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Ling C, Yang Y, Zhang B, Wang H, Chen C. Phoenixin-14 maintains the contractile type of vascular smooth muscle cells in cerebral aneurysms rats. J Biochem Mol Toxicol 2024; 38:e23813. [PMID: 39148253 DOI: 10.1002/jbt.23813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 07/15/2024] [Accepted: 08/02/2024] [Indexed: 08/17/2024]
Abstract
The rupture of intracranial aneurysm (IA) is the primary reason contributing to the occurrence of life-threatening subarachnoid hemorrhages. The oxidative stress-induced phenotypic transformation from the contractile phenotype to the synthetic phenotype of vascular smooth muscle cells (VSMCs) plays a pivotal role in IA formation and rupture. Our study aimed to figure out the role of phoenixin-14 in VSMC phenotypic switching during the pathogenesis of IA by using both cellular and animal models. Primary rat VSMCs were isolated from the Willis circle of male Sprague-Dawley rats. VSMCs were stimulated by hydrogen peroxide (H2O2) to establish a cell oxidative damage model. After pretreatment with phoenixin-14 and exposure to H2O2, VSMC viability, migration, and invasion were examined through cell counting kit-8 (CCK-8), wound healing, and Transwell assays. Intracellular reactive oxygen species (ROS) production in VSMCs was evaluated by using 2',7'-Dichlorofluorescin diacetate (DCFH-DA) fluorescence probes and flow cytometry. Rat IA models were established by ligation of the left common carotid arteries and posterior branches of both renal arteries. The histopathological changes of rat intracranial blood vessels were observed through hematoxylin and eosin staining. The levels of contractile phenotype markers (alpha-smooth muscle actin [α-SMA] and smooth muscle 22 alpha [SM22α]) in VSMCs and rat arterial rings were determined through real-time quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. Our results showed that H2O2 stimulated the production of intracellular ROS and induced oxidative stress in VSMCs, while phoenixin-14 pretreatment attenuated intracellular ROS levels in H2O2-exposed VSMCs. H2O2 exposure promoted VSMC migration and invasion, which, however, was reversed by phoenixin-14 pretreatment. Besides, phoenixin-14 administration inhibited IA formation and rupture in rat models. The decrease in α-SMA and SM22α levels in H2O2-exposed VSMCs and IA rat models was antagonized by phoenixin-14. Collectively, phoenixin-14 ameliorates the progression of IA through preventing the loss of the contractile phenotype of VSMCs.
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MESH Headings
- Animals
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/pathology
- Rats
- Male
- Rats, Sprague-Dawley
- Intracranial Aneurysm/pathology
- Intracranial Aneurysm/metabolism
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/pathology
- Reactive Oxygen Species/metabolism
- Oxidative Stress/drug effects
- Hydrogen Peroxide/pharmacology
- Muscle Contraction/drug effects
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Affiliation(s)
- Cong Ling
- Department of Neurosurgery, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Yang Yang
- Department of Radiology, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Baoyu Zhang
- Department of Neurosurgery, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Hui Wang
- Department of Neurosurgery, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Chuan Chen
- Department of Neurosurgery, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
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2
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Uchikawa H, Rahmani R. Animal Models of Intracranial Aneurysms: History, Advances, and Future Perspectives. Transl Stroke Res 2024:10.1007/s12975-024-01276-3. [PMID: 39060663 DOI: 10.1007/s12975-024-01276-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 06/17/2024] [Accepted: 06/29/2024] [Indexed: 07/28/2024]
Abstract
Intracranial aneurysms (IA) are a disease process with potentially devastating outcomes, particularly when rupture occurs leading to subarachnoid hemorrhage. While some candidates exist, there is currently no established pharmacological prevention of growth and rupture. The development of prophylactic treatments is a critical area of research, and preclinical models using animals play a pivotal role. These models, which utilize various species and induction methods, each possess unique characteristics that can be leveraged depending on the specific aim of the study. A comprehensive understanding of these models, including their historical development, is crucial for appreciating the advantages and limitations of aneurysm research in animal models.We summarize the significant roles of animal models in IA research, with a particular focus on rats, mice, and large animals. We discuss the pros and cons of each model, providing insights into their unique characteristics and contributions to our understanding of IA. These models have been instrumental in elucidating the pathophysiology of IA and in the development of potential therapeutic strategies.A deep understanding of these models is essential for advancing research on preventive treatments for IA. By leveraging the unique strengths of each model and acknowledging their limitations, researchers can conduct more effective and targeted studies. This, in turn, can accelerate the development of novel therapeutic strategies, bringing us closer to the goal of establishing an effective prophylactic treatment for IA. This review aims to provide a comprehensive view of the current state of animal models in IA research.
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Affiliation(s)
- Hiroki Uchikawa
- Department of Translational Neuroscience, Barrow Aneurysm and AVM Research Center, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Redi Rahmani
- Department of Translational Neuroscience, Barrow Aneurysm and AVM Research Center, Barrow Neurological Institute, Phoenix, AZ, USA.
- Department of Neurosurgery, Barrow Neurological Institute, Phoenix, AZ, USA.
