ISS: Chip-Based in vitro Modeling of Endocortical Microenvironment with Reduced Gravitational Loading

This project will study bone loss in in microgravity. Bone loss occurs during spaceflight, long-term bedrest and osteoporosis. Utilizing an environment that amplifies the rate of bone loss, such as low earth orbit and ground-based microgravity simulation, will accelerate our understanding of the metabolic mechanisms involved in bone maintenance. Increased understanding of the mechanics of bone loss will help identify affected mechanism(s) and pathways that can be addressed to mitigate bone loss in reduced gravity environments as well as on earth. Educational benefits from this investigation include incorporating the results into the training of undergraduate and graduate students for research careers as basic scientists or clinical investigators. The research will also be a component of the Multicultural Summer Research Opportunities Program.

A recent retrospective multi-omics analysis of hundreds of biological samples flown in space identified mitochondrial dysfunction as the probable root cause for most of the observed physiological changes in a microgravity environment which includes the loss of bone and muscle mass. Monocultures of anabolic cells, i.e., osteoblasts (OB's), and catabolic cells, i.e, osteoclasts (OC's), and an OB/OC co-culture will be grown in a collagenous carrier combined with hydroxyapatite as a slurry. These cultures will be maintained by slow perfusion of media flowing through microphysiological chips. Once initiated, the experimental apparatus is autonomous and will be maintained at 37 degrees Celsius/5% CO2 for up to 21 days. The proposed osteogenic microphysiological system, will allow real-time non-contact monitoring of oxygen and pH within the chip to yield OCR (Oxygen Consumption Rate) and ECAR (Extracellular Acidification Rate) metabolic data. These measurements will permit the evaluation of cellular response, i.e., mitochondrial function, to environment or interventions much sooner. At the conclusion of the experiments cell cultures will receive RNAprotect for later transcriptomic analyses. Spent cell media will be analyzed by spectroscopy to determine if glucose metabolic pathways change in microgravity. Utilizing an environment that amplifies the rate of bone loss, such as low earth orbit, or microgravity simulation utilizing a unique magnetic levitation apparatus, provides a setting to accelerate our understanding of underlying genomic and metabolic mechanisms. Validation of a ground-based model of spaceflight may permit a platform to test interventions potentially valuable to the development of therapies beneficial to the treatment of human disease resulting from skeletal unloading, such as paraplegia, bedrest, and metabolic osteopenia/osteoporosis. This work is jointly funded by the Biomechanics and Mechanobiology program and the Engineering of Biomedical Systems program.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.