Emerging strategies for nerve repair and regeneration in ischemic stroke: neural stem cell therapy.

Ischemic stroke is a major cause of mortality and disability worldwide, with limited treatment options available in clinical practice. The emergence of stem cell therapy has provided new hope to the field of stroke treatment via the restoration of brain neuron function. Exogenous neural stem cells are beneficial not only in cell replacement but also through the bystander effect. Neural stem cells regulate multiple physiological responses, including nerve repair, endogenous regeneration, immune function, and blood-brain barrier permeability, through the secretion of bioactive substances, including extracellular vesicles/exosomes. However, due to the complex microenvironment of ischemic cerebrovascular events and the low survival rate of neural stem cells following transplantation, limitations in the treatment effect remain unresolved. In this paper, we provide a detailed summary of the potential mechanisms of neural stem cell therapy for the treatment of ischemic stroke, review current neural stem cell therapeutic strategies and clinical trial results, and summarize the latest advancements in neural stem cell engineering to improve the survival rate of neural stem cells. We hope that this review could help provide insight into the therapeutic potential of neural stem cells and guide future scientific endeavors on neural stem cells.

Advancing stroke therapy: A deep dive into early phase of ischemic stroke and recanalization.

Ischemic stroke, accounting for the majority of stroke events, significantly contributes to global morbidity and mortality. Vascular recanalization therapies, namely intravenous thrombolysis and mechanical thrombectomy, have emerged as critical interventions, yet their success hinges on timely application and patient-specific factors. This review focuses on the early phase pathophysiological mechanisms of ischemic stroke and the nuances of recanalization. It highlights the dual role of neutrophils in tissue damage and repair, and the critical involvement of the blood-brain barrier (BBB) in stroke outcomes. Special emphasis is placed on ischemia-reperfusion injury, characterized by oxidative stress, inflammation, and endothelial dysfunction, which paradoxically exacerbates cerebral damage post-revascularization. The review also explores the potential of targeting molecular pathways involved in BBB integrity and inflammation to enhance the efficacy of recanalization therapies. By synthesizing current research, this paper aims to provide insights into optimizing treatment protocols and developing adjuvant neuroprotective strategies, thereby advancing stroke therapy and improving patient outcomes.

Changes in cerebral autoregulation, stroke-related blood biomarkers, and autonomic regulation after patent foramen ovale closure in severe migraine patients.

AIMS: This study aimed to investigate changes in dynamic cerebral autoregulation (dCA), 20 stroke-related blood biomarkers, and autonomic regulation after patent foramen ovale (PFO) closure in severe migraine patients. METHODS: Patent foramen ovale severe migraine patients, matched non-PFO severe migraine patients, and healthy controls were included. dCA and autonomic regulation were evaluated in each participant at baseline, and within 48-h and 30 days after closure in PFO migraineurs. A panel of stroke-related blood biomarkers was detected pre-surgically in arterial-and venous blood, and post-surgically in the arterial blood in PFO migraineurs. RESULTS: Forty-five PFO severe migraine patients, 50 non-PFO severe migraine patients, and 50 controls were enrolled. The baseline dCA function of PFO migraineurs was significantly lower than that of non-PFO migraineurs and controls but was rapidly improved with PFO closure, remaining stable at 1-month follow-up. Arterial blood platelet-derived growth factor-BB (PDGF-BB) levels were higher in PFO migraineurs than in controls, which was immediately and significantly reduced after closure. No differences in autonomic regulation were observed among the three groups. CONCLUSION: Patent foramen ovale closure can improve dCA and alter elevated arterial PDGF-BB levels in migraine patients with PFO, both of which may be related to the preventive effect of PFO closure on stroke occurrence/recurrence.

Role of lipocalin 2 in stroke.

Stroke is the second leading cause of death worldwide; however, the treatment choices available to neurologists are limited in clinical practice. Lipocalin 2 (LCN2) is a secreted protein, belonging to the lipocalin superfamily, with multiple biological functions in mediating innate immune response, inflammatory response, iron-homeostasis, cell migration and differentiation, energy metabolism, and other processes in the body. LCN2 is expressed at low levels in the brain under normal physiological conditions, but its expression is significantly up-regulated in multiple acute stimulations and chronic pathologies. An up-regulation of LCN2 has been found in the blood/cerebrospinal fluid of patients with ischemic/hemorrhagic stroke, and could serve as a potential biomarker for the prediction of the severity of acute stroke. LCN2 activates reactive astrocytes and microglia, promotes neutrophil infiltration, amplifies post-stroke inflammation, promotes blood-brain barrier disruption, white matter injury, and neuronal death. Moreover, LCN2 is involved in brain injury induced by thrombin and erythrocyte lysates, as well as microvascular thrombosis after hemorrhage. In this paper, we review the role of LCN2 in the pathological processes of ischemic stroke; intracerebral hemorrhage; subarachnoid hemorrhage; and stroke-related brain diseases, such as vascular dementia and post-stroke depression, and their underlying mechanisms. We hope that this review will help elucidate the value of LCN2 as a therapeutic target in stroke.

