Mammalian Cells in Space Weightlessness

Human clearly perceive and respond to microgravity as an individual unit and manifest such abnormalities as space sickness, and decrease in Calcium in the bones. It is not fully understand, however, whether each of the cells perceives and responds to microgravity. This is a problem of a major scope in gravitational and space biology. I discussed here methods of studying ceIIular response to microgravity cellular response in the space, and others. The cell culture can be applied to elucidate the mechanism of gravity response in cells. FMPT was conducted in the space shuttle Endeavor launched on September 12, 1992, and I and my colleagues had a study concerned the effects of microgravity on the ultrastructure and function of mammalian cells in culture. The study was conducted with the following three major objectives: The first objective was to study the change under microgravity in the cytoskeletons using Monkey's renal cells JTC-12. The second objective was to study energy consumption by cultured cells under microgravity and production of urokinase of the ceIIs. The third objective was to establish the basic techniques of cell culture in the space. Dr. Mouri, payload scientist, conducted the experiments during the flight as scheduled. Cells cultured in culture chambers ACCl and ACC2 were used for the objective 1 and phase contrast microscopic photographs taken in the space laboratory. After trypsinization, the cells were cultured again and fixed with glutaraldehyde after a prescribed period of time. Culture chambers ACC2 and ACC4 were for the objective 2 and 3 and the used cells were brought back to the earth alive. Analysis of photos taken by Dr. Mouri is in progress. Cultured cells were in good conditions under microgravity, and satisfactory results for establishing cell culture techniques, were obtained. Cultured human and animal cells have been used in more than 20 space experiments since Discoverer 17 Iaunched in 1960 and the cellular response to microgravity may differ depending on the cell types. It is possible to conduct experiments on earth using short term microgravity by a drop tower or simulated microgravity using clinostat. Hypergravity using a centrifuge is also useful for studying the cell response to gravity. Since opportunities for space laboratory experiments are Iimited, these equipments are believed to be most useful for sophistication of space experiments.