The Response of Single Human Cells to Zero Gravity

The 59-day Skylab III earth-orbital mission carried an experiment designed to observe the effects of zero-gravity on a strain of diploid human embryonic lung cells, WI-38. The experiment (NASA Exp. No. S015) was performed in a miniaturized, fully automated tissue-culture laboratory package called the Woodlawn Wanderer Nine. The package, which weighed less than 10 kg, photographed two perfused cultures for 28 days using phase-contrast microscopes and 16-mm time-lapse cameras; fixed 10 perfused cultures in gluter-aldehyde one at a time over a 12-day period; and returned to earth eight perfused cultures in a viable state for subsequent subculture and study. Two ground control experiments using specimens from the same clone were run simultaneously with the flight experiment in identical packages. The controls were subjected to simulated flight vibration profile within an hour after spacecraft liftoff. All packages were sealed at 1-atmosphere pressure. Analysis of the flight and control films showed no differences in mitotic index, cell cycle or migration rates. Growth curve, DNA microspectrophotometry, phase microscopy and ultrastructural studies on the fixed cultures revealed no effects of zero-gravity. Karyotyping and chromosome-banding studies were performed on subcultures of the returned viable cells and these showed no significant differences from the controls. Minor unexplained differences were found in the biochemical constituents of the spent media of the flight and control experiments. Within the limits of this experimental design it was found that the zero-gravity environment produced no detectable effects on WI-38.