Engineering Newsletter

Clark Hung | Biomedical Engineering

For many people, stiff, aching joints are the first sign of age. For more than 20 million Americans, it is also the first sign of osteoarthritis, a disease characterized by loss of the lubricating and load-bearing tissue that lines the joints and that is behind an estimated $128 billion each year in healthcare costs and lost productivity.

“Since the lifespan of most joint replacements is limited typically to 15 or 20 years, restoring joint function with living tissue is almost always preferred,” said Clark Hung, professor of biomedical engineering.

The trouble is, that tissue, known as articular cartilage, is made up of a network of chondrocyte cells embedded in a stiff matrix of collagen and other substances that is subjected to daily, repetitive mechanical deformation and a lack of nutrient-rich blood flow. Because of this, damaged tissue does not heal easily and replacement cartilage with natural properties has proved difficult to grow in a lab. Until now.

By growing chondrocytes under mechanical loads that mimic the conditions inside joints, Hung and Gerard Ateshian, professor of mechanical engineering and biomedical engineering, have been able to culture tissue that is almost identical to the body's own. The tissue loading helps transport nutrients to the chondrocytes. As a result, their engineered tissue grows faster, is more durable, and, they anticipate, will provide better restoration of the joint.

Hung, who received his Ph.D. in bioengineering from the University of Pennsylvania and recently received a third four-year grant from the NIH, has so far succeeded in growing bovine and canine articular cartilage and foresees a near future in which human cartilage will routinely be produced in the lab using his method. Good news for anyone who plans on growing older.