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The vascularization of bone repair materials is one of the key issues that urgently need to be addressed in the process of bone repair. The changes in macrophage phenotype and function play an important role in the process of vascularization, and endowing bone repair materials with immune regulatory characteristics to enhance angiogenesis is undoubtedly a new strategy to improve the effectiveness of bone repair. In order to improve the effect of tricalcium phosphate (TCP) on vascularization and bone repair, we doped strontium ions (Sr) into TCP (SrTCP) and prepared porous 3D printed SrTCP scaffolds using 3D printing technology, and studied the scaffold mediated macrophage polarization and subsequent vascularization and bone regeneration. The results of the interaction between the scaffold and macrophages showed that the SrTCP scaffold can promote the polarization of macrophages from M1 to M2 and secrete high concentrations of VEGF and PDGF-bb cytokines, which shows excellent angiogenic potential. When human umbilical vein endothelial cells (HUVECs) were co-cultured with macrophage-conditioned medium of SrTCP scaffold, HUVECs exhibited excellent early angiogenesis-promoting effects in terms of scratch healing, angiogenic gene expression, and in vitro tube formation performance. The results of in vivo bone repair experiments showed that the SrTCP scaffold formed a vascular network with high density and quantity in the bone defect area, which could increase the rate of new bone formation and advance the period of bone formation, and finally achieved a better bone repair effect. We observed a cascade effect in which Sr-doped SrTCP scaffold regulate macrophage polarization to enhance angiogenesis and promote bone repair, which may provide a new strategy for the repair of clinical bone defects.

The effects of eugenol (EG; 0, 5, 20, and 50 mg/g protein) on the structure and gel properties of pork myofibrillar protein (MPs) under a hydroxyl radical-generating system were explored in this study. The results revealed that the addition of a high concentration of EG (50 mg/g protein) markedly reduced the carbonyl content and enhanced the fluorescence intensity, surface hydrophobicity, and protected the secondary structure of MPs, compared to oxidized MPs. In addition, the high concentration group noticeably increased the storage modulus (G′), gel strength, and water-holding capacity (WHC), and significantly hindered the oxidation-induced transformation of immobilized water of the MPs gel to free water and basically favored the formation of a finer and more homogeneous three-dimensional network structure, This work verified that the adding of EG could effectively improve the gel quality of oxidized MPs and more successfully delay oxidation-induced damage to muscle protein structure.