Astronauts lose approximately 1% of their bone per month while in 0-gravity. We want to find out why astronauts lose bone since healthy astronauts get osteoporosis in space flight as older people do here on Earth. Bone loss is one of the major physiological 'show stoppers' in sending humans to Mars. If Mars Mission takes 30 months to complete, that's about 30% of our bone, so no one could return to Earth without the possibility of bone fracture. We believe that the cause of space osteoporosis is the lack of exercise (mechanical stress) against gravity which in turn causes a reduction in molecular activation of bone cell growth. We cannot reproduce 0-gravity here on earth, so we must go into space to create our test conditions. We have tested this hypothesis in Biorack hardware in Spacehab on S/MM-03, 05 and 06. We are currently in the process of analyzing our spaceflight samples. Our goal is to find the molecular basis of bone loss in 0-gravity so we can look for pharmaceuticals or environmental conditions to fix the problem.
Work on the project has been intense, selecting the correct methodology, working out a way to study gene expression on a very small (12mmx 20mm) coverslip sample, finding the right Biorack hardware and making everything work at the Cape during Experimental Science Testing. The crew added a growth stimulator during spaceflight inside the Biorack glovebox. The next day, they froze the cells and brought them back home for analysis. In the Laboratory of Cell Growth, we will isolate RNA and test the samples for early gene expression to determine if the lack of gravity causes changes in bone growth. Biorack offers 0-G,1-G and variable G environments for the bone samples.
On STS-84 we tested various levels of gravity to determine the amount of gravity needed for bone to grow. What does all of this mean? If our hypothesis is correct, we will be able to determine the minimum amount of gravity needed for normal bone growth activation. If we are able to get full growth response at 0.3 G, then if that level of gravity is kept in a small portion of the ship, say the sleeping area, we could expect to have normal bone growth during the entire mission. Of course, we would have to prove our hypothesis on the Biorack and then test this hypothesis on Station, but if it works, we could go to Mars and come back home without bone damage. It has taken 10 years to get the technology, scientific climate and hardware together for our 'Osteo' experiments and the team is excited. The missions are STS-76, STS 81 and STS-84.
This work is supported by NASA grants. Our special thanks to the NASA Ames support team lead by P. 'Tad' Savage and Lockheed Martin's Ron Schaefer.