Gradient scaffolds for osteochondral tissue engineering and regeneration

•Systematic summary of the physiological gradients at the osteochondral interface.•Fabrication method of cell, composition, pore size, mechanical gradient scaffolds.•Evaluation of repairing effect of gradient scaffolds on damaged osteochondral tissue. In recent years, the incidence of osteoarthritis (OA) has been increasing worldwide. This disease not only affects the articular cartilage but also impairs the subchondral bone and surrounding tissues. Therefore, there has been much research dedicated to osteochondral defect repair. In tissue engineering, integrated gradient tissue-engineered osteochondral scaffold has been proposed as a promising treatment, that can simultaneously repair articular cartilage, osteochondral interface, and subchondral bone. It is possible to identify a variety of physiological gradients between the surface of the articular cartilage and the subchondral bone. Simulating these gradients in scaffold design is an effective way to regenerate osteochondral tissue. Starting from various physiological gradients, this review provides an overview of current research on gradient scaffolds for the repair of osteochondral tissue.