Quantitative Morphodynamics of Endothelial Cells within Confluent Cultures in Response to Fluid Shear Stress

Abstract

To evaluate shear stress-induced effects on cultured cells we have extended the mechanical setup of a multichannel in vitro rheological system and developed software allowing entire processing control and image data analysis. The values of cell motility, degree of orientation (alignment), and cell elongation were correlated as a function of time (morphodynamics). Collective and individual endothelial cells within confluent cultures displayed a shear stress-dependent characteristic phase behavior of the following time course: resting conditions (phase I), change of motility (phase II), onset of alignment (phase III), and finally cell elongation (phase IV). Especially cell motility was characterized by a randomized zigzag movement around mean trajectories (fluctuations) together with mean cell locomotion. Onset of shear stress caused a down-regulation of fluctuations of 30% within <10 min and simultaneously increased locomotion velocities preferring the flow direction (phase II). After a lag period of 10 to 20 min cells orientated in the direction of flow (phase III) without significant cell elongation, which finally occurs within hours (phase IV). These data provide first evidence that cells within confluent endothelial monolayers respond to shear stress with a characteristic phase behavior.

Endothelial Barrier Function under Laminar Fluid Shear Stress

“…Detailed quantitative analyses of shear stress-induced morphologic changes as a function of time (morphodynamics) showed that endothelial cells within confluent cultures pass through different phases (Dieterich et al, 2000). Phase I corresponds to resting conditions or very low shear stress values, and is characterized by random cell orientation, polygonal cell shape, and a moderate mean migration (locomotion) of the cells (ie, cell centers) that is associated with extended zigzag movements (fluctuations) around the mean locomotion trajectories.…”

“…Recently we described a novel rheological setup and novel software, also used in the present study, that can be used to analyze morphodynamic parameters (Dieterich et al, 2000). Morphodynamics are defined as changes in cell motility, cell orientation, and cell elongation, as functions of time.…”

Impedance analysis of endothelial cells undergoing orbital shear stress.

“…The so-called morphodynamics approach to quantitatively analyzing shear stressinduced morphological changes in ECs with respect to time that Dieterich et al (2000) employed was able to elucidate the different phases that ECs go through in response to the onset and continuation of shear stress exposure. Phase I is characterized by random cell orientation and polygonal cell shape during resting conditions or very low shear stress.…”

“…In addition to fluorescent detection, cells can be monitored in migration assays by time-lapse video microscopy (Young and Simmons, 2010) or by using the morphodynamics approach of Dieterich et al (2000). Possible concerns involved with using fluid flow to produce chemical gradients (as is often done by mixing laminar fluid streams in microchannels) for chemotactic studies is that shear stress effects may obscure or confound results that are intended to measure cell migration towards a chemical source.…”

Computational model for adaptive fiber‐strengthened endothelial cell layers under flow induced shear‐stress

“…However, to understand pathogenic and physiological processes taking place during atherosclerotic developments in more detail we suggest a fluid mechanical model to describe the endothelial cell layer of the human vascular system. Such a model has to be combined with further experimental investigation using a cone-plate apparatus (Dieterich et al 2000, Buschmann et al 2004. …”