Osteoconductive composite graft based on bacterial synthesized hydroxyapatite nanoparticles doped with different ions: From synthesis to in vivo studies

To repair damaged bone tissues, osteoconductive bone graft substitutes are required for enhancement of the regenerative potential of osteoblast cells. Nanostructured hydroxyapatite is a bioactive ceramic used for bone tissue engineering purposes. In this study, carbonate hydroxyapatite (cHA) and zinc-magnesium substituted hydroxyapatite (Zn-Mg-HA) nanoparticles were synthesized via biomineralization method using Enterobacter aerogenes. The structural phase composition and the morphology of the samples were analyzed using appropriate powder characterization methods. Next, a composite graft was fabricated by using polyvinyl alcohol and both cHA and Zn-Mg-HA samples. In vivo osteogenic potential of the graft was then investigated in a rabbit tibial osteotomy model. Histological, radiological and morphological studies showed that the graft was mineralized by the newly formed bone tissue without signs of inflammation or infection after 4 weeks of implantation. These histomorphometric results suggest that the fabricated graft can function as a potent osteoconductive bone tissue substitute.

We proposed a biomineralization method to synthesize nanostructured hydroxyapatite (nHA) doped with carbonate, zinc and magnesium ions using Enterobacter aerogenes PTCC1221 which is similar to synthesis of bone nHA by alkaline phosphatase. The produced bacterial nHA powders and polyvinyl alcohol (PVA) were mixed to fabricate an osteoconductive bone substituted graft. We aimed to investigate the degradability and osteoconductivity of this graft in vivo by implanting it in a rabbit tibial osteotomy model.Figure optionsDownload high-quality image (302 K)Download as PowerPoint slide