E4BP4 in macrophages induces an anti-inflammatory phenotype that ameliorates the severity of colitis.

Macrophages are versatile cells of the innate immune system that work by altering their pro- or anti-inflammatory features. Their dysregulation leads to inflammatory disorders such as inflammatory bowel disease. We show that macrophage-specific upregulation of the clock output gene and transcription factor E4BP4 reduces the severity of colitis in mice. RNA-sequencing and single-cell analyses of macrophages revealed that increased expression of E4BP4 leads to an overall increase in expression of anti-inflammatory genes including Il4ra with a concomitant reduction in pro-inflammatory gene expression. In contrast, knockout of E4BP4 in macrophages leads to increased proinflammatory gene expression and decreased expression of anti-inflammatory genes. ChIP-seq and ATAC-seq analyses further identified Il4ra as a target of E4BP4, which drives anti-inflammatory polarization in macrophages. Together, these results reveal a critical role for E4BP4 in regulating macrophage inflammatory phenotypes and resolving inflammatory bowel diseases.

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

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

Allogeneic Stem Cell Therapy for Acute Ischemic Stroke: The Phase 2/3 TREASURE Randomized Clinical Trial.

Importance: Cell therapy is a promising treatment approach for stroke and other diseases. However, it is unknown whether MultiStem (HLCM051), a bone marrow-derived, allogeneic, multipotent adult progenitor cell product, has the potential to treat ischemic stroke. Objective: To assess the efficacy and safety of MultiStem when administered within 18 to 36 hours of ischemic stroke onset. Design, Setting, and Participants: The Treatment Evaluation of Acute Stroke Using Regenerative Cells (TREASURE) multicenter, double-blind, parallel-group, placebo-controlled phase 2/3 randomized clinical trial was conducted at 44 academic and clinical centers in Japan between November 15, 2017, and March 29, 2022. Inclusion criteria were age 20 years or older, presence of acute ischemic stroke (National Institutes of Health Stroke Scale [NIHSS] score of 8-20 at baseline), confirmed acute infarction involving the cerebral cortex and measuring more than 2 cm on the major axis (determined with diffusion-weighted magnetic resonance imaging), and a modified Rankin Scale (mRS) score of 0 or 1 before stroke onset. Data analysis was performed between May 9 and August 15, 2022. Exposure: Patients were randomly assigned to either intravenous MultiStem in 1 single unit of 1.2 billion cells or intravenous placebo within 18 to 36 hours of ischemic stroke onset. Main Outcomes and Measures: The primary end points were safety and excellent outcome at day 90, measured as a composite of a modified Rankin Scale (mRS) score of 1 or less, a NIHSS score of 1 or less, and a Barthel index score of 95 or greater. The secondary end points were excellent outcome at day 365, mRS score distribution at days 90 and 365, and mRS score of 0 to 1 and 0 to 2 at day 90. Statistical analysis of efficacy was performed using the Cochran-Mantel-Haenszel test. Results: This study included 206 patients (104 received MultiStem and 102 received placebo). Their mean age was 76.5 (range, 35-95) years, and more than half of patients were men (112 [54.4%]). There were no between-group differences in primary and secondary end points. The proportion of excellent outcomes at day 90 did not differ significantly between the MultiStem and placebo groups (12 [11.5%] vs 10 [9.8%], P = .90; adjusted risk difference, 0.5% [95% CI, -7.3% to 8.3%]). The frequency of adverse events was similar between treatment groups. Conclusions and Relevance: In this randomized clinical trial, intravenous administration of allogeneic cell therapy within 18 to 36 hours of ischemic stroke onset was safe but did not improve short-term outcomes. Further research is needed to determine whether MultiStem therapy for ischemic stroke has a beneficial effect in patients who meet specific criteria, as indicated by the exploratory analyses in this study. Trial Registration: ClinicalTrials.gov Identifier: NCT02961504.

RNA Analysis of Circulating Leukocytes in Patients with Alzheimer's Disease.

