Solvent isotope effect on leukocytes disintegration after large mechanical deformations

Abstract

The objective of this study was to explore the mechanisms through which water may contribute to the structural integration of the cells and to their mechanical failure at large cellular deformations. To this end, we performed acute substitution of H2O with D2O in THP-1 myeloid leukocytes, then forced them at constant flow rates through filter pores smaller than their average resting diameter and analyzed the resulting fragments by flow cytometry and confocal microscopy. We found that this solvent replacement in culture media maintained the THP-1 cells viability, as shown by maintained plasma membrane integrity and a preserved cell response to a physiological agonist, while increasing their volume and actin polymerization. However, D2O exposure dramatically reduced filterability of cells and amplified their overall fragmentation. At the same time, size distribution of cytoplasmic fragments remained larger in D2O than in water, unlike those derived from the nuclei, which remained unchanged. Our data suggests that water as biological solvent is ‘gluing’ not only on the plasma membrane through hydrophobic effects, but also the cytoplasm, via the reciprocal influence between actin polymerization and the solvent’s molecular network.