Tuning endothelial monolayer adhesion: a neutron reflectivity study

Abstract

Endothelial cells, master gatekeepers of the cardiovascular system, line its inner boundary from the heart to distant capillaries constantly exposed to blood flow. Interendothelial signaling and the monolayers adhesion to the underlying collagen-rich basal lamina are key in physiology and disease. Using neutron scattering, we report the first ever interfacial structure of endothelial monolayers under dynamic flow conditions mimicking the cardiovascular system. Endothelial adhesion (defined as the separation distance ℓ between the basal cell membrane and solid boundary) is explained using developed interfacial potentials and intramembrane segregation of specific adhesion proteins. Our method provides a powerful tool for the biophysical study of cellular layer adhesion strength in living tissues.

Analysis of biosurfaces by neutron reflectometry: From simple to complex interfaces

“…Simple systems NR is frequently executed to evaluate film thickness, roughness, packing, and chemical composition, but can also reveal the response of a (multi-)layer to external stimuli such as UV light, 56 shear, 46,57,58 electric fields, [59][60][61] change in temperature, 38,62,63 hydration, 38,64,65 or pH.…”

“…NR was used for the first time to measure the nanoscopic structure of the adhesion layer of confluent endothelial cells. 46 As in the case discussed above, neutron scattering is probing only the interfacial space between the lipid plasma membrane and the rigid substrate. Endothelial cells generate their own extracellular matrix (basal lamina) making it possible to grow monolayers on inert surfaces like quartz without prior exogenous deposition of protein layers.…”

“…NR can be applied in the study of living tissue to better understand biological mechanisms such as cellular adhesion within the vascular system and the differences that may be specifically associated with brain tumor invasion. [45][46][47] …”

Understanding dynamic changes in live cell adhesion with neutron reflectometry

“…In this study, we used neutron reflectometry to measure for the first time the nanoscopic structure of confluent endothelial monolayer interfaces. 33 The linkage between blood flow, the endothelial monolayers adhesiveness to the basal lamina and its ability to function as the gatekeeper of vascular permeability is clearly established; moreover, with examples ranging from acute respiratory distress syndrome to atherosclerosis, there is tremendous clinical importance in understanding this relationship. 34–38 We used confluent monolayers of human pulmonary arterial endothelial cells grown on single-crystal quartz blocks at 25°C and 37°C, under static conditions or a laminar fluid shear stress τ =1.5 Pa (equivalent to arterial conditions).…”

“…2,3,35,36,38,43 Our study is the first to provide a direct measure of endothelial monolayer adhesion under physiologic shear stress conditions. Biomechanical analysis of endothelial stress distributions 33 predicts that to avoid catastrophic endothelial delamination, part of the fluid shear stress τ is transmitted to the basal lamina. 2,3 Thermodynamically, luminal flow does work (proportional to the product of shear stress and cell size) against the static adhesion energy.…”