Influence of multi-axial dynamic constraint on cell alignment and contractility in engineered tissues

Noel H Reynolds,Eoin Mcevoy,Juan Alberto Panadero Pérez,Ryan J Coleman,J Patrick Mcgarry

doi:10.1016/j.jmbbm.2020.104024

Noel H Reynolds, Eoin Mcevoy + Show 3 more

Open Access

https://doi.org/10.1016/j.jmbbm.2020.104024

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Abstract

In this study an experimental rig is developed to investigate the influence of tissue constraint and cyclic loading on cell alignment and active cell force generation in uniaxial and biaxial engineered tissues constructs. Addition of contractile cells to collagen hydrogels dramatically increases the measured forces in uniaxial and biaxial constructs under dynamic loading. This increase in measured force is due to active cell contractility, as is evident from the decreased force after treatment with cytochalasin D. Prior to dynamic loading, cells are highly aligned in uniaxially constrained tissues but are uniformly distributed in biaxially constrained tissues, demonstrating the importance of tissue constraints on cell alignment. Dynamic uniaxial stretching resulted in a slight increase in cell alignment in the centre of the tissue, whereas dynamic biaxial stretching had no significant effect on cell alignment. Our active modelling framework accurately predicts our experimental trends and suggests that a slightly higher (3%) total SF formation occurs at the centre of a biaxial tissue compared to the uniaxial tissue. However, high alignment of SFs and lateral compaction in the case of the uniaxially constrained tissue results in a significantly higher (75%) actively generated cell contractile stress, compared to the biaxially constrained tissue. These findings have significant implications for engineering of contractile tissue constructs.

Highlights

A growing interest in the biomechanical behaviour of cells seeded in 3D culture has emerged in recent years
This prediction is in strong agreement with experimental data presented in Figure 6, suggesting that the model can be used to predict the influence of heterogeneous multiaxial stress states on cell alignment throughout a tissue
In this investigation we develop a novel experimental methodology that allows for the observation of cell alignment, while characterizing cell contractility through measurement of active force in both uniaxial and biaxial tissues under dynamic loading

Summary

Introduction

A growing interest in the biomechanical behaviour of cells seeded in 3D culture has emerged in recent years. The development of a robust system that can apply different uniaxial and biaxial deformation regimes to engineered hydrogel constructs while measuring the active and passive force, as presented in the current study, can provide new insights into the link between tissue constraint and active force generation. Cell contractile forces have previously been measured in tissues subjected to uniaxial stretching (Wagenseil et al, 2004; Wakatsuki et al, 2001, 2000; Wille et al, 2006; Zhao et al, 2014, 2013). Due to the significant technical challenge of tissue force measurement during dynamic biaxial stretching, the influence of constraint on dynamic force generation has not been reported to date. The current study provides a key advance investigating the influence of tissue constraint and dynamic loading on cell contractility and cell alignment

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