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Lerman LO. In Memoriam: Stephen C. Textor. Hypertension 2024; 81:e74-e76. [PMID: 38916984 DOI: 10.1161/hypertensionaha.124.23158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Affiliation(s)
- Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN
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2
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Ni C, Mu X, Wu M, Li Y, Zhang Y, Qi H, Zhang JL. Accurate exclusion of kidney regions affected by susceptibility artifact in blood oxygenation level-dependent (BOLD) images using deep-learning-based segmentation. Sci Rep 2023; 13:19191. [PMID: 37932431 PMCID: PMC10628125 DOI: 10.1038/s41598-023-46760-2] [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: 08/01/2023] [Accepted: 11/04/2023] [Indexed: 11/08/2023] Open
Abstract
Susceptibility artifact (SA) is common in renal blood oxygenation level-dependent (BOLD) images, and including the SA-affected region could induce much error in renal oxygenation quantification. In this paper, we propose to exclude kidney regions affected by SA in gradient echo images with different echo times (TE), based on a deep-learning segmentation approach. For kidney segmentation, a ResUNet was trained with 4000 CT images and then tuned with 60 BOLD images. Verified by a Monte Carlo simulation, the presence of SA leads to a bilinear pattern for the segmented area of kidney as function of TE, and the segmented kidney in the image of turning point's TE would exclude SA-affected regions. To evaluate the accuracy of excluding SA-affected regions, we compared the SA-free segmentations by the proposed method against manual segmentation by an experienced user for BOLD images of 35 subjects, and found DICE of 93.9% ± 3.4%. For 10 kidneys with severe SA, the DICE was 94.5% ± 1.7%, for 14 with moderate SA, 92.8% ± 4.7%, and for 46 with mild or no SA, 94.3% ± 3.8%. For the three sub-groups of kidneys, correction of SA led to a decrease of R2* of 8.5 ± 2.8, 4.7 ± 1.8, and 1.6 ± 0.9 s-1, respectively. In conclusion, the proposed method is capable of segmenting kidneys in BOLD images and at the same time excluding SA-affected region in a fully automatic way, therefore can potentially improve both speed and accuracy of the quantification procedure of renal BOLD data.
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Affiliation(s)
- Chang Ni
- School of Biomedical Engineering, ShanghaiTech University, Room 416, BME Building, 393 Middle Huaxia Road, Pudong, Shanghai, China
| | - Xin Mu
- School of Biomedical Engineering, ShanghaiTech University, Room 416, BME Building, 393 Middle Huaxia Road, Pudong, Shanghai, China
| | - Mingyan Wu
- Central Research Institute, United Imaging Healthcare Group, Shanghai, China
| | - Yanbin Li
- Central Research Institute, United Imaging Healthcare Group, Shanghai, China
| | - Yuyao Zhang
- School of Information Science and Technology, ShanghaiTech University, Shanghai, China
| | - Haikun Qi
- School of Biomedical Engineering, ShanghaiTech University, Room 416, BME Building, 393 Middle Huaxia Road, Pudong, Shanghai, China
| | - Jeff L Zhang
- School of Biomedical Engineering, ShanghaiTech University, Room 416, BME Building, 393 Middle Huaxia Road, Pudong, Shanghai, China.
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3
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Farooqui N, Mohan A, Isik B, Goksu BB, Thaler R, Zhu XY, Krier JD, Saadiq IM, Ferguson CM, Jordan KL, Tang H, Textor SC, Hickson LTJ, van Wijnen AJ, Eirin A, Lerman LO, Herrmann SM. Effect of Hypoxia Preconditioning on the Regenerative Capacity of Adipose Tissue Derived Mesenchymal Stem Cells in a Model of Renal Artery Stenosis. Stem Cells 2023; 41:50-63. [PMID: 36250949 PMCID: PMC9887092 DOI: 10.1093/stmcls/sxac073] [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: 04/18/2022] [Accepted: 08/26/2022] [Indexed: 02/02/2023]
Abstract
Atherosclerotic renal artery stenosis (ARAS) is associated with irreversible parenchymal renal disease and regenerative stem cell therapies may improve renal outcomes. Hypoxia preconditioning (HPC) may improve the regenerative functions of adipose tissue-derived mesenchymal stem cells (AMSC) by affecting DNA 5-hydroxymethylcytosine (5hmC) marks in angiogenic genes. Here, we investigated using a porcine ARAS model, whether growth of ARAS AMSCs in hypoxia (Hx) versus normoxia (Nx) would enhance renal tissue repair, and comprehensively analyze how HPC modifies DNA hydroxymethylation compared to untreated ARAS and healthy/normal pigs (n=5 each). ARAS pigs exhibited elevated serum cholesterol, serum creatinine and renal artery stenosis, with a concomitant decrease in renal blood flow (RBF) and increased blood pressure (BP) compared to healthy pigs. Renal artery injection of either autologous Nx or Hx AMSCs improved diastolic BP, reduced kidney tissue fibrosis, and inflammation (CD3+ T-cells) in ARAS pigs. In addition, renal medullary hypoxia significantly lowered with Nx but not Hx AMSC treatment. Mechanistically, levels of epigenetic 5hmC marks (which reflect gene activation) estimated using DNA immunoprecipitation technique were elevated in profibrotic and inflammatory genes in ARAS compared with normal AMSCs. HPC significantly reduced 5hmC levels in cholesterol biosynthesis and oxidative stress response pathways in ARAS AMSCs. Thus, autologous AMSCs improve key renovascular parameters and inflammation in ARAS pigs, with HPC mitigating pathological molecular effects on inflammatory and profibrotic genes which may play a role in augmenting regenerative capacity of AMSCs.
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Affiliation(s)
- Naba Farooqui
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Arjunmohan Mohan
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Busra Isik
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Busra B Goksu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Roman Thaler
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Xiang Yang Zhu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - James D Krier
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Ishran M Saadiq
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | | | - Kyra L Jordan
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Hui Tang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Stephen C Textor
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - La Tonya J Hickson
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | | | - Alfonso Eirin
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Sandra M Herrmann
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
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4
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Emergent players in renovascular disease. Clin Sci (Lond) 2022; 136:239-256. [PMID: 35129198 DOI: 10.1042/cs20210509] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/25/2022] [Accepted: 01/26/2022] [Indexed: 02/07/2023]
Abstract
Renovascular disease (RVD) remains a common etiology of secondary hypertension. Recent clinical trials revealed unsatisfactory therapeutic outcomes of renal revascularization, leading to extensive investigation to unravel key pathophysiological mechanisms underlying irreversible functional loss and structural damage in the chronically ischemic kidney. Research studies identified complex interactions among various players, including inflammation, fibrosis, mitochondrial injury, cellular senescence, and microvascular remodeling. This interplay resulted in a shift of our understanding of RVD from a mere hemodynamic disorder to a pro-inflammatory and pro-fibrotic pathology strongly influenced by systemic diseases like metabolic syndrome (MetS), hypertension, diabetes mellitus, and hyperlipidemia. Novel diagnostic approaches have been tested for early detection and follow-up of RVD progression, using new imaging techniques and biochemical markers of renal injury and dysfunction. Therapies targeting some of the pathological pathways governing the development of RVD have shown promising results in animal models, and a few have moved from bench to clinical research. This review summarizes evolving understanding in chronic ischemic kidney injury.
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5
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Evaluation of cardiovascular risk in children with solitary functioning kidney. Clin Exp Nephrol 2022; 26:415-423. [PMID: 35037126 DOI: 10.1007/s10157-021-02169-7] [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: 06/02/2021] [Accepted: 12/05/2021] [Indexed: 11/03/2022]
Abstract
BACKGROUND The present study investigates cardiovascular risk and kidney damage in patients with solitary kidneys. METHODS Included in the study were 40 children with a unilateral functioning kidney and 60 healthy controls, all of whom were evaluated for carotid intima-media thickness, ischemia-modified albumin and oxidative stress parameters, and 24-h ambulatory blood pressure monitoring. RESULTS Serum creatinine and urine microalbumin levels were higher and creatinine clearance was lower in the patient group than in the control group, and serum ischemia-modified albumin, carotid intima-media thickness, aldosterone, plasma renin activity and blood pressure were all higher in the patient group than in the control group. In addition, the patient group was showed a non-dipper pattern. CONCLUSION Children with a normal functioning solitary kidney are likely at higher risk of developing cardiovascular disease and such patients should be followed closely before marked kidney impairment occurs.
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Zhang B, Yao Z, Gao W, Wang C, Kong H, Zhang J, Yang M. Dynamic R2' Imaging can Be a Biomarker for Diagnosing and Staging Early Acute Kidney Injury in Animals. Front Med (Lausanne) 2022; 8:775042. [PMID: 35004744 PMCID: PMC8739497 DOI: 10.3389/fmed.2021.775042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 12/06/2021] [Indexed: 11/17/2022] Open
Abstract
Background: Early diagnosis of acute kidney injury (AKI) is essential in clinical settings. None of the current biomarkers are widely applied. The combination of pulse-shifting multi-echo asymmetric spin-echo sequence (psMASE) and a modified hemodynamic response imaging (HRI) technique is promising. The purpose of this study was to evaluate the feasibility of psMASE combined with HRI in detecting early ischemic AKI in animal models of different severities. Methods: Twenty rabbits were divided into four groups (mild, moderate, and severe AKI and control groups). Transarterial embolization with different doses of microspheres was performed to establish AKI animal models of different severities. The 3T psMASE and HRI scans of kidneys were conducted. The R2*, R2, and R2' during room air and gas stimulation were acquired and the difference of R2' (dR2') was evaluated in different AKI groups. Results: The values were not different in R2* and R2 during room air and in R2* and R2, and R2' during gas stimulation. The value of R2' was significantly different during room air (P = 0.014), but the difference was only found between control and moderate/severe AKI groups (P = 0.032 and 0.022). The values of dR2' were different among groups (P < 0.0001) and differences between every two groups except comparison of moderate and severe AKI groups were significant (P < 0.01). Conclusion: The dR2' imaging acquired by a combination of renal psMASE and HRI technique can serve as a potential quantitative biomarker for early detection and staging of AKI.