Background: One of the key symptoms of Alzheimer's disease (AD) is the impairment of short-term memory. Hippocampal neurogenesis is essential for short-term memory and is known to decrease in patients with AD. Impaired short-term memory and impaired neurogenesis are observed in aged mice alongside changes in RNA expression of gap junction and metabolism-related genes in circulating leukocytes. Moreover, after penetrating the blood-brain barrier via the SDF1/CXCR4 axis, circulating leukocytes directly interact with hippocampal neuronal stem cells via gap junctions. Objective: Evaluation of RNA expression profiles in circulating leukocytes in patients with AD. Methods: Patients with AD (MMSE≧23, n = 10) and age-matched controls (MMSE≧28, n = 10) were enrolled into this study. RNA expression profiles of gap junction and metabolism-related genes in circulating leukocytes were compared between the groups (jRCT: 1050210166). Results: The ratios of gap junction and metabolism-related genes were significantly different between patients with AD and age-matched controls. However, due to large inter-individual variations, there were no statistically significant differences in the level of single RNA expression between these groups. Conclusions: Our findings suggest a potential connection between the presence of circulating leukocytes and the process of hippocampal neurogenesis in individuals with AD. Analyzing RNA in circulating leukocytes holds promise as a means to offer novel insights into the pathology of AD, distinct from conventional markers.

Efficacy and Safety of Cilostazol in Mild Cognitive Impairment: A Randomized Clinical Trial.

Importance: Recent evidence indicates the efficacy of ß-amyloid immunotherapy for the treatment of Alzheimer disease, highlighting the need to promote ß-amyloid removal from the brain. Cilostazol, a selective type 3 phosphodiesterase inhibitor, promotes such clearance by facilitating intramural periarterial drainage. Objective: To determine the safety and efficacy of cilostazol in mild cognitive impairment. Design, Setting, and Participants: The COMCID trial (A Trial of Cilostazol for Prevention of Conversion from Mild Cognitive Impairment to Dementia) was an investigator-initiated, double-blind, phase 2 randomized clinical trial. Adult participants were registered between May 25, 2015, and March 31, 2018, and received placebo or cilostazol for up to 96 weeks. Participants were treated in the National Cerebral and Cardiovascular Center and 14 other regional core hospitals in Japan. Patients with mild cognitive impairment with Mini-Mental State Examination (MMSE) scores of 22 to 28 points (on a scale of 0 to 30, with lower scores indicating greater cognitive impairment) and Clinical Dementia Rating scores of 0.5 points (on a scale of 0, 0.5, 1, 2, and 3, with higher scores indicating more severe dementia) were enrolled. The data were analyzed from May 1, 2020, to December 1, 2020. Interventions: The participants were treated with placebo, 1 tablet twice daily, or cilostazol, 50 mg twice daily, for up to 96 weeks. Main Outcomes and Measures: The primary end point was the change in the total MMSE score from baseline to the final observation. Safety analyses included all adverse events. Results: The full analysis set included 159 patients (66 [41.5%] male; mean [SD] age, 75.6 [5.2] years) who received placebo or cilostazol at least once. There was no statistically significant difference between the placebo and cilostazol groups for the primary outcome. The least-squares mean (SE) changes in the MMSE scores among patients receiving placebo were -0.1 (0.3) at the 24-week visit, -0.8 (0.3) at 48 weeks, -1.2 (0.4) at 72 weeks, and -1.3 (0.4) at 96 weeks. Among those receiving cilostazol, the least-squares mean (SE) changes in MMSE scores were -0.6 (0.3) at 24 weeks, -1.0 (0.3) at 48 weeks, -1.1 (0.4) at 72 weeks, and -1.8 (0.4) at 96 weeks. Two patients (2.5%) in the placebo group and 3 patients (3.8%) in the cilostazol group withdrew owing to adverse effects. There was 1 case of subdural hematoma in the cilostazol group, which may have been related to the cilostazol treatment; the patient was successfully treated surgically. Conclusions and Relevance: In this randomized clinical trial, cilostazol was well tolerated, although it did not prevent cognitive decline. The efficacy of cilostazol should be tested in future trials. Trial Registration: ClinicalTrials.gov Identifier: NCT02491268.

