Stem Cells Used To Repair Congenital Defects Before Birth

Researchers have announced the use of stem cells collected from the amniotic fluid surrounding fetal lambs to grow windpipes, and then implanted the tissue back into the fetuses while they were still in the womb, a breakthrough that could lead to ways to repair congenital defects before birth.

Although rare, defects in the windpipe or trachea can be life-threatening and are difficult to repair. The procedure, involving surgery soon after birth, can have complications, including brain damage.

Experts at Children's Hospital in Boston and Dr. Dario Fauza hope their technique can offer a way around such problems by repairing the defect before the baby is born.

"The fetus doesn't need the trachea, so the repair would have time to heal in utero and fetal healing is very good -- it's better than adult healing," said Dr. Dario Fauza.

The technique involves extracting amniotic fluid, which surrounds the fetus in the womb, to obtain a type of stem cells known as mesenchymal stem cells. These cells arise directly from embryonic stem cells and they can give rise to various cell types, so they could be used to regenerate damaged or diseased tissues.

Dr. Robert Lanza, vice president of medical and scientific development at Advanced Cell Technology in Worcester, Mass., praised the results of the study. Lanza was involved in similar research in cows conducted at his company three years ago that generated a miniature kidney and heart muscle tissues.

"This study heralds a new phase of stem cell research," Lanza told United Press International. "To realize the full potential of any stem cells -- embryonic or adult-- we need to be able to use them to generate complex structures."

The technique could be used to generate a bladder and similar structures, Lanza said.

"We're many years off before we can create a functioning human kidney or heart, but this field is moving at such an enormous pace," he said. "We're very, very, likely to see this in our lifetime."

Fauza's team already is pushing ahead with the technique. They have shown it can be used in lambs to repair a condition known as congenital diaphragmatic hernia, or CDH, in which there is a hole in the diaphragm muscle in the abdominal cavity.

They have applied to the Food and Drug Administration for permission to conduct a study using the technique on human infants with CDH, and are awaiting word from the agency. They also are examining whether similar techniques could be used to correct spinal bifida and heart defects.

In the study, which Fauza plans to present Saturday at the American Academy of Pediatrics meeting in Washington, the researchers obtained amniotic fluid from fetal lambs and isolated the mesenchymal stem cells.

They multiplied the cells in lab dishes and then transferred them to a scaffolding to help direct their growth. The researchers also exposed the cells to growth factors to spur them to become cartilage cells, and the resulting cartilage cells were used to repair defective tracheas in seven lambs in utero. Two lambs were born prematurely and died, but the remaining five survived and were able to breathe on their own at birth.

One advantage of using mesenchymal stem cells is they can be obtained without harming the fetus and thus would avoid the ethical debate that currently surrounds embryonic stem cells. In addition, Lanza said, there are some indications mesenchymal stem cells equal embryonic stem cells in their ability to give rise to many of the cell types of the body.

Another advantage is that since mesenchymal cells originate from the fetus' own cells, they would not be rejected by the immune system as can happen when tissues are transplanted from one person into another.

Fauza said the amniotic fluid is readily available -- it is commonly extracted to run tests prior to birth -- and less than two tablespoons would provide enough mesenchymal stem cells to repair a congenital defect. The fluid could even be banked for future use.

"Fetal cells are the best cells you can have for tissue engineering," he said. "They grow very well, and they're very plastic -- you can coach them to do what you want."

Stem cells used to repair fetal defect