Magnesium-alloy rods reinforced bioglass bone cement composite scaffolds with cortical bone-matching mechanical properties and excellent osteoconductivity for load-bearing bone in vivo regeneration

Abstract

Various therapeutic platforms have been developed for repairing bone defects. However, scaffolds possess both cortical bone-matching mechanical properties and excellent osteoconductivity for load-bearing bone defects repair is still challenging in the clinic. In this study, inspired by the structure of the ferroconcrete, a high-strength bifunctional scaffold has been developed by combining surface-modified magnesium alloy as the internal load-bearing skeleton and bioglass-magnesium phosphate bone cement as the osteoconductive matrix. The scaffold combines the high mechanical strength and controllable biodegradability of surface-modified magnesium alloy with the excellent biocompatibility and osteoconductivity of bioglass-magnesium phosphate bone cement, thus providing support for load-bearing bone defects and subsequently bone regeneration. The scaffolds generate hydroxyapatite (HA) during the degrading in simulated body fluid (SBF), with the strength of the scaffold decreasing from 180 to 100 MPa in 6 weeks, which is still sufficient for load-bearing bone. Moreover, the scaffolds showed excellent osteoconductivity in vitro and in vivo. In a New Zealand White Rabbit radius defect model, the scaffolds degrade gradually and are replaced by highly matured new bone tissues, as assessed by image-based analyses (X-ray and Micro-CT) and histological analyses. The bone formation-related proteins such as BMP2, COL1a1 and OCN, all showed increased expression.