Profs work on regrowing cartilage tissue

For professors Jason Burdick and Robert Mauck, getting hired by Penn on the same day not only earned them a teaching position, it also landed them a research partner.

Burdick, a School of Engineering and Applied Science professor and Mauck, who works at the Perelman School of Medicine, met when they were hired on the same day in July 2005. They soon realized that they had similar interests and forged a research partnership.

Six years on, Burdick and Mauck are working on regrowing cartilage to provide better treatments for patients.

The pair has discovered that growing cartilage in a lab is no easy business. While cartilage — which is found in knees, hips, elbows and fingers and lines the bone between joints in the body — is essential to everyday movement, it stops maturing after puberty and does not heal very well once it has been damaged.

Once the joint suffers an acute trauma, a piece of the cartilage is knocked out and forms what is called a divot.

While surgeons can replace the joint with a metal or plastic joint, injured patients cannot return to normal function. Instead, the tissue surrounding the divot can also become diseased and may degenerate, making it more likely for osteoarthritis to develop.

At Penn, student-athletes are most likely to suffer from cartilage degeneration, Mauck said.

College senior and Penn cheerleader Ruani Ribe injured her knee since she has been at Penn.

“I had to come down on my whole body weight [onto my knee],” she said of the impact which caused her injury. Ribe went through surgery at Penn Presbyterian Medical Center. “My knee feels great, but there are some weird cartilage things. I do hear crackling noises.”

Ribe believed that her knee would never fully recover. Research on regrowing cartilage tissue she believes “would be huge for the athlete community” and enable them to go through surgeries with near-perfect results.

In an attempt to regrow cartilage in humans, Mauck said he and Burdick are extracting stem cells from adult bone marrow and “telling” the stem cells to become chondrocytes — the main type of cell in cartilage.

From there, the next biggest challenge is creating an environment where the stem cells are more likely to turn into chondrocytes.

“From the start, we have been trying to understand the appropriate cellular microenvironment that would optimize the differentiation of the stem cells into chondrocytes … as well as optimize the distribution of tissue produced by the cells to maximize functional properties,” Burdick wrote in an email.

With their research, the new cartilage will be able to do what normal cartilage does: remodel and respond to the environment both inside and outside the human body.

“Cartilage injuries are a common injury, and if this research proves to stand up to physical activity and integrates into the body in a positive manner, it will be extremely useful and benefit athletes at Penn and around the world,” Head Athletic Trainer for Penn Athletics Eric Laudano wrote in an email.

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