Infants and children receiving artificial heart-valve replacements face several repeat operations as they grow, since the since the replacements become too small and must be traded for bigger ones. Researchers at Childrens Hospital Boston have now developed a solution: living, growing valves created in the lab from a patients own cells.
In a special issue of Circulation published September 11, they describe making pulmonary valves through tissue engineering. These valves, which provide one-way blood flow from the hearts right ventricle into the pulmonary artery, are often malformed in congenital heart disease, putting an extra burden on the heart.
The heart valve is a complex organ, says Virna Sales, MD, a researcher in Childrens Department of Cardiac Surgery and the studys first author. It must open and close synchronously, withstand pressure, and be pliable and elastic. We are one of the few labs in the U.S. thats attempting to make heart valves through tissue engineering. We hope these could just be implanted in a child just once, instead of the many heart operations most children have to go through as they get older.
The researchers, led by Sales and senior investigator John Mayer, MD in Childrens Department of Cardiac Surgery, first isolated endothelial progenitor cells (precursors of the cells that line blood vessel walls) from the blood of laboratory animals. They then seeded the cells onto tiny, valve-shaped biodegradable molds and pre-coated with proteins found in the natural matrix that surrounds and supports cells.
Experimenting with different matrix proteins and growth factors, they were able to make pulmonary valve leaflets that had the right mechanical properties sturdy yet pliable. Tests showed the original cells had differentiated to form both endothelial cells and smooth-muscle-like cells and added to the surrounding matrix to hold them together.
With grants from the American Heart Association
|Contact: Anna Gonski|
Children's Hospital Boston