Biology subjects

Chaudhuri, O.

Publications and source records attributed to Chaudhuri, O..

14 recordsLinked to original sources

bioRxiv2026

Hydrogel confinement of the secreted nascent matrix imposes solid stress and mediates pathology of chondrocytes

Mechanical confinement of cells in 3D hydrogel scaffolds mediates cell fate and activity across a wide range of biological processes. Many cells secrete a nascent matrix within the hydrogel niche, which provides important biological signals to the cells but also obstructs direct cell-hydrogel interactions, making it unclear how the cells sense hydrogel confinement and carry out mechanotransduction. Here, we show that chondrocytes sense the solid stress arising from the accumulation of the nascent matrix in the hydrogel niche, which is mediated by hydrogel viscoelasticity and plasticity. We show that solid stresses elicit a wide range of pathophysiological responses, most notably an inflammatory response associated with cartilage osteoarthritis and injury, alongside a striking progenitor-like migratory response where the chondrocytes leverage mitosis to breach their nascent matrix and migrate to escape confinement. Our findings establish the role of the nascent matrix as an important transducer of mechanical confinement and illustrate how emergent solid stresses can drive chondrocyte pathology.

bioengineering↗

bioRxiv2026

Mechanical Checkpoint for Cell Division in Three-Dimensional Microenvironments

Cell division within mechanically confining extracellular matrices (ECMs) is a key regulator of tissue morphogenesis and cancer progression. Although the intracellular force-generation mechanisms that drive volumetric growth and mitotic elongation are well characterized, how ECMs resist these forces remains poorly understood. Unlike linearly elastic materials, fibrillar ECMs exhibit nonlinear and viscoelastic behaviors that fundamentally alter how they oppose cell-generated stresses. Using a fiber-level computational model, we dissected the origins of ECM-mediated mechanical confinement during mitosis. We identified three distinct modes of resistance: compressive resistance at the cell poles, shear resistance from a pericellular shell, and tensile resistance at the cell equator. The relative contributions of these modes depended on fiber architecture and connectivity; however, shear resistance from the pericellular shell--pre-tensed by volumetric growth during G1--consistently dominated as the primary mechanical barrier to mitotic elongation. These findings suggest that the pericellular shell functions as a natural mechanical checkpoint on cell division within collagen-rich microenvironments. Notably, a finite element continuum model, despite being the most widely used framework for tissue mechanics, failed to reproduce these behaviors, underscoring the necessity of fiber-resolution approaches. We propose that overcoming this mechanical checkpoint is a critical step in cancer progression, enabling cells to divide within the dense stromal matrices characteristic of metastatic tumors.

biophysics↗

bioRxiv2025

T Cells Tear Apart Confining Extracellular Matrix Via a Breaststroke-like Motion to Generate Migration Paths

T cells adeptly migrate through soft tissues to target aberrant cells and regulate immunity. However, how they establish migration paths in confining nanoporous extracellular matrices (ECMs), and why they often fail to do so in dense ECMs that occur during fibrosis and around tumors, remain unclear. Here, we studied T cell migration in confining collagen-rich hydrogels spanning a range of stiffness, viscoelasticity, mechanical plasticity, and shear strength. Strikingly, only shear strength--the stress required for material failure--correlated strongly with migration, challenging the long-held focus on stiffness and pore size in cell motility. During migration, T cells extend actin-rich, finger-like protrusions into the ECM, which then undergo divergent breaststroke-like motion. Thus, T cells tear apart confining matrices using breaststroke-like motion to generate migration paths.

biophysics↗

bioRxiv2025

Glassy Adhesion Dynamics Govern Transitions Between Sub-Diffusive and Super-Diffusive Cell Migration on Viscoelastic Substrates

Cell migration is pivotal in cancer metastasis, where cells navigate the extracellular matrix (ECM) and invade distant tissues. While the ECM is viscoelastic--exhibiting time-dependent stress relaxation--its influence on cell migration remains poorly understood. Here, we employ an integrated experimental and modeling approach to investigate filopodial cancer cell migration on viscoelastic substrates and uncover a striking transition from sub-diffusive to super-diffusive behavior driven by the substrates viscous relaxation timescale. Conventional motor-clutch based migration models fail to capture these anomalous migration modes, as they overlook the complex adhesion dynamics shaped by broad distribution of adhesion lifetimes. To address this, we develop a glassy motor-clutch model that incorporates the rugged energy landscape of adhesion clusters, where multiple metastable states yield long-tailed adhesion timescales. Our model reveals that migration dynamics are governed by the interplay between cellular and substrate timescales: slow-relaxing substrates prolong trapping, leading to sub-diffusion, while fast-relaxing substrates promote larger steps limiting trapping, leading to super-diffusion. Additionally, we uncover the role of actin polymerization and contractility in modulating adhesion dynamics and driving anomalous migration. These findings establish a mechanistic framework linking substrate viscoelasticity to cell motility, with implications for metastasis and cancer progression.

