Biology subjects

Hellal, F.

Publications and source records attributed to Hellal, F..

10 recordsLinked to original sources

bioRxiv2026

Reversible hypervascularization drives cognitive decline and blood-brain barrier damage during aging

Cerebrovascular dysfunction emerges early in neurodegeneration, yet how vascular structure, blood-brain barrier (BBB) failure, and cognition are linked remains undefined. Using VesselPro, a whole-brain pipeline integrating perfusion-resolved 3D imaging with spatial proteomics, we mapped vascular aging across the mouse lifespan. We identify two discrete trajectories: a hypovascular state and a previously unrecognized hyper-vascular, BBB-compromised state, defined relative to a young-adult vascular baseline. The hyper-vascular trajectory, concentrated in the cortex and hippocampus, was associated with marked spatial memory impairment and pervasive BBB leakage. Spatial proteomics revealed a coordinated program involving angiogenic activation, endothelial stress, cytoskeletal remodeling, and inflammatory signaling. Cross-species comparison with human proteomic biomarkers from the UK Biobank showed strong alignment between the mouse hypervascular signature and vascular dementia risk, but minimal concordance with Alzheimers disease, defining a vascular-specific dementia endotype. Transient Tie2 activation with AKB-9778 attenuated this trajectory, improving vessel organization, BBB integrity, and memory performance. Our findings show that endothelial instability is a key mechanistic driver of this heterogeneous vascular aging state. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/720441v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@39494aorg.highwire.dtl.DTLVardef@faa4acorg.highwire.dtl.DTLVardef@1511dd5org.highwire.dtl.DTLVardef@7db29b_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIVesselPro: we developed a pipeline for capturing perfused blood vessels in the brain: unexpected bifurcation in vascular aging: traditional hypovascular state and a novel, hypervascular, BBB-compromised state. C_LIO_LIHypervascular pathology: Linked the hypervascular profile in the cortex and hippocampus to spatial memory impairment, pervasive BBB leakage, and angiogenic inflammatory signaling. C_LIO_LIClinical endotype: Cross-species analysis via the UK Biobank confirms this hypervascular signature aligns with vascular dementia risk rather than Alzheimers disease. C_LIO_LIPharmacological stabilization: Demonstrated that Tie2 signaling activation (AKB-9778) improves the vessel organization, BBB integrity, and memory performance. C_LI

neuroscience↗

bioRxiv2026

Neutrophils are critical for placental and fetal infection with the human pathogen Listeria monocytogenes

Fetal listeriosis, caused by Listeria monocytogenes (Lm), represents a severe infectious disease. During pregnancy, the unique intrauterine environment permits Lm to breach the maternal-fetal barrier by infiltrating the placental trophoblast layer and ultimately leading to significant fetal morbidity and mortality. However, the exact pathways remain incompletely understood. In this study, we sought to elucidate the molecular mechanisms underlying the early stages of placental and fetal Lm infection. Our results reveal that neutrophils serve as a survival niche for Lm within the vasculature, facilitating placental and fetal infection in the mouse in vivo. This finding was further substantiated by in vitro studies using TLR2-stimulated trophoblast cells and Lm-infected neutrophils. Additionally, tissue-clearing analysis of Lm-infected placentas demonstrated neutrophil colocalization with Lm is rare within placental tissue. Collectively, our findings identify maternal neutrophils as an essential viability niche for Lm enabling their entry into trophoblast cells, thereby promoting placental and fetal infection. One Sentence SummaryMaternal circulating neutrophils act as survival niche for Listeria monocytogenes and facilitate placental/fetal infection with Listeria during pregnancy.

