Heng Zhao

Stroke may disrupt brain fluid and waste clearance pathways, including the glymphatic and meningeal lymphatic systems, across ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage. This review synthesizes current evidence on post-stroke alterations in these pathways, with emphasis on subtype-specific mechanisms, the distinction between experimental and human evidence, and the strengths and limitations of available imaging approaches. Experimental studies suggest that ischemic stroke may involve hyperacute perivascular cerebrospinal fluid influx followed by impaired glymphatic transport, that intracerebral hemorrhage is more closely linked to blood-product-related disruption of glymphatic and meningeal lymphatic drainage, and that subarachnoid hemorrhage may involve combined glymphatic and meningeal lymphatic failure. We further review in vivo imaging methods, particularly magnetic resonance imaging (MRI) approaches such as dynamic contrast-enhanced MRI, diffusion tensor image analysis along the perivascular space, and structural perivascular space imaging, and we discuss their biological directness and translational limitations. Across modalities, the most direct evidence still comes mainly from experimental tracer-based MRI and selected intrathecal contrast-enhanced MRI studies in humans. Among stroke subtypes, subarachnoid hemorrhage currently provides the most direct human MRI evidence of combined clearance-pathway dysfunction, whereas most other human stroke data rely on indirect surrogate markers, especially diffusion tensor image analysis along the perivascular space. Accordingly, current clearance-pathway imaging should be regarded primarily as a mechanistic and early translational research tool rather than a validated clinical biomarker. Importantly, most proposed links between molecular mechanisms, imaging readouts, and clinical outcomes remain inferential and require prospective validation in human stroke cohorts. Prospective human studies are needed to test whether targeting brain clearance pathways improves post-stroke recovery and cognition.

Ischemic stroke is a major cause of death and long-term disability worldwide, in which oxidative stress and neuroinflammation contribute substantially to secondary neuronal injury. Edaravone (EDA), a clinically approved free radical scavenger, has shown neuroprotective potential in ischemic stroke; however, its therapeutic efficacy is hindered by a short half-life, limited blood-brain barrier (BBB) penetration, and off-target effects. To overcome these limitations, we developed a biomimetic nanoplatform by encapsulating EDA within a nanoparticle core and coating it with membranes derived from M2-polarized microglia (EDA@M2 NPs). This hybrid system integrates potent antioxidant activity with inflammation-targeting and immunomodulatory capabilities. In a mouse model of middle cerebral artery occlusion (MCAO), EDA@M2 NPs selectively accumulated in the ischemic hemisphere, significantly reduced infarct volume, suppressed neuronal apoptosis, and improved neurological outcomes. Mechanistically, the nanoplatform not only scavenged excessive reactive oxygen species (ROS) but also reprogrammed microglia from a pro-inflammatory M1 phenotype toward an anti-inflammatory M2 phenotype, thereby mitigating secondary neuroinflammation. By integrating targeted delivery, oxidative stress attenuation, and immune microenvironment remodeling, this combinatorial therapeutic strategy markedly enhanced neuroprotection after ischemic stroke. Our findings demonstrate the translational promise of biomimetic nanotherapeutics for effective ischemic brain injury intervention.

Post-stroke depression (PSD) is one of the most common and debilitating neuropsychiatric complications following stroke, with a prevalence ranging from 10% to 40%. Despite its high incidence and profound impact on recovery and quality of life, current treatment options remain suboptimal. Although selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors are widely prescribed, their limited efficacy and potential safety concerns underscore the urgent need for more effective and targeted therapeutic strategies. Moreover, the underlying pathophysiological mechanisms of PSD are still not fully elucidated. Remote ischemic conditioning (RIC), a non-invasive neuroprotective intervention involving transient, repetitive ischemia-reperfusion cycles in distant limbs, has emerged as a promising therapeutic strategy. RIC activates endogenous protective pathways through neural, humoral, and immune mechanisms, potentially modulating key pathophysiological processes implicated in PSD, including neuroinflammation, impaired neuroplasticity and cerebrovascular dysfunction. This review synthesizes current evidence on the shared mechanisms between PSD and “classical” depression, highlights the neuroprotective effects of RIC, and proposes mechanistic hypotheses for RIC’s potential role in mitigating PSD. Furthermore, we discuss the clinical and research implications, outlining future directions to optimize RIC as a viable strategy for improving neuropsychiatric outcomes in stroke survivors.

