Angiogenesis: a harmonized target for recovery after stroke

Effect of BMSCs overexpressing intelectin-1 on angiogenesis in rats with cerebral infarction

Background

Cerebral infarction (CI) is a common and frequently occurring acute neurological disease in clinical practice, posing a severe threat to human health. CI results from various causes leading to local cerebral tissue ischemia and hypoxia due to vascular occlusion and impaired blood supply, which in turn leads to tissue necrosis and corresponding clinical manifestations of neurological deficits. However, to date, treatment options for cerebral infarction remain limited. Therefore, it is crucial to rapidly establish collateral circulation to compensate for the occluded vessels and restore blood flow perfusion.

Objective

To assess the effect of bone marrow mesenchymal cells transfected with intelectin-1 (Itln-1) gene on the angiogenesis and apoptosis of CI.

Method

Lentiviral-mediated transfection of the Itln-1 gene into bone marrow mesenchymal stem cells (BMSCs) was performed, followed by intravenous injection into rats with CI through the tail vein. The volume of the CI, capillary density, and apoptotic cells were detected.

Results

With the increase of AKT and eNOS phosphorylation levels, BMSCs with overexpression Itln-1 gene could significantly promote angiogenesis and reduce the infarct volume in the ischemic penumbra. Meanwhile, the ratio of Bcl-2/Bax increased, and apoptotic cells decreased.

Conclusion

The overexpression of Itln-1 can effectively promote CI angiogenesis and inhibit cell apoptosis than transplantation of Itln-1 gene or MSCS alone.

Exosome-based therapies and biomarkers in stroke: Current advances and future directions

Stroke is a challenging neurological condition caused by interrupted blood flow to the brain and presents substantial global health concerns due to its prevalence and limited treatment options. Exosomes, tiny vesicles released by cells, are gaining attention for their potential in targeted drug delivery and as diagnostic and therapeutic biomarkers for stroke. This article outlines recent advances in exosome-based drug delivery systems and examines their application in managing stroke. Stroke presents with diverse symptoms depending on the brain region affected, and current treatments primarily aim to restore blood flow and manage risk factors. Exosomes exhibit a unique structure and composition and contain bioactive molecules. Their ability to cross the blood-brain barrier and target specific cells makes them promising candidates for precise drug delivery in stroke therapy. Exosomes contribute extensively to stroke pathophysiology and present considerable therapeutic promise by promoting neuroprotection and assisting in brain repair mechanisms. They can be engineered to carry various therapeutic substances, such as small molecules, enabling highly specific targeted delivery. Furthermore, the molecular compositions of exosomes reflect the pathological changes observed in stroke, indicating their potential use as biomarkers for early diagnosis, monitoring of disease progression, and creating individualized treatment strategies. Despite promising developments, challenges remain in optimizing exosome production, purification, and cargo loading. Further investigations into their biological mechanisms and clinical validation are crucial for translating their potential into tangible benefits for patients. This article highlights recent advances and future prospects in exosome research, underscoring their application as novel diagnostic and therapeutic tools in stroke management.

Exosomes: the next-generation therapeutic platform for ischemic stroke

Current therapeutic strategies for ischemic stroke fall short of the desired objective of neurological functional recovery. Therefore, there is an urgent need to develop new methods for the treatment of this condition. Exosomes are natural cell-derived vesicles that mediate signal transduction between cells under physiological and pathological conditions. They have low immunogenicity, good stability, high delivery efficiency, and the ability to cross the blood-brain barrier. These physiological properties of exosomes have the potential to lead to new breakthroughs in the treatment of ischemic stroke. The rapid development of nanotechnology has advanced the application of engineered exosomes, which can effectively improve targeting ability, enhance therapeutic efficacy, and minimize the dosages needed. Advances in technology have also driven clinical translational research on exosomes. In this review, we describe the therapeutic effects of exosomes and their positive roles in current treatment strategies for ischemic stroke, including their anti-inflammation, anti-apoptosis, autophagy-regulation, angiogenesis, neurogenesis, and glial scar formation reduction effects. However, it is worth noting that, despite their significant therapeutic potential, there remains a dearth of standardized characterization methods and efficient isolation techniques capable of producing highly purified exosomes. Future optimization strategies should prioritize the exploration of suitable isolation techniques and the establishment of unified workflows to effectively harness exosomes for diagnostic or therapeutic applications in ischemic stroke. Ultimately, our review aims to summarize our understanding of exosome-based treatment prospects in ischemic stroke and foster innovative ideas for the development of exosome-based therapies.

Extracellular Vesicles as a Potential Therapy for Stroke

Although thrombolytic therapy has enjoyed relative success, limitations remain, such as a narrow therapeutic window and inconsistent efficacy. Consequently, there is a pressing need to develop novel therapeutic approaches. In recent years, extracellular vesicles (EVs) have garnered increasing attention as a potential alternative to stem cell therapy. Because of their ability to cross the blood-brain barrier and exert neuroprotective effects in cerebral ischemia and hemorrhage, the exploration of EVs for clinical application in stroke treatment is expanding. EVs are characterized by high heterogeneity, with their composition closely mirroring that of their parent cells. This property enables EVs to distinguish between cerebral ischemia and hemorrhage, thus facilitating a more rapid and accurate diagnosis. Additionally, EVs can be engineered to carry specific molecules, such as miRNAs, targeting them to specific cells, potentially enhancing the therapeutic outcome and improving stroke prognosis. In this review, we will also explore the methodologies for the isolation and extraction of EVs, critically evaluating the advantages and disadvantages of various commonly employed separation techniques. Furthermore, we will briefly address current EV preservation and administration methods, providing a comprehensive overview of the state of EV-based therapies in stroke treatment.

Effects of FGF-related gene polymorphisms on cerebral infarction in patients treated with direct oral anticoagulants

BACKGROUND

The development of cerebral infarction is multifactorial, including both environmental and genetic factors. This study assessed the association between fibroblast growth factor (FGF)-related gene polymorphisms and the incidence of cerebral infarction among patients on direct oral anticoagulants (DOACs).

METHODS

Patients over 18 years old with atrial fibrillation who were receiving DOACs for cerebral infarction prevention at Ewha Womans University Mokdong Hospital and Ewha Womans University Seoul Hospital were enrolled in this analysis. Twenty-one single nucleotide polymorphisms (SNPs) from FGF1, FGF2, and FGFR1 were examined. In multivariable logistic regression analysis, three models (Model I: demographic factors only, Model II: demographic factors and genetic factors, and Model III: genetic factors and the CHA2DS2-VASc score) were constructed to identify the risk factors related to cerebral infarction.

RESULTS

Among the 536 candidate patients, 21 (3.9 %) experienced cerebral infarction while taking DOACs. From Model I and Model II, age ≥ 75 years and previous thromboembolic event history increased the risk of cerebral infarction. For genetic factors in Model II and III, FGF1 rs1596776 GG, FGFR1 rs6996321 AA, and FGFR1 rs7012413 TT genotypes were associated with a higher risk of cerebral infarction. The area under the receiver operating curve increased from 0.747 (Model I) to 0.822 (Model II) by adding genetic factors, demonstrating better model performance.

CONCLUSIONS

This study uncovered the association between FGF-related gene polymorphisms and cerebral infarction among patients with atrial fibrillation undergoing DOAC therapy.

CircRNA: A new target for ischemic stroke

Ischemic stroke, a clinical emergency and disease with a poor prognosis, has a negative impact on the survival index of patients. It is frequently precipitated by a multitude of risk factors, including trauma. Currently, there is a paucity of predictive indicators for early intervention. As stable and abundant RNA in the body, circRNAs play a regulatory role in miRNAs and proteins, which affect the occurrence and development of diseases. Moreover, circRNAs can serve as predictors of clinical diseases. Several studies have demonstrated that circRNAs play pivotal roles in numerous aspects of ischemic stroke. Consequently, circRNAs have emerged as key areas of investigation in the field of ischemic stroke.

Large Scale in vivo Acquisition, Segmentation and 3D Reconstruction of Cortical Vasculature using μ Doppler Ultrasound Imaging

The brain is composed of a dense and ramified vascular network of arteries, veins and capillaries of various sizes. One way to assess the risk of cerebrovascular pathologies is to use computational models to predict the physiological effects of reduced blood supply and correlate these responses with observations of brain damage. Therefore, it is crucial to establish a detailed 3D organization of the brain vasculature, which could be used to develop more accurate in silico models. To this end, we have adapted our functional ultrasound imaging platform, previously designed for recording large scale activity, to enable rapid and reproducible acquisition, segmentation and reconstruction of the cortical vasculature. For the first time, it allows us to digitize the cortical ∼ 100 - μ m3 spatial resolution. Unlike most available strategies, our approach can be performed in vivo within minutes. Moreover, it is easy to implement since it requires neither exogenous contrast agents nor long post-processing time. Therefore, we performed a cortex-wide reconstruction of the vasculature and its quantitative analysis, including i) classification of descending arteries versus ascending veins in more than 1500 vessels/animal and ii) rapid estimation of their length. Importantly, we confirmed the relevance of our approach in a model of cortical stroke, which allows rapid visualization of the ischemic lesion. This development contributes to extending the capabilities of ultrasound neuroimaging to better understand cerebrovascular pathologies such as stroke, vascular cognitive impairment and brain tumors, and is highly scalable for the clinic.

