The lub-dub of a healthy heart

Developmental biology guides efforts to “grow” replacement heart valves

Leigh MacMillan, Ph.D.
Published: August, 2008

The containers on the conference room table are the type you might store leftovers in. But these don’t hold last night’s spaghetti or week-old casserole from the church potluck. They hold human hearts.

Joey Barnett, Ph.D., reveals an artificial valve in a preserved human heart.
Photo by Dean Dixon
As Joey Barnett, Ph.D., takes the cover off the first container and carefully lifts out the preserved specimen, one man in the group standing around the table steps back and sinks into a nearby chair. The reaction doesn’t surprise Barnett, an expert on cardiovascular development at Vanderbilt University; he’s well aware that seeing – and handling – human hearts isn’t an everyday experience.

He proceeds to describe how the heart works as a pump, opening it to reveal the heart’s right and left chambers, its muscular walls, and the valves that control blood flow. Then Barnett places the first heart into the tentative gloved hands of the man closest to him, to pass around for a closer look.

Barnett reaches for another heart, pointing out the blood vessels and the tough remains of an atherosclerotic plaque – “the most dangerous thing in the western world,” he says.

He saves for last the heart that intrigues him most. This heart has been through a lot. The valves at the openings of both the pulmonary artery and the aorta – the large blood vessels that send blood to the lungs and to the rest of the body – have been replaced. The sewn-in aortic valve is a natural tissue valve; the pulmonary valve is artificial.

“This is what we want to do away with,” Barnett says, pointing at the artificial valve.

By now, the group is eagerly examining the hearts and asking questions – even the man who originally sat down is back on his feet. These on-air radio personalities and producers will be conducting the Children’s Miracle Network radiothon in the coming weeks; they are looking at hearts in a Vanderbilt conference room to learn a bit about how biomedical research leads to new therapies.

Barnett, who also is vice chair of Pharmacology, is a good teacher. His hands-on heart tutorial evolves naturally into a discussion of his quest to discover the genes and signaling pathways that build the developing heart and its blood vessels – research that could make it possible to grow replacement heart valves in the laboratory, from a patient’s own stem cells.

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