Laminar flow through a model of collapsed veins. Morphometric response of endothelial vascular cells to a longitudinal shear stress non uniform cross-wise

¹ Department of Pharmacology, Laboratoire INNOTHERA, 94110 Arcueil, France
² Laboratoire de Physiologie du Mouvement, de Paris Sud, 91403 Orsay, France

Received: 16 October 1998
Revised: 17 May 1999
Accepted: 26 July 1999
Published online: 15 October 1999

Abstract

We studied the response of vascular endothelial cells to unidirectional laminar flow through collapsed veins. An original experimental set-up was developed, to generate and to map shear stresses with local transverse gradients. This enabled us to detect changes in the shape of endothelial cells when viscous fluid flow was applied. Porcine vena cava endothelial cells were seeded on a proof sample placed in the specifically designed flow chamber. Postconfluent endothelial cells were continuously exposed to a maximum calculated wall shear stress of 0.11 Pa (1.1 dyne/cm²) and to a maximum calculated transverse gradient of 0.045 Pa/mm for 20 hours. This paper deals with the morphometry of single cells and the angle of their major axes with respect to the flow direction. Cells in confluent monolayer underwent a shear stress intensity-dependent change in shape with a decrease of shape index from 0.55 to 0.34. The cells were not uniformly oriented in the direction of flow axes except in the region of larger gradient. In this particular region, the cells had a low angle with respect to the flow axes at some coordinates or exhibited reversal of their major and minor axes with a doubling of cell area. These observations suggest that there have been specific cytoskeleton rearrangements, associated with specific resultant forces over the cellular surface.