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3
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Sun ZH, Liu F, Kong LL, Ji PM, Huang L, Zhou HM, Sun R, Luo J, Li WZ. Interruption of TRPC6-NFATC1 signaling inhibits NADPH oxidase 4 and VSMCs phenotypic switch in intracranial aneurysm. Biomed Pharmacother 2023; 161:114480. [PMID: 37002575 DOI: 10.1016/j.biopha.2023.114480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 02/23/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023] Open
Abstract
Intracranial aneurysm (IA) is a frequent cerebrovascular disorder with unclear pathogenesis. The vascular smooth muscle cells (VSMCs) phenotypic switch is essential for IA formation. It has been reported that Ca2+ overload and excessive reactive oxygen species (ROS) are involved in VSMCs phenotypic switch. The transient receptor potential canonical 6 (TRPC6) and NADPH oxidase 4 (NOX4) are the main pathway to participate in Ca2+ overload and ROS production in VSMCs. Ca2+ overload can activate calcineurin (CN), leading to nuclear factor of activated T cell (NFAT) dephosphorylation to regulate the target gene's transcription. We hypothesized that activation of TRPC6-NFATC1 signaling may upregulate NOX4 and involve in VSMCs phenotypic switch contributing to the progression of IA. Our results showed that the expressions of NOX4, p22phox, p47phox, TRPC6, CN and NFATC1 were significantly increased, and VSMCs underwent a significant phenotypic switch in IA tissue and cellular specimens. The VIVIT (NFATC1 inhibitor) and BI-749327 (TRPC6 inhibitor) treatment reduced the expressions of NOX4, p22phox and p47phox and the production of ROS, and significantly improved VSMCs phenotypic switch in IA rats and cells. Consistent results were obtained from IA Trpc6 knockout (Trpc6-/-) mice. Furthermore, the results also revealed that NFATC1 could regulate NOX4 transcription by binding to its promoter. Our findings reveal that interrupting the TRPC6-NFATC1 signaling inhibits NOX4 and improves VSMCs phenotypic switch in IA, and regulating Ca2+ homeostasis may be an important therapeutic strategy for IA.
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Affiliation(s)
- Zheng-Hao Sun
- Department of Pharmacology, Basic Medicine College; Key Laboratory of Anti-inflammatory and Immunopharmacology, Ministry of Education; Anhui Medical University, Hefei 230032, Anhui, China
| | - Fei Liu
- Department of neurosurgery, The First Affiliated Hospital of Anhui Medical University, Hefei 230032, Anhui, China
| | - Liang-Liang Kong
- Department of Pharmacology, Basic Medicine College; Key Laboratory of Anti-inflammatory and Immunopharmacology, Ministry of Education; Anhui Medical University, Hefei 230032, Anhui, China
| | - Peng-Min Ji
- Department of Pharmacology, Basic Medicine College; Key Laboratory of Anti-inflammatory and Immunopharmacology, Ministry of Education; Anhui Medical University, Hefei 230032, Anhui, China
| | - Lei Huang
- Department of Pharmacology, Basic Medicine College; Key Laboratory of Anti-inflammatory and Immunopharmacology, Ministry of Education; Anhui Medical University, Hefei 230032, Anhui, China
| | - Hui-Min Zhou
- Department of Pharmacology, Basic Medicine College; Key Laboratory of Anti-inflammatory and Immunopharmacology, Ministry of Education; Anhui Medical University, Hefei 230032, Anhui, China
| | - Ran Sun
- Department of Pharmacology, Basic Medicine College; Key Laboratory of Anti-inflammatory and Immunopharmacology, Ministry of Education; Anhui Medical University, Hefei 230032, Anhui, China
| | - Jing Luo
- Department of neurosurgery, The First Affiliated Hospital of Anhui Medical University, Hefei 230032, Anhui, China.
| | - Wei-Zu Li
- Department of Pharmacology, Basic Medicine College; Key Laboratory of Anti-inflammatory and Immunopharmacology, Ministry of Education; Anhui Medical University, Hefei 230032, Anhui, China.
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4
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Epithelial-mesenchymal transition related genes in unruptured aneurysms identified through weighted gene coexpression network analysis. Sci Rep 2022; 12:225. [PMID: 34997174 PMCID: PMC8741966 DOI: 10.1038/s41598-021-04390-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 12/21/2021] [Indexed: 11/08/2022] Open
Abstract
Intracranial aneurysm (IA) can cause fatal subarachnoid hemorrhage (SAH) after rupture, and identifying patients with unruptured IAs is essential for reducing SAH fatalities. The epithelial-mesenchymal transition (EMT) may be vital to IA progression. Here, identified key EMT-related genes in aneurysms and their pathogenic mechanisms via bioinformatic analysis. The GSE13353, GSE75436, and GSE54083 datasets from Gene Expression Omnibus were analyzed with limma to identify differentially expressed genes (DEGs) among unruptured aneurysms, ruptured aneurysms, and healthy samples. The results revealed that three EMT-related DEGs (ADIPOQ, WNT11, and CCL21) were shared among all groups. Coexpression modules and hub genes were identified via weighted gene co-expression network analysis, revealing two significant modules (red and green) and 14 EMT-related genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses suggested that cytokine interactions were closely related. Gene set enrichment analysis revealed that unruptured aneurysms were enriched for the terms "inflammatory response" and "vascular endothelial growth". Protein-protein interaction analysis identified seven key genes, which were evaluated with the GSE54083 dataset to determine their sensitivity and specificity. In the external validation set, we verified the differential expression of seven genes in unruptured aneurysms and normal samples. Together, these findings indicate that FN1, and SPARC may help distinguish normal patients from patients with asymptomatic IAs.