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Affiliation(s)
- Bihui Zhang
- Department of Interventional Radiology and Vascular Surgery, Peking University First Hospital, Beijing, China
| | - Ziping Yao
- Department of Interventional Radiology and Vascular Surgery, Peking University First Hospital, Beijing, China
| | - Weizheng Gao
- Academy for advanced interdisciplinary studies, Peking University, Beijing, China
| | - Chengyan Wang
- Academy for advanced interdisciplinary studies, Peking University, Beijing, China.,Human Phenome Institute, Fudan University, Shanghai, China
| | - Hanjing Kong
- Academy for advanced interdisciplinary studies, Peking University, Beijing, China.,Beijing United Imaging Research Institute of Intelligent Imaging, UIH Group, Beijing, China
| | - Jue Zhang
- Academy for advanced interdisciplinary studies, Peking University, Beijing, China
| | - Min Yang
- Department of Interventional Radiology and Vascular Surgery, Peking University First Hospital, Beijing, China
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Chen F, Yan H, Yang F, Cheng L, Zhang S, Li S, Liu C, Xu K, Sun D. Evaluation of Renal Tissue Oxygenation Using Blood Oxygen Level-Dependent Magnetic Resonance Imaging in Chronic Kidney Disease. Kidney Blood Press Res 2021; 46:441-451. [PMID: 34091454 DOI: 10.1159/000515709] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 03/08/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) has been widely used to assess renal oxygenation changes in different kidney diseases in recent years. This study was designed to evaluate and compare renal tissue oxygenation using 2 BOLD-MRI analysis methods, namely, the regional and whole-kidney region of interest (ROI) selection methods. METHODS The study ended up with 10 healthy controls and 40 chronic kidney disease (CKD) patients without dialysis. Their renal BOLD-MRI data were analyzed using whole-kidney ROI selection method and compared with regional ROI selection method. RESULTS We found the cortical, medullary, and whole-kidney R2* values were significantly higher in CKD patients than those in controls. Compared with the regional ROI selection method, the whole-kidney ROI selection method yielded higher cortical R2* values in both controls and CKD patients. The whole-kidney R2* values of deteriorating renal function group were significantly higher than those in stable renal function group. CONCLUSIONS Cortical and medullary oxygenation was decreased significantly in CKD patients compared with the healthy controls, particularly in the medulla. The whole-kidney R2* values were positively correlated with kidney function and inversely correlated with the estimated glomerular filtration rate and effective renal plasma flow. Whole-Kidney R2* value might effectively predict the progression of renal function in patients with CKD.
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Affiliation(s)
- Fen Chen
- Department of Nephrology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.,Department of Internal Medicine and Diagnostics, Xuzhou Medical University, Xuzhou, China
| | - Han Yan
- Department of Nephrology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.,Department of Internal Medicine and Diagnostics, Xuzhou Medical University, Xuzhou, China
| | - Fan Yang
- Department of Nephrology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.,Department of Internal Medicine and Diagnostics, Xuzhou Medical University, Xuzhou, China
| | - Li Cheng
- Department of Radiology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Siwei Zhang
- Department of Radiology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Shulin Li
- Department of Nephrology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Caixia Liu
- Department of Nephrology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Kai Xu
- Department of Radiology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Dong Sun
- Department of Nephrology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.,Department of Internal Medicine and Diagnostics, Xuzhou Medical University, Xuzhou, China
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Li S, Wang F, Sun D. The renal microcirculation in chronic kidney disease: novel diagnostic methods and therapeutic perspectives. Cell Biosci 2021; 11:90. [PMID: 34001267 PMCID: PMC8130426 DOI: 10.1186/s13578-021-00606-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 05/06/2021] [Indexed: 12/14/2022] Open
Abstract
Chronic kidney disease (CKD) affects 8–16% of the population worldwide and is characterized by fibrotic processes. Understanding the cellular and molecular mechanisms underpinning renal fibrosis is critical to the development of new therapeutics. Microvascular injury is considered an important contributor to renal progressive diseases. Vascular endothelium plays a significant role in responding to physical and chemical signals by generating factors that help maintain normal vascular tone, inhibit leukocyte adhesion and platelet aggregation, and suppress smooth muscle cell proliferation. Loss of the rich capillary network results in endothelial dysfunction, hypoxia, and inflammatory and oxidative effects and further leads to the imbalance of pro- and antiangiogenic factors, endothelial cell apoptosis and endothelial-mesenchymal transition. New techniques, including both invasive and noninvasive techniques, offer multiple methods to observe and monitor renal microcirculation and guide targeted therapeutic strategies. A better understanding of the role of endothelium in CKD will help in the development of effective interventions for renal microcirculation improvement. This review focuses on the role of microvascular injury in CKD, the methods to detect microvessels and the novel treatments to ameliorate renal fibrosis.
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Affiliation(s)
- Shulin Li
- Department of Nephrology, Affiliated Hospital of Xuzhou Medical University, 99 West Huai-hai Road, Xuzhou, 221002, Jiangsu, China
| | - Fei Wang
- Department of Nephrology, Affiliated Hospital of Xuzhou Medical University, 99 West Huai-hai Road, Xuzhou, 221002, Jiangsu, China
| | - Dong Sun
- Department of Nephrology, Affiliated Hospital of Xuzhou Medical University, 99 West Huai-hai Road, Xuzhou, 221002, Jiangsu, China. .,Department of Internal Medicine and Diagnostics, Xuzhou Medical University, Xuzhou, 221002, China.
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9
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Detection of renal hypoxia configuration in patients with lupus nephritis: a primary study using blood oxygen level-dependent MR imaging. Abdom Radiol (NY) 2021; 46:2032-2044. [PMID: 33079255 DOI: 10.1007/s00261-020-02794-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 09/15/2020] [Accepted: 09/27/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Renal microstructure and function are closely associated with oxygenation homeostasis. Analyzing renal blood oxygen level‒dependent (BOLD) magnetic resonance imaging (MRI) examination results will provide information on the biological status of the kidneys. The current study was performed to explore the hypoxia mode of the entire renal parenchyma in patients with lupus nephritis (LN). METHODS A total of 23 adult patients with LN and 18 healthy volunteers were recruited. R2* values were acquired using BOLD MRI analysis. The narrow rectangular region of interest was used to explore the hypoxia configuration in entire depths of renal parenchyma. Acquired sequential R2* data were fitted using four categories of mathematic functions. The tendency of R2* data in both patients with LN and healthy volunteers was also compared using repeated-measures analysis of variance. RESULTS R2* data from the superficial cortex to deep medulla displayed two patterns called a sharp uptrend style and a flat uptrend style. After sequential R2* data were fitted individually with the use of four mathematic formulas, the multiple-compartment Gaussian function showed the highest goodness of fit. Compared with two categories of R2* value styles, the R2* tendency of entire parenchyma in patients with LN was different from that in healthy volunteers. CONCLUSIONS Deep renal medullary oxygenation was not always overtly lower than oxygenation in the superficial renal cortical zone. The manifestation of renal parenchyma oxygenation could be described using a Gaussian function model. Deoxygenation tolerance was damaged in patients with LN.
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Textor SC, Abumoawad A, Saad A, Ferguson C, Dietz A. Stem Cell Therapy for Microvascular Injury Associated with Ischemic Nephropathy. Cells 2021; 10:cells10040765. [PMID: 33807289 PMCID: PMC8066553 DOI: 10.3390/cells10040765] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 03/22/2021] [Accepted: 03/26/2021] [Indexed: 12/15/2022] Open
Abstract
Ischemic nephropathy reflects progressive loss of kidney function due to large vessel atherosclerotic occlusive disease. Recent studies indicate that this process is characterized by microvascular rarefaction, increased tissue hypoxia and activation of inflammatory processes of tissue injury. This review summarizes the rationale and application of functional MR imaging to evaluate tissue oxygenation in human subjects that defines the limits of renal adaptation to reduction in blood flow, development of increasingly severe tissue hypoxia and recruitment of inflammatory injury pathways in ischemic nephropathy. Human mesenchymal stromal/stem cells (MSC) are capable of modifying angiogenic pathways and immune responses, but the potency of these effects vary between individuals and various clinical characteristics including age and chronic kidney disease and levels of hypoxia. We summarize recently completed first-in-human studies applying intrarenal infusion of autologous adipose-derived MSC in human subjects with ischemic nephropathy that demonstrate a rise in blood flow and reduction in tissue hypoxia consistent with partial repair of microvascular injury, even without restoring main renal arterial blood flow. Inflammatory biomarkers in the renal vein of post-stenotic kidneys fell after MSC infusion. These changes were associated with modest but significant dose-related increments in kidney function. These data provide support a role for autologous MSC in repair of microvascular injury associated with tissue hypoxia.
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Affiliation(s)
- Stephen C. Textor
- Mayo Clinic, Division of Nephrology and Hypertension, Rochester, MN 55905, USA;
- Correspondence:
| | - Abdu Abumoawad
- Department of Medicine University of Missouri, Kansas, MO 64108, USA;
| | - Ahmed Saad
- Department of Medicine Creighton University School of Medicine, Omaha, NE 68124, USA;
| | | | - Allan Dietz
- Mayo Clinic, Human Cell Therapy Laboratory, Rochester, MN 55905, USA;
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Gibbons SM, Field HP, Fairhurst A, Fleming A, Ford C, Williams EL, Barnes SC, Barth JH. Clinical Evaluation of Assays for Plasma Renin Activity and Aldosterone Measurement by Liquid Chromatography-Tandem Mass Spectrometry. J Appl Lab Med 2020; 6:668-678. [PMID: 33928391 DOI: 10.1093/jalm/jfaa177] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 09/09/2020] [Indexed: 11/13/2022]
Abstract
BACKGROUND Aldosterone and renin are pivotal hormones in the regulation of salt and water homeostasis and blood pressure. Measurement of renin and aldosterone in serum/plasma is essential for the investigation of primary hyperaldosteronism (PA) and monitoring of glucocorticoid replacement therapy. METHODS We report 2 LC-MS/MS methods developed to measure aldosterone and plasma renin activity (PRA). PRA was determined by endogenous enzymatic generation of angiotensin I using 150 µL of sample. Generated angiotensin I was purified by solid phase extraction prior to chromatographic separation and mass spectrometry. Aldosterone measurement required 300 μL of sample extracted with MTBE prior to LC-MS/MS analysis. RESULTS The PRA method was linear (1.2-193 nmol/L), sensitive (LLOQ = 1.2 nmol/L), precise (CV = 4.1%), and specific (no cross reactivity for a number of structurally similar steroids). Dilutional linearity and recovery (84%) were acceptable. Accuracy was confirmed by comparison against our current RIA method. The aldosterone method had equally acceptable performance characteristics. Reference ranges in 110 healthy normotensive subjects were: PRA 0.2-3.7 nmol/L/h and aldosterone 50-950 pmol/L. Consecutive patients (n = 62) with adrenal incidentalomas shown to have no functional adrenal disease; their post overnight 1 mg dexamethasone test values were: PRA 0.2-2.6 nmol/L/h and aldosterone 55-480 pmol/L. Serum aldosterone values after 2 liter saline suppression were-normal subjects (n = 17): 78-238 pmol/L and confirmed primary hyperaldosteronism (n = 25): 131-1080 pmol/L. CONCLUSIONS We have developed robust assays for PRA and aldosterone with appropriate clinical evaluation. These assays are now in routine practice in the UK.
