3D Bioprinting of Bone Marrow Mesenchymal Stem Cell-Laden Silk Fibroin Double Network Scaffolds for Cartilage Tissue Repair.

3D bioprinting is one of the latest trends in regenerative medicine due to its capacity for constructing highly organized tissues with living cells. In this work, silk fibroin (SF) together with hydroxypropyl methyl cellulose (HPMC) was used to print bone marrow mesenchymal stem cell (BMSC)-laden double network (DN) hydrogel for cartilage tissue repair. The β-sheet structure formed among SF molecules was set as the rigid and brittle first network, while the cross-linking of HPMC-MA was set as the soft and ductile second network. Compared to the single network hydrogel, the fracture strength, breaking elongation, and compressive reproducibility increased significantly. Thereafter, the evaluation of cell proliferation and biochemical assay of this BMSC-laden 3D bioprinted hydrogel proved that it could ensure sufficient nutrient supply and great biochemical supportability in tissue engineering. This SF-based bioink with remarkable mechanical properties holds great promise as candidate for cartilage tissue regeneration.