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.

Keywords: bredigite; osteochondral reconstruction; scaffolds; three-dimensional printing; tissue engineering.