Effects of pemafibrate on left ventricular diastolic function in patients with type 2 diabetes mellitus: a pilot study.

Aims/introduction: Diabetic cardiomyopathy (DCM) is characterized predominantly by diastolic dysfunction. The multiple mechanisms underlying DCM include altered energy substrate utilization. Recent studies indicate that PPARα plays an important role in the pathogenesis of lipotoxic cardiomyopathy. Pemafibrate is known to be a selective PPARα modulator (SPPARMα). We thus investigated the effects of pemafibrate on cardiac diastolic function in patients with type 2 diabetes. Materials and methods: Seventeen patients with type 2 diabetes (T2D) and hypertriglyceridemia were screened and treated with pemafibrate at a dose of 0.2 mg/day for 8-16 weeks. Fourteen patients were eligible for analysis. Echocardiography was used for assessment of diastolic function. Early diastolic filling velocity (E), late atrial filling velocity (A) and the E/A ratio were included in this study. Peak early diastolic annular velocities (e') were also assessed using color tissue Doppler images. The primary endpoints were changes in the ratio of E to A (E/A), e', and the ratio of E to e' (E/e') from baseline. Results: Pemafibrate significantly increased average e' (7.24 ± 0.58 vs 7.94 ± 0.67, p = 0.019) and a significant reduction in E/e' (9.01 ± 0.94 vs 8.20 ± 0.91, p = 0.041). The increase in e' was significantly related to increases in fasting blood glucose (r = 0.607, p = 0.021) and non-esterified fatty acid (r = 0.592, p = 0.026). Conclusion: Pemafibrate improved diastolic function in patients with T2D and hypertriglyceridemia, suggesting that PPARα activation by pemafibrate prevents the development of DCM at an early stage.

Cell Therapies for Autism Spectrum Disorder Based on New Pathophysiology: A Review.

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder characterized by difficulties in social communication, repetitive behaviors, and restricted interests, with onset early in life. The prevalence of ASD has increased worldwide in the last two decades. However, there is currently no effective therapy for ASD. Therefore, it is important to develop new strategies for ASD treatment. Evidence for the relationship between ASD and neuroinflammation, ASD and microglia, and ASD and glucose metabolism has increased rapidly in recent decades. We reviewed 10 clinical studies on cell therapies for individuals with ASD. Almost all studies showed good outcomes and no remarkable adverse events. Over the past decades, the neurophysiological characteristics of ASD have been shown to be impaired communication, cognition, perception, motor skills, executive function, theory of mind, and control of emotions. Recent studies have focused on the roles of immune pathology, such as neuroinflammation, microglia, cytokines, and oxidative stress, in ASD. We also focused on glucose metabolism in patients with ASD. The significance of gap junction-mediated cell-cell interactions between the cerebral endothelium and transplanted cells was observed in both bone marrow mononuclear cells and mesenchymal stromal cells transplantation. Owing to the insufficient number of samples, cell therapies, such as umbilical cord blood cells, bone marrow mononuclear cells, and mesenchymal stromal cells, will be a major challenge for ASD. As a result of these findings, a new paradigm for cell therapy for autism may emerge.

Different Contacted Cell Types Contribute to Acquiring Different Properties in Brain Microglial Cells upon Intercellular Interaction.

