Biology subjects

Comelles, J.

Publications and source records attributed to Comelles, J..

8 recordsLinked to original sources

bioRxiv2026

Engineering a soft tumor microenvironment: fibrin-enriched hydrogel promotes cancer cell invasion in a 3D bioprinted colorectal cancer model

Accurately modeling the tumor microenvironment is crucial for advancing our understanding of colorectal cancer (CRC) progression and therapeutic response. Three-dimensional (3D) hydrogel-based models that mimic the mechanical properties of native tissue serve as a valuable tool for studying tumor-stromal interactions and tumor invasion in vitro. In this work, we developed a 3D bioprinted CRC model by embedding spheroids and human intestinal fibroblasts (HIFs) within the GelMA-PEGDA and GelMA-PEGDA-Fibrin hydrogels to assess the effect of matrix composition and stiffness on spheroid invasiveness. The addition of fibrin resulted in a softer, more viscoelastic hydrogel that promoted fibroblast migration, elongation, and alignment, facilitating more dynamic tumor-stromal interactions. Moreover, both epithelial-like HT29 and mesenchymal-like SW480 spheroids showed more invasive behavior in GelMA-PEGDA-Fibrin hydrogel. This was reflected in distinct phenotypic responses. HT29 spheroids demonstrated greater growth, irregular morphology, and more interaction with elongated fibroblasts, whereas SW480 spheroids exhibited partial dissociation and disruption with a higher number of dispersed cells in GelMA-PEGDA-Fibrin hydrogel. These findings demonstrate the role of matrix softness in promoting the invasiveness of colorectal cancer. Overall, our results highlight the potential of fibrin-enriched soft hydrogel to mimic key features of the tumor microenvironment, offering a powerful tool for studying CRC invasion dynamics and supporting future applications in drug screening and personalized medicine.

bioengineering↗

bioRxiv2024

3D micropatterned traction force microscopy: a technique to control three-dimensional cell shape while measuring cell-substrate force transmission.

Cell shape and function are intimately linked, in a way that is mediated by the forces exerted between cells and their environment. The relationship between cell shape and forces has been extensively studied for cells seeded on flat 2-dimensional (2D) substrates, but not for cells in more physiological three-dimensional (3D) settings. Here, we demonstrate a technique called 3D micropatterned traction force microscopy (3D-TFM) to confine cells in three-dimensional wells of defined shape, while simultaneously measuring the forces transmitted between cells and their microenvironment. This technique is based on the 3D micropatterning of polyacrylamide wells and on the calculation of 3D traction force from their deformation. With 3D-TFM, we show that MCF10A breast epithelial cells exert defined, reproducible patterns of forces on their microenvironment, which can be both contractile and extensile. We further show that cells switch from a global contractile to extensile behaviour as their volume is reduced. Our technique enables the quantitative study of cell mechanobiology with full access to 3D cellular forces while having accurate control over cell morphology and the mechanical conditions of the microenvironment.

bioengineering↗

bioRxiv2022

Soft topographical patterns trigger a stiffness-dependent cellular response to contact guidance

Directional migration is involved in multiple physiological and pathological processes. Among other external signals, the architecture of the extracellular matrix can trigger directed cell migration through a phenomenon known as contact guidance: cells elongate, align, and migrate along the direction set by aligned extracellular matrix fibers. This process involves the orientation of focal adhesions, actin, and tubulin cytoskeleton along the direction of those fibers. Contact guidance has been extensively studied on stiff materials with topographical grooved patterns. However, how it translates to softer physiologically relevant compliances is not known. Here we show that substrate stiffness modulates the cellular response to topographical contact guidance. We found that for fibroblasts, while focal adhesions and actin responded to topography independently of the stiffness, microtubules showed a stiffness-dependent response that regulates contact guidance. On the other hand, both clusters and single breast carcinoma epithelial cells displayed stiffness-dependent contact guidance migration, leading to more directional and efficient migration when increasing substrate stiffness. These results suggest that both matrix stiffening and alignment of extracellular matrix fibers cooperate during directional cell migration, and both should be accounted when studying processes such as cancer cell invasion. TeaserChanges in the stiffness of topographical patterns modify how mesenchymal and epithelial cells perform contact guidance.

biophysics↗

bioRxiv2021

Subepithelial Myofibroblasts Are Critical Regulators of Intestinal Epithelial Restoration

Fibroblasts reside underneath most epithelial tissues. In the intestine, recent studies have shown that fibroblast migration contributes to tissue morphogenesis and wound healing. Yet, whether physical interactions between epithelial cells and fibroblasts contribute to epithelial movement remains elusive. Here, we show that subepithelial fibroblast alignment enhances directed and persistent migration of organoid-derived intestinal epithelia. Using a reconstituted epithelial-stromal gap-closure model, we demonstrate that direct contact with fibroblasts improves gap closure by promoting cell alignment, sustaining tissue integrity, and synchronizing crypt-villus migration. Fibroblasts undergo long-range ordering to align perpendicularly to the epithelial front and deposit protein paths that act as guidance features to direct epithelial migration. In parallel, epithelial cells acquire a wound-associated epithelial-like phenotype, but insufficient to explain the effects of fibroblast contact. Our findings uncover a dual role for intestinal fibroblasts in epithelial repair, coordinating both biochemical and physical cues to ensure efficient and cohesive migration.

cell biology↗

bioRxiv2020

Temporal correlation between oscillating force dipoles drives single cell migration in 3D.

