The red blood cells carry oxygen throughout the body. Decreased red blood cells, called anemia, may result in physical limitations such as weakness or fatigue and cognitive slowing. On Earth, longstanding anemia is linked to lower quality of life and early mortality. White blood cells defend against infections, among many other functions. Malfunctioning white blood cells may predispose to severe infections and increase sensitivity to radiation.

This investigation will study, for the first time, the accumulation of bone marrow fat after a human subject has lived in microgravity and its impact on red and white blood cells. Using magnetic resonance imaging, blood samples, breath samples and possibly stool samples, bone marrow fat and blood survival and function will be measured. The expectation is that by imaging the marrow of specific bones in astronauts before and after flight, the impact of fat accumulation on blood elements in microgravity will be demonstrated. These results will complement previous results in space analogues; the long term bed rest studies performed in women (WISE 2005) and in men (BBR2-2). Results will also be applicable to people on Earth with decreased mobility or bedridden.

The specific objectives of this investigation are:

1: To measure fat accumulation in the bone marrow on astronauts pre- and post- stay aboard the International Space Station (ISS) using non-invasive magnetic resonance imaging (MRI).
2: To measure the effects of prospective marrow fat accumulation and microgravity on red and white blood cells using markers of erythrocyte degradation in blood, breath (CO) and stool (microbiome), as well as leukocyte function (transcriptome).
3: To analyze the effect of a) individual space flights, and b) cumulative exposure to microgravity on astronauts’ blood cell counts.

++ -- View more