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Affiliation(s)
- Stephen M Gibbons
- SAS Laboratory Endocrinology, St James University Hospital, Leeds, UK
| | - Helen P Field
- SAS Laboratory Endocrinology, St James University Hospital, Leeds, UK
| | - April Fairhurst
- SAS Laboratory Endocrinology, St James University Hospital, Leeds, UK
| | - Anne Fleming
- SAS Laboratory Endocrinology, St James University Hospital, Leeds, UK
| | - Clive Ford
- SAS Laboratory Endocrinology, St James University Hospital, Leeds, UK
| | - Emma L Williams
- SAS Laboratory Endocrinology (Part of North West London Pathology), Charing Cross Hospital, London, UK
| | - Sophie C Barnes
- SAS Laboratory Endocrinology (Part of North West London Pathology), Charing Cross Hospital, London, UK
| | - Julian H Barth
- SAS Laboratory Endocrinology, St James University Hospital, Leeds, UK
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12
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Renal fibrosis detected by diffusion-weighted magnetic resonance imaging remains unchanged despite treatment in subjects with renovascular disease. Sci Rep 2020; 10:16300. [PMID: 33004888 PMCID: PMC7530710 DOI: 10.1038/s41598-020-73202-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 09/11/2020] [Indexed: 02/07/2023] Open
Abstract
Tissue fibrosis is an important index of renal disease progression. Diffusion-weighted magnetic resonance imaging’s (DWI-MRI) apparent diffusion coefficient (ADC) reveals water diffusion is unobstructed by microstructural alterations like fibrosis. We hypothesized that ADC may indicate renal injury and response to therapy in patients with renovascular disease (RVD). RVD patients were treated with medical therapy (MT) and percutaneous transluminal renal angioplasty (MT + PTRA) (n = 11, 3 bilaterally, n = 14 kidneys) or MT (n = 9). ADC and renal hypoxia (R2*) by blood-oxygen-level-dependent MRI were studied before (n = 27) and 3 months after (n = 20) treatment. Twelve patients underwent renal biopsies. Baseline ADC values were correlated with changes in eGFR, serum creatinine (SCr), systolic blood pressure (SBP), renal hypoxia, and renal vein levels of pro-inflammatory marker tumor necrosis-factor (TNF)-α. Renal oxygenation, eGFR, and SCr improved after MT + PTRA. ADC inversely correlated with the histological degree of renal fibrosis, but remained unchanged after MT or MT + PTRA. Basal ADC values correlated modestly with change in SBP, but not in renal hypoxia, TNF-α levels, or renal function. Lower ADC potentially reflects renal injury in RVD patients, but does not change in response to medical or interventional therapy over 3 months. Future studies need to pinpoint indices of kidney recovery potential.
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Abstract
A gradually developing reduction in renal blood flow from atherosclerotic renovascular disease results in loss of kidney volume and a decrease in glomerular filtration rate that eventually becomes irreversible. Whether this process fundamentally reflects tissue hypoxia has been difficult to establish. Studies of human renovascular disease have indicated that reductions in blood flow of up to 30% to 40% can be tolerated with preservation of normal oxygenation and structural integrity. These observations are consistent with remarkable stability of poststenotic kidney function during sustained medical antihypertensive drug therapy in moderate renovascular disease. With more severe and sustained reductions, however, cortical oxygenation decreases and the magnitude of medullary hypoxia expands. These changes are associated with increasing renal venous levels of inflammatory cytokines, angiogenic markers, and infiltration of inflammatory cells, including tissue macrophages and T cells. Although restoring large-vessel blood flow can improve oxygenation, some of these processes reflect microvascular rarefication, remain activated, and do not depend on hemodynamic factors alone. Elucidation of tissue injury pathways associated with hypoxia opens the possibility of adjunctive therapeutic measures beyond renal revascularization. These include cell-based regeneration, mitochondrial protection, and/or angiogenic cytokine therapy to restore or preserve renal function in ischemic nephropathy.
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Affiliation(s)
- Stephen C Textor
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN.
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN
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14
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Afarideh M, Zhang X, Ferguson CM, Glockner JF, Lerman A, Textor SC, Lerman LO. Peristenotic Collateral Circulation in Atherosclerotic Renovascular Disease: Association With Kidney Function and Response to Treatment. Hypertension 2020; 76:497-505. [PMID: 32507040 DOI: 10.1161/hypertensionaha.120.15057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The significance of peristenotic collateral circulation (PCC) development around a stenotic renal artery is unknown. We tested the hypothesis that PCC is linked to loss of kidney function and recovery potential in patients with atherosclerotic renovascular disease (ARVD). Thirty-four patients with ARVD were assigned to medical-therapy with or without revascularization based on clinical indications. The PCC was visualized using multidetector computed tomography and defined relative to segmental arteries in patients with essential hypertension. PCC number before and 3 months after treatment was correlated with various renal parameters. Thirty-four stenotic kidneys from 30 patients were analyzed. PCC number correlated inversely with kidney volume. ARVD-stenotic kidneys with baseline PCC (collateral ARVD [C-ARVD], n=13) associated with elevated 24-hour urine protein and stenotic kidney vein level of tumor necrosis factor-α, lower single-kidney volume and blood flow, and greater hypoxia than in stenotic kidneys with no PCC (no collateral ARVD [NC-ARVD], n=17). Revascularization (but not medical-therapy alone) improved stenotic kidney function and reduced inflammation in both NC-ARVD and C-ARVD. In C-ARVD, revascularization also increased stenotic kidney volume, blood flow, and oxygenation to levels comparable to NC-ARVD, and induced PCC regression. However, revascularization improved systolic blood pressure, plasma renin activity, and filtration fraction only in NC-ARVD. Therefore, patients with C-ARVD have greater kidney dysfunction, atrophy, hypoxia, and inflammation compared with patients with NC-ARVD, suggesting that PCC does not effectively protect the stenotic kidney in ARVD. Renal artery revascularization improved in C-ARVD stenotic kidney function, but not hypertension or renin-angiotensin system activation. These observations may help direct management of patients with ARVD.
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Affiliation(s)
| | | | | | - James F Glockner
- From the Division of Nephrology and Hypertension and the Departments of Radiology (J.F.G.), Mayo Clinic, Rochester, MN
| | - Amir Lerman
- Cardiovascular Medicine (A.L.), Mayo Clinic, Rochester, MN
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15
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Abumoawad A, Saad A, Ferguson CM, Eirin A, Herrmann SM, Hickson LJ, Goksu BB, Bendel E, Misra S, Glockner J, Dietz AB, Lerman LO, Textor SC. In a Phase 1a escalating clinical trial, autologous mesenchymal stem cell infusion for renovascular disease increases blood flow and the glomerular filtration rate while reducing inflammatory biomarkers and blood pressure. Kidney Int 2020; 97:793-804. [PMID: 32093917 PMCID: PMC7284953 DOI: 10.1016/j.kint.2019.11.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 11/14/2019] [Accepted: 11/22/2019] [Indexed: 02/08/2023]
Abstract
Atherosclerotic renovascular disease (ARVD) reduces tissue perfusion and eventually leads to loss of kidney function with limited therapeutic options. Here we describe results of Phase 1a escalating dose clinical trial of autologous mesenchymal stem cell infusion for ARVD. Thirty-nine patients with ARVD were studied on two occasions separated by three months. Autologous adipose-derived mesenchymal stem cells were infused through the renal artery in 21 patients at three different dose levels (1, 2.5 and 5.0 × 105 cells/kg) in seven patients each. We measured renal blood flow, glomerular filtration rate (GFR) (iothalamate and estimated GFR), renal vein cytokine levels, blood pressure, and tissue oxygenation before and three months after stem cell delivery. These indices were compared to those of 18 patients with ARVD matched for age, kidney function and blood pressure receiving medical therapy alone that underwent an identical study protocol. Cultured mesenchymal stem cells were also studied in vitro. For the entire stem cell treated-cohort, mean renal blood flow in the treated stenotic kidney significantly increased after stem cell infusion from (164 to 190 ml/min). Hypoxia, renal vein inflammatory cytokines, and angiogenic biomarkers significantly decreased following stem cell infusion. Mean systolic blood pressure significantly fell (144 to 136 mmHg) and the mean two-kidney GFR (Iothalamate) modestly but significantly increased from (53 to 56 ml/min). Changes in GFR and blood pressure were largest in the high dose stem cell treated individuals. No such changes were observed in the cohort receiving medical treatment alone. Thus, our data demonstrate the potential for autologous mesenchymal stem cell to increase blood flow, GFR and attenuate inflammatory injury in post-stenotic kidneys. The observation that some effects are dose-dependent and related to in-vitro properties of mesenchymal stem cell may direct efforts to maximize potential therapeutic efficacy.
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Affiliation(s)
| | - Ahmed Saad
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA; Department of Family Medicine, Creighton University, Omaha, Nebraska, USA
| | | | - Alfonso Eirin
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Sandra M Herrmann
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - LaTonya J Hickson
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Busra B Goksu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Emily Bendel
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Sanjay Misra
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - James Glockner
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Allan B Dietz
- Transfusion Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Stephen C Textor
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA.
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16
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Bane O, Mendichovszky IA, Milani B, Dekkers IA, Deux JF, Eckerbom P, Grenier N, Hall ME, Inoue T, Laustsen C, Lerman LO, Liu C, Morrell G, Pedersen M, Pruijm M, Sadowski EA, Seeliger E, Sharma K, Thoeny H, Vermathen P, Wang ZJ, Serafin Z, Zhang JL, Francis ST, Sourbron S, Pohlmann A, Fain SB, Prasad PV. Consensus-based technical recommendations for clinical translation of renal BOLD MRI. MAGMA (NEW YORK, N.Y.) 2020; 33:199-215. [PMID: 31768797 PMCID: PMC7021747 DOI: 10.1007/s10334-019-00802-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/18/2019] [Accepted: 10/22/2019] [Indexed: 01/08/2023]
Abstract
Harmonization of acquisition and analysis protocols is an important step in the validation of BOLD MRI as a renal biomarker. This harmonization initiative provides technical recommendations based on a consensus report with the aim to move towards standardized protocols that facilitate clinical translation and comparison of data across sites. We used a recently published systematic review paper, which included a detailed summary of renal BOLD MRI technical parameters and areas of investigation in its supplementary material, as the starting point in developing the survey questionnaires for seeking consensus. Survey data were collected via the Delphi consensus process from 24 researchers on renal BOLD MRI exam preparation, data acquisition, data analysis, and interpretation. Consensus was defined as ≥ 75% unanimity in response. Among 31 survey questions, 14 achieved consensus resolution, 12 showed clear respondent preference (65-74% agreement), and 5 showed equal (50/50%) split in opinion among respondents. Recommendations for subject preparation, data acquisition, processing and reporting are given based on the survey results and review of the literature. These technical recommendations are aimed towards increased inter-site harmonization, a first step towards standardization of renal BOLD MRI protocols across sites. We expect this to be an iterative process updated dynamically based on progress in the field.
