NASHVILLE, Tenn. To develop correctly, baby hearts need rhythm...even before they have blood to pump.
"We have discovered that mechanical forces are important when making baby hearts," said Mary Kathryn Sewell-Loftin, a Vanderbilt graduate student working with a team of Vanderbilt engineers, scientists and clinicians attempting to grow replacement heart valves from a patient's own cells.
In an article published last month in the journal Biomaterials the team reported that they have taken an important step toward this goal by determining that the mechanical forces generated by the rhythmic expansion and contraction of cardiac muscle cells play an active role in the initial stage of heart valve formation.
A heart valve is a marvelous device. It consists of two or three flaps, called leaflets, which open and close to control the flow of blood through the heart. It is designed well enough to cycle two to three billion times in a person's lifetime. (Humans and chickens are outliers: Most other animals, large and small, have hearts that beat about one billion times in their lives.) However, heart valves can be damaged by diseases such as rheumatic fever and cancer, aging, heart attacks and birth defects.
"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," said Assistant Professor of Biomedical Engineering W. David Merryman. "We decided to take a step back and study how heart valves develop naturally so we can figure out how to duplicate the process." To do so, they designed a series of experiments with chickens, whose hearts develop in a fashion similar to the human heart.
"The discovery that the deformations produced by the beating cardiac muscle cells are important provides an entirely new perspective on the process," said Merryman, who directed the three-year study.
The Vanderbilt effort is part
|Contact: David Salisbury|