Biology subjects

Colombelli, J.

Publications and source records attributed to Colombelli, J..

6 recordsLinked to original sources

bioRxiv2026

Multi-Site Reproducibility Study of 3D High-Content Analysis with Dual-View Oblique Plane Microscopy

High content imaging is being applied to achieve quantitative fluorescence readouts in increasingly complex 3-dimensional (3D) cell culture models such as spheroids and organoids. Compared to conventional 2D assays, 3D assays better represent biological heterogeneity but require more complex sample preparation, 3D imaging and 3D image analysis that can affect the accuracy and precision of such assays. We used spheroids formed from the NRAS-activated melanoma cell line 19161 modified to express an ERK kinase translocation reporter (KTR) as an exemplar 3D phenotypic assay carried out in 96-well plates. The spheroids were treated with the ERK activator TPA and a range of concentrations of the MEK inhibitor Binimetinib. 3D live-cell imaging with sub-cellular spatial resolution was performed using a dual-view oblique plane microscope (dOPM) - a form of single-objective light-sheet microscope - and the experiment was performed separately at 4 different institutes. The results were analysed using an identical 3D analysis pipeline and parameters. We assessed the variation in assay readout using a linear mixed effects model. Random variance at the well level was negligible (SD = 0.0048 relative to range of KTR biosensor readout at reference site of 0.17), indicating low technical noise. Treatment effects were dose-dependent and highly statistically significant compared to DMSO control across all sites (Dunnett-corrected p < 0.001). The range in KTR readout between the minimum (3.5 M Binimetinib) and maximum (100 nM TPA) treatments varied between 59 to 96% relative to the reference site. Measured bias in KTR readout between sites was between 6 and 12% of the range of the reference site. This study quantifies the reproducibility of a 3D live spheroid-based assay employing a fluorescence biosensor requiring readout out at the per-cell level using the dOPM platform and discusses areas where experimental protocol could be improved in the future to further improve reproducibility.

bioengineering↗

bioRxiv2026

Mapping 3D tissue orientation with tensor-augmented light-sheet microscopy

Mapping the three-dimensional directional organization of biological tissues is essential for understanding their structure and function. However, existing methods cannot resolve micrometer-scale orientation in volumetric samples. We introduce tensor light-sheet scattering microscopy (tLSSM), a label-free method that reconstructs 3D fiber orientations at micrometer resolution in optically cleared tissues, enabling whole-organ imaging. We discovered that even in transparent samples, organized structures such as neural fibers scatter light in directional patterns, consistent with models of light scattering by cylinders. We compared tLSSM against diffusion MRI in the mouse brain, demonstrating strong agreement and orders of magnitude superior spatial resolution. Furthermore, we showcase tLSSMs versatility across diverse contexts, including whole-brain label-free tracing, pathological demyelination lesions, heart tissue, peripheral nerves, and human white matter. By enabling whole-organ fiber orientation mapping compatible with standard light-sheet microscopes, tLSSM establishes a new standard for mesoscopic connectivity studies by mapping tissue architecture beyond the limits of traditional sectioning.

neuroscience↗

bioRxiv2025

In-depth 3D Exploration of Autosomal Dominant Polycystic Kidney Disease Through Light Sheet Fluorescence Microscopy

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most prevalent genetic kidney disorder. Animal preclinical studies are one of the main tools to study this disease, often through either 2D histology imaging for high-resolution analysis or CT or MRI for full kidney segmentation. As an alternative to these modalities, we propose the use of Light Sheet Fluorescence Microscopy (LSFM) for high-resolution 3D imaging of healthy and ADPKD-induced mouse kidneys, enabling a detailed volumetric morphological analysis of the diseases effects. In a mouse ADPKD model, ex vivo imaging of the kidneys was performed through LSFM, after which a combination of machine learning and other processing techniques allowed us to perform an in-depth image analysis. This includes the segmentation of key structures, such as the full kidney volume and, within it, its internal cavities, cortex, glomeruli, and cysts, complemented by texture analysis of tubular structures in the cortical area. Pathological kidneys exhibited significant volume enlargement and increased internal cavities due to cystogenesis. While glomerular count remained stable, their spatial distribution was altered, showing increased interglomerular distances and show-casing the deformations produced by the disease. The texture analysis of tubules from the cortex region identified Local Binary Pattern (LBP) uniformity and porosity as key biomarkers of tissue deformation, which could be used as markers to further evaluate the development of the disease. These findings underscore the potential of LSFM imaging as a powerful tool for detailed ADPKD characterization and treatment assessment.

