Stem Cells Used to Grow Human Heart Valves

A new study reports that human heart valves have been grown for the first time by using stem cells found in amniotic fluid.

Researchers from the University of Zurich (Switzerland) harvested autologous fetal stem cells from the womb during amniocentesis and seeded them onto three-dimensional (3D) matrices--shaped like a small ink pen and made of biodegradable plastic--followed by biomimetic in-vitro conditioning that enabled the development of the neo-heart valve tissue. Four to six weeks were needed to grow each of the 12 valves created in the experiment. Tests showed the valves appeared to function normally.

The idea behind the research is to create new valves in the laboratory while the pregnancy progresses, and have them ready to implant in a baby with heart defects after it is born. Amniotic fluid is a rich source of stem cells and also could be frozen for years, the researchers said, and could therefore potentially be used to create replacement parts for aging or diseased valves in adults as well. Also, by using cells the fetus sheds in amniotic fluid, this procedure avoids controversy because it does not involve destroying embryos to obtain stem cells. The research results were presented at the American Heart Association (AHA) Scientific Sessions, held in Chicago (IL, USA) in November 2006.

"We have demonstrated that, based on a cell source which you can obtain prenatally, you can fabricate a living heart valve from these cells which may be ready to use at the time of birth. If you have to wait for the baby to arrive to collect cells, it takes another six to eight weeks before a valve is ready to implant, which is often too late,” said lead author Dr. Simon Hoerstrup, director of cardiovascular research and the division of regenerative medicine. "This may open a whole new therapy concept to the treatment of congenital heart defects.”

Since it is possible to diagnose heart malformation or heart-valve defects in the 20th week of pregnancy with the help of ultrasound tests, replacement hearts grown out of stem cells can be easily used to treat babies born with such defects, added Dr. Hoerstrup.



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