Cyclin-Dependent Kinase Inhibitor 2A is a Key Regulator of Cell Cycle Arrest and Senescence in Endothelial Colony-Forming Cells in Moyamoya Disease.

OBJECTIVE: Endothelial colony-forming cells (ECFCs) have been reported to play an important role in the pathogenesis of moyamoya disease (MMD). We have previously observed stagnant growth in MMD ECFCs with functional impairment of tubule formation. We aimed to verify the key regulators and related signaling pathways involved in the functional defects of MMD ECFCs. METHODS: ECFCs were cultured from peripheral blood mononuclear cells of healthy volunteers (normal) and MMD patients. Low-density lipoproteins uptake, flow cytometry, high content screening, senescence-associated ß-galactosidase, immunofluorescence, cell cycle, tubule formation, microarray, real-time quantitative polymerase chain reaction, small interfering RNA transfection, and western blot analyses were performed. RESULTS: The acquisition of cells that can be cultured for a long time with the characteristics of late ECFCs was significantly lower in the MMD patients than the normal. Importantly, the MMD ECFCs showed decreased cellular proliferation with G1 cell cycle arrest and cellular senescence compared to the normal ECFCs. A pathway enrichment analysis demonstrated that the cell cycle pathway was the major enriched pathway, which is consistent with the results of the functional analysis of ECFCs. Among the genes associated with the cell cycle, cyclin-dependent kinase inhibitor 2A (CDKN2A) showed the highest expression in MMD ECFCs. Knockdown of CDKN2A in MMD ECFCs enhanced proliferation by reducing G1 cell cycle arrest and inhibiting senescence through the regulation of CDK4 and phospho retinoblastoma protein. CONCLUSION: Our study suggests that CDKN2A plays an important role in the growth retardation of MMD ECFCs by inducing cell cycle arrest and senescence.

Panobinostat, a histone deacetylase inhibitor, rescues the angiogenic potential of endothelial colony-forming cells in moyamoya disease.

PURPOSE: Moyamoya disease (MMD) is one of the most common causes of pediatric stroke. We found defective angiogenic function and downregulation of retinaldehyde dehydrogenase 2 (RALDH2) in MMD endothelial colony-forming cells (ECFCs). Downregulation of RALDH2 mRNA was caused by decreased binding of acetyl-histone H3 (Ac-H3) to the RALDH2 promoter. In this study, we evaluated the feasibility of using a histone deacetylase (HDAC) inhibitor, panobinostat, to upregulate RALDH2 expression and restore the angiogenic potential of MMD ECFCs. METHODS: ECFCs from healthy normal controls and patients with MMD were isolated and characterized. After panobinostat treatment, western blot, tube formation, and chromatin immunoprecipitation (ChIP) assays were conducted in vitro. A matrigel plug assay was performed in vivo. RESULTS: Panobinostat increased the levels of Ac-H3 and Ac-H4 in both normal and MMD ECFCs but was much more effective in MMD ECFCs. Increased expression of RALDH2 by panobinostat was observed only in MMD ECFCs. Panobinostat increased the tube formation of both normal and MMD ECFCs in vitro and in vivo, but the effect was greater with MMD ECFCs. CONCLUSIONS: We demonstrated that panobinostat increases the angiogenic ability of MMD ECFCs by regulating RALDH2 acetylation. Our results suggest that panobinostat might be a potent therapeutic option for MMD patients.

Aberrant Promoter Hypomethylation of Sortilin 1: A Moyamoya Disease Biomarker.

BACKGROUND AND PURPOSE: The pathogenesis of moyamoya disease (MMD) remains poorly understood, and no reliable molecular biomarkers for MMD have been identified to date. The present study aimed to identify epigenetic biomarkers for use in the diagnosis of MMD. METHODS: We performed integrated analyses of gene expression profiles and DNA methylation profiles in endothelial colony forming cells (ECFCs) from three patients with MMD and two healthy individuals. Candidate gene mRNA expression and DNA methylation status were further validated using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and pyrosequencing analysis of an expanded ECFC sample set from nine patients with MMD and ten controls. We evaluated the diagnostic accuracy of the potential biomarkers identified here using receiver operating characteristic curve analyses and further measured major angiogenic factor expression levels using a tube formation assay and RT-qPCR. RESULTS: Five candidate genes were selected via integrated analysis; all five were upregulated by hypomethylation of specific promoter CpG sites. After further validation in an expanded sample set, we identified a candidate biomarker gene, sortilin 1 (SORT1). DNA methylation status at a specific SORT1 promoter CpG site in ECFCs readily distinguished patients with MMD from the normal controls with high accuracy (area under the curve 0.98, sensitivity 83.33%, specificity 100%). Furthermore, SORT1 overexpression suppressed endothelial cell tube formation and modulated major angiogenic factor and matrix metalloproteinase-9 expression, implying SORT1 involvement in MMD pathogenesis. CONCLUSION: s Our findings suggest that DNA methylation status at the SORT1 promoter CpG site may be a potential biomarker for MMD.

