Nanoparticle injections after injury may prevent osteoarthritis

By John Murphy, MDLinx
Published September 26, 2016

Key Takeaways

Nanoparticles injected into joints immediately after an injury reduce the early inflammatory response that leads to post-traumatic osteoarthritis, according to a study published in the September 26, 2016 early online edition of the Proceedings of the National Academy of Sciences.

If validated, this therapy could supersede steroid injections, currently the only available treatment, which stay in the joint for only a few hours before being cleared. The nanoparticles tested in this investigation remain for weeks in the chondrocytes in the knee joints of mice.

Study co-investigators Hua Pan, PhD, an Assistant Professor of Medicine, and Samuel Wickline, MD, the James R. Hornsby Family Professor of Biomedical Sciences at Washington University School of Medicine in St. Louis, MO, designed the peptide-based nanoparticle. They engineered the nanoparticles to carry small interfering RNA (siRNA) to target the NF-kB pathway, which the researchers believe is essential for the expression of catabolic mediators in the cartilage and synovium of patients with osteoarthritis.

“Previously, we’ve delivered nanoparticles through the bloodstream and shown that they inhibit inflammation in a model of rheumatoid arthritis. In this study, they were injected locally into the joint and given a chance to penetrate into the injured cartilage,” Dr. Wickline explained.

Due to their tiny size, the nanoparticles easily penetrated into the cartilage to enter the injured cells. The treatment significantly reduced chondrocyte apoptosis and reactive synovitis while maintaining cartilage homeostasis, the researchers reported. These findings suggest that the nanoparticles, if injected soon after joint injuries occur, could help maintain cartilage viability and prevent the progression to osteoarthritis.

The researchers are now planning to investigate whether such a strategy will work years after an injury, when osteoarthritis is established and cartilage loss has already occurred.

“The inflammatory molecule that we’re targeting not only causes problems after an injury, but it’s also responsible for a great deal of inflammation in advanced cases of osteoarthritis,” said Linda J. Sandell, PhD, the Mildred B. Simon Research Professor of Orthopaedic Surgery and Director of Washington University’s Center for Musculoskeletal Research. “So we think these nanoparticles may be helpful in patients who already have arthritis, and we’re working to develop experiments to test that idea.”

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