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Fischell Fellow Profile: Diana Yoon

A Kinder, Gentler Knee Surgery


Diana Yoon
Diana Yoon is explored the use of novel, injectible, biodegradable polymers in the regrowth of knee cartilage. A polymer solution means less surgery, healthy tissue, and a speedier recovery time for patients.
"The people I met here are amazing. They'll work to try to make you happy, to help you accomplish what you want to. You can get a lot from this University."

Diana Yoon

Diana Yoon received her Ph.D. in December 2008 and is now a Lead Reviewer at the Food and Drug Administration (FDA).

If Diana Yoon has her way, knee surgery might not be so bad.

Our bodies do not naturally repair and regenerate the articular cartilage in our knees, and as a result we can be left with long-term damage or deterioration. In extreme cases the entire knee must be replaced. During the years she studied at the Clark School, Yoon's goal was to support the regeneration of cartilage to restore the knee to health and functionality, without the need for highly invasive and painful surgery.

Yoon's proposal, "Implantable Hydrogel Constructs for Assisting Articular Cartilage Regeneration" earned her the 2006 Fischell Fellowship in Biomedical Engineering.

Her tissue engineering technique involved the use of polymer scaffolding, a synthetic, supportive environment in which new, healthy cartilage can grow. The scaffolding is in the form of a hydrogel that mimics the environment tissue inhabits in our knees. Healthy cartilage is grown in the hydrogel, nourished by additives of salts and proteins that would normally be provided by the body. At this point in the process, it is fluid, and can easily be injected into the injury site, taking the form of a patch. Once the hydrogel is in the body, additional substances within it induce a state change, causing it to firm up and stay in place. Over time, the new cartilage grows while the hydrogel degrades, leaving only healthy cells behind.

A polymer gel procedure is far less invasive than traditional knee surgery, resulting in less damage to the body, less inflammation, fewer immune responses and a shorter recovery time. Previous research has made use of alginate (a natural polymer made from certain types of algae and seaweed) as the scaffolding, but Yoon's used a novel polymer developed by her advisor, Professor John Fisher. Fisher's polymer, unlike alginate, produces no acidic byproducts as it degrades, making it safer for use in the human body.

Yoon worked in Professor Fisher's Tissue Engineering and Biomaterials Lab, conducting in vitro studies to determine the best growing conditions for cartilage tissue within the hydrogel.

Being able to envision the ultimate implementation of her ideas, and knowing her work will bolster others' in the biomedical engineering field, inspired Yoon as she worked. Her highest hopes are to have an impact on the regeneration of articular cartilage and to see the end product used in patients. "I want to help people," she says. "I want to affect somebody positively." She is interested in continuing her research in a hospital setting.

Yoon came to the Clark School from Carnegie Mellon University, where she majored in chemical engineering. She began her graduate studies the same year Professor Fisher joined the faculty and established the the Tissue Engineering and Biomaterials Lab. "When I met him," she says, "I felt he was, like me, very goal-oriented. He was very clear about what he thought I could accomplish, and I thought his work was very interesting."

The sense of feeling academically "at home" drew Yoon to the Clark School even before she was accepted into the graduate program in bioengineering. She was searching for a small department that would foster not only great research, but also solid academic, professional, and social relationships. On a visit to campus, she recalls, she felt very comfortable as she met faculty, staff and students while touring the Clark School's facilities. As a student, she enjoyed the bioengineering community on campus and her social life in nearby Washington, D.C. "The people I met here are amazing," she says. "They'll work to try to make you happy, to help you accomplish what you want to. The professors are understanding and helpful, and the graduate community is growing...You can get a lot from this University."