DL-3-n-butylphthalide Attenuates Cerebral Ischemia-Reperfusion Injury by Inhibiting Mitochondrial Omi/HtrA2-Mediated Apoptosis.

BACKGROUND: Ischemic stroke is a major cause of death and disability worldwide and results from inadequate cerebrovascular blood supply; mitochondrial dysfunction plays an essential role in its pathogenesis. DL-3-n-butylphthalide (NBP) is an effective medicine for ischemic stroke that reduces cell apoptosis and improves long-term prognosis. OBJECTIVE: Whether and how NBP regulates mitochondria-associated apoptosis in cerebral ischemia- reperfusion injury remains unclear. METHODS: Male Sprague Dawley rats were subjected to a middle cerebral artery occlusion (MCAO) stroke and treated with low (20 mg/kg) or high (80 mg/kg) concentrations of NBP. The Omi/HtrA2 inhibitor UCF-101 was used as a positive control. Cerebral infarction, neuron injury and neuronal apoptosis were assessed to determine the efficacy of NBP compared to UCF-101. We assessed the expression of the Omi/HtrA2 signaling pathway by western blotting and tested the mRNA expression of mitochondrial metabolism-related genes by PCR. RESULTS: Compared to the MCAO group, both low and high concentrations of NBP substantially improved cerebral infarction, neuron injury, and neuronal apoptosis; high concentrations of NBP were more potent than low concentrations. The expression of proteins of the mitochondrial Omi/HtrA2 signaling pathway, including Omi/HtrA2, XIAP, PARL, OPA1, CHOP, and ClpP, was inhibited in the NBP group. CONCLUSION: Overall, early application of NBP attenuated cerebral ischemia-reperfusion injury by inhibiting mitochondrial Omi/HtrA2-mediated apoptosis in rats. Our study supports a novel neuroprotective mechanism of NBP, making it a promising therapeutic agent for ischemic stroke.

Remote ischemic conditioning attenuates blood-brain barrier disruption after recombinant tissue plasminogen activator treatment via reducing PDGF-CC.

Treatment of acute ischemic stroke with the recombinant tissue plasminogen activator (rtPA) is associated with increased blood-brain barrier (BBB) disruption and hemorrhagic transformation. Remote ischemic conditioning (RIC) has demonstrated neuroprotective effects against acute ischemic stroke. However, whether and how RIC regulates rtPA-associated BBB disruption remains unclear. Here, a rodent model of thromboembolic stroke followed by rtPA thrombolysis at different time points was performed with or without RIC. Brain infarction, neurological outcomes, BBB permeability, and intracerebral hemorrhage were assessed. The platelet-derived growth factor CC (PDGF-CC)/PDGFRα pathway in the brain tissue, PDGF-CC levels in the skeletal muscle and peripheral blood were also measured. Furthermore, impact of RIC on serum PDGF-CC levels were measured in healthy subjects and AIS patients. Our results showed that RIC substantially reduced BBB injury, intracerebral hemorrhage, cerebral infarction, and neurological deficits after stroke, even when rtPA was administrated in a delayed therapeutic time window. Mechanistically, RIC significantly decreased PDGFRα activation in ischemic brain tissue and reduced blood PDGF-CC levels, which partially resulted from PDGF-CC reduction in the skeletal muscle of RIC-applied hindlimbs and platelets. Intravenous or intraventricular recombinant PDGF-CC supplementation abolished RIC protective effects on BBB integrity. Moreover, similar changes of PDGF-CC in serum by RIC were also observed in healthy humans and acute ischemic stroke patients. Together, our study demonstrates that RIC can attenuate rtPA-aggravated BBB disruption after ischemic stroke via reducing the PDGF-CC/PDGFRα pathway and thus supports RIC as a potential approach for BBB disruption prevention or treatment following thrombolysis.

Spatiotemporal lipidomics reveals key features of brain lipid dynamic changes after cerebral ischemia and reperfusion therapy.

