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BP: Fachverband Biologische Physik

BP 7: Poster Session I

BP 7.40: Poster

Montag, 9. März 2026, 15:00–17:00, P5

The biophysical response of HL60 cells to a millisecond osmotic stress — •Lucia Wegbünder¹, Eric Sündermann¹, Lea Graichen¹, Doreen Biedenweg¹, Marta Urbanska², and Oliver Otto¹ — ¹Institute of Physics, University of Greifswald, Greifswald, Germany — ²Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom

Local differences in the concentration of osmolytes within the human body require cells to consistently regulate their water in- and efflux. While cells are known to change their volume and mechanical properties on the timescale of seconds to minutes, their millisecond response to an osmotic stress has been, so far, unexplored.

Here, we leverage real-time deformability cytometry to apply osmotic challenges to cells and measure their physical properties including size and elastic modulus 0.5 to 10 milliseconds after exposure. We focus on HL60 cells (a myeloid precursor cell line), which are flushed through a microfluidic channel and in which they are in contact with a sheath fluid of varying osmolality. Similar to longer timescale regimes, we observe swelling under hypoosmotic, and shrinkage under hyperosmotic conditions. Independent of stress direction there is a decrease in the Young's modulus of cells. This is in contrast with long timescale findings, where cells are consistently reported to increase their stiffness under hypertonicity. The ability of cells to physically respond to osmotic stress within milliseconds can be of physiological consequences in situations where cells are exposed to steep osmotic gradients, as is the case for immune cells migrating through changing environments.

Keywords: flow cytometry; osmotic stress; millisecond timescale