The Role of Endothelial L-PGDS in the Pro-Angiogenic and Anti-Inflammatory Effects of Low-Dose Alcohol Consumption

Light alcohol consumption (LAC) may reduce the incidence and improve the prognosis of ischemic stroke. Recently, we found that LAC promotes cerebral angiogenesis and inhibits early inflammation following ischemic stroke. In addition, LAC upregulates lipocalin-type prostaglandin D2 synthase (L-PGDS) in the brain. Thus, we determined the role of endothelial L-PGDS in the protective effect of LAC. In in vitro studies, chronic exposure to low-concentration ethanol upregulated L-PGDS and significantly increased the proliferation in cultured C57BL/6J mouse brain microvascular endothelial cells (MBMVECs). AT-56, a selective L-PGDS inhibitor, abolished low-concentration ethanol exposure-induced proliferation. In in vivo studies, 8-week gavage feeding with 0.7 g/kg/day ethanol, defined as LAC, promoted cerebral angiogenesis under physiological conditions and following ischemic stroke in male C57BL/6J mice. In addition, LAC inhibited the post-ischemic expression of adhesion molecules, neutrophil infiltration, and microglial activation. AT-56 and endothelial cell (EC)-specific L-PGDS conditional knockout did not significantly alter cerebral angiogenesis and post-ischemic inflammation in the control mice but eliminated the pro-angiogenic and anti-inflammatory effects of LAC. Furthermore, EC-specific L-PGDS conditional knockout alleviated the neuroprotective effect of LAC against cerebral ischemia/reperfusion injury. These findings suggest that endothelial L-PGDS may be crucial in the pro-angiogenic and anti-inflammatory effects of LAC against ischemic stroke.

Secretome of brain microvascular endothelial cells promotes endothelial barrier tightness and protects against hypoxia-induced vascular leakage

Cell-based therapeutic strategies have been proposed as an alternative for brain and blood vessels repair after stroke, but their clinical application is hampered by potential adverse effects. We therefore tested the hypothesis that secretome of these cells might be used instead to still focus on cell-based therapeutic strategies. We therefore characterized the composition and the effect of the secretome of brain microvascular endothelial cells (BMECs) on primary in vitro human models of angiogenesis and vascular barrier. Two different secretome batches produced in high scale (scHSP) were analysed by mass spectrometry. Human primary CD34+-derived endothelial cells (CD34+-ECs) were used as well as in vitro models of EC monolayer (CMECs) and blood-brain barrier (BBB). Cells were also exposed to oxygen-glucose deprivation (OGD) conditions and treated with scHSP during reoxygenation. Protein yield and composition of scHSP batches showed good reproducibility. scHSP increased CD34+-EC proliferation, tubulogenesis, and migration. Proteomic analysis of scHSP revealed the presence of growth factors and proteins modulating cell metabolism and inflammatory pathways. scHSP improved the integrity of CMECs, and upregulated the expression of junctional proteins. Such effects were mediated through the activation of the interferon pathway and downregulation of Wnt signalling. Furthermore, OGD altered the permeability of both CMECs and BBB, while scHSP prevented the OGD-induced vascular leakage in both models. These effects were mediated through upregulation of junctional proteins and regulation of MAPK/VEGFR2. Finally, our results highlight the possibility of using secretome from BMECs as a therapeutic alternative to promote brain angiogenesis and to protect from ischemia-induced vascular leakage.

Astrocytes in functional recovery following central nervous system injuries

Astrocytes are increasingly recognised as partaking in complex homeostatic mechanisms critical for regulating neuronal plasticity following central nervous system (CNS) insults. Ischaemic stroke and traumatic brain injury are associated with high rates of disability and mortality. Depending on the context and type of injury, reactive astrocytes respond with diverse morphological, proliferative and functional changes collectively known as astrogliosis, which results in both pathogenic and protective effects. There is a large body of research on the negative consequences of astrogliosis following brain injuries. There is also growing interest in how astrogliosis might in some contexts be protective and help to limit the spread of the injury. However, little is known about how astrocytes contribute to the chronic functional recovery phase following traumatic and ischaemic brain insults. In this review, we explore the protective functions of astrocytes in various aspects of secondary brain injury such as oedema, inflammation and blood-brain barrier dysfunction. We also discuss the current knowledge on astrocyte contribution to tissue regeneration, including angiogenesis, neurogenesis, synaptogenesis, dendrogenesis and axogenesis. Finally, we discuss diverse astrocyte-related factors that, if selectively targeted, could form the basis of astrocyte-targeted therapeutic strategies to better address currently untreatable CNS disorders.

Advances in Engineered Nanoparticles for the Treatment of Ischemic Stroke by Enhancing Angiogenesis

Angiogenesis, or the formation of new blood vessels, is a natural defensive mechanism that aids in the restoration of oxygen and nutrition delivery to injured brain tissue after an ischemic stroke. Angiogenesis, by increasing vessel development, may maintain brain perfusion, enabling neuronal survival, brain plasticity, and neurologic recovery. Induction of angiogenesis and the formation of new vessels aid in neurorepair processes such as neurogenesis and synaptogenesis. Advanced nano drug delivery systems hold promise for treatment stroke by facilitating efficient transportation across the the blood-brain barrier and maintaining optimal drug concentrations. Nanoparticle has recently been shown to greatly boost angiogenesis and decrease vascular permeability, as well as improve neuroplasticity and neurological recovery after ischemic stroke. We describe current breakthroughs in the development of nanoparticle-based treatments for better angiogenesis therapy for ischemic stroke employing polymeric nanoparticles, liposomes, inorganic nanoparticles, and biomimetic nanoparticles in this study. We outline new nanoparticles in detail, review the hurdles and strategies for conveying nanoparticle to lesions, and demonstrate the most recent advances in nanoparticle in angiogenesis for stroke treatment.

Extracellular Vesicles Generated by Mesenchymal Stem Cells in Stirred Suspension Bioreactors Promote Angiogenesis in Human-Brain-Derived Endothelial Cells

Interrupted blood flow in the brain due to ischemic injuries such as ischemic stroke or traumatic brain injury results in irreversible brain damage, leading to cognitive impairment associated with inflammation, disruption of the blood-brain barrier (BBB), and cell death. Since the BBB only allows entry to a small class of drugs, many drugs used to treat ischemia in other tissues have failed in brain-related disorders. The administration of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) has shown promise in improving the functional recovery of the brain following cerebral ischemia by inducing blood vessel formation. To facilitate such a treatment approach, it is necessary to develop bioprocesses that can produce therapeutically relevant MSC-EVs in a reproducible and scalable manner. This study evaluated the feasibility of using stirred suspension bioreactors (SSBs) to scale-up the serum-free production of pro-angiogenic MSC-EVs under clinically relevant physioxic conditions. It was found that MSCs grown in SSBs generated EVs that stimulated angiogenesis in cerebral microvascular endothelial cells, supporting the use of SSBs to produce MSC-EVs for application in cerebral ischemia. These properties were impaired at higher cell confluency, outlining the importance of considering the time of harvest when developing bioprocesses to manufacture EV populations.

