# Assessing friction and damage of cell monolayers on soft substrates in vitro

## TL;DR

This paper introduces a new, cost-effective method to study how medical devices interact with cell layers in a lab setting, using realistic pressures and better mimicking real tissues.

## Contribution

The novel contribution is a cost- and time-efficient methodology for studying cell monolayer interactions with medical devices using realistic pressures and soft substrates.

## Key findings

- A soft polydimethylsiloxane substrate better mimics blood vessel mechanics compared to previous materials.
- A technique to correct experimental misalignments using raw spatial and force data is introduced.
- The methodology is successfully demonstrated using human umbilical vein endothelial cells.

## Abstract

In the area of surgical applications, understanding the interaction between medical device materials and tissue is important since this interaction may cause complications. The interaction often consists of a cell monolayer touching the medical device that can be mimicked in vitro. Prominent examples of this are contact lenses, where epithelial cells interact with the contact lens, or stents and catheters, which are in contact with endothelial cells. To investigate those interactions, in previous studies, expensive microtribometers were used to avoid pressures in the contact area far beyond physiologically relevant levels. Here, we aim to present a new methodology that is cost- and time-efficient, more accessible than those used previously and allows for the application of more realistic pressures, while permitting a quantification of the damage caused to the monolayer. For this, a soft polydimethylsiloxane is employed that better mimics the mechanical properties of blood vessels than materials used in other studies. Furthermore, a technique to account for misalignments within the experiment set-up is presented. This is carried out using the raw spatial and force data recorded by the tribometer and adjusting for misalignments. The methodology is demonstrated using an endothelial cell (human umbilical vein endothelial cells) monolayer.