authors.forename: C
authors.initials: C
authors.lastname: Giannini
authors.forename: A
authors.initials: A
authors.lastname: Guagliardi
authors.forename: R
authors.initials: R
authors.lastname: Cancedda
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001854:Bone Marrow Cells / Q000166:cytology*; D018786:Bone Substitutes; D002130:Calcium Phosphates; D002516:Ceramics; D004355:Drug Stability; D005260:Female; D008422:Materials Testing; D023421:Models, Animal; D016348:Osseointegration; D010012:Osteogenesis; D019736:Prostheses and Implants; D012756:Sheep; D012825:Silicon; D017154:Stromal Cells / Q000166:cytology; D013997:Time Factors; D023822:Tissue Engineering; D014057:Tomography, X-Ray Computed; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D002130:Calcium Phosphates; C018392:tricalcium phosphate; D012825:Silicon