Biology subjects

Samara, A.

Publications and source records attributed to Samara, A..

7 recordsLinked to original sources

bioRxiv2026

CytoLight: A Rapid and Versatile Fluorescent-Based Labeling Method for Extracellular Vesicle Characterization and Tracking

Efficient, aggregation-free extracellular vesicles (EVs) labeling is essential for studying their dynamics in-vitro and in-vivo. However, traditional dyes introduce limitations including aggregation, membrane intercalation, fluorescence transfer and inconsistent performance across EV sources thus distorting quantification, altering surface properties and confounding uptake and biodistribution analyses. Here, we systematically evaluated CytoLight, a luminal dye traditionally used for live-cell imaging, as an alternative for EV quantification, characterization, uptake analysis and in-vivo tracking, benchmarking it against PKH26, CFSE and ExoBrite across multiple platforms. CytoLight generated stable, intravesicular fluorescence without aggregation or membrane alteration, eliminating artifacts characteristic of conventional dyes. Using fluorescence-NTA and single-EV flow cytometry, CytoLight showed more consistent labeling across EV types than CFSE or ExoBrite, while avoiding PKH-related micelle-driven artifacts and exhibited compatibility with CD81 dual-detection. In uptake assays, CytoLight produced EV-specific endocytosis-dependent internalization signals exceeding labeled-BPS/protein controls. In-vivo, CytoLight-labeled EVs enabled fluorescent biodistribution mapping showing conventional EV tropism patterns distinguishable from labeled-PBS controls. These findings establish CytoLight as an effective, aggregation-free EV-labeling strategy. Its stability, specificity, compatibility with single-EV platforms and reliable performance in both cellular uptake and biodistribution studies position CytoLight as a practical, scalable alternative to current dyes, providing a stronger foundation for standardized and reproducible EV research.

cell biology↗

bioRxiv2025

Patterns of intersubject correlations parallel organizational gradients during naturalistic viewing

Recent studies have robustly demonstrated that human cortical function can be described through sensory-transmodal gradients of cortical function, while naturalistic movie watching paradigms have been leveraged to index cortical synchronization. We leveraged two independent 7T movie fMRI datasets to assess correlations between intersubject correlation and functional gradients across movies, datasets, and spatial scales. At the whole-brain level, we observed robust relationships between intersubject correlations and a visual-transmodal connectivity gradient which was independent of movie content. Within functional networks, correlations were particularly pronounced for the visual, dorsal attention, and default mode networks. Our results demonstrate that naturalistic paradigms can provide targeted insight into multiscale processing hierarchies. Robust relationships across movies suggest that movie-watching can be viewed as a brain state that is independent of movie-content. Overall, this work suggests an important confluence of within-subject functional organizational axes and inter-subject synchronization when the brain is engaged in the processing of naturalistic stimuli.

neuroscience↗

bioRxiv2025

Cortical language areas are coupled via a soft hierarchy of model-based linguistic features

Natural language comprehension is a complex task that relies on coordinated activity across a network of cortical regions. In this study, we propose that regions of the language network are coupled to one another through subspaces of shared linguistic features. To test this idea, we developed a model-based connectivity framework to quantify stimulus-driven, feature-specific functional connectivity between language areas during natural language comprehension. Using fMRI data acquired while subjects listened to spoken narratives, we tested three types of features extracted from a unified neural network model for speech and language: low-level acoustic embeddings, mid-level speech embeddings, and high-level language embeddings. Our modeling framework enabled us to quantify the proportions of stimulus features driving connectivity between regions: early auditory areas were coupled to intermediate language areas via lower-level acoustic and speech features; in contrast, higher-order language and default-mode regions were predominantly coupled through more abstract language features. We observed a clear progression of feature-specific connectivity from early auditory to lateral temporal areas, advancing from acoustic connectivity to speech- and finally to language-driven connectivity. Our findings suggest that higher-order language areas are coupled along increasingly higher level, more contextualized language features.

neuroscience↗

bioRxiv2022

Multi-omics analysis of paracetamol exposure identifies dysregulated genes involved in neurotoxicity and neuronal differentiation of human embryonic stem cells

Prenatal paracetamol exposure has been associated with neurodevelopmental outcomes in childhood. Pharmacoepigenetic studies show differences in cord blood DNA methylation between paracetamol exposed and unexposed neonates. However, causal implications and impact of long-term prenatal long-term paracetamol exposure on brain development remain unclear. Using a multi-omics approach, we investigated the effects of paracetamol on a model of early human brain development. We exposed human embryonic stem cells undergoing in vitro neuronal differentiation to daily media changes with paracetamol concentrations corresponding to maternal therapeutic doses. Single-cell RNA-seq and ATAC-seq integration identified paracetamol-induced chromatin-opening changes linked to gene expression. Differentially methylated and/or expressed genes were involved in signalling, neurotransmission, and cell fate-determination trajectories. Some genes involved in neuronal injury and development-specific pathways, such as KCNE3, overlapped with differentially methylated genes previously identified in cord blood associated with prenatal paracetamol exposure. Our data suggest that paracetamol may play a causal role in impaired neurodevelopment. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=191 HEIGHT=200 SRC="FIGDIR/small/519620v2_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@e1a75forg.highwire.dtl.DTLVardef@b36a1forg.highwire.dtl.DTLVardef@fc25e4org.highwire.dtl.DTLVardef@1bb1c8_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2022