Aberrant cortical activity, functional connectivity, and neural assembly architecture after photothrombotic stroke in mice

Despite substantial progress in mapping the trajectory of network plasticity resulting from focal ischemic stroke, the extent and nature of changes in neuronal excitability and activity within the peri-infarct cortex of mice remains poorly defined. Most of the available data have been acquired from anesthetized animals, acute tissue slices, or infer changes in excitability from immunoassays on extracted tissue, and thus may not reflect cortical activity dynamics in the intact cortex of an awake animal. Here, in vivo two-photon calcium imaging in awake, behaving mice was used to longitudinally track cortical activity, network functional connectivity, and neural assembly architecture for 2 months following photothrombotic stroke targeting the forelimb somatosensory cortex. Sensorimotor recovery was tracked over the weeks following stroke, allowing us to relate network changes to behavior. Our data revealed spatially restricted but long-lasting alterations in somatosensory neural network function and connectivity. Specifically, we demonstrate significant and long-lasting disruptions in neural assembly architecture concurrent with a deficit in functional connectivity between individual neurons. Reductions in neuronal spiking in peri-infarct cortex were transient but predictive of impairment in skilled locomotion measured in the tapered beam task. Notably, altered neural networks were highly localized, with assembly architecture and neural connectivity relatively unaltered a short distance from the peri-infarct cortex, even in regions within 'remapped' forelimb functional representations identified using mesoscale imaging with anaesthetized preparations 8 weeks after stroke. Thus, using longitudinal two-photon microscopy in awake animals, these data show a complex spatiotemporal relationship between peri-infarct neuronal network function and behavioral recovery. Moreover, the data highlight an apparent disconnect between dramatic functional remapping identified using strong sensory stimulation in anaesthetized mice compared to more subtle and spatially restricted changes in individual neuron and local network function in awake mice during stroke recovery.

Hydrogen Sulfide Exerted a Pro-Angiogenic Role by Promoting the Phosphorylation of VEGFR2 at Tyr797 and Ser799 Sites in Hypoxia-Reoxygenation Injury

The protective effects of hydrogen sulfide (H2S) against ischemic brain injury and its role in promoting angiogenesis have been established. However, the specific mechanism underlying these effects remains unclear. This study is designed to investigate the regulatory impact and mechanism of H2S on VEGFR2 phosphorylation. Following expression and purification, the recombinant His-VEGFR2 protein was subjected to LC-PRM/MS analysis to identify the phosphorylation sites of VEGFR2 upon NaHS treatment. Adenovirus infection was used to transfect primary rat brain artery endothelial cells (BAECs) with the Ad-VEGFR2WT, Ad-VEGFR2Y797F, and Ad-VEGFR2S799A plasmids. The expression of VEGFR2 and recombinant Flag-VEGFR2, along with Akt phosphorylation, cell proliferation, and LDH levels, was assessed. The migratory capacity and tube-forming potential of BAECs were assessed using wound healing, transwell, and tube formation assays. NaHS notably enhanced the phosphorylation of VEGFR2 at Tyr797 and Ser799 sites. These phosphorylation sites were identified as crucial for mediating the protective effects of NaHS against hypoxia-reoxygenation (H/R) injury. NaHS significantly enhanced the Akt phosphorylation, migratory capacity, and tube formation of BAECs and upregulated the expression of VEGFR2 and recombinant proteins. These findings suggest that Tyr797 and Ser799 sites of VEGFR2 serve as crucial mediators of H2S-induced pro-angiogenic effects and protection against H/R injury.

Histone deacetylase inhibition by suberoylanilide hydroxamic acid during reperfusion promotes multifaceted brain and vascular protection in spontaneously hypertensive rats with transient ischaemic stroke

Hypertension is the most prevalent modifiable risk factor for stroke and is associated with worse functional outcomes. Pharmacological inhibition of histone deacetylases by suberoylanilide hydroxamic acid (SAHA) modulates gene expression and has emerged as a promising therapeutic approach to reduce ischaemic brain injury. Here, we have tested the therapeutic potential of SAHA administered during reperfusion in adult male spontaneously hypertensive (SHR) rats subjected to transient middle cerebral artery occlusion (tMCAO; 90 min occlusion/24 h reperfusion). Animals received a single dose of SAHA (50 mg/kg) or vehicle i.p. at 1, 4, or 6 h after reperfusion onset. The time-course of brain histone H3 acetylation was studied. After tMCAO, drug brain penetrance and beneficial effects on behavioural outcomes, infarct volume, oedema, angiogenesis, blood-brain barrier integrity, cerebral artery oxidative stress and remodelling, and brain and vascular inflammation were evaluated. SAHA increased brain histone H3 acetylation from 1 to 6 h after injection, reaching the ischaemic brain administered during reperfusion. Treatment given at 4 h after reperfusion onset improved neurological score, reduced infarct volume and oedema, attenuated microglial activation, prevented exacerbated MCA angiogenic sprouting and blood-brain barrier breakdown, normalised MCA oxidative stress and remodelling, and modulated brain and cerebrovascular cytokine expression. Overall, we demonstrate that SAHA administered during early reperfusion exerts robust brain and vascular protection after tMCAO in hypertensive rats. These findings are aligned with previous research in ischaemic normotensive mice and help pave the way to optimise the design of clinical trials assessing the effectiveness and safety of SAHA in ischaemic stroke.

Targeting Pericytes for Functional Recovery in Ischemic Stroke

Pericytes surrounding endothelial cells in the capillaries are emerging as an attractive cell resource, which can show a large variety of functions in ischemic stroke, including preservation of the blood-brain barrier, regulation of immune function, and support for cerebral vasculature. These functions have been fully elucidated in previous studies. However, in recent years, increasing evidence has shown that pericytes play an important role in neurological recovery after ischemic stroke due to their regenerative function which can be summarized in two aspects according to current discoveries, one is that pericytes are thought to be multipotential themselves, and the other is that pericytes can promote the differentiation of oligodendrocyte progenitor cells (OPCs). Considering the neuroprotective treatment for stroke has not been much progressed in recent years, new therapies targeting pericytes may be a future direction. Here, we will review the beneficial effects of pericytes in ischemic stroke from two directions: the barrier and vascular functions and the regenerative functions of pericytes.

Intermittent hypoxia protects against hypoxic-ischemic brain damage by inducing functional angiogenesis

Ischemic stroke (IS) induces neurological damage due to cerebrovascular occlusion. Restoring blood perfusion to the ischemic brain area in a timely fashion is the most effective treatment strategy. Hypoxia is an effective way of restoring blood perfusion by improving cerebrovascular microcirculation, while the effect varies greatly depending on hypoxic mode. This study aimed to screen for the optimal hypoxic mode to improve cerebrovascular microcirculation and prevent IS. Here, we found that compared with continuous hypoxia (CH), intermittent hypoxia (IH) significantly improved cerebral blood flow and oxygen saturation in mice without causing neurological impairment. By analyzing cerebrovascular microcirculation from mice, we found that the IH mode (13%, 5*10) with 13% O2, 5 min interval, and 10 cycles per day significantly improved the cerebrovascular microcirculation by promoting angiogenesis without affecting the integrity of the blood-brain barrier. In addition, IH (13%, 5*10) treatment of distal middle cerebral artery occlusion (dMCAO) mice significantly alleviated neurological dysfunction and reduced cerebral infarct volume by improving cerebrovascular microcirculation. CH had none of these positive effects. In summary, our study screened for an appropriate intermittent hypoxic mode that could improve cerebrovascular microcirculation, laying a theoretical foundation for the prevention and treatment of IS in clinical practice.

Hesperidin ameliorates impairment in hippocampal neural stem cells related to apoptosis induced by methotrexate in adult rats

Neurogenesis is a process of generating neural stem cells (NSCs) as functional neurons can be decreased after chemotherapy treatments. Methotrexate (MTX) is a folate antagonist that is used for cancer treatment but has negative effects, including oxidative stress, neuronal apoptosis and cognitive impairments. Hesperidin (Hsd), a flavonoid found in citrus fruits, has antioxidant and neuroprotection properties. This study investigated whether Hsd could attenuate impairments of hippocampal neural stem cells related to apoptosis induced by MTX. Spraque-Dawley rats (n = 24) were divided into 4 groups: (1) Vehicle group received propylene glycol (21 days) and 0.9% normal saline (day 8 and 15), (2) Hsd group received 100 mg/kg (21 days), (3) MTX group received 75 mg/kg (days 8 and 15) and (4) MTX+Hsd group received MTX, 75 mg/kg (day 8 and 15) and Hsd 100 mg/kg (21 days). Our results showed that MTX decreased hippocampal neural stem cells including SRY (sex determining region Y)-box 2 (SOX2) and nestin. MTX diminished vascular related (VR) Ki-67 positive cells in the hippocampus but not non-vascular related (NVR) Ki-67. Additionally, MTX reduced SOX2, nestin, postsynaptic density protein 95 (PSD-95) and B-cell lymphoma-2 family of proteins (Bcl-2), whereas Bax and caspase-3 were enhanced in the hippocampal tissues. Interestingly, co-treatment with Hsd and MTX revealed upregulation of SOX2, nestin and VR Ki-67 positive cells as well as elevated SOX2, nestin, PSD-95 and Bcl-2 proteins. Moreover, receiving both Hsd and MTX significantly suppressed increased Bax and caspase-3. These results confirm that Hsd can ameliorate MTX-induced impairments of hippocampal NSC proliferation and neuronal apoptosis.

