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Bone Marrow Macrophage Differentiation is Inhibited During Space Flight: We also asked the question, does space flight affect the way bone marrow cells differentiate into macrophages? Like the previous experiment, bone marrow cells were cultured in the presence of macrophage colony stimulating factor. One important thing to know is that as bone marrow cells become macrophages they start to secrete a cytokine called interleukin-6 (IL-6). Therefore, the amount of IL-6 reflects the numbers of bone marrow cells that differentiate into macrophages. This figure shows that there is more IL-6 in bone marrow cultures grown on Earth that ones grown on the space shuttle.
Conclusion: Although growth was enhanced by space flight, the amount of differentiation was inhibited as measured by the amount of IL-6 produced. This analysis along with some other measurements that can quantitate how many macrophages are in the cultures, suggest that space flight retards the transition of progenitor cells into mature macrophages.