A team of bioengineers from Rice University is bringing a promising new strategy for growing replacement heart valves closer to reality, thanks to a four-year, $1.2 million grant from the National Institutes of Health. The team hopes to use gel-like materials to generate three-dimensional patterns called scaffolds that can simultaneously mimic the complex structural and physical properties of heart-valve tissues and guide the behavior of tissue-forming cells.
Tissue-engineering researcher Jane Grande-Allen, the lead investigator on the grant, said researchers once believed that replacement heart valves would be one of the easiest and first tissues that could be grown in the laboratory. At just a millimeter thick, the rugged flaps of tissue in heart valves seemed simple enough when researchers first started trying to engineer them in the mid-1990s.
"It's ironic because they turned out to be one of the most difficult and complex tissues of all," said Grande-Allen, associate professor in bioengineering at Rice.
Grande-Allen said it's been difficult for engineers to find synthetic materials that truly mimic the complex structure and mechanical properties of heart-valve "leaflets," the tough yet flexible flaps of tissue that form a tight seal to prevent blood from flowing backward each time the heart pumps. Having materials that can both mimic the leaflets' microscopic structure and act as a pattern for tissue-forming stem cells has been a missing link in growing replacement heart valves.
Each aortic or pulmonary heart valve contains a trio of leaflets. Prior to each heartbeat, the leaflets open, like the petals of a blooming flower, allowing blood to flow into one of the heart's chambers. Then the leaflets fold back, interlocking with one another to form a tight seal that prevents blood from flowing backward. In cases of heart-valve disease, the valves don't seal properly, and the heart must pump much harder to deliver sufficient
|Contact: David Ruth|