Medicines from Space

by Food and Drug Administration (FDA)

When the space program was younger, the "out-of-this-world" medical prospects focused on manufacturing scarce products like interferon and pancreatic beta cells in an environment virtually free of gravity.

McDonnell Douglas Corporation, Ortho Pharmaceuticals, and the National Aeronautics and Space Administration were cooperating in the early 1980s on continuous flow electrophoresis experiments. This was a process of separating biological materials from preservative solutions to produce erythropoietin, a hormone important for stimulating human red blood cell production, more efficiently than seemed possible on Earth. Those experiments seemed to point toward large-scale orbiting pharmaceutical factories to produce quantities of insulin, interferon, and other vital substances.

Today, science has a very different view, looking in space for medical breakthroughs difficult to achieve on Earth for conditions ranging from motion sickness to osteoporosis, AIDS and cancer.

Although 1983's experimental technology succeeded, earthborn science and spacecraft experience over the past decade have pushed orbiting drug factories further into the future. In space, the practical problems of prolonged low-gravity exposures, combined with the logistics of working in the limited confines and duration of orbital flight, limited progress. On Earth, the "new biotechnology" based on manipulation of the genetic material of living organisms won the race with space by developing better ways of producing products such as erythropoietin. (A form of erythropoietin, Epogen, has been approved for treating anemia in patients with chronic renal failure and also in patients infected with HIV, the virus that causes AIDS, who are taking Retrovir [zidovudine, also known as AZT].) Workable in theory, space drug factories in practice now seem remote.

Yet, separation of biological substances from the fluids necessary to preserve them remains important. The process used in space can work to separate other biological materials — indeed, almost any natural hormone or enzyme — more readily than on Earth. Additional experience in space has opened stellar new vistas in several fields of medicine.

For the short term, "we're not thinking about factories," says Barbara Ann Hale, formerly of Pennsylvania State University's Center for Cell Research (founded in 1987), one of the original 16 Centers for the Commercial Development of Space that NASA set up after 1985. Of the 16, the Center for Macromolecular Crystallography at the University of Alabama, Birmingham (1985), and the Bioserve Space Technologies Center at the University of Colorado, Boulder (1987), are the two others also cooperating with industry to find medical applications for aerospace research.

Expense a Problem

A principal objection to space manufacturing is the expense of transporting products back to Earth, which limits early options to producing rare compounds now expensive — if not impossible — to produce. Beyond purifying processes, such as continuous flow electrophoresis, that separate substances from their preservative fluids, areas worth exploring include protein crystal growth and tissue culture.

Conditions peculiar to spacecraft may make feasible experiments that are difficult or impossible to achieve in a laboratory subject to the Earth's gravity. Space has become not a factory, but a highly specialized medical laboratory. Some processes happen more slowly in its microgravity. Others speed up. Still others just work differently.

In addition, medical measures to help astronauts' bodies adjust to the stresses of space flight may bring unanticipated benefits for patients on Earth. Astronauts have served, sometimes unwittingly, as human guinea pigs, their experiences suggesting new biomedical inquiries. Weightlessness isn't a restful state. It is extraordinarily stressful on human systems splendidly adapted to Earth's gravity. Thus it can replicate stresses caused by disease.

Speeding Up

Near weightlessness — astronauts never experience "zero gravity" — takes much pressure off human systems well evolved to cope with gravity, causing rapid adjustments in the system. Major weight-bearing muscles quickly atrophy, losing a quarter of their mass in as little as nine days. The left ventricular chamber of the heart decreases, losing a tenth of its mass in 84 days. Red blood cell counts may drop by a third.

The cardiovascular reactions of astronauts have much in common with many earthly clinical problems, including effects of spinal cord lesions, adrenal insufficiency, and diabetes mellitus. Insights useful in conditioning people for weightlessness may be applicable to treatment of those diseases.

Bone material loss offers another rare research opportunity. Sturdy leg bones made needless by microgravity lose up to 0.4 percent of their calcium in a month, becoming quite brittle. Heel bones degenerate as fast as 5 percent a month. Astronauts experience a speeded-up model of osteoporosis, a type of bone erosion particularly debilitating in older women. Although the manner of bone erosion may differ somewhat, the result is similar.

Ohio State University scientists have shown that one drug prevents bone loss in rats under simulated weightlessness. In October 1992, Penn State's Center for Cell Research and the Merck pharmaceutical firm tested an osteoporosis compound in laboratory rats aboard the space shuttle Columbia. Results may be available in 1995.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.