Microglial cells (MGs), originally derived from progenitor cells in a yolk sac during early development, are glial cells located in a physiological and pathological brain. Since the brain contains various cell types, MGs could frequently interact with different cells, such as astrocytes (ACs), pericytes (PCs), and endothelial cells (ECs). However, how microglial traits are regulated via cell-cell interactions by ACs, PCs, or ECs and how they are different depending on the contacted cell types is unclear. This study aimed to clarify these questions by coculturing MGs with ACs, PCs, or ECs using mouse brain-derived cells, and microglial phenotypic changes were investigated under culture conditions that enabled direct cell-cell contact. Our results showed that ACs or PCs dose-dependently increased the number of MG, while ECs decreased it. Microarray and gene ontology analysis showed that cell fate-related genes (e.g., cell cycle, proliferation, growth, death, and apoptosis) of MGs were altered after a cell-cell contact with ACs, PCs, and ECs. Notably, microarray analysis showed that several genes, such as gap junction protein alpha 1 (Gja1), were prominently upregulated in MGs after coincubation with ACs, PCs, or ECs, regardless of cell types. Similarly, immunohistochemistry showed that an increased Gja1 expression was observed in MGs after coincubation with ACs, PCs, or ECs. Immunofluorescent and fluorescence-activated cell sorting analysis also showed that calcein-AM was transferred into MGs after coincubation with ACs, PCs, or ECs, confirming that intercellular interactions occurred between these cells. However, while Gja1 inhibition reduced the number of MGs after coincubation with ACs and PCs, this was increased after coincubation with ECs; this indicates that ACs and PCs positively regulate microglial numbers via Gja1, while ECs decrease it. Results show that ACs, PCs, or ECs exert both common and specific cell type-dependent effects on MGs through intercellular interactions. These findings also suggest that brain microglial phenotypes are different depending on their surrounding cell types, such as ACs, PCs, or ECs.

Gap Junction-Mediated Transport of Metabolites Between Stem Cells and Vascular Endothelial Cells.

We have previously demonstrated that small molecular transfer, such as glucose, between hematopoietic stem cells (HSCs) or mesenchymal stem cells (MSCs) and vascular endothelial cells via gap junctions constitutes an important mechanism of stem cell therapy. Cell metabolites are high-potential small-molecule candidates that can be transferred to small molecules between stem cells and vascular endothelial cells. Here, we investigated the differences in metabolite levels between stem cells (HSCs and MSCs), vascular endothelial cells, and the levels of circulating non-hematopoietic white blood cells (WBCs). The results showed remarkable differences in metabolite concentrations between cells. Significantly higher concentrations of adenosine triphosphate (ATP), guanosine triphosphate (GTP), total adenylate or guanylate levels, glycolytic intermediates, and amino acids were found in HSCs compared with vascular endothelial cells. In contrast, there was no significant difference in the metabolism of MSCs and vascular endothelial cells. From the results of this study, it became clear that HSCs and MSCs differ in their metabolites. That is, metabolites that transfer between stem cells and vascular endothelial cells differ between HSCs and MSCs. HSCs may donate various metabolites, several glycolytic and tricarboxylic acid cycle metabolites, and amino acids to damaged vascular endothelial cells as energy sources and activate the energy metabolism of vascular endothelial cells. In contrast, MSCs and vascular endothelial cells regulate each other under normal conditions. As the existing MSCs cannot ameliorate the dysregulation during insult, exogenous MSCs administered by cell therapy may help restore normal metabolic function in the vascular endothelial cells by taking up excess energy sources from the lumens of blood vessels. Results of this study suggested that the appropriate timing of cell therapy is different between HSCs and MSCs.

Pre-Clinical Proof of Concept: Intra-Carotid Injection of Autologous CD34-Positive Cells for Chronic Ischemic Stroke.

This study was conducted to evaluate the safety and efficacy of human peripheral blood CD34 positive (CD34+) cells transplanted into a murine chronic stroke model to obtain pre-clinical proof of concept, prior to clinical testing. Granulocyte colony stimulating factor (G-CSF) mobilized human CD34+ cells [1 × 104 cells in 50 µl phosphate-buffered saline (PBS)] were intravenously (iv) or intra-carotid arterially (ia) transplanted 4 weeks after the induction of stroke (chronic stage), and neurological function was evaluated. In this study, severe combined immune deficiency (SCID) mice were used to prevent excessive immune response after cell therapy. Two weeks post cell therapy, the ia CD34+ cells group demonstrated a significant improvement in neurological functions compared to the PBS control. The therapeutic effect was maintained 8 weeks after the treatment. Even after a single administration, ia transplantation of CD34+ cells had a significant therapeutic effect on chronic stroke. Based on the result of this pre-clinical proof of concept study, a future clinical trial of autologous peripheral blood CD34+ cells administration in the intra-carotid artery for chronic stroke patients is planned.

