Optimal antiplatelet inhibition is essential in patients undergoing neurointerventional procedures, however, variability in response to clopidogrel can contribute to thromboembolic and hemorrhagic complications. In the present study, we evaluated the impact of active management of antiplatelet reactivity in patients undergoing aneurysmal neurointerventional procedures. Between 2013 and 2016, 61 consecutive patients (male; 12, mean age; 57) underwent aneurysmal coil embolization and received clopidogrel (75 mg daily) and aspirin (100 mg daily) before the treatment under platelet function monitoring. Patients underwent prospective assessment of preoperative platelet function using VerifyNow assay and received adjunctive cilostazol (200 mg daily; triple antiplatelet therapy) in case of clopidogrel hypo-response. Patient with clopidogrel hyper-response underwent clopidogrel dose reduction according to the protocol (clopidogrel, 12.5–75 mg daily). Successful coil embolization was performed in all patients. Stent-assisted coil embolization was performed in 32 patients (53%). Preoperative clopidogrel resistance was noted in 6 patients (10%) and clopidogrel hyper response was noted in 9 patients (24%). In active management of platelet reactivity resulted in optimization of P2Y12 reaction units (PRU) value within the target range during and after the treatment. There were no symptomatic thromboembolic or hemorrhagic events. In conclusion, active management of clopidogrel dosing for clopidogrel hyper-response and adjunctive cilostazol for clopidogrel hypo-response resulted in an adjustment of PRU value to within a target range, and there were no hemorrhagic complications after the treatment.

Microglia, known as the primary immune cell of central nervous system (CNS), plays a crucial role in maintaining homeostasis of the brain tissue by dynamically surveying their cellular environment during normal development, function, and repair from the injury. In the present study, we aimed to establish a method for long-term repeated real-time imaging and analysis of microglia in the mouse cortex in vivo. To this end, genetically-modified mice (CX3CR1-GFP mice, the Jackson Laboratory, 17–33 g, N=13) in which the cortical microglia expresses green fluorescence protein (GFP) were used for the experiments. A part of the skull was replaced with a closed-cranial window by using a Tomita-Seylaz method for transparency. The GFP-positive microglia and cortical microvessels labeled with sulforhodamine 101 (SR101) were imaged with two-photon laser scanning fluorescence microscopy repeatedly up to 3 weeks after the cranial surgery. For quantification of the cellular structure and motility, cell size, number density, and number of fine processes of the GFP-positive microglia were measured with custom-written software. We observed that consistent morphology and clear visibility of the GFP-positive microglia was maintained up to a depth of 800 μm from the cortical surface during entire periods of the experiment. There were no detectable differences in the soma area (32±2 μm²), number density (6–8×10³ number/mm³), and number of processes (10.3±0.5 number/cell) of the GFP-positive microglia between 1–3 weeks following installation of the cranial window. In conclusion, the present methods provide stable and reproducible real-time measures of the morphology and motility of microglia in vivo in the living mouse cortex. The present results are beneficial for use as a control data to further understand the role and behavior of microglia in neurodegenerative diseases, such as ischemia, chronic hypoperfusion, and dementia.

Background and purpose: Timings of symptom improvement of acute ischemic stroke patients who obtained successful endovascular reperfusion with subsequent favorable outcome at 90 days are not uniform. The purpose of this study was to clarify factors related to early symptom improvement after successful endovascular reperfusion. Methods: Among consecutive stroke patients treated using endovascular therapy at our institute between April 2012 and March 2016, we retrospectively reviewed those who obtained successful (Thrombolysis In Cerebral Infarction grade ≥2b) with subsequent favorable outcome defined as a modified Rankin Scale score of 0–2 at 90 days. Early dramatic recovery (EDR) was defined as an improvement of ≥10 points in National Institutes of Health Stroke Scale (NIHSS) score or a total score of 0–3 at 24 h after onset compared with the pretreatment score. Results: A total of 53 patients (mean age, 70.3±12.1 years; 17 females; median pretreatment NIHSS score, 15; interquartile range (IQR), 11–21) were included. The leading cause of stroke was cardioembolism (36 patients) and 30 patients received intravenous thrombolysis. EDR occurred in 45 patients (85%). Patients with EDR had lower white blood cell counts (7826.7±2827.7 vs. 10,137.5±3112.2/μl, p=0.03; adjusted odds ratio (OR), 0.99; 95% confidence interval (CI), 0.99–1.00) and lower blood urea nitrogen (BUN)/serum creatinine (Cre) ratio (18.1±6.0 vs. 24.7±8.1, p=0.02; adjusted OR, 0.81; 95%CI, 0.65–0.94) compared with those without EDR. In addition, patients with EDR showed better 90-day clinical outcome (median modified Rankin Scale score, 1 (IQR, 0–2) vs. 2 (IQR, 1–2), p=0.03) than those without. Conclusions: Lower BUN/Cre ratio was associated with EDR in acute stroke patients who obtained successful endovascular reperfusion with subsequent favorable outcome at 90 days.

