Oxygen-Glucose Deprived Peripheral Blood Mononuclear Cells Protect Against Ischemic Stroke

From mechanism to classification: Understanding a novel model of cerebral small vessel disease

The studies explored cerebral small vessel disease (cSVD), emphasizing the need for precise classification to improve prevention and intervention strategies. Kang et al. introduced an intra-cisterna-magna bevacizumab injection (ICM-BI) model in mice, which induced tight junction loss, microbleeds, and amyloid deposits. However, bevacizumab's low affinity for murine vascular endothelial growth factor raises questions about its mechanism of action, suggesting potential off-target effects. While most cSVD models mimic arteriolosclerosis (type 1) or genetic variants (types 2 and 3), the ICM-BI model represents a novel approach to studying immune-mediated cSVD (type 4). The complexity and variability of cSVD remain significant research challenges.

Utility of Cerebrospinal Fluid Transferrin Receptor per Ferritin Ratio in Progressive Supranuclear Palsy

BACKGROUND

Progressive supranuclear palsy (PSP) is a major atypical parkinsonism. Because diagnosis based on the cardinal clinical features is often difficult, misdiagnosis with Parkinson's disease (PD) and multiple system atrophy (MSA) is common in PSP patients. Iron metabolism genes are reportedly involved in tau-accumulating neuronal cell death and ferroptosis in PSP, which is more severe than PD and MSA. The validity of transferrin receptor (TfR) expression as a biomarker of ferroptosis was also demonstrated.

OBJECTIVE

We investigated whether TfR and the TfR to ferritin ratio in the cerebrospinal fluid (CSF) is a diagnostic biomarker of PSP.

METHODS

This study included 2 independent retrospective CSF cohorts comprising patients, respectively, from Niigata University and a multicenter memory clinic, consisting of patients with PSP, PD, and MSA. All patients were classified as clinically probable or higher based on the Society of Movement Disorders Criteria. TfR and ferritin levels in the CSF were measured using Luminex assay.

RESULTS

The levels of TfR in patients with PSP were higher than those in patients with PD and MSA in cohort 1 (PSP: N = 16, PD: N = 13, MSA: N = 20). The TfR to ferritin ratio in patients with PSP was significantly higher than that in patients with MSA. Subsequently, we validated these results in cohort 2 (PSP: N = 23, MSA: N = 6). The TfR to ferritin ratio was significantly higher in patients with PSP than in those with MSA.

CONCLUSIONS

The CSF TfR to transferrin ratio was elevated in patients with PSP. These results should be validated in a larger cohort of patients.

Oxygen-glucose-deprived peripheral blood mononuclear cells act on hypoxic lesions after ischemia-reperfusion injury

BACKGROUND

Despite advances in reperfusion therapies, ischemic stroke remains a major cause of long-term disability due to residual hypoxic lesions persisting after macrovascular reperfusion. These residual hypoxic lesions, caused by microvascular dysfunction, represent an important therapeutic target. We previously demonstrated that oxygen-glucose-deprived peripheral blood mononuclear cells (OGD-PBMCs) migrate to ischemic brain regions and promote functional recovery after stroke. This recovery occurs through mechanisms involving hypoxia-inducible factor-1α, exosomal miR-155-5p, and vascular endothelial growth factor (VEGF). However, it remains unclear whether OGD-PBMCs target hypoxic regions.

METHODS

We evaluated cerebral blood flow using a laser speckle flow imaging system. Next, we utilized pimonidazole to investigate the presence of hypoxic lesions after ischemia-reperfusion injury in a rat suture occlusion model in immunohistochemical analyses. We also compared levels of a cell surface receptor in human PBMCs by flow cytometric analysis under normoxic and OGD conditions.