Metabolic state switches between morning and evening in association with circadian clock in people without diabetes.

AIMS/INTRODUCTION: Understanding morning-evening variation in metabolic state is critical for managing metabolic disorders. We aimed to characterize this variation from the viewpoints of insulin secretion and insulin sensitivity, including their relevance to the circadian rhythm. MATERIALS AND METHODS: A total of 14 and 10 people without diabetes were enrolled, and underwent a 75-g oral glucose tolerance test (OGTT) and hyperinsulinemic-euglycemic clamp study, respectively. Participants completed the OGTT or hyperinsulinemic-euglycemic clamp at 08.00 hours and 20.00 hours in random order. Before each study, hair follicles were collected. In mice, phosphorylation levels of protein kinase B were examined in the liver and muscle by western blotting. RESULTS: Glucose tolerance was better at 08 .00 hours, which was explained by the higher 1-h insulin secretion on OGTT and increased skeletal muscle insulin sensitivity on hyperinsulinemic-euglycemic clamp. Hepatic insulin sensitivity, estimated by the hepatic insulin resistance index on OGTT, was better at 20.00 hours. The 1-h insulin secretion and hepatic insulin resistance index correlated significantly with Per2 messenger ribonucleic acid expression. The change (evening value - morning value) in the glucose infusion rate correlated significantly with the change in non-esterified fatty acid, but not with clock gene expressions. The change in non-esterified fatty acid correlated significantly with E4bp4 messenger ribonucleic acid expression and the change in cortisol. In mice, phosphorylation of protein kinase B was decreased in the liver and increased in muscle in the beginning of the active period as, expected from the human study. CONCLUSIONS: Glucose metabolism in each tissue differed between the morning and evening, partly reflecting lipid metabolism, clock genes and cortisol levels. Deeper knowledge of these associations might be useful for ameliorating metabolic disorders.

P2Y1 purinergic receptor identified as a diabetes target in a small-molecule screen to reverse circadian ß-cell failure.

The mammalian circadian clock drives daily oscillations in physiology and behavior through an autoregulatory transcription feedback loop present in central and peripheral cells. Ablation of the core clock within the endocrine pancreas of adult animals impairs the transcription and splicing of genes involved in hormone exocytosis and causes hypoinsulinemic diabetes. Here, we developed a genetically sensitized small-molecule screen to identify druggable proteins and mechanistic pathways involved in circadian ß-cell failure. Our approach was to generate ß-cells expressing a nanoluciferase reporter within the proinsulin polypeptide to screen 2640 pharmacologically active compounds and identify insulinotropic molecules that bypass the secretory defect in CRISPR-Cas9-targeted clock mutant ß-cells. We validated hit compounds in primary mouse islets and identified known modulators of ligand-gated ion channels and G-protein-coupled receptors, including the antihelmintic ivermectin. Single-cell electrophysiology in circadian mutant mouse and human cadaveric islets revealed ivermectin as a glucose-dependent secretagogue. Genetic, genomic, and pharmacological analyses established the P2Y1 receptor as a clock-controlled mediator of the insulinotropic activity of ivermectin. These findings identify the P2Y1 purinergic receptor as a diabetes target based upon a genetically sensitized phenotypic screen.