Mitochondrial abnormalities related to the dysfunction of circulating endothelial colony-forming cells in moyamoya disease.

The authors performed morphological and functional studies of the mitochondria in particular blood cells, i.e., endothelial colony-forming cells (ECFCs), from patients with moyamoya disease. The results indicated that the mitochondria of these ECFCs exhibit morphological and functional abnormalities, which may present new insights into the pathogenesis of moyamoya disease.

Impaired functional recovery of endothelial colony-forming cells from moyamoya disease in a chronic cerebral hypoperfusion rat model.

OBJECTIVEEndothelial colony-forming cells (ECFCs) isolated from pediatric patients with moyamoya disease (MMD) have demonstrated decreased numbers and defective functioning in in vitro experiments. However, the function of ECFCs has not been evaluated using in vivo animal models. In this study, the authors compared normal and MMD ECFCs using a chronic cerebral hypoperfusion (CCH) rat model.METHODSA CCH rat model was made via ligation of the bilateral common carotid arteries (2-vessel occlusion [2-VO]). The rats were divided into three experimental groups: vehicle-treated (n = 8), normal ECFC-treated (n = 8), and MMD ECFC-treated (n = 8). ECFCs were injected into the cisterna magna. A laser Doppler flowmeter was used to evaluate cerebral blood flow, and a radial arm maze test was used to examine cognitive function. Neuropathological examinations of the hippocampus and agranular cortex were performed using hematoxylin and eosin and Luxol fast blue staining in addition to immunofluorescence with CD31, von Willebrand factor, NeuN, myelin basic protein, glial fibrillary acidic protein, and cleaved caspase-3 antibodies.RESULTSThe normal ECFC-treated group exhibited improvement in the restoration of cerebral perfusion and in behavior compared with the vehicle-treated and MMD ECFC-treated groups at the 12-week follow-up after the 2-VO surgery. The normal ECFC-treated group showed a greater amount of neovasculogenesis and neurogenesis, with less apoptosis, than the other groups.CONCLUSIONSThese results support the impaired functional recovery of MMD ECFCs compared with normal ECFCs in a CCH rat model. This in vivo study suggests the functional role of ECFCs in the pathogenesis of MMD.

Chemokine Ligand 5 (CCL5) Derived from Endothelial Colony-Forming Cells (ECFCs) Mediates Recruitment of Smooth Muscle Progenitor Cells (SPCs) toward Critical Vascular Locations in Moyamoya Disease.

The etiology and pathogenesis of moyamoya disease (MMD) are still obscure. Previous studies indicated that angiogenic chemokines may play an important role in the pathogenesis of the disease. Recently, it was discovered that peripheral blood-derived endothelial colony-forming cells (ECFCs) and smooth muscle progenitor cells (SPCs) have defective functions in MMD patients. Therefore, the interaction of ECFCs and SPCs, the precursors of two crucial cellular components of vascular walls, with some paracrine molecules is an intriguing subject. In this study, co-culture of ECFCs and SPCs from MMD patients and healthy normal subjects revealed that MMD ECFCs, not SPCs, are responsible for the defective functions of both ECFCs and SPCs. Enhanced migration of SPCs toward MMD ECFCs supported the role for some chemokines secreted by MMD ECFCs. Expression arrays of MMD and normal ECFCs suggested that several candidate cytokines differentially produced by MMD ECFCs. We selected chemokine (C-X-C motif) ligand 6 (CXCR6), interleukin-8 (IL8), chemokine (C-C motif) ligand 2 (CCL2), and CCL5 for study, based on the relatively higher expression of these ligands in MMD ECFCs and their cognate receptors in MMD SPCs. Migration assays showed that only CCL5 significantly augmented the migration activities of SPCs toward ECFCs. Treatment with siRNA for the CCL5 receptor (CCR5) abrogated the effect, confirming that CCL5 is responsible for the interaction of MMD ECFCs and SPCs. These data indicate that ECFCs, not SPCs, are the major players in MMD pathogenesis and that the chemokine CCL5 mediates the interactions. It can be hypothesized that in MMD patients, defective ECFCs direct aberrant SPC recruitment to critical vascular locations through the action of CCL5.

Association between moyamoya syndrome and the RNF213 c.14576G>A variant in patients with neurofibromatosis Type 1.