immunology↗

bioRxiv2026

Aging reprograms the response to chronic stress

Chronic stress is thought to accelerate brain aging. We find this to be true in the brains of young mice, but reversed in the old. Using chronic variable stress in young (2-month) and aged (24-month) mice, we show that aged animals perceive stress physiologically but exhibit stress-responses that differ from those of young mice on behavioral, synaptic, and molecular levels. Multi-Omics profiling of prefrontal cortex and nucleus accumbens and 3D vasculature measurements reveals that stress in aged mice activates angiogenic programs that oppose aging-related patterns. Our results demonstrate that stress cannot be universally conceptualized as an aging accelerator, but instead engages age-specific programs with opposite directionality in young and old animals.

neuroscience↗

bioRxiv2025

LipiGo: A Versatile DNA-Lipid Nanoparticle Hybrid for Precision Drug Delivery

Lipid nanoparticles (LNPs) are established carriers for nucleic acid delivery, however, achieving efficient delivery to non-hepatic tissues remains a major challenge. Here, we present LipiGo, a nanocarrier platform engineered by integrating short single stranded DNA molecules into the lipid nanoparticle structure. Using whole body tissue clearing, advanced imaging and AI-based analysis, we show that LipiGo redirects functional mRNA delivery to lymphoid organs, particularly the spleen. Immune cell profiling further reveals enhanced uptake within key immune populations, including antigen-presenting cells, compared to standard LNPs. Beyond passive redistribution, LipiGo leverages DNA hybridization to enable modular attachment of targeting ligands for active targeting as demonstrated by cell-specific delivery to white adipocytes. Overall, the dual-purpose design principle of LipiGo demonstrates high modularity and efficiency, enabling tissue and cell specific delivery beyond hepatic applications. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/676334v2_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@9b69eorg.highwire.dtl.DTLVardef@1b45bd0org.highwire.dtl.DTLVardef@1f7b79dorg.highwire.dtl.DTLVardef@37a673_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2024

Deep Learning and 3D Imaging Reveal Whole-Body Alterations in Obesity

Many diseases, such as obesity, have systemic effects that impact multiple organ systems throughout the body. However, tools for comprehensive, high-resolution analysis of disease-associated changes at the whole-body scale have been lacking. Here, we developed a suite of deep learning-based image analysis algorithms (MouseMapper) and integrated it with tissue clearing and light-sheet microscopy to enable a comprehensive analysis of diseases impacting diverse systems across the mouse body. This approach enables the quantitative analysis of cellular and structural changes across the entire mouse body at unprecedented resolution and scale, including tracking nerves over several centimeters in whole animal bodies. To demonstrate its power, we applied MouseMapper to study nervous and immune systems in high-fat diet induced obesity. We uncovered widespread changes in both immune cell distribution and nerve structures, including alterations in the trigeminal nerve characterized by a reduced number of nerve endings in obese mice. These structural abnormalities were associated with functional deficits of whisker sensing and proteomic changes in the trigeminal ganglion, primarily affecting pathways related to axon growth and the complement system. Additionally, we found heterogeneity in obesity-induced whole-body inflammation across different tissues and organs. Our study demonstrates MouseMappers capability to discover and quantify pathological alterations at the whole-body level, offering a powerful approach for investigating the systemic impacts of various diseases. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=187 SRC="FIGDIR/small/608300v1_ufig1.gif" ALT="Figure 1"> View larger version (74K): org.highwire.dtl.DTLVardef@17d2601org.highwire.dtl.DTLVardef@14a2d3dorg.highwire.dtl.DTLVardef@e04114org.highwire.dtl.DTLVardef@d0b8b5_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIWe developed MouseMapper: AI-driven pipeline for whole-body structural analysis in mice C_LIO_LIMouseMapper revealed obesity-induced changes in nerves and immune cells across multiple organs C_LIO_LIMouseMapper identified facial nerve alterations in obesity linked to impaired whisker sensitivity C_LIO_LIMouseMapper has the potential for holistic 3D analysis of systemic diseases C_LI Supplementary Videos can be seen at: http://discotechnologies.org/MouseMapper/