Circadian rhythms ­ 'inbuilt' 24-hour cycles ­ control many aspects of behaviour and physiology. In mammals, they operate in nearly all tissues, including those involved in glucose metabolism. Recent studies have shown that mice with faulty genes involved in circadian rhythms, the core clock genes, can develop diabetes. Diabetes arises when the body struggles to regulate blood sugar levels. In healthy individuals, the hormone insulin produced by beta cells in the pancreas regulates the amount of sugar in the blood. But when beta cells are faulty and do not generate sufficient insulin levels, or when insulin lacks the ability to stimulate cells to take up glucose, diabetes can develop. Marcheva, Weidemann, Taguchi et al. wanted to find out if diabetes caused by impaired clock genes could be treated by targeting pathways regulating the secretion of insulin. To do so, they tested over 2,500 potential drugs on genetically modified beta cells with faulty core clock genes. They further screened the drugs on mice with the same defect in their beta cells. Marcheva et al. identified one potential compound, the anti-parasite drug ivermectin, which was able to restore the secretion of insulin. When ivermectin was applied to both healthy mice and mice with faulty beta cells, the drug improved the control over glucose levels by activating a specific protein receptor that senses molecules important for storing and utilizing energy. The findings reveal new drug targets for treating forms of diabetes associated with deregulation of the pancreatic circadian clock. The drug screening strategy used in the study may also be applied to reveal mechanisms underlying other conditions associated with disrupted circadian clocks, including sleep loss and jetlag.

Increased RNA Transcription of Energy Source Transporters in Circulating White Blood Cells of Aged Mice.

Circulating white blood cells (WBC) contribute toward maintenance of cerebral metabolism and brain function. Recently, we showed that during aging, transcription of metabolism related genes, including energy source transports, in the brain significantly decreased at the hippocampus resulting in impaired neurological functions. In this article, we investigated the changes in RNA transcription of metabolism related genes (glucose transporter 1 [Glut1], Glut3, monocarboxylate transporter 4 [MCT4], hypoxia inducible factor 1-α [Hif1-α], prolyl hydroxylase 3 [PHD3] and pyruvate dehydrogenase kinase 1 [PDK1]) in circulating WBC and correlated these with brain function in mice. Contrary to our expectations, most of these metabolism related genes in circulating WBC significantly increased in aged mice, and correlation between their increased RNA transcription and impaired neurological functions was observed. Bone marrow mononuclear transplantation into aged mice decreased metabolism related genes in WBC with accelerated neurogenesis in the hippocampus. In vitro analysis revealed that cell-cell interaction between WBC and endothelial cells via gap junction is impaired with aging, and blockade of the interaction increased their transcription in WBC. Our findings indicate that gross analysis of RNA transcription of metabolism related genes in circulating WBC has the potential to provide significant information relating to impaired cell-cell interaction between WBC and endothelial cells of aged mice. Additionally, this can serve as a tool to evaluate the change of the cell-cell interaction caused by various treatments or diseases.

Bone Marrow Mononuclear Cells Transplantation and Training Increased Transplantation of Energy Source Transporters in Chronic Stroke.

OBJECTIVES: Bone marrow mononuclear cells (BM-MNC) show a significant therapeutic effect in combination with training even in the chronic phase of stroke. However, the mechanism of this combination therapy has not been investigated. Here, we examined its effects on brain metabolism in chronic stroke mice. MATERIALS AND METHODS: BM-MNC (1x105 cells in 100 µL of phosphate-buffered saline) were intravenously transplanted at 4 weeks (chronic stage) after the middle cerebral artery occlusion. At 3 h and 10 weeks after the administration of BM-MNC, we evaluated transcription changes of the metabolism-related genes, hypoxia inducible factor 1-α (Hif-1α), prolyl hydroxylase 3 (Phd3), pyruvate dehydrogenase kinase 1 (Pdk1), Na+/K+-ATPase (Atp1α1‒3), connexins, glucose transporters, and monocarboxylate transporters, in the brain during chronic phase of stroke using quantitative polymerase chain reaction. RESULTS: The results showed transcriptional activation of the metabolism-related genes in the contralateral cortex at 3 h after BM-MNC transplantation. Behavioral tests were performed after cell therapy, and the brain metabolism of mice with improved motor function was examined at 10 weeks after cell therapy. The therapeutic efficacy of the combination therapy with BM-MNC transplantation and training was evident in the form of transcriptional activation of ipsilateral anterior cerebral artery (ACA) cortex. CONCLUSIONS: BM-MNC transplantation combined with training for chronic stroke activated gene expression in both the ipsilateral and the contralateral side.