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Affiliation(s)
- Octavia Bane
- BioMedical Engineering and Imaging Institute and Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Iosif A Mendichovszky
- Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge University Hospitals NHS Foundation Trust, Addenbrooke's Hospital, Cambridge, UK
| | - Bastien Milani
- Center for BioMedical Imaging, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Ilona A Dekkers
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jean-Francois Deux
- Department of Radiology, Groupe Hospitalier Henri Mondor, Créteil, France
| | - Per Eckerbom
- Department of Radiology, Institution for Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Nicolas Grenier
- Department of Radiology, Université de Bordeaux, CHU de Bordeaux, Bordeaux, France
| | - Michael E Hall
- Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA
| | - Tsutomu Inoue
- Department of Nephrology, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Christoffer Laustsen
- The MR Research Center Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Department of Internal Medicine, Mayo Clinic, Rochester, MN, USA
| | - Chunlei Liu
- Electrical Engineering and Computer Science, and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, USA
| | - Glen Morrell
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA
| | - Michael Pedersen
- Department of Clinical Medicine-Comparative Medicine Lab, Aarhus University Hospital, Aarhus, Denmark
| | - Menno Pruijm
- Nephrology and Hypertension Service, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Elizabeth A Sadowski
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Erdmann Seeliger
- Institute of Physiology, Charité-University Medicine Berlin, Berlin, Germany
| | - Kanishka Sharma
- Imaging Biomarkers Group, Department of Biomedical Imaging Sciences, University of Leeds, Leeds, UK
| | - Harriet Thoeny
- Department of Radiology, Hôpital Cantonal Fribourgois, University of Fribourg, Fribourg, Switzerland
| | - Peter Vermathen
- Departments for BioMedical Research and Radiology, Inselspital, Universitaetspital Bern, Bern, Switzerland
| | - Zhen J Wang
- Department of Radiology and Biomedical Imaging, University of California San Francisco Medical Center, San Francisco, CA, USA
| | - Zbigniew Serafin
- Department of Radiology, Nicolaus Copernicus University, Collegium Medicum, Bydgoszcz, Poland
| | - Jeff L Zhang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Susan T Francis
- Sir Peter Mansfield Centre, University of Notthingham, Notthingham, UK
| | - Steven Sourbron
- Imaging Biomarkers Group, Department of Biomedical Imaging Sciences, University of Leeds, Leeds, UK
| | - Andreas Pohlmann
- Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Sean B Fain
- Departments of Biomedical Engineering, Radiology, and Medical Physics, University of Wisconsin, Madison, WI, USA
| | - Pottumarthi V Prasad
- Department of Radiology, Center for Advanced Imaging, NorthShore University Health System, Evanston, IL, USA.
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17
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A Boolean Model of Microvascular Rarefaction to Predict Treatment Outcomes in Renal Disease. Sci Rep 2020; 10:440. [PMID: 31949240 PMCID: PMC6965143 DOI: 10.1038/s41598-019-57386-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 12/17/2019] [Indexed: 12/19/2022] Open
Abstract
Despite advances in renovascular disease (RVD) research, gaps remain between experimental and clinical outcomes, translation of results, and the understanding of pathophysiological mechanisms. A predictive tool to indicate support (or lack of) for biological findings may aid clinical translation of therapies. We created a Boolean model of RVD and hypothesized that it would predict outcomes observed in our previous studies using a translational swine model of RVD. Our studies have focused on developing treatments to halt renal microvascular (MV) rarefaction in RVD, a major feature of renal injury. A network topology of 20 factors involved in renal MV rarefaction that allowed simulation of 5 previously tested treatments was created. Each factor was assigned a function based upon its interactions with other variables and assumed to be “on” or “off”. Simulations of interventions were performed until outcomes reached a steady state and analyzed to determine pathological processes that were activated, inactivated, or unchanged vs. RVD with no intervention. Boolean simulations mimicked the results of our previous studies, confirming the importance of MV integrity on treatment outcomes in RVD. Furthermore, our study supports the potential application of a mathematical tool to predict therapeutic feasibility, which may guide the design of future studies for RVD.
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18
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Bane O, Mendichovszky IA, Milani B, Dekkers IA, Deux JF, Eckerbom P, Grenier N, Hall ME, Inoue T, Laustsen C, Lerman LO, Liu C, Morrell G, Pedersen M, Pruijm M, Sadowski EA, Seeliger E, Sharma K, Thoeny H, Vermathen P, Wang ZJ, Serafin Z, Zhang JL, Francis ST, Sourbron S, Pohlmann A, Fain SB, Prasad PV. Consensus-based technical recommendations for clinical translation of renal BOLD MRI. MAGMA (NEW YORK, N.Y.) 2019. [PMID: 31768797 DOI: 10.1007/s10334‐019‐00802‐x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Harmonization of acquisition and analysis protocols is an important step in the validation of BOLD MRI as a renal biomarker. This harmonization initiative provides technical recommendations based on a consensus report with the aim to move towards standardized protocols that facilitate clinical translation and comparison of data across sites. We used a recently published systematic review paper, which included a detailed summary of renal BOLD MRI technical parameters and areas of investigation in its supplementary material, as the starting point in developing the survey questionnaires for seeking consensus. Survey data were collected via the Delphi consensus process from 24 researchers on renal BOLD MRI exam preparation, data acquisition, data analysis, and interpretation. Consensus was defined as ≥ 75% unanimity in response. Among 31 survey questions, 14 achieved consensus resolution, 12 showed clear respondent preference (65-74% agreement), and 5 showed equal (50/50%) split in opinion among respondents. Recommendations for subject preparation, data acquisition, processing and reporting are given based on the survey results and review of the literature. These technical recommendations are aimed towards increased inter-site harmonization, a first step towards standardization of renal BOLD MRI protocols across sites. We expect this to be an iterative process updated dynamically based on progress in the field.
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Affiliation(s)
- Octavia Bane
- BioMedical Engineering and Imaging Institute and Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Iosif A Mendichovszky
- Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge University Hospitals NHS Foundation Trust, Addenbrooke's Hospital, Cambridge, UK
| | - Bastien Milani
- Center for BioMedical Imaging, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Ilona A Dekkers
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jean-Francois Deux
- Department of Radiology, Groupe Hospitalier Henri Mondor, Créteil, France
| | - Per Eckerbom
- Department of Radiology, Institution for Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Nicolas Grenier
- Department of Radiology, Université de Bordeaux, CHU de Bordeaux, Bordeaux, France
| | - Michael E Hall
- Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA
| | - Tsutomu Inoue
- Department of Nephrology, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Christoffer Laustsen
- The MR Research Center Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Department of Internal Medicine, Mayo Clinic, Rochester, MN, USA
| | - Chunlei Liu
- Electrical Engineering and Computer Science, and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, USA
| | - Glen Morrell
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA
| | - Michael Pedersen
- Department of Clinical Medicine-Comparative Medicine Lab, Aarhus University Hospital, Aarhus, Denmark
| | - Menno Pruijm
- Nephrology and Hypertension Service, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Elizabeth A Sadowski
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Erdmann Seeliger
- Institute of Physiology, Charité-University Medicine Berlin, Berlin, Germany
| | - Kanishka Sharma
- Imaging Biomarkers Group, Department of Biomedical Imaging Sciences, University of Leeds, Leeds, UK
| | - Harriet Thoeny
- Department of Radiology, Hôpital Cantonal Fribourgois, University of Fribourg, Fribourg, Switzerland
| | - Peter Vermathen
- Departments for BioMedical Research and Radiology, Inselspital, Universitaetspital Bern, Bern, Switzerland
| | - Zhen J Wang
- Department of Radiology and Biomedical Imaging, University of California San Francisco Medical Center, San Francisco, CA, USA
| | - Zbigniew Serafin
- Department of Radiology, Nicolaus Copernicus University, Collegium Medicum, Bydgoszcz, Poland
| | - Jeff L Zhang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Susan T Francis
- Sir Peter Mansfield Centre, University of Notthingham, Notthingham, UK
| | - Steven Sourbron
- Imaging Biomarkers Group, Department of Biomedical Imaging Sciences, University of Leeds, Leeds, UK
| | - Andreas Pohlmann
- Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Sean B Fain
- Departments of Biomedical Engineering, Radiology, and Medical Physics, University of Wisconsin, Madison, WI, USA
| | - Pottumarthi V Prasad
- Department of Radiology, Center for Advanced Imaging, NorthShore University Health System, Evanston, IL, USA.
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19
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Santelli A, Sun IO, Eirin A, Abumoawad AM, Woollard JR, Lerman A, Textor S, Puranik AS, Lerman LO. Senescent Kidney Cells in Hypertensive Patients Release Urinary Extracellular Vesicles. J Am Heart Assoc 2019; 8:e012584. [PMID: 31433703 PMCID: PMC6585370 DOI: 10.1161/jaha.119.012584] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 05/03/2019] [Indexed: 12/13/2022]
Abstract
Background Hypertension may be associated with renal cellular injury. Cells in distress release extracellular vesicles (EVs), and their numbers in urine may reflect renal injury. Cellular senescence, an irreversible growth arrest in response to a noxious milieu, is characterized by release of proinflammatory cytokines. We hypothesized that EVs released by senescent nephron cells can be identified in urine of patients with hypertension. Methods and Results We recruited patients with essential hypertension (EH) or renovascular hypertension and healthy volunteers (n=14 each). Renal oxygenation was assessed using magnetic resonance imaging and blood samples collected from both renal veins for cytokine-level measurements. EVs isolated from urine samples were characterized by imaging flow cytometry based on specific markers, including p16 (senescence marker), calyxin (podocytes), urate transporter 1 (proximal tubules), uromodulin (ascending limb of Henle's loop), and prominin-2 (distal tubules). Overall percentage of urinary p16+ EVs was elevated in EH and renovascular hypertension patients compared with healthy volunteers and correlated inversely with renal function and directly with renal vein cytokine levels. Urinary levels of p16+/urate transporter 1+ were elevated in all hypertensive subjects compared with healthy volunteers, whereas p16+/prominin-2+ levels were elevated only in EH versus healthy volunteers and p16+/uromodulin+ in renovascular hypertension versus EH. Conclusions Levels of p16+ EVs are elevated in urine of hypertensive patients and may reflect increased proximal tubular cellular senescence. In EH, EVs originate also from distal tubules and in renovascular hypertension from Henle's loop. Hence, urinary EVs levels may be useful to identify intrarenal sites of cellular senescence.
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Affiliation(s)
- Adrian Santelli
- Division of Nephrology and HypertensionMayo ClinicRochesterMN
- Department of PhysiopathologyHospital de ClinicasMontevideoUruguay
| | - In O. Sun
- Division of Nephrology and HypertensionMayo ClinicRochesterMN
| | - Alfonso Eirin
- Division of Nephrology and HypertensionMayo ClinicRochesterMN
| | | | | | - Amir Lerman
- Department of Cardiovascular DiseasesMayo ClinicRochesterMN
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20
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Sun IO, Santelli A, Abumoawad A, Eirin A, Ferguson CM, Woollard JR, Lerman A, Textor SC, Puranik AS, Lerman LO. Loss of Renal Peritubular Capillaries in Hypertensive Patients Is Detectable by Urinary Endothelial Microparticle Levels. Hypertension 2019; 72:1180-1188. [PMID: 30354805 DOI: 10.1161/hypertensionaha.118.11766] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hypertension, an important cause of chronic kidney disease, is characterized by peritubular capillary (PTC) loss. Circulating levels of endothelial microparticles (EMPs) reflect systemic endothelial injury. We hypothesized that systemic and urinary PTC-EMPs levels would reflect renal microvascular injury in hypertensive patients. We prospectively measured by flow cytometry renal vein, inferior vena cava, and urinary levels of EMPs in essential (n=14) and renovascular (RVH; n=24) hypertensive patients and compared them with peripheral blood and urinary levels in healthy volunteers (n=14). PTC-EMPs were identified as urinary exosomes positive for the PTC marker plasmalemmal-vesicle-associated protein. In 7 RVH patients, PTC and fibrosis were also quantified in renal biopsy, and in 18 RVH patients, PTC-EMPs were measured again 3 months after continued medical therapy with or without stenting (n=9 each). Renal vein and systemic PTC-EMPs levels were not different among the groups, whereas their urinary levels were elevated in both RVH and essential hypertension versus healthy volunteers (56.8%±12.7% and 62.8%±10.7% versus 34.0%±17.8%; both P≤0.001). Urinary PTC-EMPs levels correlated directly with blood pressure and inversely with estimated glomerular filtration rate. Furthermore, in RVH, urinary PTC-EMPs levels correlated directly with stenotic kidney hypoxia, histological PTC count, and fibrosis and inversely with cortical perfusion. Three months after treatment, the change in urinary PTC-EMPs levels correlated inversely with a change in renal function ( r=-0.582; P=0.011). Therefore, urinary PTC-EMPs levels are increased in hypertensive patients and may reflect renal microcirculation injury, whereas systemic PTC-EMPs levels are unchanged. Urinary PTC-EMPs may be useful as novel biomarkers of intrarenal capillary loss.
