Rutin-magnesium complex promotes cranial bone defect repair via coordinated osteogenic and angiogenic regulation

Abstract

Critical-size bone defects remain a major clinical challenge, as the current regenerative strategies such as bone grafts, biomaterials, and exogenous cells still have limitations. Emerging evidence suggests that focusing local cells and enhancing their osteogenic and angiogenic activities represents a promising approach for bone defect repair. Rutin, a flavonoid, has shown favorable osteogenic and pro-angiogenic potential. However, its therapeutic application is constrained by limited bioavailbility and suboptimal biological performance. To address these limitations, the magnesium-rutin complex (rutin-Mg) was designed, aiming to enhance rutin functional efficacy by leveraging the biological role of magnesium ions. The biosafety of rutin and rutin-Mg was first evaluated. CCK-8 assays using human BMSCs(hBMSCs) and human umbilical vein endothelial cells (HUVECs) demonstrated that both compounds exhibited minimal cytotoxicity at concentrations below 20 µg/mL, and the best promotive effect on those cells both at the concentration of 1 µg/mL. In functional tests, rutin-Mg significantly facilitated osteogenic differentiation of hBMSCs compared with rutin, as demonstrated by stronger ALP and ARS staining and higher expression of osteogenic proteins, including ALP, RUNX2, OPN, and OCN. In parallel, rutin-Mg more effectively enhanced angiogenic activity in HUVECs, as shown by increased expression of angiogenesis-related factors, enhanced cell migration in wound healing and transwell assays, and improved tube formation capacity. In the rat critical-size calvarial defect model, rutin-Mg-loaded hydrogel significantly accelerated bone regeneration compared with rutin and vehicle groups. Then the Micro-CT, mineral deposition analysis, histological staining, and OCN, CD31, and α-SMA immunohistochemistry confirmed increased new bone formation and vascularization in the rutin-Mg group. Furthermore, network pharmacology analysis revealed substantial overlap between rutin-related targets and genes associated with osteogenesis and angiogenesis, prompting a multi-target regulatory mechanism. Collectively, these results indicated that rutin-Mg promotes bone defect repair by enhancing osteoangiogenic coupling. This study highlights rutin-Mg as a promising bioactive compound for endogenous bone regeneration and provides a biologically inspired strategy for the treatment of bone defects.