Short-Term Cell/Substrate Contact Dynamics of Subconfluent Endothelial Cells following Exposure to Laminar Flow

Abstract

The manner in which fluid stresses are transmitted from the apical to the basal surface of the endothelium will influence the dynamics of cell/substrate contacts. Such dynamics could be important in the design of synthetic vascular grafts to promote endothelial cell adhesion. To examine whether the initial response of cell/substrate contact sites to flow depends on the magnitude of the applied shear stress, subconfluent monolayers of endothelial cells were exposed to flow at 10, 20, and 30 dyn cm-2 wall shear stresses for 20 min. Cell/substrate contact sites were visualized with total internal reflection fluorescence microscopy. Flow induced a rapid fluctuation in the membrane topography, which was reflected in dynamic changes in cell/substrate contacts. Exposure to flow caused marked changes in contact area. Contact movement occurred normal and parallel to the direction of flow. Contact sites demonstrated significant variability in contact area at 30 dyn cm-2 during the experiment but no significant movement of the contact sites in flow direction after 20 min of flow. Mean square displacements of the contact center of mass were described in terms of a directed diffusion model. Prior to onset of flow, contact movement was random. Flow induced a significant convective component to contact movement for 300-600 s, followed by reestablishment of diffusive growth and movement of contacts. These results suggest that fluid stresses are rapidly transmitted from the apical to the basal surface of the cell via the cytoskeleton.

Tumor cell adhesion under hydrodynamic conditions of fluid flow

“…Initial cell binding, adhesion stabilization and further events, such as cell spreading, were completely abolished if actin filaments were disrupted. This has also been shown for other types of tumor cells, such as melanoma cells (21), and normal circulating cells, such as platelets (22).…”

“…The cytoskeleton appears to be involved in this process in two ways. First, the cytoskeleton is the most important cellular structure that can distribute mechanical forces throughout the cell for maintenance of cellular structure and integrity (22). Second, cytoskeletal integrity and adhesion stabilization appear to be related to signal transduction within the cell that leads to structural changes, such as formation of focal adhesions and increased binding affinity of integrins to ECM components.…”

Finite-Element Stress Analysis of a Multicomponent Model of Sheared and Focally-Adhered Endothelial Cells

“…Binary arrays representing both focal contacts and close contacts were constructed by choosing a height threshold of 40 nm. 39 Focal adhesion borders were delineated by a 2-D spline function and the resulting 2-D object representing the FAs were embedded in the 3-D cell solid model (Fig. 1).…”

Vascular Prostheses: Performance Related to Cell-Shear Responses

“…Initial adhesion was controlled by the underlying material; this, in turn, affected the cellular orientation and morphology [21,40,41]. Confocal images demonstrated a high degree of diffuse focal contacts present on cells on ePTFE (with little F-actin confined to the cell membrane) and specific focal contact localization on PU with high amounts of F-actin polymerization (Figs.…”

“…As previously discussed, the cellular responses, particularly those of adhesion and retention, are affected not only by the shear stresses but also by the underlying substrate (coating and topography of graft) [2][3][4][5][6][7][8][9][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Hence, for the clinical performance and outcome of the vascular graft to be optimized, an explanation for this range of responses is required.…”