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5
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Sunderland K, Jiang J, Zhao F. Disturbed flow's impact on cellular changes indicative of vascular aneurysm initiation, expansion, and rupture: A pathological and methodological review. J Cell Physiol 2022; 237:278-300. [PMID: 34486114 PMCID: PMC8810685 DOI: 10.1002/jcp.30569] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/06/2021] [Accepted: 08/16/2021] [Indexed: 01/03/2023]
Abstract
Aneurysms are malformations within the arterial vasculature brought on by the structural breakdown of the microarchitecture of the vessel wall, with aneurysms posing serious health risks in the event of their rupture. Blood flow within vessels is generally laminar with high, unidirectional wall shear stressors that modulate vascular endothelial cell functionality and regulate vascular smooth muscle cells. However, altered vascular geometry induced by bifurcations, significant curvature, stenosis, or clinical interventions can alter the flow, generating low stressor disturbed flow patterns. Disturbed flow is associated with altered cellular morphology, upregulated expression of proteins modulating inflammation, decreased regulation of vascular permeability, degraded extracellular matrix, and heightened cellular apoptosis. The understanding of the effects disturbed flow has on the cellular cascades which initiate aneurysms and promote their subsequent growth can further elucidate the nature of this complex pathology. This review summarizes the current knowledge about the disturbed flow and its relation to aneurysm pathology, the methods used to investigate these relations, as well as how such knowledge has impacted clinical treatment methodologies. This information can contribute to the understanding of the development, growth, and rupture of aneurysms and help develop novel research and aneurysmal treatment techniques.
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Affiliation(s)
- Kevin Sunderland
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI 49931
| | - Jingfeng Jiang
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI 49931,Corresponding Authors: Feng Zhao, 101 Bizzell Street, College Station, TX 77843-312, Tel : 979-458-1239, , Jingfeng Jiang, 1400 Townsend Dr., Houghton, MI 49931, Tel: 906-487-1943
| | - Feng Zhao
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843,Corresponding Authors: Feng Zhao, 101 Bizzell Street, College Station, TX 77843-312, Tel : 979-458-1239, , Jingfeng Jiang, 1400 Townsend Dr., Houghton, MI 49931, Tel: 906-487-1943
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6
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Identification of intima-to-media signals for flow-induced vascular remodeling using correlative gene expression analysis. Sci Rep 2021; 11:16142. [PMID: 34373496 PMCID: PMC8352890 DOI: 10.1038/s41598-021-95403-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 07/26/2021] [Indexed: 12/12/2022] Open
Abstract
Changes in blood flow can induce arterial remodeling. Intimal cells sense flow and send signals to the media to initiate remodeling. However, the nature of such intima-media signaling is not fully understood. To identify potential signals, New Zealand white rabbits underwent bilateral carotid ligation to increase flow in the basilar artery or sham surgery (n = 2 ligated, n = 2 sham). Flow was measured by transcranial Doppler ultrasonography, vessel geometry was determined by 3D angiography, and hemodynamics were quantified by computational fluid dynamics. 24 h post-surgery, the basilar artery and terminus were embedded for sectioning. Intima and media were separately microdissected from the sections, and whole transcriptomes were obtained by RNA-seq. Correlation analysis of expression across all possible intima-media gene pairs revealed potential remodeling signals. Carotid ligation increased flow in the basilar artery and terminus and caused differential expression of 194 intimal genes and 529 medial genes. 29,777 intima-media gene pairs exhibited correlated expression. 18 intimal genes had > 200 medial correlates and coded for extracellular products. Gene ontology of the medial correlates showed enrichment of organonitrogen metabolism, leukocyte activation/immune response, and secretion/exocytosis processes. This demonstrates correlative expression analysis of intimal and medial genes can reveal novel signals that may regulate flow-induced arterial remodeling.
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7
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Endogenous animal models of intracranial aneurysm development: a review. Neurosurg Rev 2021; 44:2545-2570. [PMID: 33501561 DOI: 10.1007/s10143-021-01481-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 01/05/2021] [Accepted: 01/18/2021] [Indexed: 12/13/2022]
Abstract
The pathogenesis and natural history of intracranial aneurysm (IA) remains poorly understood. To this end, animal models with induced cerebral vessel lesions mimicking human aneurysms have provided the ability to greatly expand our understanding. In this review, we comprehensively searched the published literature to identify studies that endogenously induced IA formation in animals. Studies that constructed aneurysms (i.e., by surgically creating a sac) were excluded. From the eligible studies, we reported information including the animal species, method for aneurysm induction, aneurysm definitions, evaluation methods, aneurysm characteristics, formation rate, rupture rate, and time course. Between 1960 and 2019, 174 articles reported endogenous animal models of IA. The majority used flow modification, hypertension, and vessel wall weakening (i.e., elastase treatment) to induce IAs, primarily in rats and mice. Most studies utilized subjective or qualitative descriptions to define experimental aneurysms and histology to study them. In general, experimental IAs resembled the pathobiology of the human disease in terms of internal elastic lamina loss, medial layer degradation, and inflammatory cell infiltration. After the early 2000s, many endogenous animal models of IA began to incorporate state-of-the-art technology, such as gene expression profiling and 9.4-T magnetic resonance imaging (MRI) in vivo imaging, to quantitatively analyze the biological mechanisms of IA. Future studies aimed at longitudinally assessing IA pathobiology in models that incorporate aneurysm growth will likely have the largest impact on our understanding of the disease. We believe this will be aided by high-resolution, small animal, survival imaging, in situ live-cell imaging, and next-generation omics technology.