Patients with chronic kidney disease (CKD) have a higher risk for cerebrovascular disease than the general population. Magnetic resonance imaging (MRI) of the brain can detect cerebral small vessel disease, including deep and subcortical white matter hyperintensity (DSWMH). DSWMH reportedly confers a risk for stroke, and it is associated with dementia. We investigated DSWMH in predialysis CKD patients without neurological abnormalities. This cross-sectional study used plain 1.5T-MRI to assess DSWMH in 505 predialysis patients with CKD and 100 individuals without CKD between January 2008 and December 2011. The frequency of DSWMH was higher in patients with CKD (58%) than in patients without CKD (27%) and was more prevalent among patients without CKD who were older and had higher blood pressure, diabetes, anemia, and a smoking habit. The prevalence of DSWMH was similar (26%) between patients without CKD and patients with early CKD (stages 1–2). However, the prevalence of DSWMH increased with worsening CKD (stages G3, G4, and G5; 59%, 74%, and 78%, respectively). Patients with advanced CKD (stages G3, G4, and G5) had significantly increased severe Fazekas-DSWMH. Multivariate logistic regression analysis adjusted for age, sex, diabetes, and blood pressure revealed that eGFR was a significant factor associated with DSWMH independent of age, sex, diabetes, and blood pressure (eGFR: p<0.01, OR 1.01, 95%CI 1.00–1.03). We found that there is a high prevalence of DSWMH in patients with advanced CKD but no apparent neurological abnormalities, and that eGFR is an independent predictor of DSWMH.

Recently, MRI arterial spin labeling (ASL) is attracting attention as the noninvasive and convenient imaging technique to evaluate cerebral circulation. However, since there is a problem regarding to arterial transit time, it remains unclear that the reliability of this new modality is equivalent to the established one, such as SPECT or PET. In this study, we analyzed cerebral circulation for 20 cases with chronic ischemic cerebrovascular disease by multiple post-labeling delay (PLD) ASL and ¹⁵O-PET to determine if ASL can truly evaluate cerebral circulation. As the results, both CBF/CBV and CBF obtained by ¹⁵O-PET were significantly correlated with PLD (1000 and 1500 msec) by ASL. In addition, there was significantly negative correlation between CBV by ¹⁵O-PET and PLD (1000 and 1500 msec) by ASL. In the cases whose right-and-left difference of CBF was more than 10%, the receiver operating characteristic (ROC) analysis of revealed area under curve (AUC) of PLD (1000 msec) was as the highest as 0.987 (p=0.001) among all PLD. The cut off value of right-and-left difference by ASL PLD (1000 msec) was 31% in the cases whose right-and-left difference of CBF was more than 10%. The sensitivity and specificity of this analysis was 100% and 93.3%, respectively. In conclusion, we suggest that short PLD, especially PLD (1000 msec) reflects the cerebral perfusion pressure. Therefore, ASL could be useful for the screening of the cerebral circulation in cases of the chronic ischemic cerebrovascular disease.

Stroke is the leading cause of disability in Japan, and development of an innovative approach has been desired. We have reported that intravenous infusion of mesenchymal stem cells (MSCs) provides therapeutic efficacy on neurological diseases including stroke. Currently, based on our favorable results of basic and clinical researches, clinical trials with intravenous infusion of autologous MSCs from bone marrow for cerebral infarction and spinal cord injury are ongoing at Sapporo Medical University. Suggested therapeutic mechanisms of MSCs in various models of central nervous system diseases include secretion of neurotrophic factors, which can provide for neuroprotection; reduction in inflammation; neovascularization. Recently, we have demonstrated that combination of intravenous infusion of MSCs and rehabilitation provides functional improvements via induction of neural plasticity as well as the suggested mechanisms above. These results might suggest that rehabilitation plays an important role in regenerative medicine when the MSC therapy is widely used at the bedside.

Identifying the neurobiological basis of depression using neuroimaging techniques has generated considerable interest amongst researchers. It may enable researchers to formulate effective interventions for major depressive disorders (MDD). Despite the development of many pharmacological and psychological interventions, many individuals with MDD fail to respond to treatment, and instead relapse. It is therefore essential that we continue exploring the underlying nature of MDD, as a greater understanding of vulnerability and phenomenological models will help us identify future intervention research efforts. Functional neuroimaging data suggest that depression is characterized by decreased prefrontal control, which has been implicated in inhibiting limbic regions, as well as by an increased and sustained limbic reactivity to emotional information. Since these mechanisms are potentially important in maintaining depression, addressing them in treatment could be useful. This article reviews a variety of neurobehavioral/neurocognitive techniques that target brain mechanisms underlying disruptions of emotional reactivity in depression. Their use as potential interventions, targeted to address neurobiological mechanisms, is discussed. In addition, this review also indicates the potential utility of these interventions as adjuncts to conventional treatment.