biophysics↗

bioRxiv2025

Swirling motion of breast cancer cells radially aligns collagen fibers to enable collective invasion

In breast cancer (BC), radial alignment of collagen fibers at the tumor-matrix interface facilitates collective invasion of cancer cells into the surrounding stromal matrix, a critical step toward metastasis. Collagen remodeling is driven by proteases and cellular forces, mediated by matrix mechanical plasticity, or irreversible matrix deformation in response to force. However, the specific mechanisms causing collagen radial alignment remain unclear. Here, we study collective invasion of BC tumor spheroids in collagen-rich matrices. Increasing plasticity to BC-relevant ranges facilitates invasion, with increasing stiffness potentiating a transition from single cell to collective invasion. At enhanced plasticity, cells radially align collagen at the tumor-matrix interface prior to invasion. Surprisingly, cells migrate tangentially to the tumor-matrix interface in a swirling-like motion, perpendicular to the direction of alignment. Mechanistically, swirling generates local shear stresses, leading to distally propagating contractile radial stresses due to negative normal stress, an underappreciated property of collagen-rich matrices. These contractile stresses align collagen fibers radially, facilitating collective invasion. The basement membrane (BM), which separates epithelia from stroma in healthy tissues, acts as a mechanical insulator by preventing swirling cells from aligning collagen. Thus, after breaching the BM, swirling of BC cells at the tumor-stroma interface radially aligns collagen to facilitate invasion.

biophysics↗

bioRxiv2024

Substrate stress relaxation regulates monolayer fluidity and leader cell formation for collectively migrating epithelia.

Collective migration of epithelial tissues is a critical feature of developmental morphogenesis and tissue homeostasis. Coherent motion of cell collectives requires large scale coordination of motion and force generation and is influenced by mechanical properties of the underlying substrate. While tissue viscoelasticity is a ubiquitous feature of biological tissues, its role in mediating collective cell migration is unclear. Here, we have investigated the impact of substrate stress relaxation on the migration of micropatterned epithelial monolayers. Epithelial monolayers exhibit faster collective migration on viscoelastic alginate substrates with slower relaxation timescales, which are more elastic, relative to substrates with faster stress relaxation, which exhibit more viscous loss. Faster migration on slow-relaxing substrates is associated with reduced substrate deformation, greater monolayer fluidity, and enhanced leader cell formation. In contrast, monolayers on fast-relaxing substrates generate substantial substrate deformations and are more jammed within the bulk, with reduced formation of transient lamellipodial protrusions past the monolayer edge leading to slower overall expansion. This work reveals features of collective epithelial dynamics on soft, viscoelastic materials and adds to our understanding of cell-substrate interactions at the tissue scale. Significance StatementGroups of cells must coordinate their movements in order to sculpt organs during development and maintain tissues. The mechanical properties of the underlying substrate on which cells reside are known to influence key aspects of single and collective cell migration. Despite being a nearly universal feature of biological tissues, the role of viscoelasticity (i.e., fluid-like and solid-like behavior) in collective cell migration is unclear. Using tunable engineered biomaterials, we demonstrate that sheets of epithelial cells display enhanced migration on slower-relaxing (more elastic) substrates relative to faster-relaxing (more viscous) substrates. Building our understanding of tissue-substrate interactions and collective cell dynamics provides insights into approaches for tissue engineering and regenerative medicine, and therapeutic interventions to promote health and treat disease.

biophysics↗

bioRxiv2024

Hydrogels for Local and Sustained Delivery of Bacteriophages to Treat Multidrug-Resistant Wound Infections

Lytic bacteriophages, viruses that lyse (kill) bacteria, hold great promise for treating infections, including wound infections caused by antimicrobial-resistant Pseudomonas aeruginosa. However, dosing and delivery strategies for phage therapy remain underdeveloped. In a mouse wound infection model, we investigated the impact of administration route, dose, and frequency on the efficacy of phage therapy. We find that topical but not systemic delivery is effective in this model. In vitro and in vivo data supported the use of high doses of phage. Repeated dosing achieves the highest eradication rates in vivo. Building on these insights, we developed "HydroPhage", a hyaluronan-based hydrogel system that uses dynamic covalent crosslinking to deliver high-titre phages over one week, a substantial improvement over existing burst-release systems. We conclude that hydrogel-based sustained phage delivery offers a practical, efficacious, and well-tolerated option for topical phage application.

