Cord Blood Stem Cells May Help Repair Babies' Heart Defects

Cardiologists at the University Hospital of Munich say they are 5 years to 7 years away from transplanting new heart valves into children with faulty hearts, derived from the children's own cord blood. The researchers reported the findings today at the annual meeting of the American Heart Association.

Heart valve abnormalities are one of the most common kinds of inherited heart defects. In these babies, the valves are too narrow or don't close as they should, keeping blood from flowing properly. While surgeons can transplant new valves from human or animal donors, or from artificial material, these valves won't grow as children do, forcing kids to undergo repeated operations to outfit them with new, larger valves, said Ralf Sodian, the cardiac surgeon who led the research.

``Imagine you had a child with congenital heart disease and this child has to be operated on every 2 to 3 years,'' Sodian said in a Nov. 7 telephone interview. ``It's very hard for children and parents. The goal is to do surgery once that would last a lifetime.''

Sodian and his colleagues collected umbilical cord blood from babies as they were being delivered and isolated a key group of stem cells that form the main tissues found in heart valves. After freezing the cells for 12 weeks to preserve them, they seeded those onto a biodegradable polymer scaffold in the laboratory.

The eight bio-engineered valves created by Sodian and his team acted much like natural heart valves when they were tested to see how they would handle blood flow and pressure, he said. The scaffolds will dissolve over time, leaving behind a fully formed structure made from the cells, he said.

Lamb Trial
The next step is to test the procedure by implanting heart valves made in this way into the hearts of young lambs, then watching to see how they grow and function over time, Sodian said. He hopes to begin these experiments next year.

Stem cells from umbilical cord blood, like adult stem cells found in the mature tissues of developed humans, have the potential to form many kinds of cells that can repair or replace damage to organs of the body. Since the umbilical cord stem cells aren't derived from human embryos, they don't raise ethical objections like those that led President George W. Bush to limit federal funding for embryonic stem cells research.

Stem cells from human embryos are more versatile, however, since they are able to form any of the roughly 210 cell types found in the body. Advisers to President-elect Barack Obama said yesterday that Obama may move quickly once he takes office on Jan. 20 to undo the Bush restrictions on embryonic stem-cell research by executive order.