Biotechnology

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Biotechnology research in space is predicated on understanding and exploiting the effects of the unique microgravity environment on chemical and biological systems. The results of these experiments could point the way not only to commercial enterprises in space but also to new research directions for laboratories on Earth. Protein crystallization and cell biology are two areas in which microgravity research is particularly promising.

Researchers are interested in determining the structure of proteins because the twists and folds of these complex molecules provide clues to their specific functions and how they have evolved over time. However, for scientists to study their structures, the molecules must be "held in place" through crystallization. Large, good-quality crystals are valued by structural biologists, but some organic molecules are easier to crystallize than others are. In some cases the resolution of important biological questions awaits the ability to produce adequate crystals for structural analysis.

For more than fifteen years it has been known that with other conditions being equal, protein crystals grown in a microgravity environment arelarger than those grown on Earth. However, the impact of this realization has been limited because of the irregular, short-term nature of space shuttle flights and the lack of a permanent laboratory with adequate vibration control.

Facilities aboard the International Space Station (ISS) may be able to address this need. Even if there is only an incremental increase in quality when crystals are produced in orbiting rather than Earth laboratories, that increase may make the difference in terms of being able to determine the structure of some proteins, providing new knowledge of biological mechanisms. An X-ray crystallography facility planned for the ISS would provide robotic equipment not only for growing the crystals but also for initial testing. Only the most promising specimens would be stored in the station's limited freezer space to be brought back to Earth aboard a shuttle.

Cell biology is another area in which space-based research may produce valuable findings. In this case the key attribute of the microgravity environment is the ability to grow three-dimensional cell cultures that more closely mimic the way the cells would behave in the organism.

When cells are grown, or "cultured," for experiments on Earth, gravity encourages them to spread out in two-dimensional sheets. For most tissues this is not a particularly realistic configuration. As a result, the interactions between the cells and the biological processes within them are different from what would be seen in nature. At a molecular level this is seen as differences in gene expression, the degree to which a particular gene is "turned on" to make a protein that serves a specific function in the organism.

In a microgravity environment it is easier to get the cells to adopt the same three-dimensional form that they have during normal growth and development. This means that the gene expression pattern in the cultured cells is more like the pattern that occurs in nature. In addition, it suggests the possibility of culturing not only realistic three-dimensional tissues but entire organs that could have both research and clinical applications.

Because of the potential importance of this work, scientists have attempted to duplicate the microgravity environment on Earth. They have done this by placing tissue cultures in rotating vessels called bioreactors where the centrifuge effect cancels out the force of gravity.

Some success has been experienced with small cultures when the rotating vessel technique has been used. However, as the cultures grow larger, the vessel must be spun faster and faster to balance out their weight and keep them in suspension. At that point rotational effects such as shear forces damage the cells and cause their behavior to diverge from what is seen in the organism. This is a problem that could be solved if the experiments were done in space.

However, in considering the potential for biotechnology in space, it is important to understand the technological and political context. Researchers are making rapid progress in both protein crystallization and three-dimensional tissue culture in laboratories on Earth, generally at significantly lower cost than that associated with space programs. Any perception that coveted research funds are being diverted to space-based programs without adequate justification causes resentment of such programs within the scientific community.

In addition, the difficulties of funding a large, expensive space station over the many years of planning and construction have resulted in numerous changes to the ISS's design, facilities, and staffing. Refrigerator and freezer space, for example, has been reduced, creating a potential problem for biology research. Exacerbating the problem is uncertainty in the schedule on which shuttles will be available to transport specimens. Another change of major concern to scientists contemplating participation in the program is a possible reduction in crew size, at least initially, from the planned complement of ten to a "skeleton crew" of only three.

The reduced crew size drastically limits the ability of astronauts to assist with the research, meaning that the experiments that will be flown must require little to no local human intervention. However, the overall budget instability also has affected hardware development funds so that it is more difficult to provide the advanced automation, monitoring, and ground-based control capabilities that are needed.

There are promising applications for biotechnology in the microgravity of space. However, the extent to which these applications will be realized depends on whether they are seen to accelerate the pace of research or whether the situation is viewed as a "zero-sum game" in which resources are diverted that might be better used on Earth. Finally, it remains to be seen whether the political and economic climate will result in an orbiting platform with the staffing and facilities needed to address real research needs.

Crystal Growth (Volume 3);; International Space Station (Volumes 1 and 3);; Microgravity (Volume 2);; Resource Utilization (Volume 4);; Space Stations of the Future (Volume 4).

National Academy of Sciences. Future Biotechnology Research on the International Space Station. Washington, DC: National Academies, 2001.

"Success Stories: Biotechnology."NASA Space Product Development. <http://www.spd.nasa.gov/biotech .html>.

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