While in orbit, astronaut John Glenn will conduct an experiment to grow heart cells in space that researchers at the University of South Carolina believe could lead to treatment for congenital heart defects and heart attacks.
Mr. Glenn, who is returning to space Thursday, 36 years after his first flight, will operate that experiment and another by South Carolina researchers on ways to stimulate muscles and prevent atrophy during space flights.
The 77-year-old senator is returning to space to study the effects of space on aging.
"Basic research is important, and Glenn has said that," said Louis Terracio, a heart muscle researcher at South Carolina's medical school. "He's been very much saying that he's not just trying to relive his glory days when he orbited the Earth but that he wants to be involved in meaningful scientific experiments."
In experiments on Earth, University of South Carolina researchers have grown a single layer of heart cells, Dr. Terracio said. But they have been unable to grow multiple layers of tissue that resemble the construction of heart cells, he said.
"We found that when we added extra cells on, they clumped on and didn't integrate and wouldn't grow multiple layers," he said.
In a 1995 spaceflight, astronauts were successful in growing multiple layers of heart cells, Dr. Terracio said. Scientists hope to replicate those results on Mr. Glenn's Discovery mission.
"NASA had this hypothesis that the reduced-gravity, buoyant atmosphere in space mimicked the development in-utero," Dr. Terracio said.
If the hypothesis is confirmed, the researchers will attempt to get funding to build a chamber on Earth where replacement heart cells can be grown in an atmosphere similar to space, Dr. Terracio said.
Instead of using synthetics, they hope to be able eventually to take living cells from a person's heart, clone them and transplant the new tissue into an organ weakened by multiple heart attacks or birth defects.
"It would be so much better to patch with human tissue that would not be rejected and would integrate into the heart," Dr. Terracio said.
The second experiment is designed to study ways to stimulate muscles to avoid the tendency to waste away because of reduced usage in weightlessness.
"Muscle atrophy and bone loss are the two major concerns for extended weightlessness," Dr. Terracio said. "One of the fundamental ways to stimulate muscle is to stretch it."
Initial research has shown that stretching muscles along their length does little to prevent atrophy, but stretching across the width of the muscle "is enough to drastically decrease atrophy," he said.
One of the practical applications might be preventing muscle atrophy in people confined to bed for a long time, said Dr. Bob Price, director of the integrated microscopic analysis facility at South Carolina's medical school.
Associated Press reports were used in this story.
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