Mussel-inspired HA@TA-CS/SA biomimetic 3D printed scaffolds with antibacterial activity for bone repair.

Bacterial infection is a major challenge that could threaten the patient's life in repairing bone defects with implant materials. Developing functional scaffolds with an intelligent antibacterial function that can be used for bone repair is very important. We constructed a drug delivery (HA@TA-CS/SA) scaffold with curcumin-loaded dendritic mesoporous organic silica nanoparticles (DMON@Cur) via 3D printing for antibacterial bone repair. Inspired by the adhesion mechanism of mussels, the HA@TA-CS/SA scaffold of hydroxyapatite (HA) and chitosan (CS) is bridged by tannic acid (TA), which in turn binds sodium alginate (SA) using electrostatic interactions. The results showed that the HA@TA-CS/SA composite scaffold had better mechanical properties compared with recent literature data, reaching 68.09 MPa. It displayed excellent degradation and mineralization capabilities with strong biocompatibility in vitro. Furthermore, the antibacterial test results indicated that the curcumin-loaded scaffold inhibited S.aureus and E.coli with 99.99% and 96.56% effectiveness, respectively. These findings show that 3D printed curcumin-loaded HA@TA-CS/SA scaffold has considerable promise for bone tissue engineering.

Aerobic Exercise Prevents Chronic Inflammation and Insulin Resistance in Skeletal Muscle of High-Fat Diet Mice.

Obesity is commonly accompanied by chronic tissue inflammation and leads to insulin resistance. Aerobic exercise is an essential treatment for insulin resistance and has anti-inflammatory effects. However, the molecular mechanisms of exercise on obesity-associated inflammation and insulin resistance remain largely unknown. Here, we evaluated the effects of aerobic exercise on inflammation and insulin resistance in skeletal muscles of high-fat diet (HFD) mice. Male C57BL/6J mice were fed a high-fat diet or a normal diet for 12 weeks, and then aerobic training was performed on a treadmill for 8 weeks. Body weight, fasting blood glucose, food intake levels, and glucose and insulin tolerance were evaluated. The levels of cytokines, skeletal muscle insulin resistance, and inflammation were also analyzed. Eight weeks of aerobic exercise attenuated HFD-induced weight gain and glucose intolerance, and improved insulin sensitivity. This was accompanied by enhanced insulin signaling. Exercise directly resulted in a significant reduction of lipid content, inflammation, and macrophage infiltration in skeletal muscles. Moreover, exercise alleviated HFD-mediated inflammation by suppressing the activation of the NF-κB pathway within skeletal muscles. These results revealed that aerobic exercise could lead to an anti-inflammatory phenotype with protection from skeletal muscle insulin resistance in HFD-induced mice.

[Effects of mice macrophages on skeletal muscle cells under high glucose treatment].

Objective: To study the effects of mice macrophages on myogenic differentiation and insulin sensitivity of skeletal muscle cells under high glucose condition. Methods: C2C12 myoblasts and RAW264. 7 macrophages were co-cultured in transwell and treated with 60 mmol/L glucose. They were randomly divided into single culture control group (SC group, n=12), co-culture control group (CC group, n=12), single culture high glucose group (SH group, n=12) and co-culture high glucose group (CH group, n=12). Cell morphology was observed by phase contrast microscope. C2C12 were collected after 1 and 3 days of co-culture. Cell viability was measured by CCK-8. Embryonic myosin heavy chain (E-MHC) and glucose transporters 4 (GLUT4) protein expressions were detected by immunofluorescence. The expressions of myogenic factor 5 (Myf5), myogenic determination gene (MyoD) and myogenin gene were detected by real-time PCR. 2-(N-(7-nitrobenz-2-oxa-13-diazol-4-yl) amino)-2-deoxyglucose (2-NBDG) assay was used to detect the cellular basis and insulin-stimulated glucose uptake. Results: Under normal glucose concentration, this co-culture with RAW264. 7 promoted C2C12 myotube formation, E-MHC protein expression (P＜0. 01), MyoD and myogenin gene expressions (P＜ 0. 05), insulin-stimulated 2-NBDG uptake (P＜0. 05), and basic GLUT4 level (P＜0. 05). High glucose stimulation inhibited myotube formation, myogenic regulatory factor gene expression, 2-NBDG uptake and GLUT4 expression in C2C12 (P＜0. 05). When co-cultured with C2C12 under high glucose treatment, compared with co-culture control group and high glucose group, cell activity, E-MHC protein expression, myogenic regulator gene expressions, 2-NBDG uptake and GLUT4 protein expression were significantly decreased (P＜0. 05). Conclusion: Co-culture with RAW264. 7 promotes myogenic differentiation and increases insulin sensitivity in C2C12, but this effect is reversed under 60 mmol/L glucose treatment, which inhibits myogenic differentiation and induces insulin resistance.

Eccentric exercise and dietary restriction inhibits M1 macrophage polarization activated by high-fat diet-induced obesity.

AIMS: Obesity induce low-grade inflammation and elicit insulin resistance (IR), exercise training accompanied by a low-fat diet has been prescribed as part of the treatment for managing obesity and IR. The purpose of this study is to evaluate the effect of eccentric exercise accompanied by a low-fat diet on glycolipid metabolism, exercise capacity, and macrophage polarization in obesity-induced IR mice. MATERIALS AND METHODS: Mice were fed with 60% high fat diet (HFD) for 12 weeks and subsequently treated with eccentric exercise or/and dietary restriction for 8 weeks. Related biochemical index were examined both before and during intervention to evaluate the ability of glycolipid metabolism. Exercise capacity was measured to verify the results of biochemical index. At 12 weeks and 12 + 8 weeks, infiltration was observed by H&E staining in adipose tissue, and macrophage polarization was detected by Immunofluorescence staining and ELISA. KEY FINDING: 1) obesity-induced IR model was established by HFD fed for 12 weeks accompanied by impaired exercise ability and increased M1 macrophage, 2) eccentric exercise accompanied by a low-fat diet markedly rescued obesity-induced IR and improved exercise capacity, 3) eccentric exercise accompanied by a low-fat diet markedly inhibited M1 macrophage polarization and activated M2 macrophage. SIGNIFICANCE: Eccentric exercise accompanied by a low-fat diet rescued obesity-induced IR and improved exercise capacity, which were associated with the inhibition of M1 macrophage polarization and the activation of M2 macrophage. These indicate that macrophage polarization provides the potential target of intervention for inflammation and IR in obesity.