Intracellular viscosity, a key mechanical property of cells, can significantly influence biochemical diffusion rates. Changes in cellular viscosity have been found in various human diseases, including diabetes and neurodegenerative diseases like Parkinson's disease, and are linked to cancer cell migration. Cell behavior changes in altered gravity and is suspected to contribute to the macroscale symptoms seen in astronauts. However, research on intracellular viscosity in altered gravity is limited. Therefore, in preparation for the European Space Agency (ESA)'s MechanoCell project, this pilot study investigates whether hypergravity affects the viscosity of HeLa cells and if this can be measured with Single-Particle Tracking (SPT). SPT analysis software was employed to track endogenous particles in cells subjected to hypergravity ranging from 1 to 12 g in the Large Diameter Centrifuge (LDC) at ESA ESTEC. The software tracks endogenous particles in the HeLa cells by comparing the video frames captured by the EVOS microscope inside the LDC while at hypergravity. The trajectories of the particles permit the calculation of the mean square displacement and subsequently the intracellular viscosity. Results indicate measurable changes in viscosity, although further research is needed to confirm these findings and account for other influencing factors.
Rijthoven et al. (Tue,) studied this question.