Epidemiologic and clinical studies have suggested that exercise intervention has an important role to improve and maintain brain function. To elucidate how exercise influences physiological aspects related with brain function, we investigated changes in regional cerebral blood flow (rCBF) and μ-opioidergic receptor system in brain. As a result of a PET study using ¹⁵O-H₂O, we explored that during aerobic exercise rCBF increased in broad areas including the primary sensorimotor cortex, cerebellum and insular cortex. This alteration in rCBF may attributable to the possible underlying mechanism for exercise-induced plasticity via the enhanced regional neural activity and influence to neurotransmitters as well. Another PET study using ¹¹C-Carfentanil suggested that positive alteration in mood status following aerobic exercise and fatigue caused by severe-intensity exercise had associated with μ-opioidergic receptor system in the limbic system and pituitary. This change in μ-opioidergic receptor system was influenced by exercise intensity and the inter-individual difference in the altered mood. Neuroimaging studies using PET is a useful method to elucidate changes in rCBF and neurotransmitter systems evoked by exercise, which may related with the underlying mechanisms for exercise-induced altered brain function.

Voxel-based morphometry (VBM) uses structural MRI data to investigate brain region volumes in a voxel-wise manner, not unlike computing z-scores in SPECT using eZIS or iSSP. Recently, we added artificial intelligence (AI) to our software “BAAD” (Brain Anatomical Analysis using Diffeomorphic deformation) that was originally developed to support diagnosis of Alzheimer’s disease (AD). The AI combines support vector machine (SVM) with a radial basis function (RBF) kernel, and cost functions and slack variables were optimized using data from the ADNI database (314 cases, 386 healthy controls). The probability of AD is computed by BAAD from the set of all regions of interest and is shown as an AD score (ADS). The accuracy and post-diagnostic odds ratio using BAAD AD scores were assessed at 89.6% and 134.1, respectively. We used the AIBL database (72 AD cases, 447 healthy controls) as an application phase for validation by comparison to results from VSRAD (voxel-based specific regional analysis system for AD) software. The accuracy and the post-diagnostic odds ratio for AD scores were 86.1% and 47.9 for BAAD but 84.8% and 14.9 for VSRAD. This suggests that the BAAD approach more fully exploits the potential of structural analysis to support AD diagnosis.

Cell-based therapies have been developed as novel therapies for ischemic stroke. Cell-based therapies are divided into 2 groups; one is stimulation of endogenous neural stem cells, and the other is exogenous (stem) cell transplantation. In the former strategy, several drugs has been investigated as stimulants for endogenous neural stem cells, besides now it has been clear exogenous cell transplantation also induce stimulation of endogenous neural stem cells. In the later strategy, exogenous (stem) cell transplantation is separated based on the type of transplanted cells; non-neural (stem) cells and neural stem cells. Transplantation of non-neural (stem) cells, such as “mesenchymal stem cells” or “mononuclear cells” is thought it will work through several mechanisms such as modulation of inflammation, neuroprotection and promotion of endogenous neurogenesis, etc. Now there are several ongoing clinical trials to evaluate transplantation of non-neural (stem) cells, and these cells can be considered as “drug” which provides several mechanisms other than neural replacement. On the other hand, neural stem cells are believed they possess not only the mechanisms which non-neural (stem) cells have but also the effect of neural replacement. Therefore, transplantation of neural stem cells will be epoch-making therapy if it works through the effect of neural replacement. However there are still problems to solve before clinical trials. In the future, we have to combine the existing therapies and novel cell-based therapies, and moreover it will be important to select the optimal cases for each therapy.

It is necessary to establish therapeutic strategies to promote functional recovery in stroke patients in the subacute and chronic phases. We hypothesized that microglia preconditioned by optimal oxygen-glucose deprivation (OGD) is a therapeutic strategy for ischemic stroke because optimal ischemia induces anti-inflammatory M2-like microglia. We confirmed marked secretion of remodeling factors using primary microglia under 18 h OGD conditions. In particular, expression of the anti-inflammatory cytokine, transforming growth factor-β (TGF-β), was 25 times higher after OGD compared with a normoxic condition (P=0.002), and the ratio of TGF-β per tumor necrosis factor-α, which shows the polarization of M1-like and M2-like microglia, was six times higher after OGD, compared with a normoxic condition (P=0.009). Finally, we found that intraarterial administration of OGD microglia caused increased expression of vascular endothelial growth factor, matrix metalloproteinase-9, and TGF-β in various cells around the injured brain parenchyma using suture technique in ischemic Sprague-Dawley rats. The treatment promoted functional recovery via angiogenesis in the border area within the ischemic core as well as axonal outgrowth in the ischemic penumbra by remodeling factors at 28 days after ischemia. In conclusion, intravascular administration of M2-like microglia preconditioned by optimal OGD might be a novel therapeutic strategy against ischemic stroke.