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8
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Tang H, Lu Z, Xue G, Li S, Xu F, Yan Y, Liu J, Zuo Q, Luo Y, Huang Q. The development and understanding of intracranial aneurysm based on rabbit model. Neuroradiology 2020; 62:1219-1230. [PMID: 32594185 DOI: 10.1007/s00234-020-02475-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 06/10/2020] [Indexed: 10/24/2022]
Abstract
In modern society, intracranial aneurysms have seriously affected people's life. To better study and treat intracranial aneurysm, animal models are ideal candidates to perform biological research and preclinical endovascular device testing. Rabbit aneurysm model is one of the most commonly used animal models, and the rabbit aneurysms share similarities in histology, morphology, and hemodynamic aspects with human intracranial aneurysms, which is an ideal model for intracranial aneurysm pre-clinical and basic research. In this review, we will summarize the main methods of establishing rabbit aneurysms model and will further discuss the current biological mechanisms of intracranial aneurysms based on rabbit model. Further improvements of rabbit aneurysm model and more deep studies based on this model are needed to provide new insights into studying and clinical treating intracranial aneurysm.
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Affiliation(s)
- Haishuang Tang
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, People's Republic of China.,Naval Medical Center of PLA, Second Military Medical University, Shanghai, 200050, People's Republic of China
| | - Zhiwen Lu
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, People's Republic of China
| | - Gaici Xue
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, People's Republic of China
| | - Sisi Li
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, People's Republic of China
| | - Fengfeng Xu
- Naval Medical Center of PLA, Second Military Medical University, Shanghai, 200050, People's Republic of China
| | - Yazhou Yan
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, People's Republic of China
| | - Jianmin Liu
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, People's Republic of China
| | - Qiao Zuo
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, People's Republic of China
| | - Yin Luo
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, People's Republic of China
| | - Qinghai Huang
- Department of Neurosurgery, Changhai Hospital, Second Military Medical University, Shanghai, 200433, People's Republic of China.
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9
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Papoutsis K, Kapelouzou A, Georgiopoulos G, Kontogiannis C, Kourek C, Mylonas KS, Patelis N, Cokkinos DV, Karavokyros I, Georgopoulos S. Tissue-specific relaxin-2 is differentially associated with the presence/size of an arterial aneurysm and the severity of atherosclerotic disease in humans. Acta Pharmacol Sin 2020; 41:745-752. [PMID: 32024951 PMCID: PMC7471450 DOI: 10.1038/s41401-019-0350-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 12/12/2019] [Indexed: 12/31/2022] Open
Abstract
Circulating or tissue-related biomarkers are of clinical value for risk stratification in patients with abdominal aortic aneurysms. Relaxin-2 (RL2) has been linked to the presence and size of arterial aneurysms, and to the extent of atherosclerosis in human subjects. Here, we assessed the expression levels of RL2 in aneurysmal (AA, n = 16) and atherosclerotic (ATH, n = 22) arteries, and established the correlation between RL2 levels and the presence/size of AA and the clinical severity of atherosclerosis. The expression levels of metalloproteinases (MMPs) and endothelial nitric oxide synthetase (eNOS) were also detected for correlations with different phenotypes of atherosclerosis and AA. Temporal artery biopsy specimens (n = 6) and abdominal aortic tissues harvested from accident victims during autopsy (n = 10) were used as controls. Quantitative tissue biomarker analysis revealed that tissue-specific RL2 was increased in patients with larger or symptomatic AA compared to subjects with atherosclerotic disease and healthy controls. In situ RL2 levels were proportional to the size and the severity of aneurysmatic disease, and were substantially elevated in patients with symptomatic aneurysm of any diameter or asymptomatic aneurysm of a diameter >350% of that of the normal artery. In contrast, tissue RL2 was inversely associated with the clinical severity of atherosclerotic lesions. Correlation between RL2 and MMP2 was different between ATH1 and ATH2, depending on atherosclerosis grade. Overall, tissue RL2 is differentially associated with discrete phenotypes of arterial disease and might exert multipotent biological effects on vascular wall integrity and remodeling in human subjects.
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10
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Preclinical Intracranial Aneurysm Models: A Systematic Review. Brain Sci 2020; 10:brainsci10030134. [PMID: 32120907 PMCID: PMC7139747 DOI: 10.3390/brainsci10030134] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/21/2020] [Accepted: 02/23/2020] [Indexed: 12/30/2022] Open
Abstract
Intracranial aneurysms (IA) are characterized by weakened cerebral vessel walls that may lead to rupture and subarachnoid hemorrhage. The mechanisms behind their formation and progression are yet unclear and warrant preclinical studies. This systematic review aims to provide a comprehensive, systematic overview of available animal models for the study of IA pathobiology. We conducted a systematic literature search using the PubMed database to identify preclinical studies employing IA animal models. Suitable articles were selected based on predefined eligibility criteria following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Included studies were reviewed and categorized according to the experimental animal and aneurysm model. Of 4266 returned results, 3930 articles were excluded based on the title and/or abstract and further articles after screening the full text, leaving 123 studies for detailed analysis. A total of 20 different models were found in rats (nine), mice (five), rabbits (four), and dogs (two). Rat models constituted the most frequently employed intracranial experimental aneurysm model (79 studies), followed by mice (31 studies), rabbits (12 studies), and two studies in dogs. The most common techniques to induce cerebral aneurysms were surgical ligation of the common carotid artery with subsequent induction of hypertension by ligation of the renal arteries, followed by elastase-induced creation of IAs in combination with corticosterone- or angiotensin-induced hypertension. This review provides a comprehensive summary of the multitude of available IA models to study various aspects of aneurysm formation, growth, and rupture. It will serve as a useful reference for researchers by facilitating the selection of the most appropriate model and technique to answer their scientific question.
