Collagen microarchitecture mechanically controls myofibroblast differentiation

Abstract

<jats:p>Altered microarchitecture of collagen type I is a hallmark of wound healing and cancer that is commonly attributed to myofibroblasts. However, it remains unknown which effect collagen microarchitecture has on myofibroblast differentiation. Here, we combined experimental and computational approaches to investigate the hypothesis that the microarchitecture of fibrillar collagen networks mechanically regulates myofibroblast differentiation of adipose stromal cells (ASCs) independent of bulk stiffness. Collagen gels with controlled fiber thickness and pore size were microfabricated by adjusting the gelation temperature while keeping their concentration constant. Rheological characterization and simulation data indicated that networks with thicker fibers and larger pores exhibited increased strain-stiffening relative to networks with thinner fibers and smaller pores. Accordingly, ASCs cultured in scaffolds with thicker fibers were more contractile, expressed myofibroblast markers, and deposited more extended fibronectin fibers. Consistent with elevated myofibroblast differentiation, ASCs in scaffolds with thicker fibers exhibited a more proangiogenic phenotype that promoted endothelial sprouting in a contractility-dependent manner. Our findings suggest that changes of collagen microarchitecture regulate myofibroblast differentiation and fibrosis independent of collagen quantity and bulk stiffness by locally modulating cellular mechanosignaling. These findings have implications for regenerative medicine and anticancer treatments.</jats:p>

Mechanical and Physical Regulation of Fibroblast–Myofibroblast Transition: From Cellular Mechanoresponse to Tissue Pathology

“…Experiments performed using adipose stromal cells (ASCs) cultured in collagen matrices of different architectures show that matrices with thicker fibers promote ASC phenotype transition into myofibroblast through regulation of VEGF and IL-8 secretion (Seo et al, 2020). Intriguingly, nanoscale changes in the ligand spacing of model ECM fibers were shown to influence the collective cell behavior and overall characteristics, such as action-potential propagation in cardiac myocytes, on the scale of centimeters, suggesting effects on the ECM organization over six orders of magnitude of length scale (Kim et al, 2010).…”

“…When ASCs that are undergoing FMT are treated with Y27632, which inhibits ROCK and reduces α-SMA levels (Seo et al, 2015), as well as diminishing the capability of the cells to sense the environment by inhibiting the receptors to TGF-β, the cells exhibit a decrease in myofibroblast transition and moreover reduced VEGF and IL-8 secretion. On the contrary, treating these cells with blebbistatin influences their morphology, confining the adhesions to the extreme cell periphery, causing actin stress fiber formation and enhancing contractility, thereby stimulating ASC myofibroblast transition (Seo et al, 2020). Consistent with this link between cell mechanosensing, force generation, mechanical properties, and organization, it is also increasingly recognized that ECM viscoelasticity, non-linear elasticity, and fiber rearrangement play a central role for cell behavior such as proliferation and multilineage differentiation (Baker et al, 2015;Chaudhuri et al, 2016;Das et al, 2016;Xie et al, 2017;Matera et al, 2019;Vining et al, 2019).…”

Hydrogel Models with Stiffness Gradients for Interrogating Pancreatic Cancer Cell Fate

“…Although the effect of stiffness has been decoupled from the effect of the pore size of a collagen matrix [ 106 ], the stiffness range is relatively low, which is suitable for the study of breast cancer and might not apply to pancreatic cancer, which showed a higher stiffness range (i.e., Young’s modulus: 1–4 kPa) [ 37 ]. Similarly, Seo et al suggested that the microarchitecture (e.g., pore size and fiber diameter) of the collagen matrix guides myofibroblast differentiation, and the effect is independent of the stiffness of the bulk collagen matrix [ 118 ].…”

Modeling Adipogenesis: Current and Future Perspective

“…As shown in Figure 2 B, the interactions between adipocytes and collagen fibrils could be observed. In addition, Seo et al reported that collagen fibril diameter can also trigger adipocyte fibrotic functions [ 118 ]. Although 3D models were used to study adipocyte functions, less is known about whether tissue microstructure and stiffness, as well as other ECM components, influence adipogenesis.…”