Strain of mice demonstrates ability to regenerate knee cartilage

A strain of mice with the natural ability to repair damaged cartilage may one day lead to significant improvements in the treatment of human knee, shoulder and hip injuries.

Researchers at Oregon Health & Science University (OHSU) discovered that males from a strain of mice called MRL/MpJ have the innate ability to repair their own knee cartilage.

“We think there is something special about these mice,” Jamie Fitzgerald, PhD, assistant professor of orthopedics and rehabilitation in the OHSU School of Medicine, said in a press release. “They have the ability to regenerate cartilage.”

This discovery could have significant benefits for future arthritis treatment.

“Human cartilage injuries heal poorly and can lead to cartilage degeneration and osteoarthritis,” Fitzgerald said. “This is an enormous clinical problem. It is estimated that one quarter of the adult population will have some kind of arthritis by 2020.”

Knee injuries are an especially sensitive issue for professional athletes. The National Football League Charities provided the initial grant to launch the study. “Cartilage injuries can be career-ending for football players,” Fitzgerald said in the news release.

Fitzgerald and fellow OHSU researchers Andrea Herzka, MD, and Cathleen Rich studied knee injuries in 150 mice. Three months after the cartilage in their knees was damaged, male MRL mice had replaced a significant amount of the injured tissue with healthy cartilage.

The results of the study will be published in Osteoarthritis and Cartilage.

Chris Little, director of the Raymond Purves Bone and Joint Research Laboratories in Sydney and one of the scientists involved in the project, said the finding is significant for human health.

“The research we have published is an early but important step in unraveling the important pathways that will facilitate development of new treatments,” Little said in the press release.

The next step is to understand why these mice are able to restore the cartilage in their knees.

“If we can identify what genes or proteins are necessary for cartilage to heal, we can work toward finding similar genes and proteins in humans,” Herzka said in the news release. An actual treatment, however, “is many years away.”

For more information:
Fitzgerald J, Rich C, Burkhardt D, et al. Evidence for articular cartilage regeneration in MRL/MpJ mice. Osteoarthritis and Cartilage. In press.