A gradient four-layered gelatin methacrylate/agarose construct as an injectable scaffold for mimicking osteochondral tissue

Due to complexity of the osteochondral (OC) lesion sites, injectable hydrogels, as minimally invasive approach, are promising OC tissue engineering scaffolds. Here, a gradient gelatin methacrylate (GelMA)/agarose structure is proposed to mimic the native OC and develop injectable hydrogels for potential OC repair. Using different hydrogel concentrations (10 and 15% w/v) and adjusting GelMA: agarose ratio (95:5, 90:10, and 85:15), an injectable four-layered scaffold was designed, in which the lower and upper layers mimic osseous and chondral ECM, respectively. The layers possessed porosity ranging 76-96% and average pore size of similar to 115 mu m. The four-layered scaffold showed a uniform swelling, with no layers' disintegration upon swelling. Degradation examinations indicated a uniform weight loss process for all layers, with average residual weights after four weeks vary from 48 to 58%. Compressive moduli of the layers were registered between 12 and 76 kPa, and the layers preserved their structures up to similar to 40% and 70% at 10% w/v and 15% w/v compositions, respectively. In addition, the layers showed appropriate injectability with viscosity values of 13.05-68.19 Pa.s at 50% torque. Cytotoxicity assay demonstrated viability above 91 and 86% after 1 and 7 days, respectively. Overall, the results indicate the scaffold's potential as an excellent injectable, gradient structure for future OC tissue engineering application. [GRAPHICS] .