Magnesium(Mg) and its alloys have been intensively studied to develop the next generation of bone implants recently, but their clinical application is restricted by rapid degradation and unsatisfied osteogenic effect ...Magnesium(Mg) and its alloys have been intensively studied to develop the next generation of bone implants recently, but their clinical application is restricted by rapid degradation and unsatisfied osteogenic effect in vivo. A bioactive chemical conversion Mg-phenolic networks complex coating(e EGCG) was stepwise incorporated by epigallocatechin-3-gallate(EGCG) and exogenous Mg^(2+)on Mg-2Zn magnesium alloy. Simplex EGCG induced chemical conversion coating(c EGCG) was set as compare group. The in vitro corrosion behavior of Mg-2Zn alloy, c EGCG and e EGCG was evaluated in SBF using electrochemical(PDP, EIS) and immersion test. The cytocompatibility was investigated with rat bone marrow mesenchymal stem cells(r BMSCs). Furthermore, the in vivo tests using a rabbit model involved micro computed tomography(Micro-CT) analysis, histological observation, and interface analysis. The results showed that the e EGCG is Mgphenolic multilayer coating incorporated Mg-phenolic networks, which is rougher, more compact and much thicker than c EGCG. The e EGCG highly improved the corrosion resistance of Mg-2Zn alloy, combined with its lower average hemolytic ratios, continuous high scavenging effect ability and relatively moderate contact angle features, resulting in a stable and suitable biological environment, obviously promoted r BMSCs adhesion and proliferation. More importantly, Micro-CT, histological and interface elements distribution evaluations all revealed that the e EGCG effectively inhibited degradation and enhanced bone tissue formation of Mg alloy implants. This study puts forward a promising bioactive chemical conversion coating with Mg-phenolic networks for the application of biodegradable orthopedic implants.展开更多
In the fast growing field of scaffold-based tissue engineering, improvement on the mechanical properties of newly formed tissues, e.g. the repaired cartilage, has always been one of the core issues. Studies on the cor...In the fast growing field of scaffold-based tissue engineering, improvement on the mechanical properties of newly formed tissues, e.g. the repaired cartilage, has always been one of the core issues. Studies on the correlations among scaffold composition, in vivo morphological changes of the construct, and the finite deformation behaviors of new tissues （e.g. creep and stress-relaxation, and equilibrium response）, have attracted increasing interests. In this paper, the correlations between the compressive biphasic mechanical properties （i.e., equilibrium elastic modulus E and permeability coefficient k） of 3D printing scaffold （consisting of collagen and fl-tricalcium phosphate） and the proteoglycans （PGs） concentration of the repaired carti- lages after 24 weeks, 36 weeks and 52 weeks of scaffold implantation were investigated. Results indicated that the repaired cartilage covered the entire cartilage surface of large cylindrical osteochondral defects （10 mm in diameter ~ 15 mm in depth） on the canine trochlea grooves after 24 weeks. The equilibrium elastic modulus of the repaired cartilage reached 22.4% at 24 weeks, 70.3% at 36 weeks, and 93.4% at 52 weeks of the native cartilage, respectively. Meanwhile, the permeability coefficient decreased with time and at 52 weeks was still inferior to that of the native cartilage in one order of magnitude. In addition, the amount of glycosaminoglycans （GAGs） of repaired cartilage increased constantly with time, which at 52 weeks approached to nearly 60% of that of native cartilage. 3D printed scaffolds have potential applications in repairing large-scale cartilage defects.展开更多
基金supported by the Key Research and Development Program of Shaanxi Province (2019ZDLSF03-06) and (2020ZDLGY13-05)the National Key Research and Development Program of China (2020YFC1107202)。
文摘Magnesium(Mg) and its alloys have been intensively studied to develop the next generation of bone implants recently, but their clinical application is restricted by rapid degradation and unsatisfied osteogenic effect in vivo. A bioactive chemical conversion Mg-phenolic networks complex coating(e EGCG) was stepwise incorporated by epigallocatechin-3-gallate(EGCG) and exogenous Mg^(2+)on Mg-2Zn magnesium alloy. Simplex EGCG induced chemical conversion coating(c EGCG) was set as compare group. The in vitro corrosion behavior of Mg-2Zn alloy, c EGCG and e EGCG was evaluated in SBF using electrochemical(PDP, EIS) and immersion test. The cytocompatibility was investigated with rat bone marrow mesenchymal stem cells(r BMSCs). Furthermore, the in vivo tests using a rabbit model involved micro computed tomography(Micro-CT) analysis, histological observation, and interface analysis. The results showed that the e EGCG is Mgphenolic multilayer coating incorporated Mg-phenolic networks, which is rougher, more compact and much thicker than c EGCG. The e EGCG highly improved the corrosion resistance of Mg-2Zn alloy, combined with its lower average hemolytic ratios, continuous high scavenging effect ability and relatively moderate contact angle features, resulting in a stable and suitable biological environment, obviously promoted r BMSCs adhesion and proliferation. More importantly, Micro-CT, histological and interface elements distribution evaluations all revealed that the e EGCG effectively inhibited degradation and enhanced bone tissue formation of Mg alloy implants. This study puts forward a promising bioactive chemical conversion coating with Mg-phenolic networks for the application of biodegradable orthopedic implants.
基金This work was supported by grants from the Native Science Foundation of China （Nos. 51323007, 51375371 and 51075320）, the National High Technology Research and Development Program of China （No. 2015AA020303） and the Fundamental Research Funds for the Central Universities. The authors would like to acknowledge the contributions of Dichen Li, Manyi Wang, Yongmei Chen and Yusheng Qiu of Xi＇an Jiaotong University.
文摘In the fast growing field of scaffold-based tissue engineering, improvement on the mechanical properties of newly formed tissues, e.g. the repaired cartilage, has always been one of the core issues. Studies on the correlations among scaffold composition, in vivo morphological changes of the construct, and the finite deformation behaviors of new tissues （e.g. creep and stress-relaxation, and equilibrium response）, have attracted increasing interests. In this paper, the correlations between the compressive biphasic mechanical properties （i.e., equilibrium elastic modulus E and permeability coefficient k） of 3D printing scaffold （consisting of collagen and fl-tricalcium phosphate） and the proteoglycans （PGs） concentration of the repaired carti- lages after 24 weeks, 36 weeks and 52 weeks of scaffold implantation were investigated. Results indicated that the repaired cartilage covered the entire cartilage surface of large cylindrical osteochondral defects （10 mm in diameter ~ 15 mm in depth） on the canine trochlea grooves after 24 weeks. The equilibrium elastic modulus of the repaired cartilage reached 22.4% at 24 weeks, 70.3% at 36 weeks, and 93.4% at 52 weeks of the native cartilage, respectively. Meanwhile, the permeability coefficient decreased with time and at 52 weeks was still inferior to that of the native cartilage in one order of magnitude. In addition, the amount of glycosaminoglycans （GAGs） of repaired cartilage increased constantly with time, which at 52 weeks approached to nearly 60% of that of native cartilage. 3D printed scaffolds have potential applications in repairing large-scale cartilage defects.