systems biology↗

bioRxiv2023

Single-cell precision nanotechnology in vivo

Targeting nanoparticle therapeutics with cellular accuracy in whole organisms could open breakthrough opportunities in precision medicine. However, evaluating and fine-tuning the biodistribution of such systems in the whole organism at the cellular level remains a major obstacle. Here, we constructed targetable DNA origami, and analyzed biodistribution in transparent mice, in addition to studying tolerability, clearance kinetics, and immune response parameters. Untargeted DNA origami primarily accumulated in the spleen and the liver, while an immune cell-targeting variant successfully attached to immune cells throughout the body. A cancer cell-targeting mimetic co-localized on solid-tumor metastasis in the liver and the lung. These findings indicate that DNA origami can be directed in vivo, providing an important proof-of-concept and highlights the potential of high-resolution tissue-clearing imaging technologies in their development. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=121 SRC="FIGDIR/small/550304v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@ce216borg.highwire.dtl.DTLVardef@f40bb4org.highwire.dtl.DTLVardef@2c6a66org.highwire.dtl.DTLVardef@1fd7fde_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIThis study demonstrates the potential of DNA origami-based drug delivery systems as versatile tool for for targeted delivery, which could be used to treat a range of diseases with applications. C_LIO_LIThe immune compatibility, half-life, targeting efficiency, and the biodistribution evaluation of DNA origami indicate its potential for systemic drug delivery. C_LIO_LIOur approach enables the assessment of biodistribution of nanoparticles in the intact body with a sensitivity to the single-cell level, highlighting the high-resolution tissue clearing technoloies in revealing DNA origamis feasibility for drug targeting. C_LI

bioengineering↗

bioRxiv2023

SARS-CoV-2 Spike Protein Accumulation in the Skull-Meninges-Brain Axis: Potential Implications for Long-Term Neurological Complications in post-COVID-19

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), has been associated mainly with a range of neurological symptoms, including brain fog and brain tissue loss, raising concerns about the viruss acute and potential chronic impact on the central nervous system. In this study, we utilized mouse models and human post-mortem tissues to investigate the presence and distribution of the SARS-CoV-2 spike protein in the skull-meninges-brain axis. Our results revealed the accumulation of the spike protein in the skull marrow, brain meninges, and brain parenchyma. The injection of the spike protein alone caused cell death in the brain, highlighting a direct effect on brain tissue. Furthermore, we observed the presence of spike protein in the skull of deceased long after their COVID-19 infection, suggesting that the spikes persistence may contribute to long-term neurological symptoms. The spike protein was associated with neutrophil-related pathways and dysregulation of the proteins involved in the PI3K-AKT as well as complement and coagulation pathway. Overall, our findings suggest that SARS-CoV-2 spike protein trafficking from CNS borders into the brain parenchyma and identified differentially regulated pathways may present insights into mechanisms underlying immediate and long-term consequences of SARS-CoV-2 and present diagnostic and therapeutic opportunities. Graphical Summary O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/535604v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@b223eforg.highwire.dtl.DTLVardef@15539e9org.highwire.dtl.DTLVardef@4d17a9org.highwire.dtl.DTLVardef@14c63af_HPS_FORMAT_FIGEXP M_FIG C_FIG Short SummaryThe accumulation of SARS-CoV-2 spike protein in the skull-meninges-brain axis presents potential molecular mechanisms and therapeutic targets for neurological complications in long-COVID-19 patients.