OBJECTIVE In a minority of patients with neurofibromatosis Type 1 (NF-1), cerebral vasculopathy reminiscent of moyamoya disease develops. This phenomenon is called moyamoya syndrome (MMS), but there are no known risk factors for the prediction of MMS in NF-1 patients. Polymorphism of the RNF213 gene has exhibited strong associations with familial and sporadic moyamoya disease and other cerebral vasculopathies. The aim of this study is to find whether the RNF213 c.14576G>A variant is associated with MMS development in the NF-1 population or not. METHODS The MMS group included 16 NF-1 patients with documented MMS. The control group consisted of 97 NF-1 patients without MMS. Genomic DNA samples were obtained from the saliva or blood of both groups, and the presence of the RNF213 c.14576G>A variant was assessed by Sanger sequencing. RESULTS In the MMS group, 3 patients had the RNF213 c.14576G>A variant (18.7%), whereas no patients with this genetic variation were observed in the control group (0%). There was a meaningful association between the RNF213 c.14576G>A variant and MMS development (p = 0.0024). The crude odds ratio was calculated as 50.57 (95% CI 1.57-1624.41). All 3 patients with MMS and the c.14576G>A variant were diagnosed with MMS at an early age and had bilateral involvement. CONCLUSIONS The RNF213 c.14576G>A variant is more common in NF-1 patients who develop MMS than in NF-1 patients without MMS. This variant might be a susceptibility gene for the NF-1-moyamoya connection.

Deregulation of Retinaldehyde Dehydrogenase 2 Leads to Defective Angiogenic Function of Endothelial Colony-Forming Cells in Pediatric Moyamoya Disease.

OBJECTIVE--: Moyamoya disease (MMD) is a common cause of childhood stroke, in which the abnormal function of the endothelial colony-forming cell (ECFC) plays a key role in the pathogenesis of the disease. This study was designed to identify genes involved in MMD pathogenesis using gene expression profiling and to understand the defective function of MMD ECFCs. APPROACH AND RESULTS--: We compared gene expression profiles of ECFCs isolated from patients with MMD and normal controls. Among the differentially expressed genes, we selected a gene with the most downregulated expression, retinaldehyde dehydrogenase 2 (RALDH2). The activity of RALDH2 in MMD ECFCs was assessed by in vitro tube formation assay and in vivo Matrigel plug assay in the presence of all-trans retinoic acid. The transcriptional control of RALDH2 was tested using ChIP assays on acetyl-histone H3. In the results, MMD ECFCs inefficiently formed capillary tubes in vitro and capillaries in vivo, a defect restored by all-trans retinoic acid treatment. Knockdown of RALDH2 mRNA in normal ECFCs also induced decreased activity of capillary formation in vitro. The decreased level of RALDH2 mRNA in MMD ECFCs was attributed to defective acetyl-histone H3 binding to the promoter region. CONCLUSIONS--: From these results, we conclude that the expression of RALDH2 was epigenetically suppressed in ECFCs from patients with MMD, which may play a key role in their functional impairment.

Smooth-muscle progenitor cells isolated from patients with moyamoya disease: novel experimental cell model.

OBJECT: Moyamoya disease (MMD) is a cerebrovascular occlusive disease affecting bilateral internal carotid termini. Smooth-muscle cells are one of the major cell types involved in this disease process. The characteristics of circulating smooth-muscle progenitor cells (SPCs) in MMD are poorly understood. The authors purified SPCs from the peripheral blood of patients with MMD and sought to identify differentially expressed genes (DEGs) in SPCs from these patients. METHODS: The authors cultured and isolated SPCs from the peripheral blood of patients with MMD (n = 25) and healthy control volunteers (n = 22). After confirmation of the cellular phenotype, RNA was extracted from the cells and DEGs were identified using a commercially available gene chip. Real-time quantitative reverse transcription polymerase chain reaction was performed to confirm the putative pathogenetic DEGs. RESULTS: The SPC-type outgrowth cells in patients with MMD invariably showed a hill-and-valley appearance under microscopic examination, and demonstrated high α-smooth muscle actin, myosin heavy chain, and calponin expression (96.5% ± 2.1%, 42.8% ± 18.6%, and 87.1% ± 8.2%, respectively), and minimal CD31 expression (less than 1%) on fluorescence-activated cell sorter analysis. The SPCs in the MMD group tended to make more irregularly arranged and thickened tubules on the tube formation assay. In the SPCs from patients with MMD, 286 genes (124 upregulated and 162 downregulated) were differentially expressed; they were related to cell adhesion, cell migration, immune response, and vascular development. CONCLUSIONS: With adequate culture conditions, SPCs could be established from the peripheral blood of patients with MMD. These cells showed specific DEGs compared with healthy control volunteers. This study provides a novel experimental cell model for further research of MMD.