[Naoluo Xintong Decoction activates caspase-1/Gasdermin D pathway to promote angiogenesis of rat brain microvascular endothelial cells after oxygen glucose deprivation/reperfusion injury]

OBJECTIVE

To investigate the effects of Naoluo Xintong Decoction (NLXTD) on pyroptosis and angiogenesis of brain microvascular endothelial cells (BMECs) and explore the possible mechanisms in rats with oxygen-glucose deprivation/ reperfusion (OGD/R).

METHODS

Rat BMECs with or without caspase-1 siRNA transfection were cultured in the presence of 10% medicated serum from NLXTD-treated rats (or blank serum) and exposed to OGD/R. CCK-8 assay, Transwell chamber assay, and tube formation assay were used to assess proliferation, migration, and tube-forming abilities of the cells. The activity of lactate dehydrogenase (LDH) in the culture supernatant was determined using a commercial assay kit, and the levels of inflammatory factors IL-1β and IL-18 were detected with ELISA. The cellular expressions of pro-caspase-1, caspase-1, NLRP3, Gasdermin D, and angiogenesis-related proteins VEGF and VEGFR2 were detected using Western blotting.

RESULTS

The BMECs showed obvious injuries after OGD/R exposure. Compared with the blank serum, the medicated serum significantly improved the cell viability, migration ability, and lumen-forming ability (P < 0.01) and lowered the levels of IL-1β and IL-18 and the LDH release (P < 0.01) of the cells with OGD/R exposure. Western blotting showed that in the BMECs exposed to OGD/R, the medicated serum strongly upregulated the expression of VEGF and VEGFR2 proteins (P < 0.01) and reduced the protein expressions of pro-caspase-1, caspase-1, NLRP3, and Gasdermin D (P < 0.01), and transfection of the cells with caspase-1 siRNA further promoted the expressions of VEGFR2 protein in the cells (P < 0.01).

CONCLUSION

NLXTD can improve the proliferation, migration, and tube- forming ability and promote angiogenesis of BMECs with OGD/R injury probably by inhibiting the caspase-1/Gasdermin D pathway in pyroptosis, alleviating cell injury, and upregulating the expressions of VEGF and VEGFR2.

Potential enhancement of post-stroke angiogenic response by targeting the oligomeric aggregation of p53 protein

Tumor suppressor gene p53 and its aggregate have been found to be involved in many angiogenesis-related pathways. We explored the possible p53 aggregation formation mechanisms commonly occur after ischemic stroke, such as hypoxia and the presence of reactive oxygen species (ROS). The angiogenic pathways involving p53 mainly occur in nucleus or cytoplasm, with one exception that occurs in mitochondria. Considering the high mitochondrial density in brain and endothelial cells, we proposed that the cyclophilin D (CypD)-dependent vascular endothelial cell (VECs) necrosis pathway occurring in the mitochondria is one of the major factors that affects angiogenesis. Hence, targeting p53 aggregation, a key intermediate in the pathway, could be an alternative therapeutic target for post-stroke management.

Molecular mediators of angiogenesis and neurogenesis after ischemic stroke

The mechanisms governing neurological and functional recovery after ischemic stroke are incompletely understood. Recent advances in knowledge of intrinsic repair processes of the CNS have so far translated into minimal improvement in outcomes for stroke victims. Better understanding of the processes underlying neurological recovery after stroke is necessary for development of novel therapeutic approaches. Angiogenesis and neurogenesis have emerged as central mechanisms of post-stroke recovery and potential targets for therapeutics. Frameworks have been developed for conceptualizing cerebral angiogenesis and neurogenesis at the tissue and cellular levels. These models highlight that angiogenesis and neurogenesis are linked to each other and to functional recovery. However, knowledge of the molecular framework linking angiogenesis and neurogenesis after stroke is limited. Studies of potential therapeutics typically focus on one mediator or pathway with minimal discussion of its role within these multifaceted biochemical processes. In this article, we briefly review the current understanding of the coupled processes of angiogenesis and neurogenesis after stroke. We then identify the molecular mediators and signaling pathways found in pre-clinical studies to upregulate both processes after stroke and contextualizes them within the current framework. This report thus contributes to a more-unified understanding of the molecular mediators governing angiogenesis and neurogenesis after stroke, which we hope will help guide the development of novel therapeutic approaches for stroke survivors.

Protective effect and underlying mechanism of muscone on acute cerebral ischemia-reperfusion injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Musk is a widely used traditional Chinese medicine, which has resuscitation, activating blood, and disperse swelling effects. Musk is commonly used in the prevention of myocardial infarction and ischemic stroke, and muscone is its main active component.

AIM OF THE STUDY

The effect and mechanism of muscone to improve the condition of ischemic stroke is not clear, accordingly, we verified its efficacy in ischemia-reperfused rats, and investigated its mechanism by PC12 and THP-1 cells.

METHODS

A transient middle cerebral artery occlusion (tMCAO) rat model was established for in vivo experiments. 2,3,5-Triphenyl Tetrazolium Chloride (TTC) staining was used to calculate infarct rate. Neuroprotection and angiogenesis were assessed by Hematoxylin-eosin (HE) staining, nissl staining, immunofluorescence staining, and quantitative real-time PCR (qRT-PCR). Oxygen glucose deprivation-reperfusion (OGD/R) model of PC12 cells was established for neuroprotection analysis, where CCK-8 assay was used to measure cell viability, flow cytometry and Hoechst 33258 staining were used to demonstrate apoptosis, and protein levels were detected by Western blot. For angiogenesis analysis, enzyme-linked immunosorbent assay (ELISA) and qRT-PCR were used to detect angiogenic factors expressed by THP-1. Cell viability assay, scratch wound assay, and tube formation assay were used to evaluate angiogenic effect of HUVECs treated with medium of THP-1. And the angiogenic pathway in HUVECs was detected by Western blot.

RESULTS

According to the results, in cerebral ischemia-reperfusion rats, the infarct rate and tissue damage were significantly reduced by muscone, and the expression of neurotrophic factors and angiogenesis-related factors were all elevated. In OGD/R-PC12 cell models, muscone could increase cell viability and inhibit apoptosis via Bax/Bcl-2/Caspase-3 pathway. In THP-1-mediated angiogenesis of HUVECs, muscone promoted the secretion of angiogenesis-related factors in THP-1 and thus indirectly promoted the proliferation, migration and tube formation of HUVECs, and then regulated phosphorylation of VEGFR2 and Akt in HUVECs.

CONCLUSIONS

Our study indicated that muscone may be a potential neuroprotective and proangiogenic agent in cerebral ischemia.

Buyang Huanwu Decoction alleviates cerebral ischemic injury through modulating caveolin-1-mediated mitochondrial quality control

Introduction: Mitochondrial quality control (MQC) is an important mechanism of neural repair after cerebral ischemia (CI). Recent studies have shown that caveolin-1 (Cav-1) is an important signaling molecule in the process of CI injury, but its mechanism of regulating MQC after CI is still unclear. Buyang Huanwu Decoction (BHD) is a classic traditional Chinese medicine formula that is often used to treat CI. Unfortunately, its mechanism of action is still obscure. Methods: In this study, we tested the hypothesis that BHD can regulate MQC through Cav-1 and exert an anti-cerebral ischemia injury effect. We used Cav-1 knockout mice and their homologous wild-type mice, replicated middle cerebral artery occlusion (MCAO) model and BHD intervention. Neurobehavioral scores and pathological detection were used to evaluate neurological function and neuron damage, transmission electron microscopy and enzymology detection of mitochondrial damage. Finally, western blot and RT-qPCR expression of MQC-related molecules were tested. Results: After CI, mice showed neurologic impairment, neuronal damage, and significant destruction of mitochondrial morphology and function, and MQC was imbalanced. Cav-1 deletion aggravated the damage to neurological function, neurons, mitochondrial morphology and mitochondrial function after CI, aggravated the imbalance of mitochondrial dynamics, and inhibited mitophagy and biosynthesis. BHD can maintain MQC homeostasis after CI through Cav-1 and improve CI injury. Discussion: Cav-1 can affect CI injury by regulating MQC, and this mechanism may be another target of BHD for anti-cerebral ischemia injury.

