"This is the second major advance that we've made," said Professor of Pharmacology Joey Barnett, co-principal investigator of the heart valve project.
Last spring, the Vanderbilt team announced that they had identified the unique genes and molecular pathways associated with valve formation. "These included both genes and pathways that we knew about and several that were previously unknown," said Barnett, who has studied heart valves for more than 20 years.
"The genetic study gave us the list of the basic parts the hardware required to build a heart valve and this latest study provides us with the information we need about the environment that is required," said the biologist. "With this information, we should have what we need to create valvular interstitial cells (VICs), that are the basic building blocks of heart valves."
The heart starts out as a simple, U-shaped tube of tissue. (In the case of the chicken embryo, it is about the size of a comma on the printed page.) The tube has three layers. The outer layer is made up of cardiac muscle cells that begin pulsing before blood vessels form and attach to the heart. The inner layer consists of specialized endothelial cells, the type of cells that line the interior of blood vessels. Sandwiched between the two is a layer of a complex gelatinous material called cardiac jelly.
At the locations of the inflow and outflow valves, the walls of the tube thicken to form "cushions" of cardiac jelly. After the cushions are formed, the endothelial cells in the region embed themselves in the cushion and transform into VICs. The VICs, in turn, begin guiding the process that transforms the cardiac jelly in the cushion into va
|Contact: David Salisbury|