Current Neurovascular Research - Volume 14, Issue 1, 2017

Although altered lipid metabolism has been extensively implicated in the pathogenesis of late onset Alzheimer’s disease (LOAD) through cell biological and epidemiological studies, genetic studies linking lipid metabolism and LOAD are still not well understood. MicroRNAs (miRNAs) exert posttranscriptional down-regulation and their target sequence on the 3’ untranslated regions (3’UTR) may be altered by single nucleotide polymorphisms (SNPs). We therefore explore whether the six loci in Clusterin gene (CLU) (rs9331949), Lipoprotein lipase gene (LPL) (rs1059507, rs3200218, rs3208305, rs3735964) and Low-density lipoprotein receptor related protein 6 (LRP6) (rs2160525) could modulate LOAD risk through the alteration of miRNA binding sites. We performed a case–control study of 2338 unrelated subjects (984 cases and 1354 age- and gender-matched controls) in the Northern Han Chinese. We found that the minor C allele in rs9331949 significantly increased the risk of LOAD (P<0.001, OR=1.31, 95% CI=1.14-1.51), even after adjusting for multiple testing. Logistic analysis identified the rs9331949 polymorphism was still strongly associated with LOAD, even in Apolipoprotein E (APOE) 4 allele noncarrier subgroups. However, the other five loci were not significantly associated with LOAD after Bonferroni adjustment. In conclusion, we have identified that the locus (rs9331949) located in the binding site of 3’ UTR of CLU has a strong association with LOAD rather than loci in LPL and LRP6. However, additional independent replication is required for further validation.

Peroxisome proliferator-activated receptors alpha (PPARα) is a therapy target in atherosclerosis and cardiovascular diseases. However, anti-inflammatory effects of PPARα in intracerebral hemorrhage (ICH) remain unknown. We investigated the anti-inflammatory effects of fenofibrate, a ligand of PPARα, in ICH rat model. We found that engagement of fenofibrate increased nissl body and astrocytes, and reduced the neuronal damage, which was observed in paraffin section of ICH rat brain. Fenofibrate also promoted the proliferation of astrocytes that were isolated from adult rat brain. Fenofibrate significantly upregulated heme oxygenase 1 (HO-1) at protein and mRNA levels in human glioblastoma LN-18 cells and rat brain astrocytes respectively, but nuclear factor kappalight- chain-enhancer of activated B cells (NFΚB) was downregulated after fenofibrate treatment. Results showed that fenofibrate-induced upregulation of HO-1 expression were inhibited after LN-18 cells were transfected with 50nM small interfering RNA (siRNAs) for 48 hours to knockdown PPARα. Further studies in rat astrocytes confirmed the rescue effects of PPARα silence against fenofibrate induced upregulation of HO-1 expression. Our data indicated that fenofibrate benefits neuronal protection through increasing HO-1 expression level and decreasing NFΚB expression in PPARα-dependent manner. In conclusion, PPARα and HO-1 may function as significant targets to protect the brain during ICH.

