Researchers found babies' hearts need rhythm even before they are born; during this time no blood is being pumped through the heart.
"We have discovered that mechanical forces are important when making baby hearts," Mary Kathryn Sewell-Loftin, a Vanderbilt graduate student working with a team of Vanderbilt engineers, said in a Vanderbilt University news release.
In order to make their findings the researchers looked at chickens because their hearts develop similarly to humans'.
"For the last 15 years, people have been trying to create a heart valve out of artificial tissue using brute-force engineering methods without any success," Assistant Professor of Biomedical Engineering W. David Merryman said in the news release. "We decided to take a step back and study how heart valves develop naturally so we can figure out how to duplicate the process."
"The discovery that the deformations produced by the beating cardiac muscle cells are important provides an entirely new perspective on the process," he said.
Recently the same team also identified "unique genes and molecular pathways" that are related to valve formation.
"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," Professor of Pharmacology Joey Barnett, co-principal investigator of the heart valve project, said in the news release. "With this information, we should have what we need to create valvular interstitial cells, which are the basic building blocks of heart valves."
The heart starts out as "U-shaped tissue." It is made of three layers; the first is made from cardiac muscle cells, the second from cardiac jelly, and the third layer is composed of blood vessels.
"Cushions" of cardiac jelly form in the walls of the developing heart, which spurs the formation of valvular interstitial cells (VICs). Sewell-Loftin found the more cells formed in areas of high-stress caused by "rhythmic expansion and contraction of cardiac muscle cells" in a cultured chick heart. The researcher made her findings using a computer program that determined the "forces caused by the pulsing cells."
In the future the researchers hope to use a type of stem cells that can be taken from adults, called "pluripotent stem cells" to produce endothelial cells; these cells could be used to produce VICs which are believed to promote valve health. Once this is accomplished they could possibly create heart valves.
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