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11
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Staarmann B, Smith M, Prestigiacomo CJ. Shear stress and aneurysms: a review. Neurosurg Focus 2019; 47:E2. [DOI: 10.3171/2019.4.focus19225] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 04/08/2019] [Indexed: 12/16/2022]
Abstract
Wall shear stress, the frictional force of blood flow tangential to an artery lumen, has been demonstrated in multiple studies to influence aneurysm formation and risk of rupture. In this article, the authors review the ways in which shear stress may influence aneurysm growth and rupture through changes in the vessel wall endothelial cells, smooth-muscle cells, and surrounding adventitia, and they discuss shear stress–induced pathways through which these changes occur.
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Affiliation(s)
| | - Matthew Smith
- 2Neurology, University of Cincinnati Medical Center, Cincinnati, Ohio
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12
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Levitt MR, Mandrycky C, Abel A, Kelly CM, Levy S, Chivukula VK, Zheng Y, Aliseda A, Kim LJ. Genetic correlates of wall shear stress in a patient-specific 3D-printed cerebral aneurysm model. J Neurointerv Surg 2019; 11:999-1003. [PMID: 30979845 DOI: 10.1136/neurintsurg-2018-014669] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 12/29/2022]
Abstract
OBJECTIVES To study the correlation between wall shear stress and endothelial cell expression in a patient-specific, three-dimensional (3D)-printed model of a cerebral aneurysm. MATERIALS AND METHODS A 3D-printed model of a cerebral aneurysm was created from a patient's angiogram. After populating the model with human endothelial cells, it was exposed to media under flow for 24 hours. Endothelial cell morphology was characterized in five regions of the 3D-printed model using confocal microscopy. Endothelial cells were then harvested from distinct regions of the 3D-printed model for mRNA collection and gene analysis via quantitative polymerase chain reaction (qPCR.) Cell morphology and mRNA measurement were correlated with computational fluid dynamics simulations. RESULTS The model was successfully populated with endothelial cells, which survived under flow for 24 hours. Endothelial morphology showed alignment with flow in the proximal and distal parent vessel and aneurysm neck, but disorganization in the aneurysm dome. Genetic analysis of endothelial mRNA expression in the aneurysm dome and distal parent vessel was compared with the proximal parent vessels. ADAMTS-1 and NOS3 were downregulated in the aneurysm dome, while GJA4 was upregulated in the distal parent vessel. Disorganized morphology and decreased ADAMTS-1 and NOS3 expression correlated with areas of substantially lower wall shear stress and wall shear stress gradient in computational fluid dynamics simulations. CONCLUSIONS Creating 3D-printed models of patient-specific cerebral aneurysms populated with human endothelial cells is feasible. Analysis of these cells after exposure to flow demonstrates differences in both cell morphology and genetic expression, which correlate with areas of differential hemodynamic stress.
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Affiliation(s)
- Michael R Levitt
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Radiology, University of Washington, Seattle, WA, USA.,Mechanical Engineering, University of Washington, Seattle, WA, USA.,Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA
| | | | - Ashley Abel
- Neurological Surgery, University of Washington, Seattle, WA, USA
| | - Cory M Kelly
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA
| | - Samuel Levy
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA
| | | | - Ying Zheng
- Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA.,Bioengineering, University of Washington, Seattle, WA, USA
| | - Alberto Aliseda
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Mechanical Engineering, University of Washington, Seattle, WA, USA.,Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA
| | - Louis J Kim
- Neurological Surgery, University of Washington, Seattle, WA, USA.,Radiology, University of Washington, Seattle, WA, USA.,Stroke and Applied Neuroscience Center, University of Washington, Seattle, WA, USA
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13
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Zou L, Hou Y, Yu B, Li S, Du Y. The effect of intravascular interventional embolization and craniotomy on MMP-2, MMP-9 and caspase3 in serum of intracranial aneurysm patients. Exp Ther Med 2018; 16:4511-4518. [PMID: 30542399 PMCID: PMC6257825 DOI: 10.3892/etm.2018.6740] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 09/05/2018] [Indexed: 01/28/2023] Open
Abstract
The effect of intravascular interventional embolization and surgical operation on matrix metalloprotein (MMP)-2, MMP-9 and caspase3 in serum of intracranial aneurysms was analyzed to study the mechanisms. Seventy-nine patients of intracranial aneurysms from September 2011 to August 2014 were divided into the intervention group (n=41) and the craniotomy group (n=38) based on treatment methods, and 40 cases of normal volunteers with normal physical examination were selected as the control group. Patients in the intervention group were treated with intravascular interventional embolization, and the surgical group was treated with craniotomy and no treatment was performed in the control group. The survival rate and adverse reaction rate were calculated. ELISA kit was used to detect the level of reactive oxygen species (ROS), interleukin-6 (IL-6), tumor necrosis factor (TNF-α) and IL-10 in serum; the mRNA and protein expression levels of MMP-2, MMP-9 and caspase3 in serum were detected by qPCR and western blotting; the protein expression levels of p-adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK), Bcl-2 and Bax were also detected. The survival rate of patients in the intervention group was significantly higher than that in the craniotomy group (P<0.05). The ROS level in the intervention and craniotomy groups was significantly higher than that in the control group (P<0.01), while the levels of IL-6 and TNF-α in the serum of the intervention group were lower than those in the craniotomy group (P<0.01). The mRNA and protein expression of MMP-2, MMP-9 and caspase3 of the intervention group was significantly lower than that of the craniotomy group (P<0.01). The protein expression of p-AMPK and Bcl-2/Bax in the intervention group were lower than that in the craniotomy group (P<0.01). Intravascular interventional surgery can significantly increase the patient's survival time, and effectively reduce the expression of MMP-2, MMP-9 and caspase3 in the serum of intracranial aneurysm patients. The mechanism may be through the impact of ROS levels, thereby affecting the p-AMPK and Bcl2/Bax expression.
