Viscoelastic Properties of Vascular Endothelial Cells Exposed to Uniaxial Stretch

Abstract

Vascular endothelial cells (VECs) that line the interior of blood vessels are continually stretched as the vessel walls expand and contract. It is widely accepted that VECs will remodel themselves in response to this mechanical stimuli, leading to changes in cell function. Few studies, however, have analyzed the mechanical properties of these cells under stretch. We hypothesize that uniaxial stretch will cause an anisotropic realignment of actin filaments, and a change in the viscoelastic properties of the cell. To test this hypothesis, VECs were grown on a thin, transparent membrane mounted on a microscope. The membrane was stretched, consequently stretching the cells. Time-lapse sequences of the cells were taken every hour with a time resolution of 10 Hz. The random trajectories of intracellular endogenous particles were tracked using in-house algorithms. Using a novel particle tracking microrheology formulation, that takes into account the anisotropic nature of the cytoplasm, these trajectories were analyzed and the mechanical properties of VECs subjected to various stretching conditions were calculated and compared.