Heart valves grown from cells in womb

CHICAGO — Scientists for the first time have grown human heart valves using stem cells obtained from the fluid that cushions fetuses in the womb, offering a revolutionary approach that may be used to repair defective hearts in the future.

The idea is to create these valves in the lab while the pregnancy progresses and have them ready to implant in a baby with heart defects after it is born.

The Swiss experiment follows recent successes at growing bladders and blood vessels and suggests that replacement heart parts that are more durable and effective than artificial or cadaver valves may one day be grown for infants and adults.

"This may open a whole new therapy concept to the treatment of congenital heart defects," said Dr. Simon Hoerstrup, a University of Zurich scientist who led the work, which was presented Wednesday at an American Heart Association conference.

One percent of all newborns, or more than 1 million babies born worldwide each year, have heart problems. They kill more babies in the United States in the first year of life than any other birth defect, according to the National Institutes of Health.

Heart-valve defects can be detected with ultrasound tests at about 20 weeks into a pregnancy. At least one-third of affected infants have problems that could be treated with replacement valves, Hoerstrup said.

Valves made from the patient's own cells are living tissue and might be able to grow with the patient, unlike artificial or cadaver valves, said Dr. Kyoko Hayashida, a scientist at the National Cardiovascular Center Research Institute in Osaka, Japan.

The Swiss procedure has another advantage: Using cells the fetus sheds in amniotic fluid avoids controversy because it doesn't involve destroying embryos to get stem cells.

Hoerstrup and co-researcher Dorthe Schmidt called their method "a promising, low-risk approach enabling the prenatal fabrication of heart valves ready to use at birth."

Hoerstrup said amniotic stem cells also can be frozen for years and could potentially be used to create replacement parts for aging or diseased valves in adults, too.