Long-term outcomes and quantitative radiologic analysis of extracranial-intracranial bypass for hemodynamically compromised chronic large artery occlusive disease

This study aimed to demonstrate the effectiveness of nonemergent extracranial-to-intracranial bypass (EIB) in symptomatic chronic large artery atherosclerotic stenosis or occlusive disease (LAA) through quantitative analysis of computed tomography perfusion (CTP) parameters using RAPID software. We retrospectively analyzed 86 patients who underwent nonemergent EIB due to symptomatic chronic LAA. CTP data obtained preoperatively, immediately postoperatively (PostOp0), and 6 months postoperatively (PostOp6M) after EIB were quantitatively analyzed through RAPID software, and their association with intraoperative bypass flow (BF) was assessed. The clinical outcomes, including neurologic state, incidence of recurrent infarction and complications, were also analyzed. The time-to-maximum (Tmax) > 8 s, > 6 s and > 4 s volumes decreased significantly at PostOp0 and up through PostOp6M (preoperative, 5, 51, and 223 ml (median), respectively; PostOp0, 0, 20.25, and 143 ml, respectively; PostOp6M, 0, 7.5, and 148.5 ml, respectively; p < 0.001, p < 0.001, and p < 0.001, respectively). The postoperative improvement in the Tmax > 6 s and > 4 s volumes was significantly correlated with the BF at PostOp0 and PostOp6M (PostOp0, r = 0.367 (p = 0.001) and r = 0.275 (p = 0.015), respectively; PostOp6M r = 0.511 (p < 0.001) and r = 0.391 (p = 0.001), respectively). The incidence of recurrent cerebral infarction was 4.7%, and there were no major complications that produced permanent neurological impairment. Nonemergent EIB under strict operation indications can be a feasible treatment for symptomatic, hemodynamically compromised LAA patients.

Analyzing angiogenesis on a chip using deep learning-based image processing

Angiogenesis, the formation of new blood vessels from existing vessels, has been associated with more than 70 diseases. Although numerous studies have established angiogenesis models, only a few indicators can be used to analyze angiogenic structures. In the present study, we developed an image-processing pipeline based on deep learning to analyze and quantify angiogenesis. We utilized several image-processing algorithms to quantify angiogenesis, including a deep learning-based cell nuclear segmentation algorithm and image skeletonization. This method could quantify and measure changes in blood vessels in response to biochemical gradients using 16 indicators, including length, width, number, and nuclear distribution. Moreover, this procedure is highly efficient for the three-dimensional quantitative analysis of angiogenesis and can be applied to diverse angiogenesis investigations.

Large vessel occlusion stroke outcomes in diabetic vs. non-diabetic patients with acute stress hyperglycemia

OBJECTIVE

This study assesses whether stress-induced hyperglycemia is a predictor of poor outcome at 3 months for patients with acute ischemic stroke (AIS) treated by endovascular treatment (EVT) and impacted by their previous blood glucose status.

METHODS

This retrospective study collected data from 576 patients with AIS due to large vessel occlusion (LVO) treated by EVT from March 2019 to June 2022. The sample was composed of 230 and 346 patients with and without diabetes mellitus (DM), respectively, based on their premorbid diabetic status. Prognosis was assessed with modified Rankin Scale (mRS) at 3-month after AIS. Poor prognosis was defined as mRS>2. Stress-induced hyperglycemia was assessed by fasting glucose-to-glycated hemoglobin ratio (GAR). Each group was stratified into four groups by quartiles of GAR (Q1-Q4). Binary logistic regression analysis was used to identify relationship between different GAR quartiles and clinical outcome after EVT.

RESULTS

In DM group, a poor prognosis was seen in 122 (53%) patients and GAR level was 1.27 ± 0.44. These variables were higher than non-DM group and the differences were statistically significant (p < 0.05, respectively). Patients with severe stress-induced hyperglycemia demonstrated greater incidence of 3-month poor prognosis (DM: Q1, 39.7%; Q2, 45.6%; Q3, 58.6%; Q4, 68.4%; p = 0.009. Non-DM: Q1, 31%; Q2, 32.6%; Q3, 42.5%; Q4, 64%; p < 0.001). However, the highest quartile of GAR was independently associated with poor prognosis at 3 months (OR 3.39, 95% CI 1.66-6.96, p = 0.001), compared to the lowest quartile in non-DM patients after logistic regression. This association was not observed from DM patients.

CONCLUSION

The outcome of patients with acute LVO stroke treated with EVT appears to be influenced by premorbid diabetes status. However, the poor prognosis at 3-month in patients with DM is not independently correlated with stress-induced hyperglycemia. This could be due to the long-term damage of persistent hyperglycemia and diabetic patients' adaptive response to stress following acute ischemic damage to the brain.

Computational models for generating microvascular structures: Investigations beyond medical imaging resolution

Angiogenesis, arteriogenesis, and pruning are revascularization processes essential to our natural vascular development and adaptation, as well as central players in the onset and development of pathologies such as tumoral growth and stroke recovery. Computational modeling allows for repeatable experimentation and exploration of these complex biological processes. In this review, we provide an introduction to the biological understanding of the vascular adaptation processes of sprouting angiogenesis, intussusceptive angiogenesis, anastomosis, pruning, and arteriogenesis, discussing some of the more significant contributions made to the computational modeling of these processes. Each computational model represents a theoretical framework for how biology functions, and with rises in computing power and study of the problem these frameworks become more accurate and complete. We highlight physiological, pathological, and technological applications that can be benefit from the advances performed by these models, and we also identify which elements of the biology are underexplored in the current state-of-the-art computational models. This article is categorized under: Cancer > Computational Models Cardiovascular Diseases > Computational Models.

Non-coding RNAs in stroke pathology, diagnostics, and therapeutics

Ischemic stroke is a leading cause of death and disability worldwide. Methods to alleviate functional deficits after ischemic stroke focus on restoration of cerebral blood flow to the affected area. However, pharmacological or surgical methods such as thrombolysis and thrombectomy have a narrow effective window. Harnessing and manipulating neurochemical processes of recovery may provide an alternative to these methods. Recently, non-coding RNA (ncRNA) have been increasingly investigated for their contributions to the pathology of diseases and potential for diagnostic and therapeutic applications. Here we will review several ncRNA - H19, MALAT1, ANRIL, NEAT1, pseudogenes, small nucleolar RNA, piwi-interacting RNA and circular RNA - and their involvement in stroke pathology. We also examine these ncRNA as potential diagnostic biomarkers, particularly in circulating blood, and as targets for therapeutic interventions. An important aspect of this is a discussion of potential methods of treatment delivery to allow for targeting of interventions past the blood-brain barrier, including lipid nanoparticles, polymer nanoparticles, and viral and non-viral vectors. Overall, several long non-coding RNA (lncRNA) discussed here have strong implications for the development of pathology and functional recovery after ischemic stroke. LncRNAs H19 and ANRIL show potential as diagnostic biomarkers, while H19 and MALAT1 may prove to be effective therapeutics for both minimising damage as well as promoting recovery. Other ncRNA have also been implicated in ischemic stroke but are currently too poorly understood to make inferences for diagnosis or treatment. Whilst the field of ncRNAs is relatively new, significant work has already highlighted that ncRNAs represent a promising novel investigative tool for understanding stroke pathology, could be used as diagnostic biomarkers, and as targets for therapeutic interventions.

Neutrophil dynamics and inflammaging in acute ischemic stroke: A transcriptomic review

Stroke is among the leading causes of death and disability worldwide. Restoring blood flow through recanalization is currently the only acute treatment for cerebral ischemia. Unfortunately, many patients that achieve a complete recanalization fail to regain functional independence. Recent studies indicate that activation of peripheral immune cells, particularly neutrophils, may contribute to microcirculatory failure and futile recanalization. Stroke primarily affects the elderly population, and mortality after endovascular therapies is associated with advanced age. Previous analyses of differential gene expression across injury status and age identify ischemic stroke as a complex age-related disease. It also suggests robust interactions between stroke injury, aging, and inflammation on a cellular and molecular level. Understanding such interactions is crucial in developing effective protective treatments. The global stroke burden will continue to increase with a rapidly aging human population. Unfortunately, the mechanisms of age-dependent vulnerability are poorly defined. In this review, we will discuss how neutrophil-specific gene expression patterns may contribute to poor treatment responses in stroke patients. We will also discuss age-related transcriptional changes that may contribute to poor clinical outcomes and greater susceptibility to cerebrovascular diseases.

The Role of the Coagulation System in Peripheral Arterial Disease: Interactions with the Arterial Wall and Its Vascular Microenvironment and Implications for Rational Therapies

Peripheral artery disease (PAD) is a clinical manifestation of atherosclerotic disease with a large-scale impact on the economy and global health. Despite the role played by platelets in the process of atherogenesis being well recognized, evidence has been increasing on the contribution of the coagulation system to the atherosclerosis formation and PAD development, with important repercussions for the therapeutic approach. Histopathological analysis and some clinical studies conducted on atherosclerotic plaques testify to the existence of different types of plaques. Likely, the role of coagulation in each specific type of plaque can be an important determinant in the histopathological composition of atherosclerosis and in its future stability. In this review, we analyze the molecular contribution of inflammation and the coagulation system on PAD pathogenesis, focusing on molecular similarities and differences between atherogenesis in PAD and coronary artery disease (CAD) and discussing the possible implications for current therapeutic strategies and future perspectives accounting for molecular inflammatory and coagulation targets. Understanding the role of cross-talking between coagulation and inflammation in atherosclerosis genesis and progression could help in choosing the right patients for future dual pathway inhibition strategies, where an antiplatelet agent is combined with an anticoagulant, whose role, despite pathophysiological premises and trials' results, is still under debate.

