Engineered microenvironment for the study of myofibroblast mechanobiology

Abstract

Myofibroblasts are mechanosensitive cells and a variety of their behaviours including differentiation, migration, force production and biosynthesis are regulated by the surrounding microenvironment. Engineered cell culture models have been developed to examine the effect of microenvironmental factors such as the substrate stiffness, the topography and strain of the extracellular matrix (ECM) and the shear stress on myofibroblast biology. These engineered models provide well-mimicked, pathophysiologically relevant experimental conditions that are superior to those enabled by the conventional two-dimensional (2D) culture models. In this perspective, we will review the recent advances in the development of engineered cell culture models for myofibroblasts and outline the findings on the myofibroblast mechanobiology under various microenvironmental conditions. These studies have demonstrated the power and utility of the engineered models for the study of microenvironment-regulated cellular behaviours. The findings derived using these models contribute to a greater understanding of how myofibroblast behaviour is regulated in tissue repair and pathological scar formation.

Keywords: culture models; engineered microenvironment; myofibroblast mechanobiology; substrate stiffness; topographic cues.

Fig. 1

Illustration of engineered microenvironmental models for the study of myofibroblast mechanobiology.

Fig. 2

(A) Schematic illustration showing spatial control of photochemical reactions using a sliding mask. (B) A representative plot of Young’s modulus versus positions for a hydrogel with stiffness gradient. (A-B) adapted from [27]. (C) A schematic showing the steps used to expose valvular interstitial cells (VICs) to a series of substrate stiffness. α-SMA stained for green and nuclei stained for red for VICs on stiff (left) and soft (right) substrates. Scale bar: 50 μm. Adapted from [16]. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. (D) Transplantation of soft substrate-primed and stiff substrate-primed MSCs in dermal wounds. Soft-primed MSCs reduces scarring by suppressing myofibroblast formation and tissue contracture. α-SMA stained for red. Scale bar: 250 μm. Adapted from [34]. Copyright © 2016, Nature Publishing Group.

Fig. 3

(A) A myofibroblast adhered to an array of 20 μm long fibronectin (Fn) islets that was created on glass by microcontact printing. Myofibroblast was stained for F-actin (green), Fn (blue), vinculin (red), and α-SMA (black and white). Scale bar: 20 μm. Adapted from [39]. Copyright © 2006, The Rockefeller University Press. (B) The wound healing process of a wounded microtissue anchored to two micropillars. Adapted from [22]. (C) Fluorescence images of a three-leaflet lung microtissue formed on an array of micropillars. (D) SEM images of an untreated (healthy) and a fibrosis-induced lung microtissue. Obvious micropillar deflection can be seen in fibrosis-induced microtissue. Scale bar: 200 μm. (C-D) Adapted from [53]. Copyright © 2018.

Fig. 4

(A) A schematic showing the cyclic stretching system for microtissues formed on micropillar arrays. (B) Images of microtissues before and under stretch. Scale bar is 200 μm. (A-B), Adapted with permission from [12]. Copyright © 2019, Springer Nature. (C) Schematic perceptive view of a microtissue being stretched by a magnetic tweezer. (D) TGF-β1 treatment caused significant increase in the cross-sectional area (Top view and Side view) and α-SMA stress fiber (green) expression in a NIH/3T3 populated microtissue. Micropillar deflection is obvious in the side view. (C-D), adapted with permission from [66]. Copyright © 2014 Elsevier Ltd.