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Affiliation(s)
- In O Sun
- From the Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN (I.O.S., A.S., A.A., A.E., C.M.F., J.R.W., S.C.T., A.S.P., L.O.L.).,Division of Nephrology, Department of Internal Medicine, Presbyterian Medical Center, Jeonju, Korea (I.O.S.)
| | - Adrian Santelli
- From the Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN (I.O.S., A.S., A.A., A.E., C.M.F., J.R.W., S.C.T., A.S.P., L.O.L.)
| | - Abdelrhman Abumoawad
- From the Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN (I.O.S., A.S., A.A., A.E., C.M.F., J.R.W., S.C.T., A.S.P., L.O.L.)
| | - Alfonso Eirin
- From the Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN (I.O.S., A.S., A.A., A.E., C.M.F., J.R.W., S.C.T., A.S.P., L.O.L.)
| | - Christopher M Ferguson
- From the Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN (I.O.S., A.S., A.A., A.E., C.M.F., J.R.W., S.C.T., A.S.P., L.O.L.)
| | - John R Woollard
- From the Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN (I.O.S., A.S., A.A., A.E., C.M.F., J.R.W., S.C.T., A.S.P., L.O.L.)
| | - Amir Lerman
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN (A.L.)
| | - Stephen C Textor
- From the Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN (I.O.S., A.S., A.A., A.E., C.M.F., J.R.W., S.C.T., A.S.P., L.O.L.)
| | - Amrutesh S Puranik
- From the Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN (I.O.S., A.S., A.A., A.E., C.M.F., J.R.W., S.C.T., A.S.P., L.O.L.)
| | - Lilach O Lerman
- From the Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN (I.O.S., A.S., A.A., A.E., C.M.F., J.R.W., S.C.T., A.S.P., L.O.L.)
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21
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Abumoawad A, Saad A, Ferguson CM, Eirin A, Woollard JR, Herrmann SM, Hickson LJ, Bendel EC, Misra S, Glockner J, Lerman LO, Textor SC. Tissue hypoxia, inflammation, and loss of glomerular filtration rate in human atherosclerotic renovascular disease. Kidney Int 2019; 95:948-957. [PMID: 30904069 PMCID: PMC6738340 DOI: 10.1016/j.kint.2018.11.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/15/2018] [Accepted: 11/29/2018] [Indexed: 12/18/2022]
Abstract
The relationships between renal blood flow (RBF), tissue oxygenation, and inflammatory injury in atherosclerotic renovascular disease (ARVD) are poorly understood. We sought to correlate RBF and tissue hypoxia with glomerular filtration rate (GFR) in 48 kidneys from patients with ARVD stratified by single kidney iothalamate GFR (sGFR). Oxygenation was assessed by blood oxygenation level dependent magnetic resonance imaging (BOLD MRI), which provides an index for the levels of deoxyhemoglobin within a defined volume of tissue (R2*). sGFR correlated with RBF and with the severity of vascular stenosis as estimated by duplex velocities. Higher cortical R2* and fractional hypoxia and higher levels of renal vein neutrophil-gelatinase-associated-lipocalin (NGAL) and monocyte-chemoattractant protein-1 (MCP-1) were observed at lower GFR, with an abrupt inflection below 20 ml/min. Renal vein MCP-1 levels correlated with cortical R2* and with fractional hypoxia. Correlations between cortical R2* and RBF in the highest sGFR stratum (mean sGFR 51 ± 12 ml/min; R = -0.8) were degraded in the lowest sGFR stratum (mean sGFR 8 ± 3 ml/min; R = -0.1). Changes in fractional hypoxia after furosemide were also absent in the lowest sGFR stratum. These data demonstrate relative stability of renal oxygenation with moderate reductions in RBF and GFR but identify a transition to overt hypoxia and inflammatory cytokine release with severely reduced GFR. Tissue oxygenation and RBF were less correlated in the setting of reduced sGFR, consistent with variable oxygen consumption or a shift to alternative mechanisms of tissue injury. Identifying transitions in tissue oxygenation may facilitate targeted therapy in ARVD.
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Affiliation(s)
| | - Ahmed Saad
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA; Department of Family Medicine, Creighton University, Omaha, Nebraska, USA
| | | | - Alfonso Eirin
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - John R Woollard
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Sandra M Herrmann
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - LaTonya J Hickson
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Emily C Bendel
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Sanjay Misra
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - James Glockner
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Stephen C Textor
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA.
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22
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Zhou JY, Wang YC, Zeng CH, Ju SH. Renal Functional MRI and Its Application. J Magn Reson Imaging 2018; 48:863-881. [PMID: 30102436 DOI: 10.1002/jmri.26180] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/10/2018] [Indexed: 12/11/2022] Open
Abstract
Renal function varies according to the nature and stage of diseases. Renal functional magnetic resonance imaging (fMRI), a technique considered superior to the most common method used to estimate the glomerular filtration rate, allows for noninvasive, accurate measurements of renal structures and functions in both animals and humans. It has become increasingly prevalent in research and clinical applications. In recent years, renal fMRI has developed rapidly with progress in MRI hardware and emerging postprocessing algorithms. Function-related imaging markers can be acquired via renal fMRI, encompassing water molecular diffusion, perfusion, and oxygenation. This review focuses on the progression and challenges of the main renal fMRI methods, including dynamic contrast-enhanced MRI, blood oxygen level-dependent MRI, diffusion-weighted imaging, diffusion tensor imaging, arterial spin labeling, fat fraction imaging, and their recent clinical applications. LEVEL OF EVIDENCE 5 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:863-881.
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Affiliation(s)
- Jia-Ying Zhou
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School, Southeast University, Nanjing, China
| | - Yuan-Cheng Wang
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School, Southeast University, Nanjing, China
| | - Chu-Hui Zeng
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School, Southeast University, Nanjing, China
| | - Sheng-Hong Ju
- Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School, Southeast University, Nanjing, China
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23
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Milani B, Ansaloni A, Sousa-Guimaraes S, Vakilzadeh N, Piskunowicz M, Vogt B, Stuber M, Burnier M, Pruijm M. Reduction of cortical oxygenation in chronic kidney disease: evidence obtained with a new analysis method of blood oxygenation level-dependent magnetic resonance imaging. Nephrol Dial Transplant 2018; 32:2097-2105. [PMID: 27798200 DOI: 10.1093/ndt/gfw362] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 08/18/2016] [Indexed: 11/12/2022] Open
Abstract
Background Determinations of renal oxygenation by blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) in chronic kidney disease (CKD) patients have given heterogeneous results, possibly due to the lack of a reproducible method to analyse BOLD-MRI. It therefore remains uncertain whether patients with CKD have a reduced renal tissue oxygenation. We developed a new method to analyse BOLD-MRI signals and applied it to CKD patients and controls. Methods MRI was performed under standardized conditions before and 15 min after IV furosemide in 104 CKD patients, 61 hypertensives and 42 controls. MR images were analysed with the new twelve-layer concentric objects method (TLCO) that divides renal parenchyma in 12 layers of equal thickness. The mean R2* value of each layer was reported, along with the change in R2* between successive layers, as measured by the slope steepness of the relevant curve. Results Inter-observer variability was 2.3 ± 0.9%, 1.9 ± 0.8% and 3.0 ± 2.3% in, respectively, controls, moderate and severe CKD. The mean R2* of the outer (more cortical) layers was significantly higher in CKD, suggesting lower cortical oxygenation as compared with controls. In CKD patients, the response to furosemide was blunted in the inner (more medullary) layers, and the R2* slope was flatter. In multivariable regression analysis, the R2* slope correlated positively with estimated glomerular filtration rate (eGFR) in patients with an eGFR <90 mL/min/1.73 m2 (P < 0.001). Conclusions Using the new TLCO method, we confirm the hypothesis that renal cortical oxygenation is reduced in CKD in humans, and that the level of cortical oxygenation correlates with CKD severity.
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Affiliation(s)
- Bastien Milani
- Service of Nephrology and Hypertension, CHUV, Lausanne, Switzerland.,Center for Biomedical Imaging, University Hospital Lausanne, Lausanne, Switzerland
| | | | | | - Nima Vakilzadeh
- Service of Nephrology and Hypertension, CHUV, Lausanne, Switzerland
| | | | - Bruno Vogt
- Service of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland
| | - Matthias Stuber
- Center for Biomedical Imaging, University Hospital Lausanne, Lausanne, Switzerland.,Department of Radiology, CHUV, Lausanne, Switzerland
| | - Michel Burnier
- Service of Nephrology and Hypertension, CHUV, Lausanne, Switzerland
| | - Menno Pruijm
- Service of Nephrology and Hypertension, CHUV, Lausanne, Switzerland
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24
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Saad A, Herrmann SMS, Eirin A, Ferguson CM, Glockner JF, Bjarnason H, McKusick MA, Misra S, Lerman LO, Textor SC. Phase 2a Clinical Trial of Mitochondrial Protection (Elamipretide) During Stent Revascularization in Patients With Atherosclerotic Renal Artery Stenosis. Circ Cardiovasc Interv 2018; 10:CIRCINTERVENTIONS.117.005487. [PMID: 28916603 DOI: 10.1161/circinterventions.117.005487] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 07/24/2017] [Indexed: 01/08/2023]
Abstract
BACKGROUND Atherosclerotic renal artery stenosis reduces renal blood flow (RBF) and amplifies stenotic kidney hypoxia. Revascularization with percutaneous transluminal renal angioplasty (PTRA) and stenting often fails to recover renal function, possibly because of ischemia/reperfusion injury developing after PTRA. Elamipretide is a mitochondrial-targeted peptide that binds to cardiolipin and stabilizes mitochondrial function. We tested the hypothesis that elamipretide plus PTRA would improve renal function, oxygenation, and RBF in patients with atherosclerotic renal artery stenosis undergoing PTRA. METHODS AND RESULTS Inpatient studies were performed in patients with severe atherosclerotic renal artery stenosis scheduled for PTRA. Patients were treated before and during PTRA with elamipretide (0.05 mg/kg per hour intravenous infusion, n=6) or placebo (n=8). Stenotic kidney cortical/medullary perfusion and RBF were measured using contrast-enhanced multidetector CT, and renal oxygenation by 3-T blood oxygen level-dependent magnetic resonance imaging before and 3 months after PTRA. Age and basal glomerular filtration rate did not differ between groups. Blood oxygen level-dependent imaging demonstrated increased fractional hypoxia 24 hours after angiography and stenting in placebo (+47%) versus elamipretide (-6%). These were reverted to baseline 3 months later. Stenotic kidney RBF rose (202±29-262±115 mL/min; P=0.04) 3 months after PTRA in the elamipretide-treated group only. Over 3 months, systolic blood pressure decreased, and estimated glomerular filtration rate increased (P=0.003) more in the elamipretide group than in the placebo group (P=0.11). CONCLUSIONS Adjunctive elamipretide during PTRA was associated with attenuated postprocedural hypoxia, increased RBF, and improved kidney function in this pilot trial. These data support a role for targeted mitochondrial protection to minimize procedure-associated ischemic injury and to improve outcomes of revascularization for human atherosclerotic renal artery stenosis. CLINICAL TRIAL REGISTRATION URL: https://www.clinicaltrials.gov. Unique identifier: NCT01755858.