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Affiliation(s)
- Liang Zou
- Department of Neurosurgery, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215004, P.R. China.,Department of Neurosurgery, The Second Clinical Medical School of Inner Mongolia University for Nationalities, Hulunbuir, Inner Mongolia 022150, P.R. China
| | - Yanyan Hou
- Department of Hematology and Oncology, The Second Clinical Medical School of Inner Mongolia University for Nationalities, Hulunbuir, Inner Mongolia 022150, P.R. China
| | - Baixiang Yu
- Department of Neurosurgery, The Second Clinical Medical School of Inner Mongolia University for Nationalities, Hulunbuir, Inner Mongolia 022150, P.R. China
| | - Shuang Li
- Department of Neurosurgery, The Second Clinical Medical School of Inner Mongolia University for Nationalities, Hulunbuir, Inner Mongolia 022150, P.R. China
| | - Yanli Du
- Department of Neurosurgery, Hulunbeier People's Hospital, Hulunbuir, Inner Mongolia 021000, P.R. China
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Row S, Swartz DD, Andreadis ST. Animal models of cardiovascular disease as test beds of bioengineered vascular grafts. ACTA ACUST UNITED AC 2018; 24:37-45. [PMID: 30505334 DOI: 10.1016/j.ddmod.2018.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The last two decades have seen many advances in regenerative medicine, including the development of tissue engineered vessels (TEVs) for replacement of damaged or diseased arteries or veins. Biomaterials from natural sources as well as synthetic polymeric materials have been employed in engineering vascular grafts. Recently, cell-free grafts have become available opening new possibilities for the next generation, off-the-shelf products. These TEVs are first tested in small or large animal models, which are usually young and healthy. However, the majority of patients in need of vascular grafts are elderly and suffer from comorbidities that may complicate their response to the implants. Therefore, it is important to evaluate TEVs in animal models of vascular disease in order to increase their predictive value and learn how the disease microenvironment may affect the patency and remodeling of vascular grafts. Small animals with various disease phenotypes are readily available due to the availability of transgenic or gene knockout technologies and can be used to address mechanistic questions related to vascular grafting. On the other hand, large animal models with similar anatomy, hematology and thrombotic responses to humans have been utilized in a preclinical setting. We propose that large animal models with certain pathologies or age range may provide more clinically relevant platforms for testing TEVs and facilitate the clinical translation of tissue engineering technologies by increasing the likelihood of success in clinical trials.
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Affiliation(s)
- Sindhu Row
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Amherst, NY 14260-4200, USA.,Angiograft LLC, Amherst NY
| | | | - Stelios T Andreadis
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Amherst, NY 14260-4200, USA.,Department of Biomedical Engineering, University at Buffalo, The State University of New York, Amherst, NY 14260-4200, USA.,New York State Center of Excellence in Bioinformatics and Life Sciences, Buffalo, NY.,Angiograft LLC, Amherst NY
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15
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Infusion of Hibiscus sabdariffa L. Modulates Oxidative Stress in Patients with Marfan Syndrome. Mediators Inflamm 2016; 2016:8625203. [PMID: 27413258 PMCID: PMC4927999 DOI: 10.1155/2016/8625203] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/12/2016] [Accepted: 05/26/2016] [Indexed: 01/16/2023] Open
Abstract
Marfan syndrome (MFS) is associated with progressive aortic dilatation, endothelial dysfunction, and oxidative stress that contribute to the early acute dissection of the vessel and can end up in rupture of the aorta and sudden death. Many studies have described that the organic acids from Hibiscus sabdariffa Linne (HSL) calyces increase cellular antioxidant capacity and decrease oxidative stress. Here we evaluate if the antioxidant properties of HSL infusion improve oxidative stress in MFS patients. Activities of extra cellular super oxide dismutase (ECSOD), glutathione peroxidase (GPx), glutathione-S-transferase (GST), glutathione reductase (GSSG-R), glutathione (GSH), lipid peroxidation (LPO) index, total antioxidant capacity (TAC), and ascorbic acid were determined in plasma from MFS patients. Values before and after 3 months of the treatment with 2% HSL infusion were compared in control and MFS subjects. After treatment, there was a significant decrease in ECSOD (p = 0.03), EGPx (p = 0.04), GST (p = 0.03), GSH (p = 0.01), and TAC and ascorbic acid (p = 0.02) but GSSG-R activity (p = 0.04) and LPO (p = 0.02) were increased in MFS patients in comparison to patients receiving the HSL treatment and C subjects. Therefore, the infusion of HSL calyces has antioxidant properties that allow an increase in antioxidant capacity of both the enzymatic and nonenzymatic systems, in the plasma of the MSF patients.
