siRNA conjugate with high albumin affinity and degradation resistance for delivery and treatment of arthritis in mice and guinea pigs.

Osteoarthritis and rheumatoid arthritis are debilitating joint diseases marked by pain, inflammation and cartilage destruction. Current osteoarthritis treatments only relieve symptoms, while rheumatoid arthritis therapies can cause immune suppression and provide variable efficacy. Here we developed an optimized small interfering RNA targeting matrix metalloproteinase 13 for preferential delivery to arthritic joints. Chemical modifications in a stabilizing 'zipper' pattern improved RNA resistance to degradation, and two independent linkers with 18 ethylene glycol repeats connecting to tandem C18 lipids enhanced albumin binding and targeted delivery to inflamed joints following intravenous administration. In preclinical models of post-traumatic osteoarthritis and rheumatoid arthritis, a single intravenous injection of the albumin-binding small interfering RNA achieved long-term joint retention, sustained gene silencing and reduced matrix metalloproteinase 13 activity over 30 days, resulting in decreased cartilage erosion and improved clinical outcomes, including reduced joint swelling and pressure sensitivity. This approach demonstrated superior efficacy over corticosteroids and small-molecule MMP inhibitors, highlighting the therapeutic promise of albumin 'hitchhiking' for targeted, systemic delivery of gene-silencing therapeutics to treat osteoarthritis and rheumatoid arthritis.