Ununited peripheral nerves represent attractive site for connectivity with neuroprostheses because their predictable internal topography allows precise sorting of motor and sensory signals. Also transplantation of bone marrow mesenchymal stem cells (BMSCs) is increasingly recognized as an effective method of restore the peripheral nervous system injury due to its neuron-directed differentiation potential. This study was to evaluate the in vivo performance of BMSCs-packed Poly(3,4-ethylenedioxythiophene) (PEDOT) scaffolds across a critical nerve conduction gap and examine the potential mechanism by which BMSCs-packed PEDOT scaffolds mediate peripheral nerve regeneration in rat model of recurrent laryngeal nerve (RLN) deletion. In this study, rat models of 8 mm-RLN deletion were randomly divided into three groups and respectively received transplantation of autologous nerve or PEDOT scaffolds or BMSCspacked PEDOT scaffolds. After transplantation, neurological function was assessed by laryngeal electromyography. BMSCs-directed neuron differentiation was induced and confirmed by the upregulation of 6 nerve cell markers. Expression level of miRs, Notch signals and 6 nerve cell markers in nerve grafts or cells were determined by quantitative real-time PCR or western blot analysis. The results showed that BMSCs-packed PEDOT scaffolds transplantation significantly improved neurological function compared with PEDOT scaffolds alone. Regenerative nerve of BMSCs-packed PEDOT scaffolds showed higher expression level of miR-21 and Notch signals (Hes-1 and Notch intracellular domain (NICD)) than PEDOT alone. We found that the expression levels of miR-21, Hes-1 and NICD are increased with timecourse of neuron-directed differentiation stimulating of BMSCs. Meanwhile, both miR-21 overexpression and Notch pathway activation promote the expression of 6 nerve cell markers in BMSCs-directed neuron, whereas the inactivation of Notch pathway abrogates miR-21-inudced upregulation of 6 nerve cell markers. Moreover, knock-down of miR-21 suppresses the pro-neural restoration action of BMSCs-packed PEDOT scaffolds. In summary, our data suggested that BMSCs-packed PEDOT effectively repairs recurrent laryngeal nerve injury and the potential mechanism is miR-21- mediated Notch signal activation.

Even though hypoxic preconditioning has been reported to produce neuroprotection, its effect on blood-brain barrier (BBB) disruption in the early stages of cerebral ischemia within the therapeutic window is not clear. Since hypoxic preconditioning increases expression of vascular endothelial growth factor (VEGF) that modulates vascular permeability, the effects of hypoxic preconditioning and VEGF on BBB permeability were investigated after one hour of focal cerebral ischemia. Rats were exposed to 8% of oxygen for two hours or room air and then 24 hours later, permanent middle cerebral artery (MCA) occlusion was performed. In some of the hypoxic preconditioned rats, a VEGF-A antibody was applied to the ischemic cortex one hour before MCA occlusion. One hour after MCA occlusion, the transfer coefficient (Ki) of 14C-α-aminoisobutyric acid was determined to measure the degree of BBB disruption. MCA occlusion increased the Ki when compared with the contralateral cortex (14.1 ± 4.0 vs 4.2 ± 1.9 μL/g/min, p < 0.0001). Hypoxic preconditioning further increased the Ki in the ischemic cortex when compared with the control rats (25.1 ± 8.7 μL/g/min, p < 0.01). Application of VEGF antibody to the ischemic cortex of the hypoxic preconditioned animals reduced the Ki to the level of the control rats (13.6 ± 5.1 μL/g/min, p < 0.01). Our data demonstrated that hypoxic preconditioning increased BBB disruption through a VEGF related pathway and suggest the possibility of aggravation of brain edema by hypoxic preconditioning in the early stages of cerebral ischemia.

Periprosthetic osteolysis induced by wear particles can lead to aseptic loosening, one main reason of arthroplasty failure. However, the role of microRNA-130b (miR-130b) in particle-induced osteolysis (PIO) has not been explored yet. In this study, PIO models were established in C57BL/J6 mice via the implantation of Co-Cr-Mo alloy particles, and evaluated by detecting tartrate-resistant acid phosphatase (TRAP) activity and bone resorption in the calvaria. Mouse preosteoblast MC3T3-E1 cells were cultured to receive particle stimulation in vitro. Real time PCR and western blotting were performed to determine the expression levels of miR-130b and frizzled-related protein (FRZB), one potential target of miR-130b. Results showed upregulated miR-130b and downregulated FRZB in both PIO mice with remarkable osteolysis and particle-treated MC3T3-E1 cells showing inhibited proliferation and differentiation assayed by bromodeoxy urodine (BrdU) incorporation and alkaline phosphatase (ALP) activity respectively. Functional studies were conducted by transfection of miR-130b inhibitor in vitro or the injections of miR-130b inhibitor or small interfering RNA (siRNA) targeting FRZB in vivo. Interestingly, particle-induced inhibition on cell proliferation, differentiation and FRZB expression were all reversed by miR-130b silence. Luciferase report assays demonstrated that miR-130b indeed negatively regulated FRZB expression by targeting, while FRZB could reverse the opposed effect of miR-130b silence on PIO development. Therefore, the upregulated miR-130b in PIO models could act as one key regulator of PIO development, partly due to its negative regulation on FRZB.

