科学家们试验治疗关节炎的新方法（在线收听）

Scientists Test New Treatment for Injuries that Produce Arthritis

American researchers are looking for new ways to reduce arthritis pain.

Arthritis is known to affect older people. Over time, the joints of the body suffer damage and become inflamed. The condition has also been found to affect younger adults who suffer knee or ankle injuries.

Now, University of Iowa scientists are using new methods for treating arthritis with existing medicines. They hope to target individuals who develop the condition shortly after an injury.

In tests, the scientists injected the medicines directly into the damaged joints. The hope is that the treatment will then block the cycle of cell dysfunction that follows an injury, and protect against arthritis.

The scientists have yet to carry out experiments with people. They used pigs instead because the animals’ joints react like human ankles.

Filling in a need

The United States Defense Department and National Institutes of Health provided money for the University of Iowa study.

The Associated Press says the scientists are now seeking financial support for human studies. The tests are part of an effort to understand why an aggressive form of arthritis can develop after some injuries, such as a broken bone in a joint, seem to have healed.

“It’s very promising,” said Farshis Guilak, a regenerative medicine specialist at Washington University in St. Louis, Missouri. He said there are no treatments right now for any form of arthritis that has been able to affect the disease.

Guilak was not involved in the study.

Osteoarthritis is the most common kind of arthritis. It usually happens when cartilage, which protects the joints, wears away over many years of use. Yet about 5.6 million people in the U.S. get post-traumatic osteoarthritis, which strikes much faster. This condition comes from injuries to weight-bearing joints, like knees and ankles.

People who suffered knee injuries are three to six times more likely to develop arthritis in that joint than other people who have never been injured. They are also more likely to get arthritis about 10 years earlier. That information comes from a report published last year in The Journal of Athletic Training.

Interrupting the process

In the Iowa study, the researchers made several observations about what happens to cartilage after an injury. They found that only some cartilage cells die immediately after the injury. But over the next 48 hours, more cells die and others begin to work less effectively.

Inside cells are tiny power plants, called mitochondria. Somehow, joint injuries causes the mitochondria inside cartilage cells to become overactive and produce substances called oxidants.

Mitchell Coleman was the lead researcher in the University of Iowa study. He noted that, “if you can interrupt that early process, whatever is going on with those mitochondria in the first day, you can have a… benefit to the tissue itself.”

In the tests, Coleman and his team used two old drugs: amobarbital, a calming drug known to limit energy production in cells, and an antioxidant named N-acetylcysteine.

To avoid body-wide side effects, the researchers created a form of the drug that is liquid while being injected, but becomes solid at body temperature. They injected one or the other drug into the pigs’ broken joints, both after the injury and again one week later.

Each drug separately helped protect cartilage, the team reported this month in the journal Science Translational Medicine. A year later, the cartilage in the treated animals appeared stronger that that in the untreated pigs. The treated animals also showed no signs of pain.

The scientists say additional research is needed to tell if the treatment works in people.

For now, people who have had joint injuries should get treatment for the injury and keeping up exercise, said Lisa Cannada, a spokesperson for the American Academy of Orthopaedic Surgeons.

I’m Phil Dierking.

Words in This Story

antioxidant - n. a substance that is added to food and other products to prevent harmful chemical reactions in which oxygen is combined with other substances?

bear - v. to accept or endure?

cartilage - n. a strong but flexible material found in some parts of the body (such as the nose, the outer ear, and some joints)?

cycle - n. a set of events or actions that happen again and again in the same order?

dysfunction - n. the state of being unable to function in a normal way?

inflame - v. to cause (a part of your body) to grow sore, red, and swollen?

ligament - n. a tough piece of tissue in your body that holds bones together or keeps an organ in place?

oxidant - n. an oxidizing agent.?

plants - n. a building or factory where something is made