A new strategy to measure intercellular adhesion forces in mature cell-cell contacts

Ana Sancho,Aernout Luttun,Jürgen Groll,Ine Vandersmissen,Sander Craps

doi:10.1038/srep46152

Abstract

Intercellular adhesion plays a major role in tissue development and homeostasis. Yet, technologies to measure mature cell-cell contacts are not available. We introduce a methodology based on fluidic probe force microscopy to assess cell-cell adhesion forces after formation of mature intercellular contacts in cell monolayers. With this method we quantify that L929 fibroblasts exhibit negligible cell-cell adhesion in monolayers whereas human endothelial cells from the umbilical artery (HUAECs) exert strong intercellular adhesion forces per cell. We use a new in vitro model based on the overexpression of Muscle Segment Homeobox 1 (MSX1) to induce Endothelial-to-Mesenchymal Transition (EndMT), a process involved in cardiovascular development and disease. We reveal how intercellular adhesion forces in monolayer decrease significantly at an early stage of EndMT and we show that cells undergo stiffening and flattening at this stage. This new biomechanical insight complements and expands the established standard biomolecular analyses. Our study thus introduces a novel tool for the assessment of mature intercellular adhesion forces in a physiological setting that will be of relevance to biological processes in developmental biology, tissue regeneration and diseases like cancer and fibrosis.

Highlights

Beyond cell-substrate interaction, cell cohesion plays a crucial role in many biological processes, such as embryogenesis, morphogenesis and malignancy[11,12]
We have measured the cell-substrate adhesion force on glass of various cell types by Single Cell Force Spectroscopy (SCFS) using FluidFM technology incorporated into the Atomic Force Microscopy (AFM) (Fig. 1a,b)
While the force measured on individual cells represents the adhesion force between a cell and the substrate, the force measured in monolayer indicates the adhesion force of a cell to the substrate and to the surrounding cells that are in direct contact with it (Fig. 1c,d)

Summary

Introduction

Beyond cell-substrate interaction, cell cohesion plays a crucial role in many biological processes, such as embryogenesis, morphogenesis and malignancy[11,12]. The detachment force, and events during retraction are recorded and quantified[24] While these techniques provide abundant information on adhesion events at the molecular level, they are restricted to work only with cells at the initial stage of the adhesion process[25], before they establish mature intercellular junctions[26]. In this framework, the need for the quantification of the intercellular adhesion forces in a physiological setting that is most representative of their natural context, such as a cell monolayer, remains unanswered. These results reinforce and complement the biomolecular analyses and expand the knowledge and understanding of the biological process

Methods

Results

Conclusion