Colloidal crystals of compliant microgel beads to study cell migration and mechanosensitivity in 3D.

Katrin Wagner,Paul Müller,Nicole Träber,Despina Soteriou,Gonzalo Rosso,Salvatore Girardo,Elke Ulbricht,Jochen Guck,Ruchi Goswami

doi:10.1039/c9sm01226e

Katrin Wagner, Paul Müller + Show 7 more

Open Access

https://doi.org/10.1039/c9sm01226e

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Abstract

Tissues are defined not only by their biochemical composition, but also by their distinct mechanical properties. It is now widely accepted that cells sense their mechanical environment and respond to it. However, studying the effects of mechanics in in vitro 3D environments is challenging since current 3D hydrogel assays convolve mechanics with gel porosity and adhesion. Here, we present novel colloidal crystals as modular 3D scaffolds where these parameters are principally decoupled by using monodisperse, protein-coated PAAm microgel beads as building blocks, so that variable stiffness regions can be achieved within one 3D colloidal crystal. Characterization of the colloidal crystal and oxygen diffusion simulations suggested the suitability of the scaffold to support cell survival and growth. This was confirmed by live-cell imaging and fibroblast culture over a period of four days. Moreover, we demonstrate unambiguous durotactic fibroblast migration and mechanosensitive neurite outgrowth of dorsal root ganglion neurons in 3D. This modular approach of assembling 3D scaffolds from mechanically and biochemically well-defined building blocks allows the spatial patterning of stiffness decoupled from porosity and adhesion sites in principle and provides a platform to investigate mechanosensitivity in 3D environments approximating tissues in vitro.

Highlights

IntroductionResearchers have investigated whether and how cell and tissue stiffness is altered during disease, how this affects processes such as wound healing and regeneration, and how important mechanical properties are for biological processes
Over recent decades, researchers have investigated whether and how cell and tissue stiffness is altered during disease, how this affects processes such as wound healing and regeneration, and how important mechanical properties are for biological processes
We demonstrated for the first time fibroblast durotaxis in 3D colloidal crystals with sequential stiffness layers and mechanosensitive neurite outgrowth of dorsal root ganglion neurons in different stiff colloidal crystals

Summary

Introduction

Researchers have investigated whether and how cell and tissue stiffness is altered during disease, how this affects processes such as wound healing and regeneration, and how important mechanical properties are for biological processes. See DOI: 10.1039/ c9sm01226e mechanical properties of hydrogels, such as collagen or polyacrylamide (PAAm), has allowed researchers to study the effect of substrate stiffness on cell behavior in vitro. Mechanosensitivity studies in 3D collagen gels showed that fibroblasts migrate towards stiffer regions, reproducing a durotactic behavior in biologically active gels.[10] It should be noted that an increased density of adhesion components, such as RGD peptides, in stiffer and denser areas can influence fibroblast migration in hydrogels.[11]

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