Biology subjects

Shrouder, J. J.

Publications and source records attributed to Shrouder, J. J..

4 recordsLinked to original sources

bioRxiv2026

A reproducible human brain tissue model to study physiological and disease-associated microglia phenotypes

Stem-cell-based in vitro models offer promising potential to elucidate human brain cell functions and interactions under physiological and pathological conditions. However, harnessing this potential is impaired by low reproducibility, maturity, or cell-type diversity of existing models. Especially, prolonged incorporation of mature microglia and studies of neuroinflammation have proven challenging. Here, we developed a 3D cortical brain tissue model (3BTM) containing neurons, astrocytes, and microglia with high reproducibility, maturity, and viability. 3BTMs show morphological, functional, and proteomic maturation of all cell types, leading to high similarity to their in vivo counterparts. Incorporated microglia survive for over 6 months and display mature morphology, functions, and gene expression. Importantly, when engineered to model Alzheimers disease pathology, 3BTMs recapitulate key disease hallmarks including amyloid deposition, increased phospho-Tau levels, and neuroinflammation, with microglia shifting their transcriptional landscape to disease-relevant signatures. Together, our model offers unprecedented possibilities for studying physiological and pathological states of human brain tissue and translational applications.

neuroscience↗

bioRxiv2025

GluTrooper: a novel reporter mouse line for whole-brain imaging of glutamate dynamics

Glutamate is the primary excitatory neurotransmitter in the mammalian brain. However, tools to image glutamate dynamics in the whole brain with high spatial and temporal resolution are lacking. Therefore, we developed GluTrooper, a novel mouse line engineered for inducible and long-lasting expression of the genetically encoded glutamate sensor iGluSnFR3. GluTrooper mice crossed with Emx1-Cre lines demonstrated uniform and stable sensor expression in excitatory neurons of the cortex, hippocampus, and olfactory bulb. iGluSnFR3 expression remained stable for at least 12 months, enabling longitudinal observations of glutamate dynamics over extended periods. Using multimodal imaging in awake mice, we demonstrated the versatility of GluTrooper across multiple spatial scales: from mesoscale widefield cortical imaging to cellular resolution with two-photon microscopy. Moreover, during cortical spreading depolarization, bilateral whole-brain glutamate dynamics and contralateral cortical disinhibition were detected with high fidelity. Accordingly, the GluTrooper may open new avenues for the better understanding of glutamatergic neurotransmission in the mammalian brain.

neuroscience↗

bioRxiv2024

Using a Foerster-resonance energy transfer (FRET)-based detection system (FedEcs) to monitor nanoparticle cargo delivery to the brain

Nanotechnology holds great promise for improving the delivery of therapeutics to the brain. However, current approaches often operate at the organ or tissue level and are limited by the lack of tools to dynamically monitor cargo delivery in vivo. We have developed highly fluorescent lipid nanodroplets (LNDs) that enable tracking of nanocarrier behaviour at the subcellular level while also carrying a Forster resonance energy transfer (FRET)-based drug delivery detection system (FedEcs) capable of monitoring cargo release in vivo. Using two-photon microscopy, we demonstrate that circulating LNDs in naive mouse brain vasculature exhibit 3D real-time FRET changes, showing size-dependent stability over two hours in blood circulation. Further, in a novel nano-stroke model, dynamic intravital two-photon imaging revealed that LNDs accumulated within cerebral post-ischemic microthrombi, where they released their cargo significantly faster than in normal blood circulation. Furthermore, the blood-brain barrier (BBB) became permeable at the microclot sites thereby allowing accumulated FedEcs-LNDs to cross the BBB and deliver their cargo to the brain parenchyma. This microthrombi-associated translocation was confirmed at the ultrastructural level via volume correlative light-electron microscopy. Consequently, our FedEcs represents a novel tool to quantitatively study the biodistribution and cargo release of nanocarriers at high resolution in real time. By enabling us to resolve passive targeting mechanisms post-stroke, - specifically, accumulation, degradation and extravasation via post-stroke microthrombi - this system could significantly enhance the translational validation of nanocarriers for future treatments of brain diseases.

neuroscience↗

bioRxiv2023

Continued dysfunction of capillary pericytes promotes no-reflow after experimental stroke in vivo

Incomplete reperfusion of the microvasculature ("no-reflow") after ischemic stroke damages salvageable brain tissue. Previous ex-vivo studies suggest pericytes are vulnerable to ischemia and may exacerbate no-reflow, but the viability of pericytes and their association with no-reflow remains underexplored in vivo. Using longitudinal in vivo 2-photon single-cell imaging over seven days we show 87% of pericytes constrict during cerebral ischemia, remain constricted post-reperfusion and 50% of the pericyte population are acutely damaged. Moreover, we reveal ischemic pericytes are fundamentally implicated in capillary no-reflow by limiting and arresting blood flow within the first 24 hours post-stroke. Despite sustaining acute membrane damage, we observe up to 80% of cortical pericytes survive ischemia, upregulate unique transcriptomic profiles and replicate. Finally, we demonstrate delayed recovery of capillary diameter by ischemic pericytes after reperfusion predicts vessel reconstriction in the sub-acute phase of stroke. Cumulatively, these findings demonstrate surviving cortical pericytes remain both viable and promising therapeutic targets to counteract no-reflow after ischemic stroke.

neuroscience↗