Osteocytes Space Testbed Experiment Onboard Dragon (OSTEO-D)

Principal Investigator: Dava Newman, PhD

Harvard-MIT Division of Health Sciences and Technology (HST)

Five decades after the launch of the first person into space, bone loss and associated skeletal fragility remain difficult challenges. Countermeasures to reduce bone loss, including exercise, increased calcium or phosphate intake, Vitamin D supplementation, exposure to ultraviolet light, and whole body vibration have proven largely ineffective during space flight and/or bed rest [1-4]. In the near future, human spaceflight via commercial enterprises holds the promise of providing orbital access to paying customers who undoubtedly will expect a medically and operationally acceptable, cost-effective countermeasure to mitigate the risk of bone loss and musculoskeletal injury. Commercial orbital spaceflight missions provide a microgravity platform to investigate bone regulatory pathways. Better understanding of these pathways may lead to novel countermeasures for both terrestrial diseases, such as osteoporosis, and space-induced bone loss. Osteocytes are the most abundant cells in bone, and microgravity analog models have recently shown that osteocytes, through the Sclerostin-mediated Wnt signaling pathway, act as key cellular sensors of bone mechanotransduction and regulators of bone formation and resorption. To date, no spaceflight microgravity experiments have been conducted with osteocyte-like cell lines to quantify on-orbit Sclerostin activity. We propose to test the hypothesis that microgravity will increase Sclerostin expression and decrease osteocyte cell number and size, demonstrating the Sclerostin pathway as a prime target for drug development. Our team, comprised of investigators from the Harvard-MIT Health Sciences and Technology (HST) Bioastronautics PhD Program in cooperation with the University of Colorado at Boulder BioServe Space Technologies, submit OSTEO-D (“Osteocytes Space Testbed Experiment Onboard Dragon”) for the Heinlein Prize. OSTEO-D will utilize BioServe’s space qualified, automated Fluid Processing Apparatus (i.e. microgravity test tube) to culture osteocyte-like cell lines followed by fixation of a number of cultures each flight day for post-mission ground-based immunolabeling to assess cell number, size and Sclerostin expression compared to ground controls.

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