Directional cell locomotion requires symmetry breaking between the front and rear of the cell. In some cells, symmetry breaking manifests itself in a directional flow of actin from the front to the rear of the cell. Many cells, especially in physiological 3D matrices do not show such coherent actin dynamics and present seemingly competing protrusion/retraction dynamics at their front and back. How symmetry breaking manifests itself for such cells is therefore elusive. We take inspiration from the scallop theorem proposed by Purcell for micro-swimmers in Newtonian fluids: self-propelled objects undergoing persistent motion at low Reynolds number must follow a cycle of shape changes that breaks temporal symmetry. We report similar observations for cells crawling in 3D. We quantified cell motion using a combination of 3D live cell imaging, visualization of the matrix displacement and a minimal model with multipolar expansion. We show that our cells embedded in a 3D matrix form myosin-driven force dipoles at both sides of the nucleus, that locally and periodically pinch the matrix. The existence of a phase shift between the two dipoles is required for directed cell motion which manifests itself as cycles with finite area in the dipole-quadrupole diagram, a formal equivalence to the Purcell cycle. We confirm this mechanism by triggering local dipolar contractions with a laser. This leads to directed motion. Our study reveals that these cells control their motility by synchronizing dipolar forces distributed at front and back. This result opens new strategies to externally control cell motion as well as for the design of micro-crawlers.

biophysics↗

bioRxiv2019

Elongations of epithelial colony in vitro: symmetry breaking through collective effects

Epithelial tissues of the developing embryos elongate by different mechanisms, such as neighbor exchange, cell elongation, and oriented cell division. Since autonomous tissue self-organization is influenced by external cues such as morphogen gradients or neighboring tissues, it is difficult to distinguish intrinsic from directed tissue behavior. The mesoscopic processes leading to the different mechanisms remain elusive. Here, we study the spontaneous elongation behavior of spreading circular epithelial colonies in vitro. By quantifying deformation kinematics at multiple scales, we report that global elongation happens primarily due to cell elongations, and its direction correlates with the anisotropy of the average cell elongation. By imposing an external time-periodic stretch, the axis of this global symmetry breaking can be modified and elongation occurs primarily due to orientated neighbor exchange. These different behaviors are confirmed using a vertex model for collective cell behavior, providing a framework for understanding autonomous tissue elongation and its origins.

biophysics↗

bioRxiv2019

Ends and middle: global force balance determines septum location in fission yeast

The fission yeast cell is shaped as a very regular cylinder ending by hemi-spheres at both cell ends. Its conserved phenotypes are often used as read-outs for classifying interacting genes and protein networks. Using Pascal and Young-Laplace laws, we proposed a framework where scaling arguments predicted shapes. Here we probed quantitatively one of these relations which predicts that the division site would be located closer to the cell end with the larger radius of curvature. By combining genetics and quantitative imaging, we tested experimentally whether altered shapes of cell end correlate with a displaced division site, leading to asymmetric cell division. Our results show that the division site position depends on the radii of curvatures of both ends. This new geometrical mechanism for the proper division plane positioning could be essential to achieve even partitioning of cellular material at each cell division.

cell biology↗

bioRxiv2017

An Arf6- And Caveolae-Dependent Pathway Links Hemidesmosome Remodeling And Mechanoresponse

Hemidesmosomes (HDs) are epithelial-specific cell-matrix adhesions, which stably anchor the intracellular keratin network to the extracellular matrix. Although their main role is to protect the epithelial sheet from external mechanical strain, how HDs respond to mechanical stress remains poorly understood. Here we identify a pathway essential for HD remodeling, and outline its role with respect to 6{beta}4 integrin recycling. We find that 6{beta}4 integrin chains localize to the plasma membrane/caveolae and Arf6+ endocytic compartments. Based on FRAP and endocytosis assays, integrin recycling between both sites requires the small GTPase Arf6 and its co-regulators GIT1/{beta}PIX, but neither Caveolin1 (Cav1) nor Cavin1. Strikingly, when keratinocytes are stretched or hypo-osmotically shocked, 6{beta}4 integrin accumulates at cell edges, whereas Cav1 disappears from it. This process, which is isotropic relative to the orientation of stretch, depends on Arf6, Cav1 and Cavin1. We propose that mechanically-induced HD growth involves the isotropic flattening of caveolae (known for their mechanical buffering role) associated with integrin diffusion and turnover.

cell biology↗