Microgravity Uses in Cell Biology

Cell Biology

In biotechnology, particularly in cellular based systems, microgravity has attracted keen interest among nations with space programs. Early findings show opportunities in disease modeling, tissue engineering for research and transplantation, new biopharmaceuticals, vaccine development, propagation of stem cells, and drug testing.

Microgravity provides environmental characteristics which are difficult to obtain on Earth. Using such extreme conditions to investigate life processes affords opportunities for discovery and development of applications which enhance research and the probability for pathfinding mechanisms in life processes. For example, the elevation of cell culture temperatures brought new concepts to cell biology in the discovery of heat shock proteins and the refined stress response suites observed in gene expression. Indeed, Thermophilus aquaticus isolated from marine thermal vents provided the Taq polymerase so critical in molecular genetics advances.

Microgravity thus affords a new window through which to observe life processes. Throughout the evolution on Earth, life has not had to adapt to lowering of the gravitational force. It has been constant for the 4.3 billion years of evolving life. In the short time we have studied microgravity, it is

apparent that terrestrial life responds to the physical change in gravity by altering gene expression, inhibiting cellular locomotion, promoting differentiation, and facilitating tissue morphogenesis. Novel adaptational responses have been observed in bacteria, yeast, plants, lower animals, and human cells. Mammalian cells tend to become spherical, alter signal transduction pathways, and produce secretory products. Cells adapt and most survive the transition. In experiments conducted over short durations in microgravity, the changes are genuinely phenotypic and therefore resolve when returned to 1g. Microgravity is thus a probe which, as with other physical stresses, can reveal novel mechanisms that are fundamental to cell processes, disease process, and the adaptation of living systems to changes in physical forces. Microbial cells do not show the same physical change. Nevertheless, microbes display a profound set of metabolic and genetic changes. No experiments have been conducted for sufficient periods in microgravity to determine if microgravity constitutes a selective pressure leading to emergence of stable genotypic changes. (Cell biology continues on the next two pages.)