CDU

CHICAGO — A stem cell research effort that appears tantalizingly possible was described at the Scientific Sessions of the American Heart Association (Dallas). Put it under the category, "grow-your-own heart valves."

Simon Hoerstrup, MD, PhD, professor of biomedical engineering and director of cardiovascular research and the division of regenerative medicine at University Hospital (Zurich, Switzerland), described the use of a pregnant woman's amniotic fluid to produce heart valves that can then be used to repair her baby's defective heart valve. Researchers at the University of Zurich harvested stem cells from the amniotic fluid and "seeded" them on heart valve-shaped polymeric scaffolds. The result was the creation of biological heart valves that the researchers hope can be used to replace a defective heart valve of the mother's baby, once born.

Hoerstrup said the stem cell-produced valves were then placed in a biological environment simulating the pulsatile flow of the real heart and they showed the characteristics of healthy valves, chiefly the ability to naturally open and close.

Replacement of the defective valve would be made at a time determined by the degree of the baby's defect, Hoerstrup told Cardiovascular Device Update. He said this has not yet been done. The next step in the research, he said, will be to replace the valves of sheep and follow these for two years to determine their ability to grow and change with the animal.

This ability is the essential key benefit of the amniotic fluid stem cell use, he said, because mechanical and biological valves don't grow as a child matures — though the attempt to achieve this with biological valves is ongoing. Thus, babies with these defects must have repeat replacements as they grow older, the repeat procedures greatly shortening their life span.

Hoerstrup said that 1% of all babies have a heart valve defect and one-third of these need valve replacement. He suggested the need to target women determined to have high genetic risk factors and for their babies to have such defects, but that ultimately all women might be encouraged to have samples of their amniotic fluid cryopreserved for future use.

These processes, of course, provide a fairly large barrier given the infrequency of such preservation and the still embryonic sector of the companies providing this type of service.

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