Endothelial connexin-integrin crosstalk in vascular inflammation.

Cardiovascular diseases including blood vessel disorders represent a major cause of death globally. The essential roles played by local and systemic vascular inflammation in the pathogenesis of cardiovascular diseases have been increasingly recognized. Vascular inflammation triggers the aberrant activation of endothelial cells, which leads to the functional and structural abnormalities in vascular vessels. In addition to humoral mediators such as pro-inflammatory cytokines and prostaglandins, the alteration of physical and mechanical microenvironment - including vascular stiffness and shear stress - modify the gene expression profiles and metabolic profiles of endothelial cells via mechano-transduction pathways, thereby contributing to the pathogenesis of vessel disorders. Notably, connexins and integrins crosstalk each other in response to the mechanical stress, and, thereby, play an important role in regulating the mechano-transduction of endothelial cells. Here, we provide an overview on how the inter-play between connexins and integrins in endothelial cells unfold during the mechano-transduction in vascular inflammation.

Gap junction-mediated cell-cell interaction between transplanted mesenchymal stem cells and vascular endothelium in stroke.

We have shown previously that transplanted bone marrow mononuclear cells (BM-MNC), which are a cell fraction rich in hematopoietic stem cells, can activate cerebral endothelial cells via gap junction-mediated cell-cell interaction. In the present study, we investigated such cell-cell interaction between mesenchymal stem cells (MSC) and cerebral endothelial cells. In contrast to BM-MNC, for MSC we observed suppression of vascular endothelial growth factor uptake into endothelial cells and transfer of glucose from endothelial cells to MSC in vitro. The transfer of such a small molecule from MSC to vascular endothelium was subsequently confirmed in vivo and was followed by suppressed activation of macrophage/microglia in stroke mice. The suppressive effect was absent by blockade of gap junction at MSC. Furthermore, gap junction-mediated cell-cell interaction was observed between circulating white blood cells and MSC. Our findings indicate that gap junction-mediated cell-cell interaction is one of the major pathways for MSC-mediated suppression of inflammation in the brain following stroke and provides a novel strategy to maintain the blood-brain barrier in injured brain. Furthermore, our current results have the potential to provide a novel insight for other ongoing clinical trials that make use of MSC transplantation aiming to suppress excess inflammation, as well as other diseases such as COVID-19 (coronavirus disease 2019).

New Mechanistic Insights, Novel Treatment Paradigms, and Clinical Progress in Cerebrovascular Diseases.

The past decade has brought tremendous progress in diagnostic and therapeutic options for cerebrovascular diseases as exemplified by the advent of thrombectomy in ischemic stroke, benefitting a steeply increasing number of stroke patients and potentially paving the way for a renaissance of neuroprotectants. Progress in basic science has been equally impressive. Based on a deeper understanding of pathomechanisms underlying cerebrovascular diseases, new therapeutic targets have been identified and novel treatment strategies such as pre- and post-conditioning methods were developed. Moreover, translationally relevant aspects are increasingly recognized in basic science studies, which is believed to increase their predictive value and the relevance of obtained findings for clinical application.This review reports key results from some of the most remarkable and encouraging achievements in neurovascular research that have been reported at the 10th International Symposium on Neuroprotection and Neurorepair. Basic science topics discussed herein focus on aspects such as neuroinflammation, extracellular vesicles, and the role of sex and age on stroke recovery. Translational reports highlighted endovascular techniques and targeted delivery methods, neurorehabilitation, advanced functional testing approaches for experimental studies, pre-and post-conditioning approaches as well as novel imaging and treatment strategies. Beyond ischemic stroke, particular emphasis was given on activities in the fields of traumatic brain injury and cerebral hemorrhage in which promising preclinical and clinical results have been reported. Although the number of neutral outcomes in clinical trials is still remarkably high when targeting cerebrovascular diseases, we begin to evidence stepwise but continuous progress towards novel treatment options. Advances in preclinical and translational research as reported herein are believed to have formed a solid foundation for this progress.