Repair of rabbit articular cartilage defect by a novel injectable bioactive glass scaffold

Abstract

Objective By comparing different repairing effects of different methods on articular cartilage defects in rabbit model, the ability of a new bioactive glass scaffold to repair cartilage defect was studied. Methods We prepared the PSC/CS bone cement by mixing the bioactive glass (BG) powder composed of 10.8%P2O5-54.2%SiO2-35%CaO (PSC), chitosan solution (CS) and calcium sulfate hemihydrate (CSH), then the bone cement was sized by a mold to form cylindrical scaffold. In vivo experiment, 18 male rabbits were divided into three groups randomly, including blank group, BG group and TGF-β1 group, which was added TGF-β1 into BG scaffold. Both knees of each rabbit were made cartilage defect for the same group, and no intervention was applied in B group, then implanted scaffolds into defects in both experimental groups. At 6 and 12 weeks after surgery, observed the macroscopic growth, histologic staining and collagen II immunohistochemistry (IHC), and the International Cartilage Repair Society (ICRS) and Wakitani score were used to analyze the experimental results quantitatively. Results At 6 weeks after surgery, there was no obvious difference between blank group and BG groups, but the macroscopic result of TGF-β1 group was better than the other two groups and its ICRS score 4.67±0.52 points was statistically higher than BG group 2.83±0.75 points (t=-2.817, P=0.015). As to the comparison of histologic staining and Wakitani socre among three groups, no statistical difference was observed (blank group=13.67±0.52, BG group=13.83±0.41, TGF-β1 group=13.33±1.03). At 12 weeks after surgery, there was still no obvious difference between blank and BG groups, while the results of macroscopic observation and ICRS score in TGF-β1 group were significantly higher than them 9.01±0.63 points (blank group vs TGF-β1 group: t=-2.289, P=0.022; BG group vs TGF-β1 group: t=-2.326, P=0.020). More importantly, much deeper positive staining were observed in TGF-β1 group, and the Wakitani score was higher than the other two groups (blank group=9.83±1.33, BG group=9.51±1.05, TGF-β1 group=6.50±1.38, blank group vs TGF-β1 group: t=-2.771, P=0.007; BG group vs TGF-β1 group: t=-2.756, P=0.006). By comparing the degree of histologic staining and Col II expression with normal cartilage, the regenerated tissue in TGF-β1 group was similar. Conclusion Single PSC/CS scaffold doesn’t possess excellent ability to repair cartilage defect. When TGF-β1 was added into PSC/CS bioactive glass, the scaffold was able to promote cartilage defect repair, and the regenerated tissue was similar to normal cartilage. Key words: Tissue engineering; Glass; Tissue scaffolds; Chondrocytes