According to the American Heart Association (AHA), primitive dilated cardiomyopathy (PDCM) is a “progressive dilation of the left or both ventricles and a depressed contractility in the absence of abnormal load conditions”. It evolves in progressive heart-failure. The term “cardiogenic dementia" expresses the intimate connection between heart diseases and cognitive functions. The association between PDCM and the neuropsychological functions is unclear: the main pathophysiological hypotheses are cerebral hypoperfusion and cardiogenic emboli. The aim of this study is to evaluate the impact that the PDCM has on neuropsychological decline and to detect early echocardiographic markers of cognitive impairment. We enrolled 235 patients: 168 suffering from PDCM as sample group and 67 suffering from hypertensive dilated cardiomyopathy (HTCM) as control group. They underwent a cardiology examination and a neuropsychological assessment. A p <0.05 was considered significant. The two groups showed no differences in risk factors, demographic and cardiovascular parameters (except for dimensions of aortic root, left atrium and ventricle which appeared greater in PDCM and left ventricle ejection fraction that appeared lower in PDCM). Among administered neuropsychological tests, only the Stroop Test (which explores executive and attentive functions) appeared significantly lower in PDCM (p = 0.029). Moreover left ventricle end-diastolic diameter was inversely related to the Stroop Test Score (r= -0.32). PDCM doesn’t appear to be at the basis of a generalized cognitive and neuropsychological decline. Only the executive functions seem impaired in PDCM. Left ventricle dilation seems to be associated to attentive and executive functions decline.

This study aimed to evaluate the effect of liposomes loaded with diclofenac, a potent cyclooxygenase (COX)-1 and COX-2 inhibitor, on laser-induced choroidal neovascularization (CNV) in mice and non-human primates (common marmosets). CNV was induced by laser irradiation on the unilateral or bilateral eye of each mouse or common marmoset, respectively, under anesthesia. The CNV was visualized using fluorescence labeling with intravenous injection of fluoresceinconjugated dextran (molecular weight = 2,000 kDa), and quantified in the retinal pigment epithelia (RPE)–choroidal flatmounts. Diclofenac-loaded liposome or diclofenac ophthalmic solution was instillated to the eye surface daily for 14 days and 21 days in mice and common marmosets, respectively. In the mouse CNV model, 0.1% diclofenac-loaded liposome eye drops administered four times a day (q.i.d.) significantly reduced CNV formation in the RPE–choroidal flatmounts compared with those in empty liposome eye drops. Diclofenac-loaded liposome (0.1%) eye drops, administered once a day (s.i.d.), twice a day (b.i.d.), and three times a day (t.i.d.), also reduced CNV formation in a frequency-dependent manner. Furthermore, diclofenac-loaded liposome (0.03% and 0.1%) eye drops administered t.i.d. reduced CNV formation in a dose-dependent manner, significantly so at 0.1%. In the common marmoset CNV model, late hyperfluorescence and leakage by fluorescein angiograms was observed within or beyond the lesion borders at 17 days after laser irradiation, and diclofenac-loaded liposome eye drops (0.1% t.i.d.) tended to attenuate the late hyperfluorescence and leakage. Diclofenac-loaded liposomes had significantly reduced CNV formation in the RPE– choroidal flatmounts at 21 days after laser irradiation. In conclusion, diclofenac-loaded liposome eye drops enhance penetration to the RPE–choroid, and reduce the CNV formation. These results suggest that a drug-loaded liposome is a useful tool for drug delivery into the posterior segment of the eye.

