Enhanced osteochondral regeneration with a 3D-Printed biomimetic scaffold featuring a calcified interfacial layer
The challenge of achieving integrative regeneration of both articular cartilage and subchondral bone remains a significant clinical hurdle due to the complex spatial structure of native osteochondral tissues, which is difficult to replicate in artificial implants. Layer-by-layer fabrication methods, such as 3D printing, have emerged as promising technologies for mimicking the stratified zonal architecture, as well as the distinct microstructures and mechanical properties of these tissues. However, the dynamic physiological conditions, including mass transport and cell migration, often compromise the pre-defined biological functions of these layered implants, leading to blurred spatial distinctions and inefficient regeneration.
In this study, a biomimetic calcified interfacial layer was introduced into the scaffold as a compact barrier between the cartilage and subchondral bone layers, with the goal of enhancing osteochondral repair. This interfacial layer, made up of compact polycaprolactone (PCL), nano-hydroxyapatite, and tasquinimod (TA), serves to physically and biologically separate the cartilage layer (comprising TA-infused, chondrocyte-loaded gelatin methacrylate) from the porous PCL-based subchondral bone layer. The addition of this calcified interface maintained the distinct biological environments required for independent cartilage and bone regeneration, successfully preventing vascular invasion into the cartilage layer and reducing the risk of cartilage calcification due to the TA-induced devascularization.
The enhanced integrative regeneration of cartilage and subchondral bone was confirmed through gross examination, micro-computed tomography (micro-CT), and both histological and immunohistochemical analyses in an in vivo rat model. Furthermore, gene and protein expression analyses highlighted the critical role of Caveolin-1 (CAV-1) in promoting angiogenesis via the Wnt/β-catenin pathway. The study also demonstrated that TA in the calcified layer effectively inhibited angiogenesis by suppressing CAV-1 activity.