We do clinical research on cerebral blood flow of patients with miscellaneous cerebrovascular diseases to know “What kind of surgical intervention is beneficial to which subgroup of patients”. In this context, for example, in patients with acute major cerebral artery occlusion, we want to identify patients’ subgroup who derive benefit from mechanical thrombectomy besides intravenous infusion of alteplase. And in patients with chronic cerebral artery occlusion, we want to identify patients subgroup who derive a benefit from EC-IC bypass surgery. In the report, we summarized our data of CT perfusion study on patients with cerebrovascular diseases.

Chemokine is a group of cytokines related with chemotaxis and is important for the evolution of inflammation. RANTES (regulated on activation, normal T-cell expressed and secreted), also called CCL5, is generally secreted from various cells such as T cell, platelet, macrophage, endothelium and so on. And it can induce migration of T cell, monocyte, etc. through its receptor such as CCR1, CCR3, CCR5. In the infarcted tissue, RANTES is secreted from astrocyte and microglia by the stimuli of proinflammatory mediators, leading to activation and migration of inflammatory cells. In the blood, plasma RANTES is shed mainly from platelet and deposited on glycosaminoglycans along the lining of endothelium like a “sign post” followed by infiltration of macrophage and T cell. However, on the other hand, in the perifocal site, RANTES is reported to have a neuroprotective potential through its receptor CCR3, CCR5. Emerging reports are supporting the possibility that RANTES can play both proinflammatory and neuroprotective role, and the understanding of its pleiotropic effect is needed for the future therapy against brain infarction.

Brain temperature (BT) elevation indicated misery perfusion that cerebral blood flow decreased and cerebral metabolic ration of oxygen (CMRO₂) was maintained in patients with chronic ischemia. In the previous work, it has been reported that carbon monoxide (CO) poisoning also caused abnormal cerebral perfusion and metabolism like misery perfusion. Thus, BT may be also associated with states of the abnormal cerebral perfusion and metabolism in patients with CO poisoning. Here, we investigated that CO poisoning was associated with BT change in the patients.

We analyzed the characteristics of regional cerebral blood flow (rCBF) in genetically confirmed spinocerebellar ataxia type 6 (SCA6) patients. Decreased rCBF was found in the cerebellum and was associated with duration of illness. We also analyzed the modification of tau in cerebral ischemia and reperfusion (I/R) in rats. Both 4-repeat and 3-repeat tau isoforms are heperphosphorylated in cerebral I/R, similar to Alzheimer’s disease.

Intracranial major artery stenosis/occlusion (ICASO) is one of the most common causes of stroke. The most common cause of ICASO is atherosclerosis, caused by acquired factors, such as hypertension, diabetes mellitus, dyslipidemia, and smoking. However, ICASO is known to be common among nonwhite populations, particularly Asian populations, indicating a potential involvement of genetic factors. Recently, a susceptibility gene for moyamoya disease (MMD), ring finger protein 213 (RNF213) was identified in the East Asian population. We have reported that the same genetic variant (nonsynonymous mutation), c.14576G>A (p.R4859K) variant, in RNF213 has significant association with various phenotypes of ICASO. This identification of a common genetic variant among ICASO lesions may lead to a new genetic diagnosis system in the field of stroke, conventionally thought to be caused by acquired risk factors. Preventive treatment for stroke, such as blood pressure management, and image screening, such as MR angiography, for intracranial cerebral arterial lesion would be very important, especially for individuals with this specific allele, which is present in ≈2% of the Japanese population.

Using a mouse model of permanent ischemic stroke, we previously showed that injury-induced neural stem cells (iNSCs) develop within the post-stroke areas. More recently, using a mouse model of transient ischemia/reperfusion injury, we investigated the threshold of ischemic periods. In addition, we examined the origin of iNSCs and their possible contribution to neurogenesis under such pathologic conditions. Although iNSCs were induced following not only lethal ischemic injury by more than 30-min ischemia but also non-lethal ischemic injury by 15-min ischemia, the numbers of iNSCs were fewer under 15-min ischemic conditions compared with those observed under 30-min ischemic conditions. We also found that iNSCs are likely derived from brain pericytes stimulated by ischemic insult and that they had an activity of producing neuronal cells. These findings indicate that iNSCs can be a strategy target to promote neurogenesis after transient ischemia/reperfusion injury. In this article, we refer to iNSCs following transient ischemia/reperfusion injury.