Mitochondria play a key role in cell survival by perfoming functions such as adenosine tri-phosphate (ATP) synthesis, regulation of apoptotic cell death, calcium storage. Hypoxic conditions induce mitochondrial dysfunction, which leads to endothelial injury in cerebral ischemia. Functional disorders include the following: collapse of mitochondrial membrane potential, reduction of ATP synthesis, and generation of reactive oxygen species (ROS). Bendavia, a novel tetra-peptide, has been reported to restrict the uncoupling of the mitochondrial membrane chain, protect the synthesis of ATP, and inhibit ROS generation. In the present study, we investigated whether bendavia protects mitochondria under hypoxic and starved conditions by using human brain microvascular endothelial cells (HBMVECs). After pre-treatment with bendavia, we exposed HBMVECs to oxygen glucose deprivation (OGD) for 6 h. We then assessed cell viability, the level of caspase-3/7 activity, ROS generation, mitochondrial membrane potential, ATP contents, and the number of mitochondria. Bendavia recovered cell viability and reduced the caspase-3/7 activity induced by OGDinduced damage. Bendavia also recovered mitochondrial functions. These results suggest that bendavia protects mitochondrial function against OGD-induced injury and inhibits apoptosis in HBMVECs. Consequently, our findings indicate that bendavia might become the new therapeutic drug of choice to target mitochondria in case of cerebral ischemia.

Congenital Muscular Dystrophy type 1D (CMD1D) is characterized by an abnormal glycosylation of α-DG (α-dystroglycan) and is associated to the central nervous system (CNS) abnormalities such as cognitive impairment. The purpose of the research was to evaluate the blood-brain barrier permeability (BBB) permeability and matrix metalloproteinases (MMP) -2 and -9 in adult Largemyd-/- mice in order to understand the physiopathology of brain involvement during the CMD1D process. To this aim, we used adult homozygous Largemyd-/- (mutation in Large), heterozygous Largemyd+/- as well as wild-type (C57BL/6) mice. The animals were submitted to the evaluation of BBB permeability and MMP-2 and MMP-9 in striatum, hippocampus and cerebral cortex. There was an increase in BBB permeability in the hippocampus and striatum associated with an increase in the protein levels of MMP-2 in the cerebral cortex and striatum and MMP-9 in the hippocampus in adult Largemyd-/- mice. Our results suggest that the pathophysiologic processes can be associated to the action of MMPs and BBB disruption and that the BBB breakdown is relevant to the perpetuation of brain inflammation and can be related to brain dysfunction observed in CMD1D patients.

Reduced cerebrovascular reactivity (CVR) was found in patients with recent lacunar infarct. However, its mechanisms were controversial. The breath holding maneuver as a vasodilatory stimulus is clinically useful for an estimation of cerebrovasomotor reactivity in well co-operative patients. Patients with lacunar infarct have no higher cortical dysfunction and remain well co-operation. The breath holding maneuver is feasible and safe to perform in patients with lacunar infarct. Autonomic nervous system regulates systemic vascular activity. Regulation of autonomic function to cerebrovascular reactivity has been reported in the literature. We examined the correlation between autonomic functions with frequency and nonlinear heart rate variability (HRV) and cerebrovascular reactivity in patients with lacunar infarct by application of breath holding maneuver. Fifteen patients with lacunar infarct (8 women, age 65.6 ± 13.61) and 16 healthy controls (11 women, age 27.33 ± 3.85) were continuously monitored at baseline before maneuver (basal phase), during CVR induction (experimental phase) with breath holding maneuver and after maneuver (recovery phase), for arterial blood pressure (ABP), electrocardiography (EKG), mean cerebral blood flow velocity (mCBFV) of middle cerebral arteries (MCA) by transcranial doppler (TCD). The short term-one minute HRV was analyzed from EKG signals for low frequency (LF)/ high frequency (HF) ratio, nonlinear of standard deviation 1 (SD1), standard deviation 2 (SD2), cardiac Sample Entropy (SampEn) and Shannon Entropy. Significant increasing in mCBFV, LF/HF ratio, SD2/SD1, Shannon Entropy and inversely decreasing SampEn during breath holding maneuver compared with baseline were found in both groups (p<0.05). The trend of cerebrovascular reactivity is similar in both groups. However, there were differences of mCBFV, systolic blood pressure (SysBP) in the whole phases (basal, experiment and recovery) between patients and controls (p<0.05). Less scattered signals of SD1 with low value in patient group were illustrated from Poincaré (p<0.05). This indicated less degree of parasympathetic drive in the patients compared to the controls. Moreover, significant positive correlation between systolic bloods pressure and mCBFV in patients suggests impact of autonomic control and cerebral blood flow on the patho-physiological mechanism of vasodilatation, triggered by hypercapnia from breath holding maneuver in patients with lacunar infarct. Reduction of cerebrovascular reactivity in patients with lacunar infarct may relate with decreased parasympathetic activity. Further study is required to demonstrate whether these findings mean mechanisms of lacunar infarct or the effect of hypertensive response.