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16
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Soto ME, Iturriaga Hernández AV, Guarner Lans V, Zuñiga-Muñoz A, Aranda Fraustro A, Velázquez Espejel R, Pérez-Torres I. Participation of oleic acid in the formation of the aortic aneurysm in Marfan syndrome patients. Prostaglandins Other Lipid Mediat 2016; 123:46-55. [PMID: 27163200 DOI: 10.1016/j.prostaglandins.2016.05.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 05/04/2016] [Accepted: 05/05/2016] [Indexed: 02/07/2023]
Abstract
Marfan syndrome (MFS) is associated with progressive aortic dilatation and endothelial dysfunction that lead to early acute dissection and rupture of the aorta and sudden death. Alteration in fatty acid (FA) metabolism can stimulate nitric oxide (NO) overproduction which increases the activity of the inducible form of NO synthase (iNOS) that is involved in endothelial dysfunction. We evaluated the participation of FA in the formation of thoracic aneurysms in MFS and its relation to the iNOS. Oleic acid (OA), iNOS, citrulline, nitrates and nitrites, TGF-β1, TNF-α, monounsaturated FA and NO synthase activity were significantly increased (p<0.05) in tissue from the aortas of MFS. Saturated FA, eNOS and HDL were significantly decreased (p<0.05). Arachidonic acid, delta-9 desaturase tended to increase and histological examination showed an increase in cystic necrosis, elastic fibers and collagen in MFS. The increase in OA contributes to the altered pathway of iNOS, which favors endothelial dysfunction and formation of the aortic aneurysms in MFS.
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Affiliation(s)
- María Elena Soto
- Department of Immunology, Instituto Nacional de Cardiología "Ignacio Chávez", Juan Badiano 1, Sección XVI, Tlalpan, 14080 México City, DF, Mexico
| | - Alejandra Valeria Iturriaga Hernández
- Department of Cardiothoracic Surgery, Instituto Nacional de Cardiología "Ignacio Chávez", Juan Badiano 1, Sección XVI, Tlalpan, 14080 México City, DF, Mexico
| | - Verónica Guarner Lans
- Department of Physiology, Instituto Nacional de Cardiología "Ignacio Chávez", Juan Badiano 1, Sección XVI, Tlalpan, 14080 México City, DF, Mexico
| | - Alejandra Zuñiga-Muñoz
- Department of Pathology, Instituto Nacional de Cardiología "Ignacio Chávez", Juan Badiano 1, Sección XVI, Tlalpan, 14080 México City, DF, Mexico
| | - Alberto Aranda Fraustro
- Department of Pathology, Instituto Nacional de Cardiología "Ignacio Chávez", Juan Badiano 1, Sección XVI, Tlalpan, 14080 México City, DF, Mexico
| | - Rodrigo Velázquez Espejel
- Department of Pathology, Instituto Nacional de Cardiología "Ignacio Chávez", Juan Badiano 1, Sección XVI, Tlalpan, 14080 México City, DF, Mexico
| | - Israel Pérez-Torres
- Department of Pathology, Instituto Nacional de Cardiología "Ignacio Chávez", Juan Badiano 1, Sección XVI, Tlalpan, 14080 México City, DF, Mexico.
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Yunchang M, Qinxue D, Binbin J, Xin H, Lili Y, Linbi C, Wujun G, Pengbo Z, Junlu W. Human tissue kallikrein ameliorates cerebral vasospasm in a rabbit model of subarachnoid hemorrhage. Neurol Res 2016; 37:1082-9. [PMID: 26923578 DOI: 10.1080/01616412.2015.1110305] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
OBJECTIVES Cerebral vasospasm (CVS) and early brain injury are major causes of morbidity and mortality following subarachnoid hemorrhage (SAH). We investigated the efficiency of human tissue kallikrein (HTK) to prevent CVS in a rabbit model of SAH. METHODS Forty-eight Japanese white rabbits were randomly divided into four groups (n = 12 each): control (sham-operated), SAH, SAH + phosphate-buffered saline (PBS, vehicle), and SAH + HTK. Basilar artery (BA) diameters were measured by three-dimensional computed tomography angiography at three time points. Endothelin-1 (ET-1) and nitric oxide (NO) levels in the cerebrospinal fluid (CSF) were assayed 24 h before and 5 and 7 days after SAH. After the last measurement, the animals were killed, and endothelial cell apoptosis was assessed. Bax and Bcl-2 levels in the BA were measured by western blotting. RESULTS HTK was found to significantly reduce CVS following SAH in rabbits. Inverse changes were observed in ET-1 and NO levels in the CSF collected from the SAH group. HTK increased levels of NO, which has a vasodilatory effect, but did not affect levels of ET-1, which has a vasoconstrictive effect. CTA revealed that HTK treatment significantly increased BA diameter. Moreover, HTK treatment reduced the number of apoptotic cells following SAH, presumably by increasing and decreasing Bcl-2 and Bax expression, respectively. CONCLUSION HTK ameliorated CVS and inhibited apoptosis in the BA in a rabbit model of SAH.