Expression of cellular retinoic acid-binding protein-I (CRABP-I) in the cerebrospinal fluid of adult onset moyamoya disease and its association with clinical presentation and postoperative haemodynamic change.

OBJECTIVE: The elevation of cellular retinoic acid-binding protein-I (CRABP-I) has been suggested as a candidate in the pathogenesis of paediatric moyamoya disease (MMD). However, few studies have addressed CRABP-I in adult onset MMD. The aim of this study was to examine the expression of CRABP-I in the cerebrospinal fluid (CSF) of adult onset MMD, and to evaluate its association with clinical presentation and postoperative haemodynamic change. METHODS: This study examined the CSF from 103 patients: bilateral MMD, n=58 (56.3%); unilateral MMD, n=19 (18.4%); atherosclerotic cerebrovascular disease (ACVD), n=21 (20.4%); and control group, n=5 (4.9%). The intensity of CRABP-I was confirmed by western blotting and expressed as the median (25th-75th percentile). The differences in CRABP-I expression according to disease entity (unilateral MMD vs bilateral MMD vs ACVD), initial presenting symptoms (haemorrhage vs ischaemia) and postoperative haemodynamic change (vascular reserve in single photon emission CT and basal collateral vessels in digital subtraction angiography) were analysed. RESULTS: CRABP-I intensities in bilateral MMD (1.45(0.86-2.52)) were significantly higher than in unilateral MMD (0.91(0.78-1.20)) (p=0.044) or ACVD (0.85(0.66-1.11)) (p=0.004). No significant differences were noted based on the initial presenting symptoms (p=0.687). CRABP-I was not associated with improvement in vascular reserve (p=0.327), but with decrease in basal collateral vessels (p=0.023) postoperatively. CONCLUSIONS: Higher CRABP-I in the CSF can be associated with typical bilateral MMD pathogenesis in adults. Additionally, postoperative basal collateral change may be related to the degree of CRABP-I expression.

Inhibition of inflammation and oxidative stress by Angelica dahuricae radix extract decreases apoptotic cell death and improves functional recovery after spinal cord injury.

Inflammation and oxidative stress play major roles in the pathogenesis after spinal cord injury (SCI). Here, we examined the neuroprotective effects of Angelica dahuricae radix (ADR) extract after SCI. ADR extract significantly decreased the levels of proinflammatory factors such as tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in a lipopolysaccharide (LPS)-activated microglial cell line, BV2 cells. ADR extract also significantly alleviated the level of reactive oxygen species in LPS-activated BV2 cells. To examine the neuroprotective effect of ADR extract after SCI, spinally injured rats were administered ADR extract orally at a dose of 100 mg/kg for 14 days. ADR extract treatment significantly reduced the levels of TNF-α, IL-1ß, IL-6, iNOS, and COX-2. The levels of superoxide anion (O(2·)(-)) and protein nitration were also significantly decreased by ADR extract. In addition, ADR extract inhibited p38 mitogen-activated protein kinase activation and pronerve growth factor expression in microglia after SCI. Furthermore, ADR extract significantly inhibited caspase-3 activation following apoptotic cell death of neurons and oligodendrocytes, thereby improving functional recovery after injury. Thus, our data suggest that ADR extract provides neuroprotection by alleviating inflammation and oxidative stress and can be used as an orally administered therapeutic agent for acute SCI.

Contribution of the delayed-rectifier potassium channel Kv2.1 to acute spinal cord injury in rats.

Recent studies have reported that delayed-rectifier Kv channels regulate apoptosis in the nervous system. Herein, we investigated changes in the expression of the delayed-rectifier Kv channels Kv1.2, Kv2.1, and Kv3.1 after acute spinal cord injury (SCI) in rats. We performed RT-PCR analysis and found an increase in the level of Kv2.1 mRNA after SCI but no significant changes in the levels of Kv1.2 and Kv3.1 mRNA. Western blot analysis revealed that Kv2.1 protein levels rapidly decreased and then dramatically increased from 1 day, whereas Kv3.1b protein levels gradually and sharply decreased at 5 days. Kv1.2 protein levels did not change significantly. In addition, Kv2.1 clusters were disrupted in the plasma membranes of motor neurons after SCI. Interestingly, the expressional changes and translocation of Kv2.1 were consistent with the apoptotic changes on day 1. Therefore, these results suggest that Kv2.1 channels probably contribute to neuronal cell responses to SCI.