Advanced hydrogels for the repair of cartilage defects and regeneration

Cartilage defects are one of the most common symptoms of osteoarthritis (OA), a degenerative disease that affects millions of people world-wide and places a significant socio-economic burden on society. Hydrogels, which are a class of biomaterials that are elastic, and display smooth surfaces while exhibiting high water content, are promising candidates for cartilage regeneration. In recent years, various kinds of hydrogels have been developed and applied for the repair of cartilage defects in vitro or in vivo , some of which are hopeful to enter clinical trials. In this review, recent research findings and developments of hydrogels for cartilage defects repair are summarized. We discuss the principle of cartilage regeneration, and outline the requirements that have to be fulfilled for the deployment of hydrogels for medical applications. We also highlight the development of advanced hydrogels with tailored properties for different kinds of cartilage defects to meet the requirements of cartilage tissue engineering and precision medicine. Hydrogels applied in joints for the repair of cartilage defects and cartilage regeneration. Hydrogels are three-dimensional hydrophilic polymer networks that can be fabricated from synthetic polymers, polysaccharides, protein, and peptides, and can be designed as injectable or in situ forming for practical clinical application. • The biotechnology of developing hydrogels for cartilage defects repair is promising. • The principle for cartilage regeneration using hydrogels and requirements for clinical transformation are summarized. • Advanced hydrogels with tailored properties for different kinds of cartilage defects are discussed.