Hydrophobic Derivatives of Sulfated Hyaluronic Acid as Drug Delivery Systems for Multi-Target Intra-Articular Treatment of Post-Traumatic Osteoarthritis

During osteoarthritis (OA) development, chondrocytes progressively decompensate, upregulating proteolytic enzymes and reducing the key growth factors involved in promoting chondrocyte anabolism. A combined therapeutic approach is needed to address this multifactorial pathology, which affects the whole joint. Based on the literature, three promising targets for OA treatment have been selected: MMP3 (matrix metallopeptidase 3), TRPV4 (transient receptor potential cation channel subfamily V member 4) and mTOR (mammalian target of rapamycin). In this study, a novel water-soluble and biocompatible amphiphilic polymer named "sHA-oleylamide" was synthesized and screened from a series of hyaluronic acid derivatives for its anticatabolic activity. This MMP inhibitor showed no cytotoxicity, and in an in vitro model of inflammatory OA, it reversed the inflammatory outcome at a concentration of 0.011 mg/mL. The ability of sHA-oleylamide to form 20-50 nm micelles in water with a critical micelle concentration of 0.27±0.1 mg/mL, was confirmed by TEM images and measured by Nile red staining. RN-1747 and rapamycin molecules were successfully loaded in sHA-oleylamide, previously prepared at 12 mg/mL in PBS; both formulations were stable, sterile and confirmed in vitro to have mTOR inhibition by rapamycin and TRPV4 activation activity by RN-1747. The controlled release of RN-1747 from the micellar formulation with sHA-oleylamide showed that only approximately 60% of the total loaded RN-1747 was released within 7 days. These micellar formulations can potentially increase the bioavailability and pharmaceutical efficacy of the selected active molecules, combining their anti-catabolic and pro-anabolic activities and making them suitable for i.a. administration as OA treatments.