Reperfusion therapy with recombinant tissue plasminogen activator (rtPA) or mechanical thrombectomy is the most effective treatment for ischemic stroke. However, a large proportion of stroke patients remain severely disabled even after receiving timely reperfusion therapy. It remains unclear how reperfusion therapy results in secondary injury to the brain tissue and whether different reperfusion therapies induce differential effects. Here, we comprehensively determined the spatiotemporal dynamic changes in brain lipids during the acute phase after reperfusion in a mouse model of transient middle cerebral artery occlusion, with or without rtPA administration, using desorption electrospray ionization (DESI)-mass spectrometry imaging (MSI). Several phospholipids, sphingolipids, and neutral lipids were significantly altered both spatially and temporally at multiple timepoints after reperfusion, many of which were closely associated with expansion of the brain infarction territory and neurological function impairment. Furthermore, rtPA treatment significantly increased brain infarction, cerebral edema, and neurological deficits. Consistently, rtPA treatment caused extensive brain lipid alterations by facilitating brain-wide changes in lipid metabolism and inducing ischemic region-specific lipid changes. Overall, these results provide novel insights into how reperfusion therapy affects brain tissue and the outcome of stroke patients, and thus may facilitate the optimization of the treatment of ischemic stroke.

The Impact of Serial Remote Ischemic Conditioning on Dynamic Cerebral Autoregulation and Brain Injury Related Biomarkers.

Objective: Recent studies have demonstrated the positive roles of remote ischemic conditioning (RIC) in patients with cerebrovascular diseases; however, the mechanisms remain unclear. This study aimed to explore the effect of serial RIC on dynamic cerebral autoregulation (dCA) and serum biomarkers associated with brain injury, both of which are related to the prognosis of cerebrovascular disease. Methods: This was a self-controlled interventional study in healthy adults. The RIC was conducted twice a day for 7 consecutive days (d1-d7) and comprised 4 × 5-min single arm cuff inflation/deflation cycles at 200 mmHg. All participants underwent assessments of dCA ten times, including baseline, d1, d2, d4, d7, d8, d10, d14, d21, and d35 of the study. Blood samples were collected four times (baseline, d1, d7, and d8) immediately after dCA measurements. The transfer function parameters [phase difference (PD) and gain] were used to quantify dCA. Four serum biomarkers associated with brain injury, ubiquitin C-terminal hydrolase-L1, neuron-specific enolase, glial fibrillary acidic protein, and S100ß were tested. Results: Twenty-two healthy adult volunteers (mean age 25.73 ± 1.78 years, 3 men [13.6%], all Asian) were enrolled in this study. Bilateral PD values were significantly higher since four times of RIC were completed (d2) compared with PD values at baseline (left: 53.31 ± 10.53 vs. 45.87 ± 13.02 degree, p = 0.015; right: 54.90 ± 10.46 vs. 45.96 ± 10.77 degree, p = 0.005). After completing 7 days of RIC, the significant increase in dCA was sustained for at least 28 days (d35, left: 53.11 ± 14.51 degree, P = 0.038; right: 56.95 ± 14.57 degree, p < 0.001). No difference was found in terms of different serum biomarkers related to brain injury before and after RIC. Conclusion: The elevation in dCA was detected immediately after four repeated times of RIC, and 7-day consecutive RIC induced a sustained increase in dCA for at least 28 days and did not affect blood biomarkers of brain injury in healthy adults. These results will help us to formulate detailed strategies for the safe and effective application of RIC in patients with cerebrovascular disease.

Biological Functions and Regulatory Mechanisms of Hypoxia-Inducible Factor-1α in Ischemic Stroke.

Ischemic stroke is caused by insufficient cerebrovascular blood and oxygen supply. It is a major contributor to death or disability worldwide and has become a heavy societal and clinical burden. To date, effective treatments for ischemic stroke are limited, and innovative therapeutic methods are urgently needed. Hypoxia inducible factor-1α (HIF-1α) is a sensitive regulator of oxygen homeostasis, and its expression is rapidly induced after hypoxia/ischemia. It plays an extensive role in the pathophysiology of stroke, including neuronal survival, neuroinflammation, angiogenesis, glucose metabolism, and blood brain barrier regulation. In addition, the spatiotemporal expression profile of HIF-1α in the brain shifts with the progression of ischemic stroke; this has led to contradictory findings regarding its function in previous studies. Therefore, unveiling the Janus face of HIF-1α and its target genes in different type of cells and exploring the role of HIF-1α in inflammatory responses after ischemia is of great importance for revealing the pathogenesis and identifying new therapeutic targets for ischemic stroke. Herein, we provide a succinct overview of the current approaches targeting HIF-1α and summarize novel findings concerning HIF-1α regulation in different types of cells within neurovascular units, including neurons, endothelial cells, astrocytes, and microglia, during the different stages of ischemic stroke. The current representative translational approaches focused on neuroprotection by targeting HIF-1α are also discussed.

