In vitro and in vivo evaluation of a novel nanosize hydroxyapatite particles/poly(ester-urethane) composite scaffold for bone tissue engineering

Scaffolds for bone tissue engineering should provide an osteoconductive surface to promote the ingrowth of new bone after implantation into bone defects. This may be achieved by hydroxyapatite loading of distinct scaffold biomaterials. Herein, we analyzed the in vitro and in vivo properties of a novel nanosize hydroxyapatite particles/poly(ester-urethane) (nHA/PU) composite scaffold which was prepared by a salt leaching–phase inverse process. Microtomography, scanning electron microscopy and X-ray spectroscopy analyses demonstrated the capability of the material processing to create a three-dimensional porous PU scaffold with nHA on the surface. Compared to nHA-free PU scaffolds (control), this modified scaffold type induced a significant increase in in vitro adsorption of model proteins. In vivo analysis of the inflammatory and angiogenic host tissue response to implanted nHA/PU scaffolds in the dorsal skinfold chamber model indicated that the incorporation of nHA particles into the scaffold material did not affect biocompatibility and vascularization when compared to control scaffolds. Thus, nHA/PU composite scaffolds represent a promising new type of scaffold for bone tissue engineering, combining the flexible material properties of PU with the advantage of an osteoconductive surface.