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Affiliation(s)
- Ahmed Saad
- From the Division of Nephrology and Hypertension (A.S., S.M.S.H., A.E., C.M.F., L.O.L., S.C.T.) and Department of Radiology (J.F.G., H.B., M.A.M., S.M.), Mayo Clinic, Rochester, MN
| | - Sandra M S Herrmann
- From the Division of Nephrology and Hypertension (A.S., S.M.S.H., A.E., C.M.F., L.O.L., S.C.T.) and Department of Radiology (J.F.G., H.B., M.A.M., S.M.), Mayo Clinic, Rochester, MN
| | - Alfonso Eirin
- From the Division of Nephrology and Hypertension (A.S., S.M.S.H., A.E., C.M.F., L.O.L., S.C.T.) and Department of Radiology (J.F.G., H.B., M.A.M., S.M.), Mayo Clinic, Rochester, MN
| | - Christopher M Ferguson
- From the Division of Nephrology and Hypertension (A.S., S.M.S.H., A.E., C.M.F., L.O.L., S.C.T.) and Department of Radiology (J.F.G., H.B., M.A.M., S.M.), Mayo Clinic, Rochester, MN
| | - James F Glockner
- From the Division of Nephrology and Hypertension (A.S., S.M.S.H., A.E., C.M.F., L.O.L., S.C.T.) and Department of Radiology (J.F.G., H.B., M.A.M., S.M.), Mayo Clinic, Rochester, MN
| | - Haraldur Bjarnason
- From the Division of Nephrology and Hypertension (A.S., S.M.S.H., A.E., C.M.F., L.O.L., S.C.T.) and Department of Radiology (J.F.G., H.B., M.A.M., S.M.), Mayo Clinic, Rochester, MN
| | - Michael A McKusick
- From the Division of Nephrology and Hypertension (A.S., S.M.S.H., A.E., C.M.F., L.O.L., S.C.T.) and Department of Radiology (J.F.G., H.B., M.A.M., S.M.), Mayo Clinic, Rochester, MN
| | - Sanjay Misra
- From the Division of Nephrology and Hypertension (A.S., S.M.S.H., A.E., C.M.F., L.O.L., S.C.T.) and Department of Radiology (J.F.G., H.B., M.A.M., S.M.), Mayo Clinic, Rochester, MN
| | - Lilach O Lerman
- From the Division of Nephrology and Hypertension (A.S., S.M.S.H., A.E., C.M.F., L.O.L., S.C.T.) and Department of Radiology (J.F.G., H.B., M.A.M., S.M.), Mayo Clinic, Rochester, MN
| | - Stephen C Textor
- From the Division of Nephrology and Hypertension (A.S., S.M.S.H., A.E., C.M.F., L.O.L., S.C.T.) and Department of Radiology (J.F.G., H.B., M.A.M., S.M.), Mayo Clinic, Rochester, MN.
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25
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Ow CPC, Ngo JP, Ullah MM, Hilliard LM, Evans RG. Renal hypoxia in kidney disease: Cause or consequence? Acta Physiol (Oxf) 2018; 222:e12999. [PMID: 29159875 DOI: 10.1111/apha.12999] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/10/2017] [Accepted: 11/15/2017] [Indexed: 02/06/2023]
Abstract
Tissue hypoxia has been proposed as an important factor in the pathophysiology of both chronic kidney disease (CKD) and acute kidney injury (AKI), initiating and propagating a vicious cycle of tubular injury, vascular rarefaction, and fibrosis and thus exacerbation of hypoxia. Here, we critically evaluate this proposition by systematically reviewing the literature relevant to the following six questions: (i) Is kidney disease always associated with tissue hypoxia? (ii) Does tissue hypoxia drive signalling cascades that lead to tissue damage and dysfunction? (iii) Does tissue hypoxia per se lead to kidney disease? (iv) Does tissue hypoxia precede pathology? (v) Does tissue hypoxia colocalize with pathology? (vi) Does prevention of tissue hypoxia prevent kidney disease? We conclude that tissue hypoxia is a common feature of both AKI and CKD. Furthermore, at least under in vitro conditions, renal tissue hypoxia drives signalling cascades that lead to tissue damage and dysfunction. Tissue hypoxia itself can lead to renal pathology, independent of other known risk factors for kidney disease. There is also some evidence that tissue hypoxia precedes renal pathology, at least in some forms of kidney disease. However, we have made relatively little progress in determining the spatial relationships between tissue hypoxia and pathological processes (i.e. colocalization) or whether therapies targeted to reduce tissue hypoxia can prevent or delay the progression of renal disease. Thus, the hypothesis that tissue hypoxia is a "common pathway" to both AKI and CKD still remains to be adequately tested.
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Affiliation(s)
- C. P. C. Ow
- Cardiovascular Disease Program Biomedicine Discovery Institute and Department of Physiology Monash University Melbourne Vic. Australia
| | - J. P. Ngo
- Cardiovascular Disease Program Biomedicine Discovery Institute and Department of Physiology Monash University Melbourne Vic. Australia
| | - M. M. Ullah
- Cardiovascular Disease Program Biomedicine Discovery Institute and Department of Physiology Monash University Melbourne Vic. Australia
| | - L. M. Hilliard
- Cardiovascular Disease Program Biomedicine Discovery Institute and Department of Physiology Monash University Melbourne Vic. Australia
| | - R. G. Evans
- Cardiovascular Disease Program Biomedicine Discovery Institute and Department of Physiology Monash University Melbourne Vic. Australia
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26
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Hall ME, Jordan JH, Juncos LA, Hundley WG, Hall JE. BOLD magnetic resonance imaging in nephrology. Int J Nephrol Renovasc Dis 2018; 11:103-112. [PMID: 29559807 PMCID: PMC5856054 DOI: 10.2147/ijnrd.s112299] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Magnetic resonance (MR) imaging, a non-invasive modality that provides anatomic and physiologic information, is increasingly used for diagnosis of pathophysiologic conditions and for understanding renal physiology in humans. Although functional MR imaging methods were pioneered to investigate the brain, they also offer powerful techniques for investigation of other organ systems such as the kidneys. However, imaging the kidneys provides unique challenges due to potential complications from contrast agents. Therefore, development of non-contrast techniques to study kidney anatomy and physiology is important. Blood oxygen level-dependent (BOLD) MR is a non-contrast imaging technique that provides functional information related to renal tissue oxygenation in various pathophysiologic conditions. Here we discuss technical considerations, clinical uses and future directions for use of BOLD MR as well as complementary MR techniques to better understand renal pathophysiology. Our intent is to summarize kidney BOLD MR applications for the clinician rather than focusing on the complex physical challenges that functional MR imaging encompasses; however, we briefly discuss some of those issues.
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Affiliation(s)
- Michael E Hall
- Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
| | - Jennifer H Jordan
- Department of Internal Medicine, Section on Cardiovascular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Luis A Juncos
- Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
| | - W Gregory Hundley
- Department of Internal Medicine, Section on Cardiovascular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - John E Hall
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
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27
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Chen F, Li S, Sun D. Methods of Blood Oxygen Level-Dependent Magnetic Resonance Imaging Analysis for Evaluating Renal Oxygenation. Kidney Blood Press Res 2018. [PMID: 29539614 DOI: 10.1159/000488072] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) has recently been utilized as a noninvasive tool for evaluating renal oxygenation. Several methods have been proposed for analyzing BOLD images. Regional ROI selection is the earliest and most widely used method for BOLD analysis. In the last 20 years, many investigators have used this method to evaluate cortical and medullary oxygenation in patients with ischemic nephropathy, hypertensive nephropathy, diabetic nephropathy, chronic kidney disease (CKD), acute kidney injury and renal allograft rejection. However, clinical trials of BOLD MRI using regional ROI selection revealed that it was difficult to distinguish the renal cortico-medullary zones with this method, and that it was susceptible to observer variability. To overcome these deficiencies, several new methods were proposed for analyzing BOLD images, including the compartmental approach, fractional hypoxia method, concentric objects (CO) method and twelve-layer concentric objects (TLCO) method. The compartmental approach provides an algorithm to judge whether the pixel belongs to the cortex or medulla. Fractional kidney hypoxia, measured by using BOLD MRI, was negatively correlated with renal blood flow, tissue perfusion and glomerular filtration rate (GFR) in patients with atherosclerotic renal artery stenosis. The CO method divides the renal parenchyma into six or twelve layers of thickness in each coronal slice of BOLD images and provides a R2* radial profile curve. The slope of the R2* curve associated positively with eGFR in CKD patients. Indeed, each method invariably has advantages and disadvantages, and there is generally no consensus method so far. Undoubtedly, analytic approaches for BOLD MRI with better reproducibility would assist clinicians in monitoring the degree of kidney hypoxia and thus facilitating timely reversal of tissue hypoxia.
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Affiliation(s)
- Fen Chen
- Department of Nephrology, Xuzhou Medical University, Xuzhou, China
| | - Shulin Li
- Department of Nephrology, Xuzhou Medical University, Xuzhou, China.,Department of Nephrology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Dong Sun
- Department of Nephrology, Xuzhou Medical University, Xuzhou, China.,Department of Nephrology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
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28
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Vanmassenhove J, Kielstein J, Jörres A, Biesen WV. Management of patients at risk of acute kidney injury. Lancet 2017; 389:2139-2151. [PMID: 28561005 DOI: 10.1016/s0140-6736(17)31329-6] [Citation(s) in RCA: 151] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 04/01/2017] [Accepted: 04/04/2017] [Indexed: 02/02/2023]
Abstract
Acute kidney injury (AKI) is a multifaceted syndrome that occurs in different settings. The course of AKI can be variable, from single hit and complete recovery, to multiple hits resulting in end-stage renal disease. No interventions to improve outcomes of established AKI have yet been developed, so prevention and early diagnosis are key. Awareness campaigns and education for health-care professionals on diagnosis and management of AKI-with attention to avoidance of volume depletion, hypotension, and nephrotoxic interventions-coupled with electronic early warning systems where available can improve outcomes. Biomarker-based strategies have not shown improvements in outcome. Fluid management should aim for early, rapid restoration of circulatory volume, but should be more limited after the first 24-48 h to avoid volume overload. Use of balanced crystalloid solutions versus normal saline remains controversial. Renal replacement therapy should only be started on the basis of hard criteria, but should not be delayed when criteria are met. On the basis of recent evidence, the risk of contrast-induced AKI might be overestimated for many conditions.
