Cartilage Is Grown in the Arthritic Joints of Mice – The New York Times

The painful knees and hips experienced by so many people with osteoarthritis result from a loss of cartilage, which serves as a sort of cushioning in the joints. It had long been thought that cartilage, once gone, cannot grow back.

Now researchers at Stanford University have grown new cartilage in the joints of arthritic mice. Primitive cells that can be transformed into new cartilage lie dormant at the ends of bones, the researchers reported in Nature Medicine. The cells just have to be awakened and stimulated to grow.

The researchers say the next step is to try to grow cartilage in larger animals, like dogs or pigs. They are optimistic that the finding could eventually lead to treatments to prevent the often debilitating pain that arises when cartilage erodes away.

“It is really a major advance in field of osteoarthritis,” said Dr. Gerard Karsenty, a bone specialist at Columbia University who was not involved in the research.

Although scientists often question whether findings in mice may apply to humans, diseases of the skeleton are often do, he added.

“When you demonstrate something in the mouse, I don’t know of any example where it has not applied to humans,” Dr. Karsenty said.

But Dr. Robert Marx, an orthopedic surgeon at the Hospital for Special Surgery in Manhattan, cautions that the path to a treatment that helps patients may be long and unpredictable.