Continuous Visualization of Morphological Changes in Endothelial Cells in Response to Cyclic Stretch

Abstract

Endothelial cells are known to change their shapes in alignment with the direction perpendicular to that of cyclic stretch. However, the mechanisms are still not clear. In this study, we developed a new cell-stretching device which allows continuous observation of cyclically stretched/relaxed cells. Using this apparatus, morphological changes of single cells in response to cyclic stretch (1Hz, 10%, 2 hours) were visualized and analyzed. The data showed that there were two major patterns of morphological changes of ECs, depending on their initial shapes. While ECs with round shapes at the initial state changed their shapes to become more elongated in a direction perpendicular to that of stretch, cells oriented and elongated in the stretch direction at the initial state changed their shapes to first become rounder and then elongated to align perpendicular to the stretch direction at the second step. These results suggest that cell retraction as well as elongation is important in the stretch-induced endothelial morphological changes, and that the elucidation of the mechanisms of the morphological changes requires studies of cell retraction, elongation, and their coordination at the single-cell level.