A simple yet effective new treatment for rheumatoid arthritis may be in sight; researchers have now created a hydrogel that could absorb the excess joint fluid that arises with disease, as well as deliver medications to affected joints.
Created by researchers from the Institute for Basic Science (IBS) in the Republic of Korea, the gel works by responding to nitric oxide, which is a gas that has been linked to the development of rheumatoid arthritis.
The team recently reported the details of their novel hydrogel in the journal Advanced Materials.
Rheumatoid arthritis is an autoimmune disorder estimated to affect around 1.5 million people in the United States. According to the Arthritis Foundation, rheumatoid arthritis is almost three times more common among women than men, and women are likely to develop the condition at an earlier age.
In rheumatoid arthritis, the immune system mistakingly attacks healthy joint tissue, primarily in the joints of the hands, wrists, elbows, knees, ankles, and feet.
This can lead to a buildup of synovial fluid. While synovial fluid normally helps to lubricate the joints and make it easier for us to move, an excess of this fluid can cause swelling and pain.
Previous studies have suggested that nitric oxide is a key player in rheumatoid arthritis.
"Nitric oxide is like a double-edge sword," explains study leader Won Jong Kim, of the Center for Self-Assembly and Complexity at IBS. "It regulates inflammation and protects our body by killing external pathogens."
"However," he adds, "when in excess, it is toxic and may cause RA [rheumatoid arthritis], as well as other autoimmune diseases, cardiovascular diseases, and cancer."
Targeting nitric oxide with a hydrogel
With this in mind, Kim and colleagues sought to develop a new rheumatoid arthritis treatment strategy that targets nitric oxide, setting it apart from current treatments for the disease, which primarily consist of anti-inflammatory drugs.
The result is a hydrogel that responds to nitric oxide once the transient gas has left circulation and bound to other molecules.
The hydrogel consists of polyacrylamide - a water-soluble acrylamide polymer - and a new cross-linking agent called NOCCL.
The researchers explain that NOCCL forms connections between acrylamide molecules, producing "nets" that can catch and hold drug molecules. In response to nitric oxide, the nets change shape, which enables them to release the drug molecules and absorb liquid.
In this way, the team suggests that the hydrogel could help to treat rheumatoid arthritis; it could deliver drugs to affected sites and absorb synovial liquid, thereby reducing swelling and pain.
The researchers now plan to test a nano-sized form of the hydrogel in mouse models of rheumatoid arthritis.
If their results show success, we could be one step closer to a topical treatment for the condition.