3D-Bioprinted Difunctional Scaffold for In Situ Cartilage Regeneration Based on Aptamer-Directed Cell Recruitment and Growth Factor-Enhanced Cell Chondrogenesis.

Articular cartilage (AC) lesions are fairly common but remain an obstacle for clinicians and researchers due to their poor self-healing capacity. Recently, a promising therapy based on the recruitment of autologous mesenchymal stem cells (MSCs) has been developed for the regeneration of full-thickness cartilage defects in the knee joint. In this study, a 3D-bioprinted difunctional scaffold was developed based on aptamer HM69-mediated MSC-specific recruitment and growth factor-enhanced cell chondrogenesis. The aptamer, which can specifically recognize and recruit MSCs, was first chemically conjugated to the decellularized cartilage extracellular matrix and then mixed with gelatin methacrylate to form a photocrosslinkable bioink ready for 3D bioprinting. Together with the growth factor that promoted cell chondrogenic differentiation, the biodegradable polymer poly(ε-caprolactone) was further chosen to impart mechanical strength to the 3D bioprinted constructs. The difunctional scaffold specifically recruited MSCs, provided a favorable microenvironment for cell adhesion and proliferation, promoted chondrogenesis, and thus greatly improved cartilage repair in rabbit full-thickness defects. In conclusion, this study demonstrated that 3D bioprinting of difunctional scaffolds could be a promising strategy for in situ AC regeneration based on aptamer-directed cell recruitment and growth-factor-enhanced cell chondrogenesis.