Tetrahedral Framework Nucleic Acid-Based Delivery of Astaxanthin Suppresses Chondrocyte Pyroptosis and Modulates Oxidative Stress for the Treatment of Osteoarthritis.

Worldwide, osteoarthritis (OA) is regarded as the most widespread, distressing, and limiting chronic disease that affects degenerative joints. Currently, there is no treatment available to modify the progression of OA. The pathogenesis of OA is significantly linked with oxidative stress and pyroptosis. Astaxanthin (Ast) is a natural ketocarotenoid pigment with potent antioxidant activity and is shown to effectively alleviate cartilage damage in OA. However, its bioavailability is greatly limited due to poor water solubility, high sensitivity to light, temperature, and pH. In this study, Ast-loaded tetrahedral framework nucleic acids (tFNAs) or tFNA/Ast complexes (TAC) for Ast delivery are developed. Compared with free Ast and tFNA alone, TAC exhibits improved drug stability and cellular uptake. Most importantly, TAC effectively protects chondrocytes against oxidative stress-induced pyroptosis while promoting extracellular matrix anabolism by chondrocytes, and ultimately alleviates cartilage damage in a mouse destabilization of the medial meniscus (DMM) model. Thus, TAC holds great promise for the treatment of OA patients.