bioengineering↗

bioRxiv2024

The Influence of Crosslinker Architecture on Dynamic Covalent Hydrogel Viscoelasticity

Dynamic covalent crosslinked (DCC) hydrogels represent a significant advance in biomaterials for regenerative medicine and mechanobiology. These gels typically offer viscoelasticity and self-healing properties that more closely mimic in vivo tissue mechanics than traditional, predominantly elastic, covalent crosslinked hydrogels. Despite their promise, the effects of varying crosslinker architecture - side chain versus telechelic crosslinks - on the viscoelastic properties of DCC hydrogels have not been thoroughly investigated. This study introduces hydrazone-based alginate hydrogels and examines how side-chain and telechelic crosslinker architectures impact hydrogel viscoelasticity and stiffness. In hydrogels with side-chain crosslinking (SCX), higher polymer concentrations enhance stiffness and decelerates stress relaxation, while an off-stoichiometric hydrazine-to-aldehyde ratio leads to reduced stiffness and shorter relaxation time. In hydrogels with telechelic crosslinking, maximal stiffness and slowest stress relaxation occurs at intermediate crosslinker concentrations for both linear and star crosslinkers, with higher crosslinker valency further increasing stiffness and relaxation time. Our result suggested different ranges of stiffness and stress relaxation are accessible with the different crosslinker architectures, with SCX hydrogels leading to slower stress relaxation relative to the other architectures, and hydrogels with star crosslinking (SX) providing increased stiffness and slower stress relaxation relative to hydrogels with linear crosslinking (LX). The mechanical properties of SX hydrogels are more robust to changes induced by competing chemical reactions compared to LX hydrogels. Our research underscores the pivotal role of crosslinker architecture in defining hydrogel stiffness and viscoelasticity, providing crucial insights for the design of DCC hydrogels with tailored mechanical properties for specific biomedical applications.

bioengineering↗

bioRxiv2023

Monocytes use protrusive forces to generate migration paths in viscoelastic collagen-based extracellular matrices

Circulating monocytes are recruited to the tumor microenvironment, where they can differentiate into macrophages that mediate tumor progression. To reach the tumor microenvironment, monocytes must first extravasate and migrate through the type-1 collagen rich stromal matrix. The viscoelastic stromal matrix around tumors not only stiffens relative to normal stromal matrix, but often exhibits enhanced viscous characteristics, as indicated by a higher loss tangent or faster stress relaxation rate. Here, we studied how changes in matrix stiffness and viscoelasticity, impact the three-dimensional migration of monocytes through stromal-like matrices. Interpenetrating networks of type-1 collagen and alginate, which enable independent tunability of stiffness and stress relaxation over physiologically relevant ranges, were used as confining matrices for three-dimensional culture of monocytes. Increased stiffness and faster stress relaxation independently enhanced the 3D migration of monocytes. Migrating monocytes have an ellipsoidal or rounded wedge-like morphology, reminiscent of amoeboid migration, with accumulation of actin at the trailing edge. Matrix adhesions were dispensable for monocyte migration in 3D, but migration did require actin polymerization and myosin contractility. Mechanistic studies indicate that actin polymerization at the leading edge generates protrusive forces that open a path for the monocytes to migrate through in the confining viscoelastic matrices. Taken together, our findings implicate matrix stiffness and stress relaxation as key mediators of monocyte migration and reveal how monocytes use pushing forces at the leading edge mediated by actin polymerization to generate migration paths in confining viscoelastic matrices. Significance StatementCell migration is essential for numerous biological processes in health and disease, including for immune cell trafficking. Monocyte immune cells migrate through extracellular matrix to the tumor microenvironment where they can play a role in regulating cancer progression. Increased extracellular matrix (ECM) stiffness and viscoelasticity have been implicated in cancer progression, but the impact of these changes in the ECM on monocyte migration remains unknown. Here, we find that increased ECM stiffness and viscoelasticity promote monocyte migration. Interestingly, we reveal a previously undescribed adhesion-independent mode of migration whereby monocytes generate a path to migrate through pushing forces at the leading edge. These findings help elucidate how changes in the tumor microenvironment impact monocyte trafficking and thereby disease progression.

