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The Marrow Study (Bone Marrow Adipose Reaction: Red or White?) (Marrow)
Principal Investigator
Research Area:
Network physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

Blood cells are formed inside the bone marrow. The bone marrow has a finite volume. Fat cells are also found here. These fat cells grow both in size and number when the bone is not exposed to mechanical loading. Because the fat cells and blood cells must share the available volume in the bone marrow, accumulation of fat cells directly impacts blood cells. In addition to limited volume, the fat cells produce factors that affect the formation of the blood cells.

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.

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Trudel G, Shahin N, Ramsay T, et al. Hemolysis contributes to anemia during long-duration space flight. Nature Medicine 28, 59-62 (2022). [DOI]

Trudel G, Shafer J, Laneuville O, Ramsay T. Characterizing the effect of exposure to microgravity on anemia: more space is worse. American Journal of Hematology. 2020 Mar;95(3):267-273.

Culliton, K., Louati, H., Laneuville, O. et al. Six degrees head-down tilt bed rest caused low-grade hemolysis: a prospective randomized clinical trial. The Nature Partner Journals Microgravity 7, 4 (2021). [DOI]

Bone marrow

Data Information
Data Availability
Archiving in Progress. Some restricted access data exist for this experiment.
Data Sets+ Request data

Blood biomarkers
Carbon monoxide in alveolar air
Carbon monoxide in ambient air
Exercise logs
Fat fraction
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Expedition 46 12/11/2015 03/02/2016 82 days
Expedition 47 03/02/2016 06/18/2016 108 days
Expedition 48 06/18/2016 09/06/2016 80 days
Expedition 49 09/06/2016 10/30/2016 54 days
Expedition 50 10/28/2016 04/09/2017 164 days
Expedition 51 04/09/2017 06/02/2017 55 days
Expedition 52 06/02/2017 09/02/2017 92 days
Expedition 53 09/02/2017 12/14/2017 102 days
Expedition 54 12/14/2017 02/27/2018 75 days
Expedition 55 02/27/2018 06/03/2018 96 days
Expedition 56 06/03/2018 10/04/2018 123 days
Expedition 57 10/04/2018 12/20/2018 77 days
Expedition 58 12/18/2018 03/14/2019 85 days
Expedition 59 03/14/2019 06/24/2019 102 days

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Jessica Keune
Institutional Support
Canadian Space Agency (CSA)
Alternate Experiment Name
Proposal Date
Proposal Source