Backward translation to the cellular Level: Studies under artificial gravity

Suitable platforms providing well defined and reproducible artificial gravityconditions, particularly simulated microgravity and hypergravity, have a pivotal role in preparing space-based experiments. Clinostatsand Random Positioning Machines(RPM) are commonly applied in gravitational cell biology to simulate microgravity conditions. To exclude potential non-gravitational cellular responses to both methodologies, we applied the highly sensitive reporter organism, the dinoflagellate Pyrocystis noctiluca. The organism responds to shear stress with detectable bioluminescence emission. Pyrocystis noctiluca was exposed to different microgravity simulations while varying operational modes. With cells in a RPM rotating around two axes with random velocities and directions, we observed significantly greater mechanical stress compared with clinostatexperiments applying constant rotation around one axis. We conclude that in contrast to RPM, one axis clinorotation induces substantially less non-gravitational responses through shear forces. Therefore, we apply clinostatsas our preferred and validated method for the simulation of microgravity in ongoing cellular experiments. Altered gravity conditions elicit physiological changes in the human body. Translation from humans to cells will help identifying fundamental gravity-related mechanisms and targets for preventative measures. Our cell models include stem cells, neurons, glia, cardiac muscle, and immune cells. Case studies applying a broad range of ground-based artificial gravityfacilities, which are available in our research platform :envihab, will be presented.