Developmentally Inspired, Mechanical-Metabolic Dual Gradient Osteochondral Constructs Bridging Regeneration and Therapeutic Screening.

The osteochondral interface is a finely tuned junction between cartilage and bone, coordinated by gradients in mechanics and metabolism. Recreating this complexity in vitro has remained elusive. Here, we present a developmentally inspired, dual-gradient 3D-printed construct that unites native-like stiffness and metabolic microenvironments to drive spatially resolved regeneration and model osteoarthritis in a phase-specific manner. Human bone marrow-derived mesenchymal stem cell spheroids are placed in soft, hypoxic niches to promote chondrogenesis, and in stiff, vascular-rich regions to induce osteogenesis-preserving cartilage-bone crosstalk within one platform. This integration of gradients amplifies extracellular matrix formation beyond single-cue designs through the synergistic effect of porosity and stiffness. Furthermore, its anisotropic architecture maintains cartilage-bone crosstalk and allows drug response assessment, highlighting its potential as a physiologically relevant platform for osteoarthritis modeling and therapy screening. By bridging functional regeneration with preclinical drug screening, this model offers a physiologically relevant translational platform for advancing both osteochondral repair and disease research.