Antagonism of histamine H3 receptor promotes angiogenesis following focal cerebral ischemia

Our previous study showed that H3 receptor antagonists reduced neuronal apoptosis and cerebral infarction in the acute stage after cerebral ischemia, but through an action independent of activation of histaminergic neurons. Because enhanced angiogenesis facilitates neurogenesis and neurological recovery after ischemic stroke, we herein investigated whether antagonism of H3R promoted angiogenesis after brain ischemia. Photothrombotic stroke was induced in mice. We showed that administration of H3R antagonist thioperamide (THIO, 10 mg·kg-1·d-1, i.p., from D1 after cerebral ischemia) significantly improved angiogenesis assessed on D14, and attenuated neurological defects on D28 after cerebral ischemia. Compared with wild-type mice, Hrh3-/- mice displayed more blood vessels in the ischemic boundary zone on D14, and THIO administration did not promote angiogenesis in these knockout mice. THIO-promoted angiogenesis in mice was reversed by i.c.v. injection of H3R agonist immepip, but not by H1 and H2 receptor antagonists, histidine decarboxylase inhibitor α-fluoromethylhistidine, or histidine decarboxylase gene knockout (HDC-/-), suggesting that THIO-promoted angiogenesis was independent of activation of histaminergic neurons. In vascular endothelial cells (bEnd.3), THIO (10-9-10-7 M) dose-dependently facilitated cell migration and tube formation after oxygen glucose deprivation (OGD), and H3R knockdown caused similar effects. We further revealed that H3R antagonism reduced the interaction between H3R and Annexin A2, while knockdown of Annexin A2 abrogated THIO-promoted angiogenesis in bEnd.3 cells after OGD. Annexin A2-overexpressing mice displayed more blood vessels in the ischemic boundary zone, which was reversed by i.c.v. injection of immepip. In conclusion, this study demonstrates that H3R antagonism promotes angiogenesis after cerebral ischemia, which is independent of activation of histaminergic neurons, but related to the H3R on vascular endothelial cells and its interaction with Annexin A2. Thus, H3R antagonists might be promising drug candidates to improve angiogenesis and neurological recovery after ischemic stroke.

Low-Frequency Repetitive Transcranial Magnetic Stimulation in the Early Subacute Phase of Stroke Enhances Angiogenic Mechanisms in Rats

Objective To characterize the repetitive transcranial magnetic stimulation (rTMS) induced changes in angiogenic mechanisms across different brain regions.Methods Seventy-nine adult male Sprague-Dawley rats were subjected to a middle cerebral artery occlusion (day 0) and then treated with 1-Hz, 20-Hz, or sham stimulation of their lesioned hemispheres for 2 weeks. The stimulation intensity was set to 100% of the motor threshold. The neurological function was assessed on days 3, 10, and 17. The infarct volume and angiogenesis were measured by histology, immunohistochemistry, Western blot, and real-time polymerase chain reaction (PCR) assays. Brain tissue was harvested from the ischemic core (IC), ischemic border zone (BZ), and contralateral homologous cortex (CH).Results Optical density of angiopoietin1 and synaptophysin in the IC was significantly greater in the low-frequency group than in the sham group (p=0.03 and p=0.03, respectively). The 1-Hz rTMS significantly increased the level of Akt phosphorylation in the BZ (p<0.05 vs. 20 Hz). Endothelial nitric oxide synthase phosphorylation was increased in the IC (p<0.05 vs. 20 Hz), BZ (p<0.05 vs. 20 Hz), and CH (p<0.05 vs. 20 Hz and p<0.05 vs. sham). Real-time PCR demonstrated that low-frequency stimulation significantly increased the transcriptional activity of the TIE2 gene in the IC (p<0.05).Conclusion Low-frequency rTMS of the ipsilesional hemisphere in the early subacute phase of stroke promotes the expression of angiogenic factors and related genes in the brain, particularly in the injured area.

Remodeling of the Neurovascular Unit Following Cerebral Ischemia and Hemorrhage

Formulated as a group effort of the stroke community, the transforming concept of the neurovascular unit (NVU) depicts the structural and functional relationship between brain cells and the vascular structure. Composed of both neural and vascular elements, the NVU forms the blood-brain barrier that regulates cerebral blood flow to meet the oxygen demand of the brain in normal physiology and maintain brain homeostasis. Conversely, the dysregulation and dysfunction of the NVU is an essential pathological feature that underlies neurological disorders spanning from chronic neurodegeneration to acute cerebrovascular events such as ischemic stroke and cerebral hemorrhage, which were the focus of this review. We also discussed how common vascular risk factors of stroke predispose the NVU to pathological changes. We synthesized existing literature and first provided an overview of the basic structure and function of NVU, followed by knowledge of how these components remodel in response to ischemic stroke and brain hemorrhage. A greater understanding of the NVU dysfunction and remodeling will enable the design of targeted therapies and provide a valuable foundation for relevant research in this area.

Post-stroke low-frequency whole-body vibration improves cognition in middle-aged rats of both sexes

Low-frequency whole-body vibration (WBV; 40 Hz), a low impact form of exercise, intervention for a month following moderate transient middle-cerebral artery occlusion (tMCAO) reduces infarct volume and improves motor function in reproductively senescent, middle-aged female rats. Since post-stroke cognitive decline remains a significant problem, the current study aims to investigate the efficacy of WBV in ameliorating post-tMCAO cognitive deficits and to determine the underlying putative mechanism(s) conferring benefits of WBV in middle-aged rats. Middle-aged rats of both sexes were randomly assigned to tMCAO (90 min) or sham surgery followed by exposure to either WBV (twice a day for 15 min each for 5 days a week over a month) or no WBV treatment groups. Following the last WBV treatment, rats were tested for hippocampus-dependent learning and memory using a water maze followed by harvesting brain and blood samples for histopathological and inflammatory marker analyses, respectively. Results show that post-tMCAO WBV significantly lessens cognitive deficits in rats of both sexes. Post-tMCAO WBV significantly decreased circulating pro-inflammatory cytokines and increased serum levels of irisin, a muscle-derived hormone that may play a role in brain metabolism and inflammation regulation, which suggests putative beneficial mechanisms of WBV.

New insight into ischemic stroke: Circadian rhythm in post-stroke angiogenesis

The circadian rhythm is an endogenous clock system that coordinates and optimizes various physiological and pathophysiological processes, which accord with the master and the peripheral clock. Increasing evidence indicates that endogenous circadian rhythm disruption is involved in the lesion volume and recovery of ischemic stroke. As a critical recovery mechanism in post-stroke, angiogenesis reestablishes the regional blood supply and enhances cognitive and behavioral abilities, which is mainly composed of the following processes: endothelial cell proliferation, migration, and pericyte recruitment. The available evidence revealed that the circadian governs many aspects of angiogenesis. This study reviews the mechanism by which circadian rhythms regulate the process of angiogenesis and its contribution to functional recovery in post-stroke at the aspects of the molecular level. A comprehensive understanding of the circadian clock regulating angiogenesis in post-stroke is expected to develop new strategies for the treatment of cerebral infarction.

Pericytes Regulate Cerebral Perfusion through VEGFR1 in Ischemic Stroke

Neurons in the penumbra (the area surrounding ischemic tissue that consists of still viable tissue but with reduced blood flow and oxygen transport) may be rescued following stroke if adequate perfusion is restored in time. It has been speculated that post-stroke angiogenesis in the penumbra can reduce damage caused by ischemia. However, the mechanism for neovasculature formation in the brain remains unclear and vascular-targeted therapies for brain ischemia remain suboptimal. Here, we show that VEGFR1 was highly upregulated in pericytes after stroke. Knockdown of VEGFR1 in pericytes led to increased infarct area and compromised post-ischemia vessel formation. Furthermore, in vitro studies confirmed a critical role for pericyte-derived VEGFR1 in both endothelial tube formation and pericyte migration. Interestingly, our results show that pericyte-derived VEGFR1 has opposite effects on Akt activity in endothelial cells and pericytes. Collectively, these results indicate that pericyte-specific expression of VEGFR1 modulates ischemia-induced vessel formation and vascular integrity in the brain.

