PLGA Cage-Like Structures Loaded with Sr/Mg-Doped Hydroxyapatite for Repairing Osteoporotic Bone Defects

Poly(lactic-co-glycolic acid) (PLGA)-based porous structures have a widespread application in bone defects. To solve its flaws in the bone application, hydroxyapatite (HA) is often introduced into PLGA-based systems, and ion doping endows HA with more biological activity. In osteoporotic bone defects, the decreased activity of osteoblasts and the hyperactive osteoclasts results in slow bone repair. Strontium (Sr) can promote bone regeneration and inhibit bone resorption and has been used in the treatment of osteoporosis. Magnesium (Mg) cannot only enhance the regeneration of bone tissue but also vessels. In this study,the aim is to fabricate a multifunctional porous structure that can promote osteogenesis, and angiogenesis and inhibit osteoclasts for repairing osteoporotic bone defects. PLGA cage-like structures loaded with Sr- and Mg-doped HA (Sr/Mg@HA/PLGA-CAS) are prepared; they have large pores, suitable hydrophilicity, and can continuously release Mg²⁺ and Sr²⁺ , which facilitate cell adhesion and growth. The results show that Sr/Mg@HA/PLGA-CAS can motivate the osteogenic activity of osteoblast precursor cells and angiogenic ability of endothelial cells, and suppress osteoclast differentiation in vitro. This study indicates that Sr/Mg@HA/PLGA-CAS can assist osteogenesis, and angiogenesis while restraining osteoclast differentiation, which may have a potential application value in osteoporotic bone defects.