Introduction: Mild ischemic stroke accounts for over half of all stroke cases, yet how peripheral immune responses evolve over time—and how they differ by infarct location—remains poorly defined. Methods: Peripheral blood was collected from ten patients with mild ischemic stroke and five matched controls at days 1, 3, and 7 after onset. Patients were stratified by cortical or subcortical infarction. High-dimensional mass cytometry was used to characterize immune cell composition and immune checkpoint expression. Results: Subcortical infarction was associated with sustained expansion of classical monocytes, persistent reduction of intermediate monocytes, and delayed PD-1/PD-L1 regulatory signaling, indicating prolonged myeloid-driven inflammation. In contrast, cortical infarction exhibited a more balanced monocyte profile and earlier PD-1 upregulation on dendritic cells and classical monocytes. CD4⁺ and CD8⁺ T-cell subsets showed distinct, location-dependent dynamics: cortical infarction induced earlier modulation of memory and regulatory phenotypes, whereas subcortical infarction produced slower but more persistent shifts. CCR5-defined CD8⁺ T-cell subsets also differed markedly, with subcortical infarction showing enrichment of CCR5⁺ effector cells, reduced checkpoint expression, and contraction of the CCR5⁻ compartment. Discussion: Peripheral immune remodeling in mild ischemic stroke displays clear infarct location–specific trajectories. These findings highlight infarct topology as a critical determinant of post-stroke immune regulation and support the development of location-adapted immunomodulatory strategies.

Objective: The “blend sign” is a critical CT imaging marker for predicting hematoma expansion in intracerebral hemorrhage (ICH). This study aimed to elucidate its underlying pathological mechanisms by comparing proteomic profiles between hyperdense and hypodense regions within the hematoma. Methods: Hematoma samples from nine ICH patients exhibiting the blend sign were obtained via minimally invasive puncture. Isotope‐labeled proteomics and bioinformatic analyses were performed to identify differentially expressed proteins (DEPs), which were further validated by Western blotting and ELISA. Results: A total of 77 DEPs were identified, including 66 upregulated and 11 downregulated in hyperdense regions compared to hypodense areas. Functional enrichment analysis revealed significant involvement of inflammatory responses, apoptosis, oxidative stress, and metabolic dysregulation. Notably, cytochrome C, growth‐associated protein 43 (GAP43), and tau were markedly upregulated in hyperdense regions. Conclusions: The blend sign is associated with region‐specific molecular changes involving inflammation, apoptosis, and metabolic alterations. These findings provide mechanistic insights into hematoma heterogeneity and lay a foundation for future studies exploring their role in hematoma expansion and clinical outcomes.

Background Endovascular therapy within 24 hours of stroke onset is effective and safe, but successful recanalization does not always give favorable outcomes. Ischemic postconditioning (IPostC), a reperfusion strategy with potential neuroprotective effects, has been extensively studied in preclinical models, but its impact in humans remains unclear. Building on a previous dose escalation study, we aimed to investigate the effect of in situ IPostC on infarct volume in patients with acute ischemic stroke following mechanical thrombectomy. Methods This prospective, externally controlled, non-randomized trial compared in situ IPostC (four cycles of 2 min of occlusion/2 min of release) plus thrombectomy with contemporaneous external controls receiving thrombectomy alone. Propensity score matching (PSM) minimized selection bias. The primary outcome was infarct volume at 72 hours post-thrombectomy. Deep infarct volume was also compared in post hoc analyses. Peripheral blood was collected 24 hours post-procedure to assess leukocyte populations, with mononuclear cell subsets characterized by flow cytometry. Serum inflammatory biomarkers were also measured in both groups. Results After 1:1 PSM, 19 patients per group were analyzed. The IPostC group showed significantly less deep infarct volume progression (median 2.3 vs 4.7 mL; P=0.045), lower interleukin 6 levels (median 26.4 vs 32.6 pg/mL; P=0.032), higher Th/CTL ratios (median 2.04 vs 1.65; PConclusions In situ IPostC following thrombectomy for large vessel occlusion stroke may be associated with reduced deep infarct volume progression and favorable immunomodulatory effects, warranting further validation in phase II trials. Trial registration ClinicalTrials.gov NCT05909982.

