Biology subjects

Ardaya, M.

Publications and source records attributed to Ardaya, M..

3 recordsLinked to original sources

bioRxiv2026

Reperfusion reshapes the temporal evolution of neurovascular injury after ischemic stroke

Reperfusion is the cornerstone of acute ischemic stroke treatment, yet how it reshapes the temporal trajectory of neurovascular injury beyond the acute phase remains unclear. Here, we developed permanent (pStroke) and transient (tStroke) cortical ischemia mouse models compatible with longitudinal in vivo two-photon imaging to investigate the evolution of neurovascular injury following ischemia and reperfusion. Although reperfusion markedly reduced acute infarct development and neuronal loss, it failed to restore neurovascular homeostasis. Longitudinal two-photon imaging of ischemic mice revealed neuronal hyperexcitability and aberrant network synchronization, concomitant with impaired vascular remodeling and sustained vascular leakage following reperfusion. Histological analyses further demonstrated progressive neurodegeneration, chronic microglial activation and persistent alterations in the neurovascular unit despite improved preservation of brain tissue during the acute phase. Analysis of dextran permeability revealed size-selective BBB dysfunction, indicating that reperfusion induces prolonged impairment of vascular barrier properties rather than complete vascular recovery. Together, our findings demonstrate that reperfusion might reshape the temporal evolution of ischemic brain injury by limiting acute tissue damage while also promoting chronic neurovascular dysfunction, identifying persistent vascular instability as a potential therapeutic target for improving long-term recovery after ischemic stroke.

neuroscience↗

bioRxiv2025

Viral-mediated fluorescent labeling of hyaluronan reveals extracellular matrix dynamics in the mouse brain in vivo

The extracellular matrix (ECM) of the brain is primarily composed of the glycan polymer hyaluronan (HA), a core scaffold that nucleates proteoglycans forming a self-assembled matrix that acts as structural framework and signaling hub. Since most of the neural matrix is composed of sugars, development of genetically encoded tags has been limited. Therefore, although several staining protocols exist for ECM in fixed tissue, there are no reliable matrix labels for live imaging. Here we report a viral-mediated fluorescent probe that binds to HA and labels the mouse brain ECM. The vector encodes the HA binding domain from neurocan fused to GFP and an externalization tag (AAV-Ncan-GFP), enabling transduced cells to secrete the fluorescent hyalectan into the extracellular space, thereby labeling HA. We demonstrate stable probe expression in organotypic brain slices, as well as in vivo in the mouse cortex, where it labels both perineuronal nets and interstitial matrix. We validate HA labeling through colocalization with HABP and sensitivity to hyaluronidase, and confirm the probes extracellular localization by shadow imaging. As a proof of concept, we combine AAV-Ncan-GFP with dendritic spine imaging ex vivo and calcium transient imaging in vivo, providing a real-time map of local ECM alongside neural function. The probe enables time-lapse imaging of ECM dynamics in live mice, facilitating longitudinal studies across a wide range of timescales, from minutes to days. The results establish AAV-Ncan-GFP as a valuable tool for real-time observation of brain ECM and a promising resource to explore ECM dynamics and brain function in vivo.

neuroscience↗

bioRxiv2023

Gliogenesis from the subventricular zone modulates the extracellular matrix at the glial scar after brain ischemia

Activation of the subventricular zone (SVZ) following cerebral ischemia is one of the brains early responses to counteract neuron loss and minimize tissue damage. Impaired brain regions communicate with the SVZ through various chemotactic signals that promote cell migration and differentiation, primarily involving neural stem cells (NSC), neuroblasts, or glioblasts. However, the activation of gliogenesis and the role of newly formed astrocytes in the post-ischemic scenario remain subjects of debate. We have previously demonstrated that adenosine release after brain ischemia prompts the SVZ to generate new astrocytes. Here, we used transient brain ischemia in mice to identify the cellular origin of these astrocytes within the SVZ neurogenic niche and to investigate their role in the pathological process. By combining immunofluorescence, BrdU-tracing, and genetic cell labeling, we tracked the migration of newborn astrocytes, positive for the proteoglycan marker Thbs4, from the dorsal and medial SVZ to the perilesional barrier surrounding the ischemic core, known as the "glial scar". We found that these Thbs4-positive astrocytes modulate the dense extracellular matrix at the lesion border by both synthesizing and degrading hyaluronan. We also show that while the accumulation of hyaluronan at the lesion site is sufficient to recruit newborn astrocytes, its degradation at the SVZ correlates with gliogenesis. These findings suggest that newborn astrocytes could be a promising pharmacological target for modulating the glial scar after brain ischemia and facilitate tissue regeneration.

neuroscience↗