Gut Microbiota in Adipose Tissue Dysfunction Induced Cardiovascular Disease: Role as a Metabolic Organ.

The gut microbiome has emerged as a key regulator of host metabolism. Accumulating evidence has indicated that the gut microbiota is involved in the development of various human diseases. This association relies on the structure and metabolites of the gut microbiota. The gut microbiota metabolizes the diet ingested by the host into a series of metabolites, including short chain fatty acids, secondary bile acids, trimethylamine N-oxide, and branched-chain amino acids, which affects the physiological processes of the host by activating numerous signaling pathways. In this review, we first summarize the various mechanisms through which the gut microbiota influences adipose tissue dysfunction and metabolic processes that subsequently cause cardiovascular diseases, highlighting the complex interactions between gut microbes, their metabolites, and the metabolic activity of the host. Furthermore, we investigated the current status of clinical therapies for adipose tissue dysfunction directed at the gut microbiota. Finally, we discuss the challenges that remain to be addressed before this field of research can be translated to everyday clinical practice.

T Cell Response in Ischemic Stroke: From Mechanisms to Translational Insights.

Ischemic stroke, caused by a sudden disruption of blood flow to the brain, is a leading cause of death and exerts a heavy burden on both patients and public health systems. Currently available treatments for ischemic stroke are very limited and are not feasible in many patients due to strict time windows required for their administration. Thus, novel treatment strategies are keenly required. T cells, which are part of the adaptive immune system, have gained more attention for its effects in ischemic stroke. Both preclinical and clinical studies have revealed the conflicting roles for T cells in post-stroke inflammation and as potential therapeutic targets. This review summarizes the mediators of T cell recruitment, as well as the temporal course of its infiltration through the blood-brain-barrier, choroid plexus, and meningeal pathways. Furthermore, we describe the mechanisms behind the deleterious and beneficial effects of T cells in the brain, in both antigen-dependent and antigen-independent manners, and finally we specifically focus on clinical and preclinical studies that have investigated T cells as potential therapeutic targets for ischemic stroke.

Therapeutic Potential of Remote Ischemic Conditioning in Vascular Cognitive Impairment.

Vascular cognitive impairment (VCI) is a heterogeneous disease caused by a variety of cerebrovascular diseases. Patients with VCI often present with slower cognitive processing speed and poor executive function, which affects their independence in daily life, thus increasing social burden. Remote ischemic conditioning (RIC) is a non-invasive and efficient intervention that triggers endogenous protective mechanisms to generate neuroprotection. Over the past decades, evidence from basic and clinical research has shown that RIC is promising for the treatment of VCI. To further our understanding of RIC and improve the management of VCI, we summarize the evidence on the therapeutic potential of RIC in relation to the risk factors and pathobiologies of VCI, including reducing the risk of recurrent stroke, decreasing high blood pressure, improving cerebral blood flow, restoring white matter integrity, protecting the neurovascular unit, attenuating oxidative stress, and inhibiting the inflammatory response.

The Role of Immune Cells in Post-Stroke Angiogenesis and Neuronal Remodeling: The Known and the Unknown.

Following a cerebral ischemic event, substantial alterations in both cellular and molecular activities occur due to ischemia-induced cerebral pathology. Mounting evidence indicates that the robust recruitment of immune cells plays a central role in the acute stage of stroke. Infiltrating peripheral immune cells and resident microglia mediate neuronal cell death and blood-brain barrier disruption by releasing inflammation-associated molecules. Nevertheless, profound immunological effects in the context of the subacute and chronic recovery phase of stroke have received little attention. Early attempts to curtail the infiltration of immune cells were effective in mitigating brain injury in experimental stroke studies but failed to exert beneficial effects in clinical trials. Neural tissue damage repair processes include angiogenesis, neurogenesis, and synaptic remodeling, etc. Post-stroke inflammatory cells can adopt divergent phenotypes that influence the aforementioned biological processes in both endothelial and neural stem cells by either alleviating acute inflammatory responses or secreting a variety of growth factors, which are substantially involved in the process of angiogenesis and neurogenesis. To better understand the multiple roles of immune cells in neural tissue repair processes post stroke, we review what is known and unknown regarding the role of immune cells in angiogenesis, neurogenesis, and neuronal remodeling. A comprehensive understanding of these inflammatory mechanisms may help identify potential targets for the development of novel immunoregulatory therapeutic strategies that ameliorate complications and improve functional rehabilitation after stroke.