Objective: Aging has a profound impact on the pathophysiology of ischemic stroke and the effectiveness of therapeutic interventions. This study aims to evaluate the therapeutic efficacy of programmed death‐ligand 1 (PD‐L1) monoclonal antibody (mAb) in modulating immune responses and neurovascular repair following ischemic stroke, with a focus on age‐dependent differences.Methods: Young and aged mice were subjected to middle cerebral artery occlusion (MCAO) followed by PD‐L1 mAb treatment. RNA sequencing, immunofluorescence, and molecular analyses were employed to assess immune modulation, blood–brain barrier (BBB) integrity, and functional recovery.Results: RNA sequencing revealed significant differential gene expression in ischemic brain tissues, with CD274 (PD‐L1) prominently upregulated among immune checkpoint‐related genes in young mice. Immunofluorescence confirmed PD‐L1 expression in microglia/macrophages, with significantly higher upregulation in young mice. PD‐L1 mAb treatment showed superior efficacy in young mice, significantly reducing infarct volume, enhancing neurological recovery, and preserving BBB integrity through greater upregulation of tight junction proteins such as ZO‐1, Claudin‐5, and Occludin compared to aged mice. It also more effectively reduced neuroinflammation, apoptosis, and pro‐inflammatory cytokines (TNF‐α, IL‐1β), eliciting stronger spleen responses in young mice. These findings underscore the age‐dependent advantages of PD‐L1‐targeted therapies for ischemic stroke recovery.Conclusions: PD‐L1 plays a critical role in ischemic stroke recovery, with PD‐L1 mAb treatment demonstrating age‐dependent therapeutic efficacy by enhancing BBB integrity, reducing neuroinflammation and apoptosis, and modulating peripheral immune responses.

AIM: To explore the immune cell infiltration and molecular mechanisms of retinal ischemia-reperfusion injury (RIRI) to identify potential therapeutic targets. METHODS: In the bulk RNA-seq analysis, This study performed differential gene expression analysis, weighted gene co-expression network analysis, and protein-protein interaction network analysis to identify hub genes. QuanTIseq was used to determine the composition of infiltrating immune cells. Following the identification of hub genes, single-cell RNA-seq analysis was employed to pinpoint the specific immune cell types expressing these hub genes. Cell-cell communication analysis to explore signaling pathways and interactions between immune cells was further performed. Finally, the expression of these key immune regulators in vivo using quantitative real-time polymerase chain reaction (qRT-PCR) was validated. RESULTS: Bulk RNA-seq analysis identified Stat2, Irf7, Irgm1, Igtp, Parp9, Irgm2, Nlrc5, and Tap1 as hub genes, with strong correlations to immune cell infiltration. Single-cell RNA-seq analysis further revealed six immune cell clusters, showing Irf7 predominantly in microglia and Tap1 in dendritic cells (DCs). And cell-cell communication analysis showed that microglia and DCs play central roles in coordinating immune activity. qRT-PCR validated the upregulation of these genes. CONCLUSION: In the acute phase of RIRI, Irf7 and Tap1 may be the potential therapeutic targets to reduce inflammation and promote neurological function recovery.