The information the insects bring back could not only have implications for astronauts, but it could lead to a better understanding of how the body grows older for the general earth-bound populace as well.
"A lot of what we see in space is an accelerated rate of aging," Lee said.
The fruit flies, a species of Drosophila, will arrive at the U.S. National Laboratory on the International Space Station 240 miles above earth. Hundreds of the insects will travel in a box called a NanoLab. They'll reside in test tubes filled with nutrients to sustain them for their month-long orbit.
"We'll be looking at how well the flies' hearts squeeze and look after being in space — whether there are more arrhythmias or any changes in gene expression," Lee said.
Researchers have long studied the effects of weightlessness on astronauts' skeletal muscles and bones. They learned that bone loss and muscle atrophy take place in space. Every system in the body appears to be negatively impacted by space flight, Lee said. But little is known about the heart. Astronauts do seem to have increased risk of irregular heart rhythms, some decrease in heart mass and a little decrease in heart function. What the long-term effects might be of prolonged space habitation are not known, he said.
Experiments Lee has done on muscle tissue in space show some direct effect. Weightlessness causes a shift in body fluid. Standing on earth, gravity causes blood to go to the legs. But in space, less flows to the lower extremities, and more flows to the upper body. The body compensates in part through greater excretion, but more fluid still goes to the heart. It appears that there might be small changes because of that fluid buildup, he said.
In Lee's cubicle in Stanford's Falk Building, his computer screensaver has an image of the space shuttle Endeavour atop a 747 airliner. And there is a photo of Lee shaking hands with astronaut Neil Armstrong. Lee said he kept his childhood interest in space in college and searched for ways to stay in the profession. His adviser at Brown University had an experiment on the space shuttle, and Lee did his doctoral research in that project, he said. He was a principal investigator on the study of the effect of weightlessness on muscle tissue, and the experiment traveled on the space shuttle with astronaut-turned-senator John Glenn.
Lee joined a Mars-simulation team for a month-long expedition to an Arctic island that approximated the Martian environment, and he has conducted cardiopulmonary resuscitation experiments on reduced-gravity aircraft designed for astronaut training. He is also a full fellow of the Aerospace Medical Association.
He turned to Sanford-Burnham Medical Research Institute in San Diego, which has heart research on fruit flies, and to NASA Ames Research Center, which has experience sending the insects on space missions, as collaborators for the fruit-fly project. The team was one of eight to win a Space Florida research competition in December for their experiment.
"Drosophila work really well for space-flight experiments. You don't get a lot of 'space' for space experiments. You can't send very heavy or big things up. When you do science in space, you make do with as little resources as possible," said Sharmila Bhattacharya, principal investigator of the Biomodel Performance Lab at NASA Ames, who is part of the team.
Lee said using tiny creatures by the hundreds also has the advantage of producing many live subjects from which to gather data, he said. A human study would be limited to only two or three subjects, since there are few people who fly into space, he said.
Fruit fly and human hearts are not similar in structure — the insects have a tubular rather than chambered heart — but the genes are very similar. When the fruit flies are in space, genes will be turned on and off as organs change in response to weightlessness. Changes caused by space travel that might cause defects or arrhythmias could be found and compared to similar gene changes that cause the same defects in humans, he said.
Lee isn't holding out great hope of taking a similar space flight as his insect subjects. Only 10 to 15 human positions will be selected out of the 6,000-plus applicants, he said. But he does have great hopes for the information his proxies will bring upon their return. And there is always that slim hope of a future as a doctor in space. Results will be announced this spring or summer, he said.
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