RESULTS

We found persistent pimonidazole-positive hypoxic lesions at 10- and 28-days post-reperfusion despite restored gross cerebral perfusion. Treatment with the C-X-C motif chemokine receptor 4 (CXCR4) inhibitor AMD3100 before and after OGD-PBMCs administration reduced the number of OGD-PBMCs in the brain parenchyma compared to the control group (P = 0.018). Administered OGD-PBMCs localized within these hypoxic regions via the stromal cell-derived factor-1/CXCR4 chemotactic axis. OGD-PBMCs enhanced VEGF expression, specifically within hypoxic lesions, compared to the phosphate-buffered saline group (P < 0.01). Furthermore, OGD-PBMCs reduced the number of pimonidazole-positive hypoxic cells in the ischemic core on 28 days. These findings demonstrate that OGD-PBMCs selectively migrate to and modulate the microenvironment of hypoxic lesions following cerebral ischemia-reperfusion injury.

CONCLUSION

Targeting these residual hypoxic regions may underline the therapeutic effects of OGD-PBMC treatment and represent a promising strategy for improving stroke recovery despite successful recanalization.

LncRNA MSTRG.13,871/miR155-5p/Grip1 network involved in the post-cardiac arrest brain injury

Post-cardiac arrest brain (PCABI) is a severe medical condition characterized by a significant risk of neurological impairment and death. Nevertheless, the specific process and essential molecules responsible for its development are not fully understood. Profiling based on competing endogenous RNAs (ceRNA) has been implicated in the onset and progression of neurological disorders, yet its role in PCABI remains unclear. In this study, we performed RNA transcriptome sequencing analysis to identify differentially expressed genes in the rat model for cardiac arrest and cardiopulmonary resuscitation (CA/CPR). A hub ceRNA regulatory network was constructed using miRWalk 2.0 and Cytohubba plug-in in Cytoscape. Subsequently, real-time quantitative reverse transcription-polymerase chain reaction and dual-luciferase activity assays validated MSTRG.13,871, miR-155-5p, and Grip1 as differentially expressed in CA/CPR group, with MSTRG.13,871 capable of targeting both miR-155-5p and Grip1. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed the ceRNA network enrichment in immunoregulation mechanisms such as mitochondrion, apoptotic process, and negative regulation cell death. Our research highlights the mechanism of PCABI by revealing a critical regulatory axis involving MSTRG.13,871-miR-155-5p-Grip1 in the hippocampus CA1 region after CA/CPR in rats, proposing a feasible controlled mechanism, which may serve as a theoretical basis for designing innovative therapies.

X-irradiated umbilical cord blood cells retain their regenerative effect in experimental stroke

Although regenerative therapy with stem cells is believed to be affected by their proliferation and differentiation potential, there is insufficient evidence regarding the molecular and cellular mechanisms underlying this regenerative effect. We recently found that gap junction-mediated cell-cell transfer of small metabolites occurred very rapidly after stem cell treatment in a mouse model of experimental stroke. This study aimed to investigate whether the tissue repair ability of umbilical cord blood cells is affected by X-irradiation at 15 Gy or more, which suppresses their proliferative ability. In this study, X-irradiated mononuclear (XR) cells were prepared from umbilical cord blood. Even though hematopoietic stem/progenitor cell activity was diminished in the XR cells, the regenerative activity was surprisingly conserved and promoted recovery from experimental stroke in mice. Thus, our study provides evidence regarding the possible therapeutic mechanism by which damaged cerebrovascular endothelial cells or perivascular astrocytes may be rescued by low-molecular-weight metabolites supplied by injected XR cells in 10 min as energy sources, resulting in improved blood flow and neurogenesis in the infarction area. Thus, XR cells may exert their tissue repair capabilities by triggering neo-neuro-angiogenesis, rather than via cell-autonomous effects.

