Biology subjects

Pinon, L.

Publications and source records attributed to Pinon, L..

6 recordsLinked to original sources

bioRxiv2025

Tumor-on-Chip as a Personalised Platform for Rapid Drug-Testing in Breast Cancer

Breast cancer (BC) remains one of the most common malignancies worldwide and continues to pose major therapeutic challenges, emphasizing the need for functional models that can inform fast treatment selection. Currently, patient-derived xenografts (PDXs) and organoids (PDOs) are valuable biological models for functional precision oncology; however, variable success rates of establishment and prolonged timelines limit their clinical application for real-time drug testing. To overcome this, we developed a Tumor-on-Chip (ToC) platform that enables functional drug sensitivity profiling within a clinically actionable 4-day timeframe. We compared ToC models with PDX results, and demonstrated high reproducibility and strong concordance with in vivo PDX responses. Drug sensitivity was correctly identified ex vivo in 88% of PDX-responsive cases, while resistance was detected in 91%, with no false positives at clinically relevant drug concentrations. To facilitate clinical translation, we engineered a custom microfluidic chip optimized for minimal breast cancer biopsy material, yielding results similar to those obtained from resection samples. We ultimately demonstrated the proof-of-concept for applying this platform to patient samples as a further tool for guiding clinical decision-making and discriminated between resistance and sensitive profiles among patients. These findings demonstrate the feasibility and translational potential of ToC models for personalized drug profiling in breast cancer, laying the groundwork for their integration into real-time clinical decision-making workflows.

bioengineering↗

bioRxiv2024

Infection-on-Chip: an in vitro human vessel to study Neisseria meningitidis colonization and vascular damages

Systemic infections leading to sepsis are life-threatening conditions that remain difficult to treat, and the limitations of current experimental models hamper the development of innovative therapies. Animal models are constrained by species-specific differences, while 2D cell culture systems fail to capture the complex pathophysiology of infection. To overcome these limitations, we developed a laser photoablation-generated, three-dimensional microfluidic model of meningococcal vascular colonization, a human-specific bacterium that causes sepsis and meningitis. Laser photoablation-generated hydrogel engineering allows the reproduction of vascular networks that are major infection target sites, and this model provides the relevant microenvironment reproducing the physiological endothelial integrity and permeability in vitro. By comparing with a human-skin xenograft mouse model, we show that the model system not only replicates in vivo key features of the infection, but also enables quantitative assessment with a higher spatiotemporal resolution of bacterial microcolony growth, endothelial cytoskeleton rearrangement, vascular E-selectin expression, and neutrophil response upon infection. Our device thus provides a robust solution bridging the gap between animal and 2D cellular models, paving the way for a better understanding of disease progression and developing innovative therapeutics.

synthetic biology↗

bioRxiv2023

TAp73 regulates mitochondrial dynamics and multiciliated cell homeostasis through an OPA1 axis

Dysregulated mitochondrial fusion and fission has been implicated in the pathogenesis of numerous diseases. We have identified a novel function of the p53 family protein TAp73 in regulating mitochondrial dynamics. TAp73 regulates the expression of Optic atrophy 1, a protein responsible for controlling mitochondrial fusion, cristae biogenesis and electron transport chain function. Disruption of this axis results in a fragmented mitochondrial network and an impaired capacity for energy production via oxidative phosphorylation. Owing to the role of OPA1 in modulating cytochrome c release, TAp73-/- cells also display an increased sensitivity to apoptotic cell death, e.g., via BH3-mimetics. We also show that the TAp73/OPA1 axis has functional relevance in the upper airway, where TAp73 expression is essential for multiciliated cell differentiation and function. Consistently, ciliated epithelial cells of Trp73-/- (global p73 KO) mice display decreased expression of OPA1 and perturbations of the mitochondrial network, which may drive multiciliated cell loss. In support of this, Trp73 and OPA1 gene expression is decreased in COPD patients, a disease characterised by alterations in mitochondrial dynamics. We therefore highlight a potential mechanism involving the loss of p73 in COPD pathogenesis. This work also adds to the growing body of evidence for growth-promoting roles of TAp73 isoforms.

cell biology↗

bioRxiv2022

Microtubules restrict F-actin to the immune synapse via GEF-H1 to maintain polarity in lymphocytes

Immune synapse formation is a key step for lymphocyte activation. In B lymphocytes, the immune synapse controls the production of high-affinity antibodies, thereby defining the efficiency of humoral immune responses. While the key roles played by both the actin and microtubule cytoskeletons in the formation and function of the immune synapse have become increasingly clear, how the different events involved in synapse formation are coordinated in space and time by actin-microtubule interactions is not understood. Using a microfluidic pairing device, we studied with unprecedented resolution the dynamics of the various events leading to immune synapse formation and maintenance. Our results identify two groups of events, local and global dominated by actin and microtubules dynamics, respectively. They further highlight an unexpected role for microtubules and the GEF-H1-RhoA axis in restricting F-actin polymerization at the immune synapse to define the cell polarity axis, allowing the formation and maintenance of a unique competent immune synapse.

cell biology↗

bioRxiv2021

Phenotyping Polarization Dynamics Of Immune Cells Using A Lipid Droplet - Cell Pairing Microfluidic Platform

The immune synapse is the tight contact zone between a lymphocyte and a cell presenting its cognate antigen. This structure serves as a signaling platform and entails a polarization of intra-cellular components, necessary to the immunological function of the cell. While the surface properties of the presenting cell are known to control the formation of the synapse, their impact on polarization has not yet been studied. Using functional lipid droplets as tunable artificial presenting cells combined with a microfluidic pairing device, we simultaneously observe synchronized synapses and dynamically quantify polarization patterns of individual B cells. By assessing how ligand concentration, surface fluidity and substrate rigidity impact lysosome polarization, we show that its onset and kinetics depend on the local antigen concentration at the synapse and on substrate rigidity. Our experimental system enables a fine phenotyping of monoclonal cell populations based on their synaptic readout.

biophysics↗

bioRxiv2018

A multiparametric, quantitative and high-throughput assay to quantify the influence of target size on phagocytic uptake

Phagocytosis by macrophages represents a fundamental process essential for both immunity and tissue homeostasis. It consists in the uptake of pathogenic or cellular targets larger than 0.5m. For the biggest particles, the phagocytic process involves a massive reorganization of membrane and actin cytoskeleton as well as an important intracellular deformation, all in a matter of minutes. The study of the role of the size of objects in their phagocytosis has lead to contradictory results in the last decades.\n\nWe designed a method using confocal microscopy, automated image analysis and databases for fast quantitative analysis of phagocytosis assays. It yields comprehensive data on the cells and targets geometric and fluorescence intensity parameters, automatically discriminates internalized from external targets, and stores the relationship between a cell and the targets it has engulfed. We used two types of targets, solid polystyrene beads and liquid lipid droplets, to investigate the influence of size on the phagocytic uptake of macrophages. The method made it possible, not only to perform phagocytic assays with functionalized droplets and beads of different sizes, but to use polydisperse particles to further our understanding of the role of size in phagocytosis.\n\nThe use of monodisperse and polydisperse objects shows that while smaller monodisperse objects are internalized in greater numbers, objects of different sizes presented simultaneously are internalized without preferred size. Throughout results, the total surface engulfed by the cell appeared to be the main factor limiting the uptake of particles, regardless of their nature or size. A meta-analysis of the literature reveals that this dependence in surface is consistently conserved throughout cell types, targets nature or activated receptors.

biophysics↗