Effects of dynamic mechanical stimulations on the regeneration of in vitro and in vivo cartilage tissue based on silk fibroin scaffold

Due to the lack of blood and nutrition supply, the repairing of cartilage defect has become a challenging topic in clinical treatment. Herein, a unique porous scaffold based on regenerated silk fibroin (RSF) was fabricated by using freeze-drying after enzymatical crosslinking. Results showed that the pore size, mechanical properties and cytocompatibility of the scaffold were all significantly improved by proper combination of bacterial cellulose nanofiber ribbon (BCNR), thus much appropriate for cartilage regeneration. Based on this RSF/BCNR composite scaffold, the effects of stair-stepping shaped dynamic hydrostatic pressure (DHP) on the construction of tissue engineered cartilage in vitro and dynamic loading microenvironment on the regeneration of cartilage defect in vivo have been comprehensively investigated for the first time. Compared with traditional static culture, DHP has obviously enhancing chondrocyte growth and cartilage specific matrix deposition. Compared with the unloading microenvironment in vivo, corresponding dynamic loading microenvironment significantly improved cartilage regeneration, as it presented apparent cartilage lacuna like structure and thicker newly formed cartilage tissue. The insights of in vitro and in vivo dynamic mechanical stimulations enhancing effects on cartilage regeneration based on the RSF/BCNR composite scaffold revealed in this study could provide valuable guidance for the construction of optimal tissue engineered cartilage and the clinical prevention and treatment of orthopedic diseases.