In vitro and in vivo evaluation of biomimetic hydroxyapatite/whitlockite inorganic scaffolds for bone tissue regeneration

Abstract

Native bone tissue can be formed by developing collagen fibrils coated with hydroxyapatite (HA) and whitlockite (WH) nanoparticles after mineralization. WH has attracted much attention as the second most abundant bone mineral in human bones. It has a negatively charged surface, which can adsorb osteogenesis-related proteins such as bone sialoprotein in vivo, thus having a stronger possibility to induce osteogenesis. However, due to its poor thermodynamic stability and intermediate phases, the preparation of WH is relatively tricky, so WH inorganic scaffolds are still rarely studied. Therefore, this study explored the preparation of WH inorganic scaffolds using the hydrothermal method and prepared pure inorganic WH scaffolds. The prepared scaffolds exhibited apparent WH crystal phases in the x-ray powder diffraction (XRD) characterization. In the scanning electron microscopy (SEM) images, the WH scaffolds had an apparent hexagonal crystal form, which had a pronounced effect on promoting cell proliferation and differentiation in vitro experiments compared to the HA and HA/WH scaffolds. Furthermore, the scaffolds were used to verify the osteogenic properties of subcutaneous ectopic osteogenesis or repair of the calvarial defect in vivo and proved that the WH inorganic scaffolds have an excellent synergistic osteogenic ability.