cell electrophoresis and to obtain better data on mobility distributions in a variety of cell populations.

C. Protein electrophoresis. The situation is rather different for protein electrophoresis, where there are a variety of well established techniques which are in world-wide use in literally thousands of laboratories. There are no major unresolved scientific problems and the usefulness of electrophoresis is based on the fact that there is an exquisite correlation between the molecular structure of the protein and its electrophoretic characteristics. As a result, electrophoresis is used for various analytical and micropreparative purposes in the most diverse areas of biological research, clinical medicine, and quality control in industry. Despite numerous efforts, ground-based technology has failed in one important respect: scaling up the capacity of the instruments for the separation of meaningful quantities of purified components. There are no theoretical reasons that electrophoresis could not be used on the largest possible industrial scale, only limitations in present instrument designs. Some of these limitations may be gravity-dependent, due to the need for fluid stabilization against gravity driven convection.

We are currently actively engaged in an effort to overcome these limitations, using a new principle of recycling isoelectric focusing. Isoelectric focusing is generally recognized as a variant among electrophoretic methods giving the highest resolution, but it offers small throughputs useful only in research. The recycling principle has already shown promise for far greater throughputs, possibly even of industrial capacity. These studies are only in their initial phase, and it is not yet clear to what degree this new process could benefit from weightlessness.

Should our present ground-based studies confirm the expectation that

the process may benefit from weightlessness in terms of increased throughputs and higher resolution, then its adaptation to the Shuttle would have to be justified only on the basis of its cost. It is my personal opinion that there is a wide array of proteins and other biologically important molecules which have sufficient economic, medical or scientific value to warrant the expense of space processing. Our current efforts are particularly directed towards the purification of peptide hormones which seem to uniquely qualify for this purpose.

Peptide hormones are biological messengers produced in the minutest quantities by the pituitary, hypothalamus, thymus and other body organs. They regulate and modulate human growth, metabolism, immune responses, fertility, and even some brain activities. They are of major medical importance. Insulin, ACTH, Oxytocin, Vasopressin, to name only a few, are in daily clinical usage. Many other known peptides could find medical application, if they could be isolated in sufficient quantity, or synthesized. With both natural and synthetic materials, purification is often a major bottleneck, as impurities may possess antagonistic effects. To illustrate the potential economic value of their space processing, a tentative listing of some better known peptide is included, showing their usage, estimated price, and potential annual total sales.

POTENTIAL FUTURE APPLICATIONS OF SPACE BIOPROCESSING

Wisely or not, electrophoresis has been singled out as the major focus of the current space bioprocessing effort. Within the broad outlines of Life Sciences, there are numerous other areas that could and should be explored in the weightless state. Unfortunately, NASA has flown only two Biosatellites exclusively dedicated to biological experimentation.

The first one failed on recovery, and all data were lost. The second one, flown in 1967, was largely dedicated to proving the biological safety of space, i.e. the safety of sending man into orbit. A few other scattered experiments were conducted aboard the Apollos and the Skylab.

A Colloquium on Bioprocessing in Space, held at the Lyndon B. Johnson Space Center, March 10-12, 1976 was a first major step directed specifically towards exploring the wider potentials of space bioprocessing. The published Proceedings (11) comprise the recommendations of the four Workshops on Biotechnology, Cell Biology, Industrial Biosynthesis, and The specific recommendations by these four Workshops cover far too wide a range of topics to be reviewed in detail. Some of the most important recommendations for further studies were:

Pharmaceuticals.

Cellular Interactions,

Biological Transport and Permeability,

Embryological Development and Reproductive Biology,

Electron Microscopy in Space,

Modification of Cells by Heavy High Energy Particles,

Tissue and Organ Culture,

Drug Metabolism,

Circadian Rhythms,

Geotropism.

CONCLUSIONS

The major emphasis in space bioprocessing within the NASA program on Materials Processing in Space has been in the exploration of the potential benefits of weightlessness for the separative process of electrophoresis.

This work is aimed at the development of a space facility for electrophoresis

aboard the Shuttle. Four pilot experiments conducted aboard the Apollo 16, Skylab and Apollo-Soyuz have demonstrated the potential usefulness of weightlessness but were too few and too limited in scope to fully document it. Present ground-based research is aimed at the optimization of eventual space equipment, as well as the selection of candidate materials for space processing. Two broad categories of candidate materials are being considered. The first category comprises living cells, including various blood and bone marrow cells, pancreas cells, kidney cells, and several other cell types. Its objectives are the purification of cell subpopulations having specific functional properties. This area of investigation is central to much of current biological research in such diverse fields as immunology, cancer research, diabetes, organ transplant, tissue culture, manufacture of biologicals, etc. The art of cell separation is still in its infancy and much further ground-based research is needed. Because of the rapid scientific advances in this field, it is not possible to precise at this time the needs and requirements for specific cell fractions when and if a space facility for cell separation becomes available, or its economic value. There is no doubt, however, that it would greatly contribute to our knowledge of cell biology and its application to urgent medical problems.

The second category of materials for space processing comprises a broad range of biologically active substances, such as proteins, enzymes, vaccines, peptide hormones, genetic materials, etc. The instrumental requirements for their space purification will surely be different than those for cell separation. Research in this area is currently being actively pursued. The economic and medical benefits of space processing of these biomolecules can be easily accessed, as many have established