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Affiliation(s)
| | - Jan Kielstein
- Medical Clinic V, Nephrology, Hypertension and Blood Purification, Academic Teaching Hospital Braunschweig, Braunschweig, Germany
| | - Achim Jörres
- Department of Medicine 1, Nephrology, Transplantation and Medical Intensive Care, University Witten/Herdecke, Medical Centre Cologne Merheim, Cologne, Germany
| | - Wim Van Biesen
- Renal Division, Ghent University Hospital, Ghent, Belgium.
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29
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Saad A, Dietz AB, Herrmann SMS, Hickson LJ, Glockner JF, McKusick MA, Misra S, Bjarnason H, Armstrong AS, Gastineau DA, Lerman LO, Textor SC. Autologous Mesenchymal Stem Cells Increase Cortical Perfusion in Renovascular Disease. J Am Soc Nephrol 2017; 28:2777-2785. [PMID: 28461553 DOI: 10.1681/asn.2017020151] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 03/24/2017] [Indexed: 01/12/2023] Open
Abstract
Atherosclerotic renovascular disease (RVD) reduces renal blood flow (RBF) and GFR and accelerates poststenotic kidney (STK) tissue injury. Preclinical studies indicate that mesenchymal stem cells (MSCs) can stimulate angiogenesis and modify immune function in experimental RVD. We assessed the safety and efficacy of adding intra-arterial autologous adipose-derived MSCs into STK to standardized medical treatment in human subjects without revascularization. The intervention group (n=14) received a single infusion of MSC (1.0 × 105 or 2.5 × 105 cells/kg; n=7 each) plus standardized medical treatment; the medical treatment only group (n=14) included subjects matched for age, kidney function, and stenosis severity. We measured cortical and medullary volumes, perfusion, and RBF using multidetector computed tomography. We assessed tissue oxygenation by blood oxygen level-dependent MRI and GFR by iothalamate clearance. MSC infusions were well tolerated. Three months after infusion, cortical perfusion and RBF rose in the STK (151.8-185.5 ml/min, P=0.01); contralateral kidney RBF increased (212.7-271.8 ml/min, P=0.01); and STK renal hypoxia (percentage of the whole kidney with R2*>30/s) decreased (12.1% [interquartile range, 3.3%-17.8%] to 6.8% [interquartile range, 1.8%-12.9%], P=0.04). No changes in RBF occurred in medical treatment only subjects. Single-kidney GFR remained stable after MSC but fell in the medical treatment only group (-3% versus -24%, P=0.04). This first-in-man dose-escalation study provides evidence of safety of intra-arterial infusion of autologous MSCs in patients with RVD. MSC infusion without main renal artery revascularization associated with increased renal tissue oxygenation and cortical blood flow.
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Affiliation(s)
- Ahmed Saad
- Divisions of *Nephrology and Hypertension and
| | | | | | | | | | | | - Sanjay Misra
- Interventional Radiology, Mayo Clinic, Rochester, Minnesota
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30
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Bruno RM, Reesink KD, Ghiadoni L. Advances in the non-invasive assessment of vascular dysfunction in metabolic syndrome and diabetes: Focus on endothelium, carotid mechanics and renal vessels. Nutr Metab Cardiovasc Dis 2017; 27:121-128. [PMID: 27773467 DOI: 10.1016/j.numecd.2016.09.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 06/28/2016] [Accepted: 09/04/2016] [Indexed: 12/29/2022]
Abstract
AIM The present paper is a selective review on the methodology and clinical significance of techniques to assess specifically endothelial function, carotid mechanics and renal vascular function, particularly in the light of vascular dysfunction in metabolic syndrome and type 2 diabetes. DATA SYNTHESIS Endothelial dysfunction appears to be earlier detectable in the microcirculation of patients with altered glucose metabolism, while it attains significance in the macrocirculation at more advanced disease stages. Smooth muscle cell dysfunction is now increasingly recognized to play a role both in the development of endothelial dysfunction and abnormal arterial distensibility. Furthermore, impaired glucose metabolism affects carotid mechanics through medial calcification, structural changes in extracellular matrix due to advanced glycation and modification of the collagen/elastin material stiffness. The assessment of renal vascular function by dynamic ultrasound or magnetic resonance imaging has recently emerged as an appealing target for identifying subtle vascular alterations responsible for the development of diabetic nephropathy. CONCLUSIONS Vascular dysfunction represents a major mechanism for the development of cardiovascular disease in patients with abnormal glucose metabolism. Hence, the currently available non-invasive techniques to assess early structural and vascular abnormalities merit recommendation in this population, although their predictive value and sensitivity to monitor treatment-induced changes have not yet been established and are still under investigation.
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Affiliation(s)
- R M Bruno
- Department of Clinical and Experimental Medicine, University of Pisa, Italy
| | - K D Reesink
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Netherlands; Department of Biomedical Engineering, Cardiovascular Center, Maastricht University Medical Center, Netherlands
| | - L Ghiadoni
- Department of Clinical and Experimental Medicine, University of Pisa, Italy.
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31
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Pruijm M, Milani B, Burnier M. Blood Oxygenation Level-Dependent MRI to Assess Renal Oxygenation in Renal Diseases: Progresses and Challenges. Front Physiol 2017; 7:667. [PMID: 28105019 PMCID: PMC5214762 DOI: 10.3389/fphys.2016.00667] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 12/19/2016] [Indexed: 11/13/2022] Open
Abstract
BOLD-MRI (blood oxygenation-level dependent magnetic resonance imaging) allows non-invasive measurement of renal tissue oxygenation in humans, without the need for contrast products. BOLD-MRI uses the fact that magnetic properties of hemoglobin depend of its oxygenated state:: the higher local deoxyhemoglobin, the higher the so called apparent relaxation rate R2* (sec-1), and the lower local tissue oxygen content. Several factors other than deoxyhemoglobin (such as hydration status, dietary sodium intake, and susceptibility effects) influence the BOLD signal, and need to be taken into account when interpreting results. The last 5 years have witnessed important improvements in the standardization of these factors, and the appearance of new, highly reproducible analysis techniques of BOLD-images, that are reviewed in this article. Using these new BOLD-MRI analysis techniques, it has recently been shown that persons suffering from chronic kidney diseases (CKD) have lower cortical oxygenation than normotensive controls, thus confirming the chronic hypoxia hypothesis. The acute alterations in R2* after the administration of furosemide are smaller in CKD, and represent an estimate of the oxygen-dependent tubular transport of sodium. BOLD-MRI-alone or in combination with other functional MRI methods- can be used to monitor the renal effects of drugs, and is increasingly used in the preclinical setting. The near future will tell whether or not BOLD-MRI represents a new tool to predict renal function decline an adverse renal outcome.
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Affiliation(s)
- Menno Pruijm
- Service of Nephrology and Hypertension, Department of Medicine, Centre Hospitalier Universitaire VaudoisLausanne, Switzerland
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32
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Wang C, Zhao K, Zhang R, Jiang L, Wang R, Zhang X, Wang H, Jin L, Zhang J, Wang X, Fang J. Evaluation of renal oxygenation change under the influence of carbogen breathing using a dynamic R 2 , R 2 ' and R 2 * quantification approach. NMR IN BIOMEDICINE 2016; 29:1601-1607. [PMID: 27670144 DOI: 10.1002/nbm.3625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 08/03/2016] [Accepted: 08/22/2016] [Indexed: 06/06/2023]
Abstract
The purpose of this study is to demonstrate the feasibility of dynamic renal R2 /R2 '/R2 * measurements based on a method, denoted psMASE-ME, in which a periodic 180° pulse-shifting multi-echo asymmetric spin echo (psMASE) sequence, combined with a moving estimation (ME) strategy, is adopted. Following approval by the institutional animal care and use committee, a block design of respiratory challenge with interleaved air and carbogen (97% O2 , 3% CO2 ) breathing was employed in nine rabbits. Parametrical R2 /R2 '/R2 * maps were computed and average R2 /R2 '/R2 * values were measured in regions of interest in the renal medulla and cortex. Bland-Altman plots showed good agreement between the proposed method and reference standards of multi-echo spin echo and multi-echo gradient echo sequences. Renal R2 , R2 ' and R2 * decreased significantly from 16.2 ± 4.4 s-1 , 9.8 ± 5.2 s-1 and 25.9 ± 5.0 s-1 to 14.9 ± 4.4 s-1 (p < 0.05), 8.5 ± 4.1 s-1 (p < 0.05) and 23.4 ± 4.8 s-1 (p < 0.05) in the cortex when switching the gas mixture from room air to carbogen. In the renal medulla, R2 , R2 ' and R2 * also decreased significantly from 12.9 ± 4.7 s-1 , 15.1 ± 5.8 s-1 and 27.9 ± 5.3 s-1 to 11.8 ± 4.5 s-1 (p < 0.05), 14.2 ± 4.2 s-1 (p < 0.05) and 25.8 ± 5.1 s-1 (p < 0.05). No statistically significant differences in relative R2 , R2 ' and R2 * changes were observed between the cortex and medulla (p = 0.72 for R2 , p = 0.39 for R2 ' and p = 0.61 for R2 *). The psMASE-ME method for dynamic renal R2 /R2 '/R2 * measurements, together with the respiratory challenge, has potential use in the evaluation of renal oxygenation in many renal diseases.
