Novel TOCNF reinforced injectable alginate / β-tricalcium phosphate microspheres for bone regeneration

An innovative, moldable and injectable bone substitute material comprised of microspheres of sodium alginate (SA)/TOCNF and β-tricalcium phosphate (β-TCP) as the solid phase and carrier SA as the gel phase was developed. The microspheres were prepared by a droplet extrusion crosslinking technique using an aqueous calcium chloride solution. The purpose of this study was to explore the osteoconductivity of the prepared injectable microspheres by filling critically sized bone defects. The in vitro biocompatibility and cytotoxicity of the microspheres were analyzed in MC3T3-E1 osteoblast-like cells using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide) assay. An in vivo investigation in a rabbit model indicated that the prepared SO3T20 microspheres showed significantly better bone formation than the control after two and four weeks of implantation. The outcomes demonstrated that the microspheres delivered support for osteogenic differentiation. These results suggest that this novel injectable bone substitute material may be useful for bone tissue engineering.