Application and progress of smart hydrogels in regulating oxidative stress and improving the immune microenvironment in osteoarthritis

Osteoarthritis (OA) is a stubborn, degenerating, complex chronic degenerative joint disease. Inflammation and joint pain are the main symptoms, characterized by cartilage degeneration and loss, as well as articular margins and subchondral bone hyperplasia, which are more common in the knee joint and are most common in middle-aged and older people. Chondrocyte apoptosis and degradation of the extracellular matrix are the main causes of cartilage degeneration. At present, there are certain limitations of drugs commonly used in clinical treatment for bone and joint, such as low bioavailability, short half-life, poor targeting, and high systemic toxicity. As an emerging smart drug delivery system, hydrogels are capable of delivering growth factors, anti-inflammatory drugs, steroids, and cells. It has the performance of articular cartilage bionic and slow and controlled release of loads. It can accelerate cartilage repair, stimulate cartilage regeneration, regulate the inflammatory microenvironment, and delay the progression of osteoarthritis. The aim of this review was to describe the classification of different hydrogels, the use of hydrogels for improving the various symptoms of osteoarthritis, their current shortcomings and future prospects.