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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 Pharmaceuticals. 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:
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,
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
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
commercial value and documented needs.
A far broader range of possible bioprocessing applications of orbiting spacecraft has been considered, but has received little or no attention for lack of adequate financial resources. As a matter of fact, if anything has been demonstrated up till now, it is the need for continuing extensive research. For orbiting spacecraft provide an entirely new set of environmental conditions, such as the virtual absence of gravity, and the effects of these conditions are as yet quite unknown. Gravity has been taken for granted for so many years that few scientists have ever given consideration to the consequences of its absence. Urgently needed are studies on the effects of weightlessness on fluid behavior, biological transport phenomena, embryologic and reproductive behavior, isolated but interacting cell systems,
tissue culture, etc.
Some of these studies are possible only within the orbiting spacecraft, and it is hoped that the Shuttle will provide the necessary ready access. Within this context, the Shuttle has to be regarded primarily as a unique national research resource and only secondarily as a vehicle for establishing a space-based technology. A far broader range of problems can be attacked by ground-based studies, oriented towards the elucidation of the role of gravity in the phenomena being studied. There is no doubt that this groundbased effort is not only essential for the development of a space bioprocessing technology, but that it will also surely advance the art of ground-based technologies. Within the electrophoresis program, this has already taken place. Due to the stimulation of this field of research, new instruments have been devised, patents issued, and better understanding of the processes achieved. This would not have been possible without the multidisciplinary approach characteristic of all NASA activities, and may alone justify the efforts and moneys so far expended.