cell biology↗

bioRxiv2023

Actin polymerization drives lumen formation in a human epiblast model

Lumens or fluid-filled cavities are a ubiquitous feature of mammals and are often evolutionarily linked to the origin of body-plan complexity. Post-implantation, the pluripotent epiblast in a human embryo forms a central lumen, paving the way for gastrulation. While osmotic pressure gradients drive lumen formation in many developmental contexts, mechanisms of human epiblast lumenogenesis are unknown. Here, we study lumenogenesis in a pluripotent-stem-cell-based model of the epiblast using engineered hydrogels that model the confinement faced by the epiblast in the blastocyst. Actin polymerization into a dense mesh-like network at the apical surface generates forces to drive early lumen expansion, as leaky junctions prevent osmotic pressure gradients. Theoretical modeling reveals that apical actin polymerization into a stiff network drives lumen opening, but predicts that a switch to pressure driven lumen growth at larger lumen sizes is required to avoid buckling of the cell layer. Consistent with this prediction, once the lumen reaches a radius of around 12 m, tight junctions mature, and osmotic pressure gradients develop to drive further lumen growth. Human epiblasts show a transcriptional signature of actin polymerization during early lumenogenesis. Thus, actin polymerization drives lumen opening in the human epiblast, and may serve as a general mechanism of lumenogenesis.

developmental biology↗

bioRxiv2022

Collective invasion of the basement membrane in breast cancer driven by forces from cell volume expansion and local contractility

Breast cancer becomes invasive when carcinoma cells collectively invade through the basement membrane (BM), a nanoporous layer of matrix that physically separates the primary tumor from the stroma, in a first step towards metastasis. Single cells can invade through nanoporous three-dimensional (3D) matrices via protease-mediated degradation or, when the matrix exhibits sufficient mechanical plasticity, force-mediated widening of pores. However, how cells invade collectively through physiological BM layers in cancer remains unclear. Here, we developed a 3D in vitro model of collective invasion of the BM during breast cancer. We show that cells utilize both proteases and forces to breach the BM. Forces are generated from a combination of global cell volume expansion that stretch the BM with local contractile forces that act in the plane of the BM to breach it, allowing invasion. These results uncover a mechanism by which cells collectively interact to overcome a critical barrier to metastasis.

cancer biology↗

bioRxiv2021

Delivery of CAR-T Cells in a Transient Injectable Stimulatory Hydrogel Niche Improves Treatment of Solid Tumors

Adoptive cell therapy (ACT) has proven to be highly effective in treating blood cancers such as B cell malignancies, but traditional approaches to ACT are poorly effective in treating the multifarious solid tumors observed clinically. Locoregional cell delivery methods have shown promising results in treating solid tumors compared to standard intravenous delivery methods, but the approaches that have been described to date have several critical drawbacks ranging from complex manufacturing and poor modularity to challenging adminstration. In this work, we develop a simple-to-implement self-assembled and injectable hydrogel material for the controlled co-delivery of CAR-T cells and stimulatory cytokines that improves treatment of solid tumors. We evaluate a range of hydrogel formulations to optimize the creation of a transient inflammatory niche that affords sustained exposure of CAR-T cells and cytokines. This facile approach yields increased CAR-T cell expansion, induces a more tumor-reactive CAR-T phenotype, and improves efficacy in treating solid tumors in mice.

bioengineering↗

bioRxiv2020

The nature of mitotic forces in epithelial monolayers

Epithelial cells undergo striking morphological changes during mitosis to ensure proper segregation of genetic and cytoplasmic materials. These morphological changes occur despite dividing cells being mechanically restricted by neighboring cells, indicating the need for extracellular force generation. While forces generated during mitotic rounding are well understood, forces generated after rounding remain unknown. Here, we identify two distinct stages of mitotic force generation that follow rounding: (1) protrusive forces along the mitotic axis that drive mitotic elongation, and (2) outward forces that facilitate post-mitotic re-spreading. Cytokinetic ring contraction of the mitotic cell, but not activity of neighboring cells, generates extracellular forces that propel mitotic elongation and also contribute to chromosome separation. Forces from mitotic elongation are observed in epithelia across many model organisms. Thus, forces from mitotic elongation represent a universal mechanism that powers mitosis in confining epithelia.

cell biology↗

bioRxiv2018

YAP-independent mechanotransduction drives breast cancer progression

Increased tissue stiffness is a driver of breast cancer progression. The transcriptional regulator YAP is considered a universal mechanotransducer, based largely on 2D culture studies. However, the role of YAP during in vivo breast cancer remains unclear. Here, we find that mechanotransduction occurs independently of YAP in breast cancer patient samples and mechanically tunable 3D cultures. Mechanistically, the lack of YAP activity in 3D culture and in vivo is associated with the absence of stress fibers and an order of magnitude decrease in nuclear cross-sectional area relative to 2D culture. This work highlights the context-dependent role of YAP in mechanotransduction, and establishes that YAP does not mediate mechanotransduction in breast cancer.\n\nOne Sentence SummaryBreast cancer mechanotransduction occurs independently of YAP, due to compact nuclear morphologies in vivo.

cancer biology↗