Astronauts tend to get sick —15 of the 29 astronauts
who flew on Apollo missions in the 1960s and ’70s came down with
infections during flight or immediately after — and
biologist and former astronaut anxiously awaits the imminent return of
16 mice from a two-week stay aboard the space shuttle Discovery, as
part of an experiment she designed to study how their immune cells
handle spaceflight. The scheduled landing:
NASA Ames researcher
hoping to find clues about a constellation of space-travelers’
maladies: weakened bones and muscles, and compromised immune systems.
Both projects aim to help humans survive years-long
journeys to Mars and beyond. The work might also have implications for
health problems on Earth.
The astronauts’ maladies are similar to
muscular-skeletal diseases in paralyzed or comatose patients on Earth,
Almeida said, and to the weakening of the immune system with aging,
according to Hughes-Fulford. She has seen young astronauts come down
with shingles, which commonly occur in people past the age of 60.
“Over the years I’ve been able to do several
experiments on the shuttle,” Hughes-Fulford said. “We’ve found that the
immune system is suppressed when it doesn’t have gravity.”
The research is set up differently than when
Hughes-Fulford traveled to space herself, on a 1991 shuttle mission
devoted to science.
“We had a dedicated lab where all four people on the
payload side were doing experiments, even our pilot and flight
engineer,” she said.
These days, researchers automate experiments as much
as possible to conserve the crew’s valuable time. They prepare
rigorously in the months and weeks before take-off.
“You have this one opportunity,” said
The team poured millions of the cells in culture
into 12 six-inch-long reactors, to fly in the comfort of a mid-deck
locker. Over time, the cells grow into various tissues — muscle, liver,
neurons. Under the microscope, the researchers can even see tiny
glimmers of twitching heart tissue.
When the cells return, the team will track the genes
and biochemical pathways that were active during flight, and compare
those to the activity in stem cells that remained on Earth. Dvorochkin
said completing the analysis will take roughly a year.
During the George W. Bush administration, after the space shuttle
This time, Hughes-Fulford was able to send 16 mice
in climate-controlled containers along with Discovery. Her team will
analyze how mouse white blood cells respond to a simulated infection
during flight and upon return, and compare that to how white blood
cells behave in 16 Earth-bound mice.
“Her results from previous flight experiments are pretty compelling,” said
Bikle also said studying how stem cells turn into various tissues has implications for astronauts’ health.
“If there’s any failure of these stem cells to
differentiate into normal tissues that could cause problems,” he said.
“If we ever do get around to sending somebody to Mars and somebody gets
pregnant, if stem cells fail to differentiate you wouldn’t get a normal
baby.”
By looking at how different biochemical pathways are
regulated in spaceflight, both experiments might shed light on how
things work naturally on Earth, said immunologist
Sonnenfeld himself has done nine spaceflight experiments since 1976; he
was not involved in Hughes-Fulford’s or Almeida’s studies.
In previous studies, Hughes-Fulford found T-cells, a type of white blood cell, were malfunctioning during spaceflight.
“We found that the T-cell is dependent on gravity,”
she said. After the mice return, “we’ll know exactly where the change
is occurring. We’ll be able to map out which genes are not being
activated.”
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