Therapeutic potential of hair follicle-derived stem cell intranasal transplantation in a rat model of ischemic stroke

BACKGROUND

Stem cell-based therapy has received considerable attention as a potential candidate in the treatment of ischemic stroke; however, employing an appropriate type of stem cells and an effective delivery route are still challenging. In the present study, we investigated the therapeutic effect of safe, noninvasive, and brain-targeted intranasal administration of hair follicle-derived stem cells (HFSCs) in a rat model of ischemic stroke.

METHODS

Stem cells were obtained from the adult rat hair follicles. In experiment 1, stroke was induced by 30 min middle cerebral artery occlusion (MCAO) and stem cells were intranasally transplanted immediately after ischemia. In experiment 2, stroke was induced by 120 min MCAO and stem cells were administered 24 h after cerebral ischemia. In all experimental groups, neurological performance, short-term spatial working memory and infarct volume were assessed. Moreover, relative expression of major trophic factors in the striatum and cortex was evaluated by the quantitative PCR technique. The end point of experiment 1 was day 3 and the end point of experiment 2 was day 15.

RESULTS

In both experiments, intranasal administration of HFSCs improved functional performance and decreased infarct volume compared to the MCAO rats. Furthermore, NeuN and VEGF expression were higher in the transplanted group and stem cell therapy partially prevented BDNF and neurotrophin-3 over-expression induced by cerebral ischemia.

CONCLUSIONS

These findings highlight the curative potential of HFSCs following intranasal transplantation in a rat model of ischemic stroke.

Hippocampal neuroprotection mediated by secretome of human mesenchymal stem cells against experimental stroke

Aims

Regenerative medicine literature has demonstrated that the therapeutic potentials of mesenchymal stem cells (MSCs) in experimental stroke are attributed to secreted bioactive factors rather than to cell replacement. Here, we explored the effects of secretome or conditioned medium (CM) derived from human embryonic stem cell‐derived MSCs (hESC‐MSCs) on hippocampal neurogenesis, inflammation, and apoptosis in experimental stroke.

Methods

Ischemic stroke was induced by right middle cerebral artery occlusion (MCAO) in male Wistar rats, and CM was infused either one time (1‐h post‐stroke; CM1) or three times (1‐, 24‐, and 48‐h post‐stroke; CM3) into left lateral ventricle. Neurogenesis markers (Nestin, Ki67, Doublecortin, and Reelin) were assessed at transcript and protein levels in the dentate gyrus of the hippocampus on day seven following MCAO. In parallel, changes in the gene expression of markers of apoptosis (Bax and Bim, as well as an anti‐apoptotic marker of Bcl2), inflammation (IL‐1β and IL‐6, as well as IL‐10 as an anti‐inflammatory cytokine), trophic factors (BDNF, GDNF, NGF, and NT‐3), and angiogenesis (CD31 and VEGF) in the hippocampus were assessed.

Results

Our results demonstrate that CM3 treatment could stimulate neurogenesis and angiogenesis concomitant with inhibition of inflammation, apoptosis, and neuronal loss in ischemic brains. Furthermore, rats treated with CM3 exhibited upregulation in neurotrophic factors.

Conclusion

Our results suggest that hESC‐MSC‐CM could promote neurogenesis and protect brain tissue from ischemic injury, partly mediated by induction of angiogenesis and neurotrophic factors and inhibition of inflammatory and apoptotic factors expression.

Biomimetic Surface Topography from the Rubus fruticosus Leaf as a Guidance of Angiogenesis in Tissue Engineering Applications

The promotion of angiogenesis is a fundamental step for efficient organ/tissue reconstitution and replacement. Thus, several strategies to promote vascularization of scaffolds were studied to satisfy this unsolved clinical need. The interface between cells and substrates is a determinant for the success of tissue engineering (TE) strategies. Substrate's topography is reported to play a key role in influencing endothelial cell behavior, namely, on its proliferation, metabolic activity, morphology, migration, and secretion of cytokines and chemokines. Therefore, surface topography of the biomaterial-based grafts is a crucial property that is considered in the development of a new TE approach. Herein, we hypothesize that the surface of Rubus fruticosus leaf plays a crucial role in driving angiogenesis since its architecture resembles the vascular structures at a biologically relevant size scale. For this, we produced biomimetic polycaprolactone (PCL) membranes (BpMs) replicating the surface topography of a R. fruticosus leaf by replica molding and nanoimprint lithography. Our results showed an enhanced performance in terms of proliferation of the human endothelial cell line on top of the BpM. Moreover, an asymmetric cellular spatial distribution among the surface of the BpM was observed. These cells seem to have higher density for longer time periods in the region that replicates the leaf veins. Finally, we assess the angiogenic capacity through a chick chorioallantoic membrane assay, revealing that BpMs are more prone to support angiogenesis than flat PCL membranes. We strongly believe that this strategy can bring new insights into developing TE strategies with an enhanced performance in terms of the vascular integration between the host and the scaffolds implanted.

Diabetes complications and extracellular vesicle therapy

Diabetes is a chronic disorder characterized by dysregulated glycemic conditions. Diabetic complications include microvascular and macrovascular abnormalities and account for high morbidity and mortality rates in patients. Current clinical approaches for diabetic complications are limited to symptomatic treatments and tight control of blood sugar levels. Extracellular vesicles (EVs) released by somatic and stem cells have recently emerged as a new class of potent cell-free therapeutic delivery packets with a great potential to treat diabetic complications. EVs contain a mixture of bioactive molecules and can affect underlying pathological processes in favor of tissue healing. In addition, EVs have low immunogenicity and high storage capacity while maintaining nearly the same regenerative and immunomodulatory effects compared to current cell-based therapies. Therefore, EVs have received increasing attention for diabetes-related complications in recent years. In this review, we provide an outlook on diabetic complications and summarizes new knowledge and advances in EV applications. Moreover, we highlight recommendations for future EV-related research.

Prolonged release of VEGF and Ang1 from intralesionally implanted hydrogel promotes perilesional vascularization and functional recovery after experimental ischemic stroke

Injectable hydrogels can generate and support pro-repair environments in injured tissue. Here we used a slow-releasing drug carrying in situ-forming hydrogel to promote post-stroke recovery in a rat model. Release kinetics were measured in vitro and in vivo with MRI, using gadolinium-labeled albumin (Galbumin), which demonstrated prolonged release over multiple weeks. Subsequently, this hydrogel was used for long-term delivery of vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang1) (Gel VEGF + Ang1, n = 14), in a photothrombotically induced cortical stroke lesion in rats. Control stroke animals were intralesionally injected with saline (Saline, n = 10), non-loaded gel (Gel, n = 10), or a single bolus of VEGF + Ang1 in saline (Saline VEGF + Ang1, n = 10). MRI was executed to guide hydrogel injection. Functional recovery was assessed with sensorimotor function tests, while tissue status and vascularization were monitored by serial in vivo MRI. Significant recovery from sensorimotor deficits from day 28 onwards was only measured in the Gel VEGF + Ang1 group. This was accompanied by significantly increased vascularization in the perilesional cortex. Histology confirmed (re)vascularization and neuronal sparing in perilesional areas. In conclusion, intralesional injection of in situ-forming hydrogel loaded with pro-angiogenic factors can support prolonged brain tissue regeneration and promote functional recovery in the chronic phase post-stroke.

Circulating miRNA-195-5p and -451a in Patients with Acute Hemorrhagic Stroke in Emergency Department

(1) Background: In our previous study, acute ischemic stroke (AIS) patients showed increased levels of circulating miRNAs (-195-5p and -451a) involved in vascular endothelial growth factor A (VEGF-A) regulation. Here, we evaluated, for the first time, both circulating miRNAs in acute intracerebral hemorrhagic (ICH) patients. (2) Methods: Circulating miRNAs and serum VEGF-A were assessed by real-time PCR and ELISA in 20 acute ICH, 21 AIS patients, and 21 controls. These were evaluated at hospital admission (T0) and after 96 h (T96) from admission. (3) Results: At T0, circulating miRNAs were five-times up-regulated in AIS patients, tending to decrease at T96. By contrast, in the acute ICH group, circulating miRNAs were significantly increased at both T0 and T96. Moreover, a significant decrease was observed in serum VEGF-A levels at T0 in AIS patients, tending to increase at T96. Conversely, in acute ICH patients, the levels of VEGF-A were significantly decreased at both T0 and T96. (4) Conclusions: The absence of a reduction in circulating miRNAs (195-5p and -451a), reported in acute ICH subjects after 96 h from hospital admission, together with the absence of increment of serum VEGF-A, may represent useful biomarkers indicating the severe brain damage status that characterizes acute ICH patients.

