Amniotic Stem Cells Offer Hope Against Congenital Heart Defects

By Amanda Gardner
HealthDay Reporter
Tuesday, November 14, 2006 12:00 AM

TUESDAY, Nov. 14 (HealthDay News) -- A young mother-to-be learns her 5-month-old fetus has a congenital heart defect.

Today, this news is met with anger, sorrow, denial. Doctors will watch the unborn baby closely and may even be able to correct the problem. But the fact remains that congenital heart disease is responsible for more deaths in the first year of life than any other birth defects, the National Institutes of Health reports.

But if findings from a Swiss study prove true, in the future doctors will be able to use a simple procedure to extract stem cells from the mother's amniotic fluid and use them to make a new heart valve, ready to place in the baby as soon as it is born.

"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," said study senior author Dr. Simon Hoerstrup, director of cardiovascular research and the division of regenerative medicine at University Hospital in Zurich. "This may open a whole new therapy concept for the treatment of congenital heart disease."

Hoerstrup presented his paper Tuesday at the American Heart Association's annual meeting, in Chicago.

According to Hoerstrup, some 1 percent of newborns have congenital heart problems and one-third of these babies need surgery for a heart valve.

"It's a substantial group of patients," he said.

Malformation of the heart or one of its valves can be diagnosed by ultrasound in the 20th week of pregnancy. Amniotic stem cells can be obtained as part of a routine procedure already in use to search for genetic problems, especially in women over the age of 35.

For this study, Hoerstrup and his colleagues extracted amniotic stem cells, created miniature heart scaffolds, then watched them grow into functioning valves.

"The concept is that we can obtain cells during pregnancy and use the cells to create a living heart valve replacement, which is ready to use at birth," Hoerstrup said. "Advantages are that they are made from the baby's own cells and are living and can grow with the baby later on."

Although not yet transplanted into a baby, the valves created by Hoerstrup did function. "We saw a very nice opening-and-closing behavior," he said.

This study was one of several in the area of tissue reengineering presented at the heart association meeting.

"Tissue engineering is very, very attractive because you can manufacture the valve exactly as you want to," said Dr. Valentin Fuster, director of the Cardiovascular Institute at Mount Sinai School of Medicine in New York City, president of the World Heart Federation, and past president of the American Heart Association.

"I think this is going to have significant implications in the future," Fuster said.

Not all stem cell research presented at the meeting related to valves. Another group of researchers found that the fat tissue of older adults appears to be a good source for stem cells.

"A major problem with any type of cell for tissue engineering is you want to get a reliable source of cells," said Dr. Paul DiMuzio, an assistant professor of surgery at Thomas Jefferson University in Philadelphia. "They can be used from bone marrow but this source tends to decrease with age, making it a limited source of cells in the exact population you need the cells for."

In this study, DiMuzio and his team harvested stem cells from the adipose tissue of 49 patients undergoing elective vascular surgery. The number of stem cells obtained was roughly equivalent, regardless of the person's age, body-mass index or whether they had end-stage kidney disease or arterial disease. The one surprise was that patients with diabetes tended to have fewer stem cells available from fat, DiMuzio said. In fact, the number of stem cells available is remarkably constant in each decade of life, he noted.

"Age appeared to be not a big problem," he said.

Other related research presented in Chicago found that acute heart attack patients who were infused with bone marrow cells saw an improvement in heart function when compared with patients who received a placebo infusion. "Magnetic resonance imaging findings confirmed that bone marrow-derived progenitor cell therapy holds great promise for post-infarction heart failure," said study author Dr. Thorsten Dill, of the department of cardiology and cardiac imaging at Kerckhoff Heart Center in Bad Nauheim, Germany.

In other news, researchers in Japan reported that they successfully used rabbit cells to grow a heart-valve-shaped tissue inside the animal. And investigators at Johns Hopkins University have grown large numbers of stem cells taken from pig heart tissue, then used those cells to repair damage caused by laboratory-induced heart attacks. No overall improvements in heart function have yet been shown, the Hopkins authors cautioned.

More information

The American Heart Association has more on congenital heart defects in children.

SOURCES: Valentin Fuster, M.D., Ph.D., director, Cardiovascular Institute, Mount Sinai School of Medicine, New York City, and president, World Heart Federation; Nov. 14, 2006, news conference with Simon P. Hoerstrup, M.D., Ph.D., professor, biomedical engineering, and director, cardiovascular research and division of regenerative medicine, University Hospital, Zurich, Switzerland; Paul J. DiMuzio, M.D., assistant professor, surgery, Thomas Jefferson University, Philadelphia; Thorsten Dill, M.D., department of cardiology and cardiac imaging, Kerckhoff Heart Center, Bad Nauheim, Germany

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