A New Multilayered Composite Bioceramic for Bone Graft
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1187-KK09-02
A New Multilayered Composite Bioceramic for Bone Graft José I. Arias1, Andrónico Neira-Carrillo2, Mehrad Yazdani-Pedram2, María S. Fernandez2, and Jose L. Arias2 1 2
Instituto Ciencias Clinicas Veterinarias, Universidad Austral de Chile, Valdivia, Chile. Dept. Animal Biology, Universidad de Chile and CIMAT, Santiago, Chile.
ABSTRACT Bone grafts need to comply with some criteria of biocompatibility, including favoring neovascularization, new bone formation, and discourage inflammatory response and graft rejection. It is also expected that these materials should have mechanical properties similar to those of natural bone, that is, having enough pores to permit osteoprogenitor cells and vascular endothelium penetration but maintaining strength and flexibility. Here, a new resistant and flexible tridimensional multilayered bioceramic composite was obtained by using chitosan and hydroxyapatite in combination with cells and their associated growth factors from the bone marrow tissue, allowing the development of a biocompatible bone graft. This multilayered graft made out of chitosan functionalized with phosphate groups and mineralized with calcium phosphate (hydroxyapatite) was analyzed with scanning electron microscopy (SEM), X ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR) to assess the degree of phosphorylation and the amount of hydroxyapatite present in the graft. The composite was further characterized by mechanical testing (Vicker's microhardness test), in vitro osteoblasts culture citotoxicity tests. The results showed that this multilayered graft has mechanical properties comparable to that of trabecular bone and it was capable to keed osteogenic cells alive.
INTRODUCTION Bone is a remodeling composite material made out of an organic matrix of collagen and dozens of non-collagenous proteins and proteoglycans, and an inorganic moiety of carbonated hydroxyapatite, having remarkable mechanical properties [1,2]. When bone is destroyed, several mechanisms tending to repair and remodel it are triggered. However, when the defect is too extended, the mechanisms of repair fail or are delayed in such a way that a non functional fibrocartilage callus formed instead of bone, persists. Here is when a bone graft or bone graft substitute is needed. The ideal bone graft is the autogenous bone transplantation. However, the problem is availability together with complications such as donor-site morbidity and increased intraoperative time [3]. Therefore synthetic osteoconductive matrices, such as bioabsorbable, bioactive or bioinert ceramics, have been largely used and improved to overcome such problems. However, most attempts in this effort lack mechanical strength and at best function as bone graft fillers that must be supported by other means during healing. Here, the fabrication and characterization of a new multilayered chitosan-hydroxyapatite-based composite material for bone graft is reported.
EXPERIMENTAL DETAILS Mother solution of 2% low mol
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