Muntz, I. | Search bioRxiv

bioRxiv2024

EMT-dependent cell-matrix interactions are linked to unjamming transitions in cancer spheroid invasion

The plasticity of cancer cells allows them to switch between different migration modes, promoting their invasion into the extracellular matrix (ECM) and hence increasing the risks of metastasis. Epithelial-to-mesenchymal transitions (EMT) and unjamming transitions provide two distinct pathways for cancer cells to become invasive, but it is still unclear to what extent these pathways are connected. Here we addressed this question by performing 3D spheroid invasion assays of lung adenocarcinoma (A549, epithelial) and melanoma (MV3, mesenchymal-like) cancer cell lines in collagen-based hydrogels, where we varied both the invasive character of the cells (using Transforming Growth Factor (TGF)-{beta} to promote EMT and matrix metalloprotease (MMP) inhibition to block cell-mediated matrix degradation) and the porosity of the matrix. Using a quantitative image analysis method to track spheroid invasion, we discovered that the onset time of invasion mostly depended on the matrix porosity and corresponded with vimentin levels, while the subsequent spheroid expansion rate mostly depended on metalloprotease MMP1 levels and thus cell-matrix interaction. Morphological analysis revealed that spheroids displayed solid-like (non-invasive) behavior in small-pore hydrogels and switched to fluid-like (strand-based) or gas-like (disseminating cells) phases in large-pore hydrogels and when cells were more mesenchymal-like. Our findings are consistent with unjamming transitions as a function of cell motility and matrix confinement predicted in recent models for cancer invasion, but show that cell motility and matrix confinement are coupled via EMT-dependent matrix degradation.

cancer biology↗

bioRxiv2023

The Impact of the Local Mechanical Environment on Cell Shape and Chondrogenesis of Mesenchymal Stromal Cells in 3D Biomimetic Composite Materials

Efforts to model and repair connective tissue through engineered tissue constructs have generated great interest in culturing cells in 3d polymer network environments. It has been shown that the polymer environment is influential in determining cellular responses such as differentiation, migration and morphology. Hydrogels are used to mimic the cellular microenvironment, but in most cases hydrogels consisting of one polymeric component are used whereas tissues are composites of different polymers. A clear understanding of how different extracellular components and their mechanical characteristics influence cell behaviour is lacking. Here we developed and characterised composite hydrogels of hyaluronan and fibrin and evaluated their use for cartilage tissue engineering. We demonstrate that these cartilage-mimicking composites have a higher stiffness relative to the individual constituents. Next, we cultured human mesenchymal stromal cells in these 3D hydrogels with chondrogenic media and revealed marked differences in cell morphology, gene expression and cartilage-like matrix deposition depending on the specific extracellular composition. We found that, despite evidence for strong adhesion of the cells to fibrin networks in 2D systems, in 3D systems the primary determinant of cellular morphology is the significantly denser hyaluronan network. Dense hyaluronan hydrogels cause local cell confinement evidenced by rounder cell morphologies, independent of the presence of fibrin. While the composite fibrin-hyaluronan hydrogels led to lower expression of chondrogenic genes than hyaluronan alone, the larger linear modulus and resistance to cell-mediated contraction due to the composite nature of the matrix provides a strong advantage in terms of macroscopic mechanical stability. These findings highlight the potential of multi-component hydrogels for controlling cellular behaviour and bulk mechanical properties of cell-hydrogel constructs independently, therefore opening avenues for better understanding the complex interplay between cells and their extracellular environment and thus improve the biofabrication of connective tissues for disease modelling and tissue regeneration. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/555478v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@151962org.highwire.dtl.DTLVardef@1358890org.highwire.dtl.DTLVardef@198dcedorg.highwire.dtl.DTLVardef@d04f80_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