Effect of Hyperhomocysteinemia on Clinical Outcome and Hemorrhagic Transformation After Thrombolysis in Ischemic Stroke Patients.

Background and Purpose: Hyperhomocysteinemia (Hhcy) is a well-known risk factor for ischemic stroke. However, the role of Hhcy in the clinical outcome of ischemic stroke has not been fully elucidated. In addition, previous studies have found that Hhcy was implicated in the disruption of the blood-brain barrier, which may increase the risk of hemorrhagic transformation (HT) after thrombolysis. Thus, the aim of this study was to investigate the effect of Hhcy on the clinical outcome and HT after thrombolysis in ischemic stroke patients. Methods: Patients who were diagnosed with ischemic stroke and received intravenous thrombolytic therapy between January 2016 and September 2018 were included in this study. Multivariate logistic regression analysis was used to assess the association between Hhcy, clinical outcome, and HT after thrombolysis. Furthermore, the potential interaction between Hhcy and hypertension on the clinical outcome and HT after thrombolysis was also assessed. Results: Of 568 patients, 455 (80.1%) had Hhcy, 66 (11.6%) had HT, and 219 (38.6%) had poor outcome. Patients with Hhcy had a higher incidence of poor outcome than the patients with non-Hhcy (40.9 vs. 29.2%, p = 0.022). However, there was no significant difference in the incidence of HT (11.9 vs. 10.6%, p = 0.711) between patients with Hhcy and non-Hhcy. After adjustment for major covariates, multivariate logistic regression analysis disclosed that Hhcy was independently associated with increased risk of poor outcome (OR = 1.760; 95% CI: 1.069-2.896) but was not associated with the risk of HT (OR = 1.017; 95% CI: 0.495-2.087). In addition, we found no significant interaction between Hhcy and hypertension on the clinical outcome (p = 0.513) or HT (p = 0.170) after thrombolysis. Conclusion: We found that Hhcy was an independent risk factor for poor outcome, but not an independent risk factor for HT after thrombolysis in ischemic stroke patients. In addition, there was no significant interaction of Hhcy and hypertension on the clinical outcome or HT after thrombolysis.

Technical Skills Required in Split Liver Transplantation.

The number of liver grafts obtained from a cadaver can be greatly increased with the application of split liver transplantation. In the last 10 years, pediatric waiting list mortality has been reduced significantly with the use of this form of liver transplantation, which has 2 major forms. In its most commonly used form, the liver can be transplanted into 1 adult and 1 child by splitting it into a right extended and a left lateral graft. For adult and pediatric recipients, the results of this procedure are comparable to those of whole-organ techniques. In another form, 2 hemi-grafts are obtained by splitting the liver, which can be transplanted into a medium-sized adult (the right side) and a large child/small adult (the left side). The adult liver graft pool is expanded through the process of full right/full left splitting; but it is also a critical technique when one considers the knowledge required of the potential anatomic variations and the high technical skill level needed. In this review, we provide some basic insights into the technical and anatomical aspects of these 2 forms of split liver transplantation and present an updated summary of both forms.

Ascertain the Safe Range From Foramen Rotundum to the Siphon of Internal Carotid Artery for Operation Through Pterygopalatine Fossa With Thin-Section Computed Tomographic Image.

OBJECTIVE: This study aimed to ascertain the safe range from foramen rotundum to the siphon of internal carotid artery using three-dimensional reconstruction technique. METHODS: We scanned skulls of 121 volunteers to get the final results with thin-section computed tomographic image. RESULTS: The distance of AC was measured as 13.22 (3.79) mm (range, 8.33-105.67 mm; 95% CI [confidence interval], 8.55-21.39 mm). The angle to the sagittal plane was measured as 33.54 (9.23) mm (range, 5.38-66.58; 95% CI, 30.88-34.20). The angle to the coronal plane was measured as 53.17 (10.48) mm (range, 5.60-75.02; 95% CI, 51.29-55.06). The angle to the horizontal plane was measured as 9.43 (12.91) mm (range, -28.44 to 82.22; 95% CI, 7.11-11.76). CONCLUSIONS: These above-mentioned results can help locate these structures to help in minimizing surgical trauma to the nerves and blood vessels of the operation through pterygopalatine fossa under nasoendoscope.