Abstract: Osteochondral defects involving both articular cartilage and subchondral bone remain challenging in clinical treatment. Inspired by the zonal organization of native osteochondral tissue and the sophisticated architecture of articular cavity, we designed a biomimetic bilayer scaffold system using 3D printing technology. The scaffold recreates the natural structural and mechanical gradients of the osteochondral interface, featuring a gradient transition from cartilage to bone phase. To enhance the bio-functionality of this biomimetic design, we incorporated the small molecule Kartogenin (KGN), which has shown promising potential in cartilage regeneration by promoting chondrogenic differentiation and inhibiting cartilage degeneration. However, the reparative efficacy of KGN is highly concentration-dependent, and the optimal concentration within complex three-dimensional scaffold environments remains unclear. Through both in vitro and in vivo evaluations of this bio-inspired scaffold system loaded with varying KGN concentrations, we identified that 5 μM KGN (SCS@K5) achieved optimal outcomes. At 12 weeks, the SCS@K5 treatment resulted in better organized osteochondral tissue with improved interface integration relative to other groups. This biomimetic gradient design incorporating KGN release offers a viable approach for osteochondral defect repair.

Key words: Biomimetic')">Biomimetic, Kartogenin, Scaffold, 3D printing, Osteochondral repair