Three-Dimensional-Printed Ordered Bredigite Scaffolds with Dual Bioactivities Promote Osteochondral Regeneration

Abstract Osteochondral tissues have limited self-healing abilities, making it challenging to achieve complete healing following injury. Osteochondral defects present significant clinical challenges. Bredigite (BRT, Ca7MgSi4O16) bioceramic scaffolds exhibit excellent physicochemical properties, biocompatibility, osteoinductivity, and osteoconductivity, making them promising candidates for osteochondral repair and regeneration. Herein, a BRT bioceramic was fabricated into structurally ordered scaffolds (BRT-O) and random morphology scaffolds (BRT-R) by using 3D printing techniques, while the tricalcium phosphate (TCP) scaffolds that are used in the clinic were fabricated as controls. The physicochemical properties, effects on bone marrow-derived stem cells (BMSCs) and chondrocytes in vitro, and performance in cartilage and subchondral bone regeneration were evaluated and compared among the three scaffolds. The results showed that the BRT-O scaffolds possessed the highest compressive strength, controllable biodegradability, and ability to regulate the local microenvironment by releasing bioactive ion products and altering the pH. In vitro, BRT-O scaffolds significantly enhanced the migration and osteogenic/chondrogenic differentiation of BMSCs, as well as the adhesion and maturation of chondrocytes. In vivo experiments revealed that the BRT-O scaffolds promoted the simultaneous and effective regeneration of hyaline cartilage and subchondral bone in rabbit osteochondral defect models. In summary, the monophasic BRT-O scaffold demonstrated dual bioactivity, promoting both osteogenesis and chondrogenesis, and thus, it holds significant clinical potential for osteochondral defect repair.