Oxidative stress in the brain microvasculature is a common characteristic in models of cerebrovascular disease. Considering the effects of reactive oxygen species activity in vascular-derived insults, it is naturally prudent to hypothesize those interventions inhibiting reactive oxygen species activity, such as antioxidant supplementation, may be beneficial for cerebrovascular disease. Hyper doses of antioxidant supplements, and foods with high antioxidant concentrations, are commonly used as an ongoing remedial and ‘over-the-counter’ treatments for most seasonal ailments. For the first time, this study reports the adverse effects of excess antioxidants on angiogenic properties of the blood-brain barrier (BBB) which have clinical implications. A medicinal tea, known as Rooibos, commonly used in South Africa and marketed globally, for its prominent antioxidant profile, demonstrated its effects on brain endothelial cellular proliferation, toxicology, mitochondrial activity and permeability. Mouse brain endothelial cells were seeded at cell densities ranging from 103-106 cells/ml and were incubated at pre-determined time intervals of 24 to120 hours. Daily exposure of a selected concentration range of fermented Rooibos tea caused dose-related decreases in cellular proliferation, and unequivocally decreased permeability across our in vitro BBB model. Despite the negative effects on cellular proliferation, no toxicity was observed for all selected fermented Rooibos concentrations. Our data conclusively shows that the use of excess antioxidants perturbs BBB functionality and angiogenic properties, adversely implicating the homeostatic regulation of the brain microenvironment, while suppression in cellular proliferation impacts both the maintenance and repair function of brain capillaries. Our study indicates that excess antioxidants will lead to an impaired response to mechanical-induced injury and pathogenic infection of the BBB, compromising patient recovery.

Noncommunicable diseases (NCDs) contribute to a significant amount of disability and death in the world. Of these disorders, vascular disease is ranked high, falls within the five leading causes of death, and impacts multiple other disease entities such as those of the cardiac system, nervous system, and metabolic disease. Targeting the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1) pathway and the modulation of micro ribonucleic acids (miRNAs) may hold great promise for the development of novel strategies for the treatment of vascular disease since each of these pathways are highly relevant to cardiac and nervous system disorders as well as to metabolic dysfunction. SIRT1 is vital in determining the course of stem cell development and the survival, metabolism, and life span of differentiated cells that are overseen by both autophagy and apoptosis. SIRT1 interfaces with a number of pathways that involve forkhead transcription factors, mechanistic of rapamycin (mTOR), AMP activated protein kinase (AMPK) and Wnt1 inducible signaling pathway protein 1 (WISP1) such that the level of activity of SIRT1 can become a critical determinant for biological and clinical outcomes. The essential fine control of SIRT1 is directly tied to the world of non-coding RNAs that ultimately oversee SIRT1 activity to either extend or end cellular survival. Future studies that can further elucidate the crosstalk between SIRT1 and non-coding RNAs should serve well our ability to harness the power of SIRT1 and non-coding RNAs for the treatment of vascular disorders.