Q. How do you want to see the results of space medicine experiments applied on Earth?
Long-Term Bed Rest studies performed with international cooperation
Similar to the microgravity environment in space, being bedridden on Earth doesn't put any load on the bones. Thus, if you are lying in bed all the time, the bone metabolism becomes unbalanced and causes loss of bone mass, just as if you are in space. In bed there is gravity, and you might think it's a bit different, since you can toss and turn and move a little bit, but actually the load on the bones is as little as in space.
In 2000 and 2001, JAXA, the European Space Agency and the Centre National d'Études Spatiales conducted joint studies on longterm bed rest, and used bisphosphonate on a trial basis. These studies were conducted to investigate the effects on the human body of lying in bed for three months. The subjects used bedpans and ate meals in bed. As a result, femoral bone density was reduced by more than 2% per month and sand-like urinary lithiasis particles (i.e. kidney stones) were detected by X-ray in one in three subjects. (The bone density of astronauts who performed long-term expeditions was reduced by about 1.5% per month on average, so the effect of bed rest is even greater.) But in subjects administered with bisphosphonate, the loss of bone mass and urinary lithiasis were not seen.
Medical care for the aged is currently a big issue, as there are many bedridden elderly people. Among them are some who break their bones while just changing their body position to change their diapers. Before these fractures happen, the patients should be treated to prevent the weakening of their bones, but the current Japanese insurance scheme doesn't allow this. The system decides the medical treatment fee depending on the diagnosis of the principal illness. Thus, the fees for the treatment of osteoporosis are not covered because it does not have a direct relationship to the main diagnosis. So currently, not enough treatment is provided. I think we must educate patients and their families by publicizing the results of these bisphosphonate experiments, so that they can ask their doctors for this treatment.
Q. Full scale space activities by Japanese astronauts have just begun, with the installation of Kibo. What changes in Japanese medicine do you expect to see as a result?
Astronaut Wakata performing an experiment (Courtesy of NASA)
This is not limited to Japan, as the development of medicine is a task for all humankind. There has never before been an international project as big as the ISS. This is a great opportunity to collaborate on medical research, and I think it's important that people from a variety of countries participate and use the fruits of this work to benefit as many people as possible. I think "utilization for people's health" is the best example of the peaceful use of the ISS, so the bigger the medical results we achieve, the deeper the potential for the public's understanding and acceptance of space development.
Achievements in space medicine are also anticipated in the prevention of muscle mass reduction. In the microgravity environment of space, the loss of muscles is as drastic as that of bones. In our rapidly aging society, how to extend our "healthy life expectancy," i.e., the period of independence in which we don't require daily care from others, is a big issue for us. Loss of muscle power becomes a big problem for those with a condition that confines them to bed. So even if we can prevent broken bones, we will still need muscle power to maintain our motor functions. Thus, I think it is very important to conduct research to prevent the loss of bone strength and muscle power in space from the viewpoint of locomotorium. Astronauts can recover their bone and muscle strength by exercising upon their return to Earth, but for elderly people, we need to find ways to allow recovery without exercise. For example, research on the control factor for gene transcription, which is deeply related to muscle formation, is advancing and becoming an important target of drug research. If this becomes possible, it will lead to the prevention of muscle power reduction both on the ground and in space.
Another anticipated achievement of space medicine is in the treatment of vertigo. If good treatments for vertigo and space sickness in zero gravity can be found, these results could be applied to motion sickness on the ground. When you think about the loss of bones and muscles, or even space sickness, you will realize how much indirect influence gravity has on our daily life and health. Medical research on problems caused while traveling between space and Earth, going from no gravity to 1G, has the potential to create new treatments and prevention methods on Earth. Specifically, I think these experiments will become an important information source for medical issues in our aging society to prevent the loss of bones and muscle mass. So, I hope space medicine experiments continue.
Q. What is your next goal?
For the moment, my goal is to analyze the data from this bisphosphonate experiment and publish the results. We started this space experiment after performing bed-rest studies and investigating the effect of bisphosphonate. From the bed-rest studies we did on Earth, we can see that bisphosphonate is useful in preventing the loss of bone mass and urinary lithiasis, so I'm expecting it will also work in space. Only some of the astronauts participated in the experiment this time, but in the future I hope to be able to use bisphosphonate to prevent health problems in most astronauts during their long stays in space. After solving the bone problem, we would like to overcome the loss of muscle power, and cure other health problems in order to allow much longer stays in space. Furthermore, I'd like to set a goal of transfering as much science as possible from space experiments to medicine for an ageing society.
Professor and Chair, Department of Medicine and Bioregulatory Science, University of Tokushima Graduate School of Medical Science.
Dr. Matsumoto graduated from the Faculty of Medicine at the University of Tokyo in 1974, and became a clinical fellow in the First Internal Medicine Department of the Faculty of Medicine, University of Tokyo in 1977. In 1987, he was a research associate at the Yale School of Medicine in the United States. Dr. Matsumoto became an instructor at the Fourth Internal Medicine Department of the Faculty of Medicine, University of Tokyo in 1988, and a professor at the First Department of Internal Medicine of the Faculty of Medicine, University of Tokushima in 1996. Subsequently, he was posted to his current position. In 2006 and 2009, he was Principal of the Faculty of Medicine and Dean of the Education Department at the Graduate School of Medical Science, University of Tokushima. His specialty is internal medicine, specifically endocrinology and bone metabolism.
Teamwork between ground and space is the key to success
Space Medicine Contributes to Medical Advances on Earth
A Mission with Astronaut Wakata
