Are astronauts at risk of developing coronary artery disease from spending time in space, or can their blood vessels adapt to the change in gravity? To find out, Johns Hopkins researchers are preparing a cargo of special cells to board the shuttle Atlantis for a 10-day trip including a stop at space station Mir. The shuttle is scheduled to launch from Cape Canaveral, Fla., on Sept. 25.
The first-of-its-kind Hopkins experiment is one of several supported by the Space Tissue Loss Program, an ongoing effort by the Department of Space Biosciences at the Walter Reed Army Institute of Research, the National Aeronautics and Space Administration and the Department of Defense. Investigators are looking at changes that develop in various types of cells at zero gravity.
At Hopkins, the target is endothelial cells, the cells that line the inside of arteries and veins. Endothelial cells are responsible for making sure blood flows smoothly through the body without clotting. Healthy endothelial cells also suppress arteriosclerosis, known as hardening of the arteries.
These cells are continuously subjected to the "shear stress" generated by the force of blood flow across their surfaces. When these cells are healthy, they can sense shear stress and alter their function as necessary to continue serving their protective role. Barbara J. Ballermann, M.D., associate professor of nephrology at Hopkins and principal investigator, says that microgravity could have a wide variety of effects on endothelial cells.
"We are very excited to participate in this research collaboration," Ballermann says. "Although it is not possible to predict our results, we hope to find out how endothelial cells respond to changes in their physical environment. Any favorable or detrimental effects of space flight on these cells could have implications for future prolonged excursions into space."
Researchers from Ballermann's lab, Eudora Eng, M.D., and Veronica Fergusson, will travel to the Kennedy Space Center a week before lift-off to prepare the cells in a series of 16 specially designed cartridges. Eight will ride in a research bay in the mid-deck of the shuttle -- the same section where astronauts reside during space flight. The remaining eight will serve as a control by staying in a lab on the ground.
The bioreactor cartridges, manufactured by Cellco Inc., of Germantown, Md., are flown in cell culture modules specifically designed at Walter Reed to aid in the study of microgravity effects at the cellular level. Tom Cannon, payload manager for the cell culture module experiment, says this collaboration is a truly advanced research effort that takes advantage of a unique cell culture modeling technique developed jointly by Ballermann and Cellco.
The endothelial cells will be placed inside groups of hollow fibers that simulate either arteries or veins, which experience different stresses. A liquid medium will be pumped through the fibers to simulate blood flow and measure shear stress.
The Hopkins team will set up some cartridges to study high shear stress, as would affect arteries, and others to study low shear stress, as would affect veins.
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