Cortical gradients during naturalistic processing are hierarchical and modality-specific

Understanding cortical topographic organization and how it supports complex perceptual and cognitive processes is a fundamental question in neuroscience. Previous work has characterized functional gradients that demonstrate large-scale principles of cortical organization. How these gradients are modulated by rich ecological stimuli remains unknown. Here, we utilize naturalistic stimuli via movie-fMRI to assess macroscale functional organization. We identify principal movie gradients that delineate separate hierarchies anchored in sensorimotor, visual, and auditory/language areas. At the opposite/heteromodal end of these perception-to-cognition axes, we find a more central role for the frontoparietal network along with the default network. Even across different movie stimuli, movie gradients demonstrated good reliability, suggesting that these hierarchies reflect a brain state common across different naturalistic conditions. The relative position of brain areas within movie gradients showed stronger and more numerous correlations with cognitive behavioral scores compared to resting state gradients. Together, these findings provide an ecologically valid representation of the principles underlying cortical organization while the brain is active and engaged in multimodal, dynamic perceptual and cognitive processing. HighlightsO_LIMovie-fMRI reveals novel, more granular principles of hierarchical cortical organization C_LIO_LITop movie gradients delineate three separate perception-to-cognition hierarchies C_LIO_LIA distinctive third gradient in movie-watching is anchored by auditory/language regions C_LIO_LIGradient scores demonstrate good reliability even across different movie stimuli C_LIO_LIMovie gradients yield stronger correlations with behavior relative to resting state gradients C_LI

neuroscience↗

bioRxiv2022

A multi-omics approach to visualize early neuronal differentiation in 4D

Neuronal differentiation of pluripotent stem cells is an established method to study physiology, disease and medication safety. However, the sequence of events in human neuronal differentiation and the ability of in vitro models to recapitulate early brain development are poorly understood. We developed a protocol optimized for the study of early human brain development and neuropharmacological applications. We comprehensively characterized gene expression and epigenetic profiles at four timepoints, as the cells differentiate from embryonic stem cells towards a heterogenous population of progenitors, immature and mature neurons bearing telencephalic signatures. A multi-omics roadmap of neuronal differentiation, combined with searchable interactive gene analysis tools, allows for extensive exploration of early neuronal development and the effect of medications. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=178 SRC="FIGDIR/small/478732v1_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@163539forg.highwire.dtl.DTLVardef@72c09org.highwire.dtl.DTLVardef@dc04eforg.highwire.dtl.DTLVardef@c821d2_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIMulti-omics charting a new neuronal differentiation protocol for human ES cells C_LIO_LISingle-cell analyses reveals marker genes during neuronal differentiation C_LIO_LIIdentified transcriptional waves similar to early human brain development C_LIO_LISearchable tools to visualize single-cell gene expression and chromatin state C_LI In BriefWe have developed a novel protocol for human embryonic stem cells to study neural induction and early neuronal differentiation. Multi-omics analyses uncovered cell populations, genes and transcriptional waves defining cell fate commitment. We comprehensively describe epigenetic landscapes and gene expression and provide searchable analysis tools for exploration of the data.

cell biology↗

bioRxiv2022

Robust and reproducible neuronal differentiation of human embryonic stem cells for neurotoxicology

Neuronal differentiation from pluripotent cells is commonly used to recapitulate events in early brain development. Neuronal precursors and developing neurons cultured in vivo, rely on attachment, density and cell-to-cell communication, and cell-passaging steps should be minimised to avert disruption of network cross-connectivity. This is crucial both for viability and maturation, and the former also applies to human embryonic stem cells (hESCs). Neuronal differentiation protocols from hESCs for neurotoxicology assessment studies should therefore provide standardized cell density requirements, and optimised coating matrix conditions. The effect of drug treatments may be masked by compound instability and degradation in cell culture medium but performing daily media changes can circumvent these issues. Here, we describe a robust neuronal differentiation protocol using dual SMAD/WNT signalling inhibitors LDN193189, SB431542 and XAV939 (LSX) for neural induction of hESCs, followed by self-patterning and cell maturation stages, for the generation of ventral telencephalic progenitors and neurons. We provide critical information on the optimized cell culture parameters and standardized methods of stage-specific validation. Using cell counts, immunofluorescence, qRT-PCR, and a proof of principle treatment with valproic acid to showcase issues with drug-induced cell toxicity, we facilitate reproducibility of the protocol. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=193 SRC="FIGDIR/small/477818v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@19f0f89org.highwire.dtl.DTLVardef@1b4feaaorg.highwire.dtl.DTLVardef@1bb832borg.highwire.dtl.DTLVardef@1a07efd_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