Can replacement valves be grown?

USA Today (Society for the Advancement of Education), Feb, 1996

Replacement heart valves grown from a patient's own cells could save the lives of those suffering from serious heart valve disease, indicates Christopher Breuer, a surgical research fellow at Children's Hospital, Boston. The heart cells would be taken from a patient needing a new valve and put in an incubator, where they would grow and reproduce. The desired cells would be recovered from this culture and placed on a biodegradable synthetic matrix that acts as a three-dimensional scaffold. The matrix is made of polyglycolic acid, the same material used to produce absorbable sutures. The cells on the matrix would reproduce and develop into tissue, while the matrix itself gradually degrades over a period of six weeks.

The advantage of a grown valve is that it is a living structure. As such, it should avoid many of the complications associated with the valves used today. About 60,000 heart valve replacement operations are performed in the U.S. annually. Most replacements either are mechanical valves or pig valves treated with glutaraldehyde to preserve them and prevent rejection in humans. These can be complicated by serious infections or clot formation, which, in turn, can cause strokes, pulmonary embolisms, or even death. In addition, as non-living structures, they "can not utilize the body's own mechanisms for growth, repair, and development," Breuer points out. "Thus, their durability and longevity are limited."

Consequently, these valves "wear out and the patient dies, or if they are lucky enough, they can sometimes get a second valve replacement. But it's a much more difficult operation, and to go beyond a second operation is often impossible."

At this stage, the question is whether a whole heart could be grown in the same way Breuer is cultivating valves. Cardiac myocytes (heart muscle cells) "don't grow well in culture the way smooth muscle cells and fibroblasts and endothelial cells do," he explains. Those three types are the cells that make up heart valves.