Transcription Factor HEY1 Improves Brain Vascular Endothelial Cell Function and Alleviates Ischemic Stroke by Upregulating NOTCH3

To investigate the function of hairy/enhancer-of-split related with YRPW motif protein 1 (HEY1) and Notch receptor 3 (NOTCH3) in ischemic stroke. Stroke models were established by middle cerebral artery occlusion (MCAO) and oxygen glucose deprivation (OGD) in rats and rat brain microvascular endothelial cells (BMVECs), respectively. Neurological deficit evaluation and 2,3,5-triphenyltetrazolium chloride staining were used to assess cerebral injury. The expression of HEY1 and NOTCH3 was manipulated using gain and loss of function approaches. Terminal deoxynucleotidyl transferase dUTP nick end labeling and Western blotting analysis of cleaved caspase-3 and B-cell lymphoma-2 (Bcl2) were used to evaluate apoptosis. Enzyme-linked immunosorbent assay was performed to measure the expression levels of interleukin (IL)-1β, IL-6 and IL-18. The proliferation and migration of BMVECs were analyzed by Ki-67 immunofluorescence and scratch assay, respectively. Tube formation assay was conducted to measure the length of capillary-like tubes formed by BMVECs. Co-immunoprecipitation was used to testify the relationship between HEY1 and NOTCH3. HEY1 and NOTCH3 were upregulated in MCAO and OGD models. HEY1 ameliorated ischemic injuries in MCAO rats. Knockdown of HEY1 or NOTCH3 promoted OGD-induced apoptosis and inflammation and inhibited proliferation and migration in BMVECs. NOTCH3 was a binding protein of HEY1. Overexpression of HEY1 offset the disease-promoting effect of NOTCH3 silencing. HEY1 suppresses apoptosis and inflammation and promotes proliferation and migration in BMVECs by upregulating NOTCH3, thereby ameliorating ischemic stroke.

Blood-Brain Barrier Mechanisms in Stroke and Trauma

The brain microenvironment is tightly regulated. The blood-brain barrier (BBB), which is composed of cerebral endothelial cells, astrocytes, and pericytes, plays an important role in maintaining the brain homeostasis by regulating the transport of both beneficial and detrimental substances between circulating blood and brain parenchyma. After brain injury and disease, BBB tightness becomes dysregulated, thus leading to inflammation and secondary brain damage. In this chapter, we overview the fundamental mechanisms of BBB damage and repair after stroke and traumatic brain injury (TBI). Understanding these mechanisms may lead to therapeutic opportunities for brain injury.

Diet-induced weight loss in obese/diabetic mice normalizes glucose metabolism and promotes functional recovery after stroke

BACKGROUND

Post-stroke functional recovery is severely impaired by type 2 diabetes (T2D). This is an important clinical problem since T2D is one of the most common diseases. Because weight loss-based strategies have been shown to decrease stroke risk in people with T2D, we aimed to investigate whether diet-induced weight loss can also improve post-stroke functional recovery and identify some of the underlying mechanisms.

METHODS

T2D/obesity was induced by 6 months of high-fat diet (HFD). Weight loss was achieved by a short- or long-term dietary change, replacing HFD with standard diet for 2 or 4 months, respectively. Stroke was induced by middle cerebral artery occlusion and post-stroke recovery was assessed by sensorimotor tests. Mechanisms involved in neurovascular damage in the post-stroke recovery phase, i.e. neuroinflammation, impaired angiogenesis and cellular atrophy of GABAergic parvalbumin (PV)+ interneurons were assessed by immunohistochemistry/quantitative microscopy.

RESULTS

Both short- and long-term dietary change led to similar weight loss. However, only the latter enhanced functional recovery after stroke. This effect was associated with pre-stroke normalization of fasting glucose and insulin resistance, and with the reduction of T2D-induced cellular atrophy of PV+ interneurons. Moreover, stroke recovery was associated with decreased T2D-induced neuroinflammation and reduced astrocyte reactivity in the contralateral striatum.

CONCLUSION

The global diabetes epidemic will dramatically increase the number of people in need of post-stroke treatment and care. Our results suggest that diet-induced weight loss leading to pre-stroke normalization of glucose metabolism has great potential to reduce the sequelae of stroke in the diabetic population.

Chronic Low-Dose Alcohol Consumption Promotes Cerebral Angiogenesis in Mice

Chronic alcohol consumption dose-dependently affects the incidence and prognosis of ischemic stroke. We determined the influence of chronic alcohol consumption on cerebral angiogenesis under physiological conditions and following ischemic stroke. In in vitro studies, acute exposure to low-concentration ethanol significantly increased angiogenic capability and upregulated vascular endothelial growth factor A (VEGF-A) and vascular endothelial growth factor receptor 2 (VEGFR2) in C57BL/6J mouse brain microvascular endothelial cells (MBMVECs). The increased angiogenic capability was abolished in the presence of a VEGFR2 inhibitor. In addition, the increased angiogenic capability and upregulated VEGF-A and VEGFR2 remained in chronically low-concentration ethanol-exposed MBMVECs. In in vivo studies, 8-week gavage feeding with low-dose ethanol significantly increased vessel density and vessel branches and upregulated VEGF-A and VEGFR2 in the cerebral cortex under physiological conditions. Furthermore, vessel density, vessel branches, and expression of VEGF-A and VEGFR2 in the peri-infarct cortex were significantly greater in low-dose ethanol-fed mice at 72 h of reperfusion. Although low-dose ethanol did not alter cerebral vasoreactivity and regional cerebral blood flow (rCBF) either before or during ischemia, it significantly augmented post-ischemic hyperemia during reperfusion. In contrast, exposure to high-concentration ethanol and 8-week gavage feeding with high-dose ethanol only had a mild inhibitory effect on angiogenic capability and cerebral angiogenesis, respectively. We conclude that heavy alcohol consumption may not dramatically alter cerebral angiogenesis, whereas light alcohol consumption significantly promotes cerebral angiogenesis.

Effect of cycling exercise on motor excitability and gait abnormalities in stroke patients

Background

The concepts of brain excitability are still re-wiring in response to changes in environment. Ambulation is often limited in stroke patients.

Objective

To determine the effect of cycling exercise on motor excitability and consequences on spatiotemporal gait parameters in stroke patients.

Methods

Forty male ischemic stroke patients were included; their age ranged from 45 to 60 years. The patients were assigned into two equal groups: control group (GI) and study group (GII). The GI is treated by a design physical therapy program in the form of task-oriented progressive resistance exercise for lower limb muscles, and the GII is treated by the same program in addition to cycling exercise for 30 min. Treatment was conducted three times per week for 10 weeks. The excitability over motor area (Cz) was assessed by the quantitative electroencephalogram (QEEG). The spatiotemporal gait parameters were assessed by the Biodex Gait Trainer 2TM.

Results

There was a significant increase of speed, step cycle, and step length of the affected side (P < 0.05) and a non-significant difference of step length of the non-affected side in the study group compared with that of the control group (P > 0.05). There was a significant increase of excitability over motor area (Cz) in the study group compared with that of the control group (P < 0.05).

Conclusion

Cycling exercise has a positive effect on excitability over motor area of lower limbs and can improve gait parameters in stroke patients.

Common and unique structural plasticity after left and right hemisphere stroke

Strokes to the left and right hemisphere lead to distinctive behavioral profiles. Are left and right hemisphere strokes (LHS and RHS) associated with distinct or common poststroke neuroplasticity patterns? Understanding this issue would reveal hemispheric neuroplasticity mechanisms in response to brain damage. To this end, we investigated poststroke structural changes (2 weeks to 3 months post-onset) using longitudinal MRI data from 69 LHS and 55 RHS patients and 31 demographic-matched healthy control participants. Both LHS and RHS groups showed statistically common plasticity independent of the lesioned hemisphere, including 1) gray matter (GM) expansion in the ipsilesional and contralesional precuneus, and contralesional superior frontal gyrus; 2) GM shrinkage in the ipsilesional medial orbital frontal gyrus and middle cingulate cortex. On the other hand, only RHS patients had significant GM expansion in the ipsilesional medial superior and orbital frontal cortex. Importantly, these common and unique GM changes post-stroke largely overlapped with highly-connected cortical hub regions in healthy individuals. Moreover, they correlated with behavioral recovery, indicating that post-stroke GM volumetric changes in cortical hubs reflect compensatory rather than maladaptive mechanisms. These results highlight the importance of structural neuroplasticity in hub regions of the cortex, along with the hemispheric specificity, for stroke recovery.