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Affiliation(s)
- Mo Yunchang
- 1 Department of Anesthesiology, The Second Affiliated Hospital of Xi'an Jiaotong University , Xi'an, Shanxi 710004, China
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18
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Frösen J. Flow Dynamics of Aneurysm Growth and Rupture: Challenges for the Development of Computational Flow Dynamics as a Diagnostic Tool to Detect Rupture-Prone Aneurysms. ACTA NEUROCHIRURGICA. SUPPLEMENT 2016; 123:89-95. [PMID: 27637634 DOI: 10.1007/978-3-319-29887-0_13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Saccular intracranial aneurysm (sIA) is a relatively common disease that can potentially cause a devastating, life-threatening intracranial hemorrhage. Many sIAs never rupture and thus do not necessitate interventions, making the detection of rupture-prone sIAs a very relevant clinical problem. Moreover, because currently available methods to prevent sIA rupture have significant risks of morbidity and mortality, diagnostic tools that can predict imminent rupture and help plan proper timing of prophylactic interventions, can improve patient care. Hemorrhage from an sIA occurs when hemodynamic stress exceeds sIA wall strength. Computational fluid dynamics (CFD) is a tool with which the hemodynamic stress to which the sIA wall is exposed can be determined non-invasively. Studies using CFD in sIAs have demonstrated associations of wall shear stress (WSS) with aneurysm growth, fragile sIA wall, and sIA rupture; these studies show the potential of CFD as a diagnostic tool. This review discusses the limitations of CFD and of the studies performed, and what needs to be done in order to develop CFD into a useful diagnostic tool to determine aneurysm-specific rupture risk.
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Affiliation(s)
- Juhana Frösen
- Department of Neurosurgery, Kuopio University Hospital, Puijonlaaksontie 2, Kuopio, 00029, Finland.
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Rodriguez-Régent C, Edjlali-Goujon M, Trystram D, Boulouis G, Ben Hassen W, Godon-Hardy S, Nataf F, Machet A, Legrand L, Ladoux A, Mellerio C, Souillard-Scemama R, Oppenheim C, Meder JF, Naggara O. Non-invasive diagnosis of intracranial aneurysms. Diagn Interv Imaging 2014; 95:1163-74. [DOI: 10.1016/j.diii.2014.10.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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20
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Yu L, Gao LX, Ma XQ, Hu FX, Li CM, Lu Z. Involvement of superoxide and nitric oxide in BRAF(V600E) inhibitor PLX4032-induced growth inhibition of melanoma cells. Integr Biol (Camb) 2014; 6:1211-7. [PMID: 25363644 DOI: 10.1039/c4ib00170b] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The BRAF(V600E) inhibitor PLX4032 (Vemurafenib) is an FDA-approved new drug for the treatment of metastatic melanomas, which specifically inhibits the RAS/MEK/ERK signaling pathway to control cell proliferation and adhesion. However, no study has been carried out to investigate the role of intracellular oxidative balance in PLX4032-induced tumor growth inhibition. Herein, for the first time, superoxide (O2˙(-)) and nitric oxide (NO) generated from PLX4032-challenged melanoma cells were monitored using electrochemical sensors and conventional fluorescein staining techniques. Impacts of superoxide dismutase (SOD) and NG-monomethyl-L-arginine monoacetate (L-NMMA), a nitric oxide synthase inhibitor, were also examined to demonstrate the specificity of ROS/NO generation and its biological consequences. PLX4032 specifically triggers production of O2˙(-) and NO from BRAF(V600E) mutant A375 cells. SOD and L-NMMA could abolish the PLX4032-induced increase in intracellular O2˙(-) and NO production, thereby rescuing cell growth in BRAF mutant A375 cells (A375(BRAFV600E)). In addition, PLX4032 treatment could decrease the mitochondrial membrane potential in A375(BRAFV600E) cells. The results suggest that PLX4032 can selectively cause ROS production and depolarization of mitochondrial membranes, potentially initiating apoptosis and growth inhibition of PLX4032-sensitive cells. This work not only proposes a new mechanism for PLX4032-induced melanoma cell inhibition, but also highlights potential applications of electrochemical biosensors in cell biology and drug screening.
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Affiliation(s)
- Ling Yu
- Institute for Clean Energy & Advanced Materials, Faculty of Materials and Energy, Southwest University, Chongqing 400715, China.
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21
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Crosstalk between nitrite, myoglobin and reactive oxygen species to regulate vasodilation under hypoxia. PLoS One 2014; 9:e105951. [PMID: 25148388 PMCID: PMC4141839 DOI: 10.1371/journal.pone.0105951] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 07/28/2014] [Indexed: 11/19/2022] Open
Abstract
The systemic response to decreasing oxygen levels is hypoxic vasodilation. While this mechanism has been known for more than a century, the underlying cellular events have remained incompletely understood. Nitrite signaling is critically involved in vessel relaxation under hypoxia. This can be attributed to the presence of myoglobin in the vessel wall together with other potential nitrite reductases, which generate nitric oxide, one of the most potent vasodilatory signaling molecules. Questions remain relating to the precise concentration of nitrite and the exact dose-response relations between nitrite and myoglobin under hypoxia. It is furthermore unclear whether regulatory mechanisms exist which balance this interaction. Nitrite tissue levels were similar across all species investigated. We then investigated the exact fractional myoglobin desaturation in an ex vivo approach when gassing with 1% oxygen. Within a short time frame myoglobin desaturated to 58±12%. Given that myoglobin significantly contributes to nitrite reduction under hypoxia, dose-response experiments using physiological to pharmacological nitrite concentrations were conducted. Along all concentrations, abrogation of myoglobin in mice impaired vasodilation. As reactive oxygen species may counteract the vasodilatory response, we used superoxide dismutase and its mimic tempol as well as catalase and ebselen to reduce the levels of reactive oxygen species during hypoxic vasodilation. Incubation of tempol in conjunction with catalase alone and catalase/ebselen increased the vasodilatory response to nitrite. Our study shows that modest hypoxia leads to a significant nitrite-dependent vessel relaxation. This requires the presence of vascular myoglobin for both physiological and pharmacological nitrite levels. Reactive oxygen species, in turn, modulate this vasodilation response.
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