bioengineering↗

bioRxiv2024

Open-hardware solutions for light sheet microscopy specimen chambers

Light sheet fluorescence microscopy (LSFM) is a powerful tool for imaging large three-dimensional biological samples. However, the design and fabrication of specimen chambers for these systems present significant challenges, particularly in maintaining water-tight seals, preventing contamination, and ensuring the flexibility needed for precise positioning of the objective and sample. This study introduces open-hardware solutions to address these challenges, utilising a combination of 3D printing, silicone injection moulding, and FEP-foil thermoforming. We describe the development of custom, highly flexible silicone seals and connectors through a laboratory-scale injection moulding process. These components enable precise, low-resistance movement of imaging objectives and specimen holders, which is crucial for maintaining imaging accuracy. Additionally, we introduce a novel "optical window" design that isolates the objective lens from the immersion medium, significantly reducing the risk of contamination and facilitating easy exchange of chambers and lenses without compromising sterility. The practicality of these designs is demonstrated through their application in long-term live imaging of Tribolium castaneum embryos, honey bee embryos, and human mesenchymal stem cell spheroids. By providing open-source CAD and 3D printing files, this work promotes accessibility and customization in microscopy, enabling researchers to easily replicate and adapt these solutions to their specific needs.

developmental biology↗

bioRxiv2020

The P4-ATPase Drs2 regulates the homeostasis of Atg9

Multisubunit Tethering Complexes (MTCs) are a set of conserved protein complexes that tether transported vesicles at the acceptor membrane. Interactions with other components of the trafficking machinery regulate MTCs through mechanisms that are just partially understood. Here we systematically investigate the interactome that regulates the function of MTCs. We found that P4-ATPases, a family of lipid transporters involved in the biogenesis of vesicles, interact with MTCs that participate in the anterograde and retrograde transport at the Golgi, such as TRAPPIII. We used the lipid flippase Drs2 as a model to investigate the mechanism and biological relevance of such interplay during the transport of Atg9 vesicles. Binding to the N-terminal tail of Drs2 stabilizes TRAPPIII on membrane compartments loaded with Atg9 and it is required for the delivery of Atg9 during selective autophagy, a role that is independent of previously reported functions of the P4-ATPase. This mechanism relies on the I(S/R)TTK motif nested in the N-terminal tail cavity of Drs2, a motif that is required for the interaction with MTCs.

cell biology↗

bioRxiv2019

Reversible silencing of endogenous receptors in intact brain tissue using two-photon pharmacology

The physiological activity of proteins is often studied with loss-of-function genetic approaches, but the corresponding phenotypes develop slowly and can be confounding. Photopharmacology allows direct, fast and reversible control of endogenous protein activity, with spatiotemporal resolution set by the illumination method. Here, we combine a photoswitchable allosteric modulator (alloswitch) and two-photon excitation (2PE) using pulsed near-infrared lasers to reversibly silence mGlu5 receptor activity in intact brain tissue. Endogenous receptors can be photoactivated in neurons and astrocytes with pharmacological selectivity and with an axial resolution between 5 and 10 m. Thus, two-photon pharmacology (2PP) using alloswitch allows investigating mGlu5-dependent processes in wild type animals, including synaptic formation and plasticity, and signaling pathways from intracellular organelles.

pharmacology and toxicology↗