neuroscience↗

bioRxiv2023

Whole mouse body histology using standard IgG antibodies

Most diseases involve multiple interconnected physiological systems, but histological evaluation of their pathology is currently limited to small tissue samples. Here, we present wildDISCO, a technology that uses cholesterol extraction to enable deep tissue penetration of standard 150 kDa IgG antibodies in chemically fixed whole mice. Combining wildDISCO with whole mouse clearing, we generate whole-body maps of the nervous, immune, and lymphatic systems and show their close interactions throughout the mouse body. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=158 SRC="FIGDIR/small/528921v1_ufig1.gif" ALT="Figure 1"> View larger version (64K): org.highwire.dtl.DTLVardef@f0de23org.highwire.dtl.DTLVardef@187fe94org.highwire.dtl.DTLVardef@15ac0faorg.highwire.dtl.DTLVardef@133703e_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIWildDISCO uses new tissue chemistry based on {beta}-cyclodextrin to enable histology in whole mouse bodies using full-size antibodies C_LIO_LIWildDISCO generates the first whole mouse body atlases for neurons, immune cells, blood and lymph vessels C_LIO_LIThe whole mouse atlases are available online to study the biological systems in health and disease C_LIO_LIVirtual Reality (VR) exploration of these atlases disentangles complex anatomical structures between organs and biological systems C_LI Supplementary Videos can be seen athttp://discotechnologies.org/wildDISCO/

biochemistry↗

bioRxiv2021

Multi-omics and 3D-imaging reveal bone heterogeneity and unique calvaria cells in neuroinflammation

The meninges of the brain are an important component of neuroinflammatory response. Diverse immune cells move from the calvaria marrow into the dura mater via recently discovered skull-meninges connections (SMCs). However, how the calvaria bone marrow is different from the other bones and whether and how it contributes to human diseases remain unknown. Using multi-omics approaches and whole mouse transparency we reveal that bone marrow cells are highly heterogeneous across the mouse body. The calvaria harbors the most distinct molecular signature with hundreds of differentially expressed genes and proteins. Acute brain injury induces skull-specific alterations including increased calvaria cell numbers. Moreover, TSPO-positron-emission-tomography imaging of stroke, multiple sclerosis and neurodegenerative disease patients demonstrate disease-associated uptake patterns in the human skull, mirroring the underlying brain inflammation. Our study indicates that the calvaria is more than a physical barrier, and its immune cells may present new ways to control brain pathologies. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/473988v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@978194org.highwire.dtl.DTLVardef@bc45e8org.highwire.dtl.DTLVardef@91afdborg.highwire.dtl.DTLVardef@b06bc6_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIBone marrow across the mouse body display heterogeneity in their molecular profile C_LIO_LICalvaria cells have a distinct profile that is relevant to brain pathologies C_LIO_LIBrain native proteins are identified in calvaria in pathological states C_LIO_LITSPO-PET imaging of the human skull can be a proxy of neuroinflammation in the brain C_LI Supplementary Videos can be seen at: http://discotechnologies.org/Calvaria/

cell biology↗

bioRxiv2020

Highly fluorescent biodegradable PLGA nano-carriers allows real-time tracking of individual particles in vivo

Poly(lactic-co-glycolic acid) (PLGA)-based drug formulations are approved for the use in humans, however, the potential of PLGA to design nanoparticles (NPs) and target the central nervous system remains to be exploited. The aim of the current study was design PLGA NPs, loading them with bulky fluorophores thereby increasing single particle fluorescence to a level visible by in vivo microscopy, and investigate their brain biodistribution. We developed, highly fluorescent 70 nm PLGA NPs significantly brighter then quantum dots enabling their visualization by intravital real-time 2-photon microscopy. We found that PLGA NPs coated with pluronic F-68 (PF-68) had a substantially longer plasma half-life than uncoated NPs and were taken up by cerebro-vascular endothelial cells. High resolution confocal microscopy revealed that coated PLGA NPs were present in late endothelial endosomes of cerebral vessels within 1 hour after systemic injection and were more readily taken up by endothelial cells in peripheral organs. The current data suggest that PF-68 coated PLGA NPs are taken up by mouse cerebral and peripheral endothelial cells in vivo. The combination of ultra-bright NPs and in vivo imaging may thus represent a promising approach to reduce the gap between development and clinical application of nanoparticle-based drug carriers.

bioengineering↗