Pratt Fellow Wilusz Advances on a Solution to a Common Knee Injury

February 1, 2007

WiluszPratt Undergraduate Research Fellow Rebecca Wilusz has made a discovery that could lead to changes in the way that physicians treat a common form of knee injury. Her studies in the lab of Professor Farshid Guilak suggest that anti-inflammatory medications might help to encourage tears of the knee cartilage, or meniscus, to heal.

“Meniscus tears are fairly common -- something like 15 percent of all knee injuries and 75 percent of knee injuries in athletes under the age of 40,” said Wilusz, a native of central New Jersey whose parents now live in Pennsylvania.

The meniscus -- two-thirds of which lacks blood vessels--also tends not to heal well, she added. As a result, physicians frequently resort to surgery to remove the damaged cartilage, but that can lead to an increased risk for osteoarthritis since the meniscus plays an important load-bearing role.

Wilusz, working with postdoctoral researcher Amy McNulty, wanted to see if there might be another factor that limits the meniscus’ ability to heal.

Scientists have known that chronic inflammation, as occurs in patients with osteoarthritis, can increase the activity of enzymes that further damage joint surfaces, she said. But it was less clear whether the more transient periods of acute inflammation that can occur after an injury might be enough to stall healing.

Wilusz and McNulty isolated small disks of knee cartilage from an animal and punched a hole through their centers, to mimic a meniscus tear. They kept the damaged tissue in lab dishes under different conditions: one exposed to an inflammatory factor called interleukin-1 (IL-1) for three days, one exposed to the same factor for the duration of the experiment and a third control group that wasn’t exposed to the IL-1 “cytokine” at all.

They found that even three days’ exposure to the inflammatory factor, as might occur in a human following a knee injury, was enough to thwart healing. The shear strength of repair at the tissue interface was significantly reduced in the three-day group compared to the control after two weeks. They also found a significant increase in the tissue treated briefly with IL-1 in an enzyme that “chews” cartilage. That enzyme elevation lasted for several days following the exposure.

“Our study shows that treatment of explants with IL-1 for three days was sufficient to significantly reduce integrative repair of meniscal lesions in vitro,” Wilusz wrote in a research abstract, which was accepted for presentation at the Meeting of the Orthopaedic Research Society to be held in San Diego, Calif., in February 2007.

If the findings hold up in people, the results might have treatment implications, she said.

“If you limit inflammation, or block inflammatory cytokines, you might improve healing of the meniscus,” Wilusz said.

Wilusz and McNulty are now beginning a follow-up pilot study, to test whether load-bearing conditions, as would normally exist in the knee, might influence healing in the knee cartilage samples.

Wilusz’ initial interest in orthopedics was inspired by an uncle who suffered from severe osteoarthritis. She also became an early fan of Duke, thanks to her parents, who are both Duke alums. Her interest in biology led her to Pratt’s biomedical engineering program. She knew she’d made the right decision after taking a class in biomaterials that related engineering to anatomy. After a summer research internship, where she studied the effects of painkillers on fracture healing, she applied to be a Pratt Fellow in Guilak’s lab. Wilusz is also a lifelong dancer and president of two campus dance clubs: On Tap and Dance Slam. She is a member of E-Team, a mentoring group for freshmen engineers, and a campus tour guide for the admissions office. She will be beginning graduate school in Fall 2007.