ULK1 confers neuroprotection by regulating microglial/macrophages activation after ischemic stroke

Microglial activation and autophagy play a critical role in the progression of ischemic stroke and contribute to the regulation of neuroinflammation. Unc-51-like kinase 1 (ULK1) is the primary autophagy kinase involved in autophagosome formation. However, the impact of ULK1 on neuroprotection and microglial activation after ischemic stroke remains unclear. In this study, we established a photothrombotic stroke model, and administered SBI-0206965 (SBI), an ULK1 inhibitor, and LYN-1604 hydrochloride (LYN), an ULK1 agonist, to modulate ULK1 activity in vivo. We assessed sensorimotor deficits, neuronal apoptosis, and microglial/macrophage activation to evaluate the neurofunctional outcome. Immunofluorescence results revealed ULK1 was primarily localized in the microglia of the infarct area following ischemia. Upregulating ULK1 through LYN treatment significantly reduced infarct volume, improved motor function, promoted the increase of anti-inflammatory microglia. In conclusion, ULK1 facilitated neuronal repair and promoted the formation of anti-inflammatory microglia pathway after ischemic injury.

Microglia and Stem Cells for Ischemic Stroke Treatment-Mechanisms, Current Status, and Therapeutic Challenges

Ischemic stroke is one of the major causes of death and disability. Since the currently used treatment option of reperfusion therapy has several limitations, ongoing research is focusing on the neuroprotective effects of microglia and stem cells. By exerting the bystander effect, secreting exosomes and forming biobridges, mesenchymal stem cells (MSCs), neural stem cells (NSCs), induced pluripotent stem cells (iPSCs), and multilineage-differentiating stress-enduring cells (Muse cells) have been shown to stimulate neurogenesis, angiogenesis, cell migration, and reduce neuroinflammation. Exosome-based therapy is now being extensively researched due to its many advantageous properties over cell therapy, such as lower immunogenicity, no risk of blood vessel occlusion, and ease of storage and modification. However, although preclinical studies have shown promising therapeutic outcomes, clinical trials have been associated with several translational challenges. This review explores the therapeutic effects of preconditioned microglia as well as various factors secreted in stem cell-derived extracellular vesicles with their mechanisms of action explained. Furthermore, an overview of preclinical and clinical studies is presented, explaining the main challenges of microglia and stem cell therapies, and providing potential solutions. In particular, a highlight is the use of novel stem cell therapy of Muse cells, which bypasses many of the conventional stem cell limitations. The paper concludes with suggestions for directions in future neuroprotective research.

Regeneration of the cerebral cortex by direct chemical reprogramming of macrophages into neuronal cells in acute ischemic stroke

Theoretically, direct chemical reprogramming of somatic cells into neurons in the infarct area represents a promising regenerative therapy for ischemic stroke. Previous studies have reported that human fibroblasts and astrocytes transdifferentiate into neuronal cells in the presence of small molecules without introducing ectopic transgenes. However, the optimal combination of small molecules for the transdifferentiation of macrophages into neurons has not yet been determined. The authors hypothesized that a combination of small molecules could induce the transdifferentiation of monocyte-derived macrophages into neurons and that the administration of this combination may be a regenerative therapy for ischemic stroke because monocytes and macrophages are directly involved in the ischemic area. Transcriptomes and morphologies of the cells were compared before and after stimulation using RNA sequencing and immunofluorescence staining. Microscopic analyses were also performed to identify cell markers and evaluate functional recovery by blinded examination following the administration of small molecules after ischemic stroke in CB-17 mice. In this study, an essential combination of six small molecules [CHIR99021, Dorsomorphin, Forskolin, isoxazole-9 (ISX-9), Y27632, and DB2313] that transdifferentiated monocyte-derived macrophages into neurons in vitro was identified. Moreover, administration of six small molecules after cerebral ischemia in model animals generated a new neuronal layer in the infarct cortex by converting macrophages into neuronal cells, ultimately improving neurological function. These results suggest that altering the transdifferentiation of monocyte-derived macrophages by the small molecules to adjust their adaptive response will facilitate the development of regenerative therapies for ischemic stroke.