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Affiliation(s)
- Chengyan Wang
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Kai Zhao
- Department of Radiology, Peking University First Hospital, Beijing, China
| | - Rui Zhang
- College of Engineering, Peking University, Beijing, China
| | - Li Jiang
- Philips Healthcare, Suzhou, Jiangsu, China
| | - Rui Wang
- Department of Radiology, Peking University First Hospital, Beijing, China
| | - Xiaodong Zhang
- Department of Radiology, Peking University First Hospital, Beijing, China
| | - He Wang
- Philips Healthcare, Suzhou, Jiangsu, China
| | - Lixin Jin
- Philips Healthcare, Suzhou, Jiangsu, China
| | - Jue Zhang
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
- College of Engineering, Peking University, Beijing, China.
| | - Xiaoying Wang
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
- Department of Radiology, Peking University First Hospital, Beijing, China.
| | - Jing Fang
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- College of Engineering, Peking University, Beijing, China
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Thacker JM, Li LP, Li W, Zhou Y, Sprague SM, Prasad PV. Renal Blood Oxygenation Level-Dependent Magnetic Resonance Imaging: A Sensitive and Objective Analysis. Invest Radiol 2016; 50:821-7. [PMID: 26193455 DOI: 10.1097/rli.0000000000000190] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVES The aim of this study was to determine a robust (sensitive and objective) method for analyzing renal blood oxygenation level-dependent magnetic resonance imaging data. MATERIALS AND METHODS Forty-seven subjects (30 with chronic kidney disease [CKD] and 17 controls) were imaged at baseline and after furosemide with a multiecho gradient recalled echo sequence. Conventional analysis consisted of regional segmentation (small cortex, large cortex, and medulla), followed by computing the mean of each region. In addition, we segmented the entire parenchyma and computed the mean (μ1) plus higher moments (μ2, μ3, and μ4). Two raters performed each of the segmentation steps, and agreement was assessed with intraclass correlation coefficients (ICCs). We used a measure of effect size (Cohen's d value), in addition to the usual measure of statistical significance, P values, for determining significant results. RESULTS The mean of the renal parenchyma showed the highest agreement between raters (ICC, 0.99), and the higher parenchyma moments were on par with large cortical region of interest (ROI) ICC. The renal parenchymal mean also exhibited significant sensitivity to changes after furosemide administration in healthy subjects (P = 0.002, d = 0.84), in agreement with medullary ROIs (P = 0.002, d = 1.59). When comparing controls and subjects with CKD at baseline, cortical ROI showed a significant difference (P = 0.015, d = -0.69), whereas the parenchyma ROI did not (P = 0.152, d = 0.39). Post-furosemide data in all regions resulted in a significant difference (large cortex: P = 0.026, d = -0.51; medulla: P = 0.019, d = -0.61) with the renal parenchyma ROI resulting in the largest effect size (P = 0.003, d = -0.75). Higher moments of the renal parenchyma showed similar significant differences as well. CONCLUSIONS Overall, our data support the use of the entire parenchyma to evaluate changes in the medulla after administration of furosemide, a widely used pharmacological maneuver. Changes in higher moments indicate that there is more than just a shift in the mean renal R2* and may provide clinically relevant information without the need for subjective regional segmentation. For evaluating differences between controls and subjects with CKD at baseline; large cortical ROI provided the highest sensitivity and objectivity. A combination of renal parenchyma assessment and large cortical ROI may provide the most robust method of evaluating renal blood oxygenation level-dependent magnetic resonance imaging data.
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Affiliation(s)
- Jon M Thacker
- From the *Department of Biomedical Engineering, Northwestern University; †Department of Radiology/Center for Advanced Imaging, NorthShore University Healthsystem, Evanston; ‡Department of Medicine, University of Chicago Pritzker School of Medicine, Chicago; §Center for Biomedical and Research Informatics, and ║Department of Medicine, NorthShore University Healthsystem, Evanston, IL
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Thacker J, Zhang JL, Franklin T, Prasad P. BOLD quantified renal pO2 is sensitive to pharmacological challenges in rats. Magn Reson Med 2016; 78:297-302. [PMID: 27501515 DOI: 10.1002/mrm.26367] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 06/22/2016] [Accepted: 07/12/2016] [Indexed: 11/06/2022]
Abstract
PURPOSE Blood oxygen level-dependent (BOLD) MRI has been effectively used to monitor changes in renal oxygenation. However, R2* (or T2*) is not specific to blood oxygenation and is dependent on other factors. This study investigates the use of a statistical model that takes these factors into account and maps BOLD MRI measurements to blood pO2. METHODS Spin echo and gradient echo images were obtained in six Sprague-Dawley rats and R2 and R2* maps were computed. Measurements were made at baseline, post-nitric oxide synthase inhibitor (L-NAME), and post-furosemide administration. A simulation of each region was performed to map R2' (computed as R2*-R2) to blood pO2. RESULTS At baseline, blood pO2 in the outer medulla was 30.5 ± 1.2 mmHg and 51.9 ± 5.2 mmHg in the cortex, in agreement with previous invasive studies. Blood pO2 was found to decrease within the outer medulla following L-NAME (P < 0.05) and increase after furosemide (P < 0.05). Blood pO2 in the cortex increased following furosemide (P < 0.05). CONCLUSIONS Model-derived blood pO2 is sensitive to pharmacological challenges, and baseline pO2 is comparable to literature values. Reporting pO2 instead of R2* could lead to a greater clinical impact of renal BOLD MRI and facilitate the identification of hypoxic regions. Magn Reson Med 78:297-302, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Jon Thacker
- Biomedical Engineering, Northwestern University, Evanston, Illinois, USA
| | - Jeff L Zhang
- Department of Radiology, University of Utah, Salt Lake City, Utah, USA
| | - Tammy Franklin
- Department of Radiology/Center for Advanced Imaging, NorthShore University HealthSystem, Evanston, Illinois, USA
| | - Pottumarthi Prasad
- Department of Radiology/Center for Advanced Imaging, NorthShore University HealthSystem, Evanston, Illinois, USA.,Department of Radiology, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA
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Saad A, Wang W, Herrmann SMS, Glockner JF, Mckusick MA, Misra S, Bjarnason H, Lerman LO, Textor SC. Atherosclerotic renal artery stenosis is associated with elevated cell cycle arrest markers related to reduced renal blood flow and postcontrast hypoxia. Nephrol Dial Transplant 2016; 31:1855-1863. [PMID: 27474749 DOI: 10.1093/ndt/gfw265] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 06/04/2016] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Atherosclerotic renal artery stenosis (ARAS) reduces renal blood flow (RBF), ultimately leading to kidney hypoxia and inflammation. Insulin-like growth factor binding protein-7 (IGFBP-7) and tissue inhibitor of metalloproteinases-2 (TIMP-2) are biomarkers of cell cycle arrest, often increased in ischemic conditions and predictive of acute kidney injury (AKI). This study sought to examine the relationships between renal vein levels of IGFBP-7, TIMP-2, reductions in RBF and postcontrast hypoxia as measured by blood oxygen level-dependent (BOLD) magnetic resonance imaging. METHODS Renal vein levels of IGFBP-7 and TIMP-2 were obtained in an ARAS cohort (n= 29) scheduled for renal artery stenting and essential hypertensive (EH) healthy controls (n = 32). Cortical and medullary RBFs were measured by multidetector computed tomography (CT) immediately before renal artery stenting and 3 months later. BOLD imaging was performed before and 3 months after stenting in all patients, and a subgroup (N = 12) underwent repeat BOLD imaging 24 h after CT/stenting to examine postcontrast/procedure levels of hypoxia. RESULTS Preintervention IGFBP-7 and TIMP-2 levels were elevated in ARAS compared with EH (18.5 ± 2.0 versus 15.7 ± 1.5 and 97.4 ± 23.1 versus 62.7 ± 9.2 ng/mL, respectively; P< 0.0001); baseline IGFBP-7 correlated inversely with hypoxia developing 24 h after contrast injection (r = -0.73, P< 0.0001) and with prestent cortical blood flow (r = -0.59, P= 0.004). CONCLUSION These data demonstrate elevated IGFBP-7 and TIMP-2 levels in ARAS as a function of the degree of reduced RBF. Elevated baseline IGFBP-7 levels were associated with protection against postimaging hypoxia, consistent with 'ischemic preconditioning'. Despite contrast injection and stenting, AKI in these high-risk ARAS subjects with elevated IGFBP-7/TIMP-2 was rare and did not affect long-term kidney function.
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Affiliation(s)
- Ahmed Saad
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Wei Wang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | | | - James F Glockner
- Department of Interventional Radiology, Mayo Clinic, Rochester, MN, USA
| | | | - Sanjay Misra
- Department of Interventional Radiology, Mayo Clinic, Rochester, MN, USA
| | | | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Stephen C Textor
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
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Eirin A, Saad A, Tang H, Herrmann SM, Woollard JR, Lerman A, Textor SC, Lerman LO. Urinary Mitochondrial DNA Copy Number Identifies Chronic Renal Injury in Hypertensive Patients. Hypertension 2016; 68:401-10. [PMID: 27324229 DOI: 10.1161/hypertensionaha.116.07849] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 05/25/2016] [Indexed: 12/12/2022]
Abstract
Mitochondrial injury contributes to renal dysfunction in several models of renal disease, but its involvement in human hypertension remains unknown. Fragments of the mitochondrial genome released from dying cells are considered surrogate markers of mitochondrial injury. We hypothesized that hypertension would be associated with increased urine mitochondrial DNA (mtDNA) copy numbers. We prospectively measured systemic and urinary copy number of the mtDNA genes cytochrome-c oxidase-3 and NADH dehydrogenase subunit-1 by quantitative polymerase chain reaction in essential (n=25) and renovascular (RVH, n=34) hypertensive patients and compared them with healthy volunteers (n=22). Urinary kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin served as indices of renal injury. Renal blood flow and oxygenation were assessed by multidetector computed tomography and blood oxygen level-dependent magnetic resonance imaging. Blood pressure, urinary neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1 were similarly elevated in essential hypertension and RVH, and estimated glomerular filtration rate was lower in RVH versus healthy volunteers and essential hypertension. Renal blood flow was lower in RVH compared with essential hypertension. Urinary mtDNA copy number was higher in hypertension compared with healthy volunteers, directly correlated with urinary neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 and inversely with estimated glomerular filtration rate. In RVH, urinary mtDNA copy number correlated directly with intrarenal hypoxia. Furthermore, in an additional validation cohort, urinary mtDNA copy number was higher in RVH compared with healthy volunteers (n=10 each). The change in serum creatinine levels and estimated glomerular filtration rate 3 months after medical therapy without or with revascularization correlated with the change in urinary mtDNA. Therefore, elevated urinary mtDNA copy numbers in hypertensive patients correlated with markers of renal injury and dysfunction, implicating mitochondrial injury in kidney damage in human hypertension.
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Affiliation(s)
- Alfonso Eirin
- From the Department of Internal Medicine, Division of Nephrology and Hypertension (A.E., A.S., H.T., S.M.H., J.R.W., S.C.T., L.O.L.) and Division of Cardiovascular Diseases (A.L., L.O.L.), Mayo Clinic, Rochester, MN
| | - Ahmed Saad
- From the Department of Internal Medicine, Division of Nephrology and Hypertension (A.E., A.S., H.T., S.M.H., J.R.W., S.C.T., L.O.L.) and Division of Cardiovascular Diseases (A.L., L.O.L.), Mayo Clinic, Rochester, MN
| | - Hui Tang
- From the Department of Internal Medicine, Division of Nephrology and Hypertension (A.E., A.S., H.T., S.M.H., J.R.W., S.C.T., L.O.L.) and Division of Cardiovascular Diseases (A.L., L.O.L.), Mayo Clinic, Rochester, MN
| | - Sandra M Herrmann
- From the Department of Internal Medicine, Division of Nephrology and Hypertension (A.E., A.S., H.T., S.M.H., J.R.W., S.C.T., L.O.L.) and Division of Cardiovascular Diseases (A.L., L.O.L.), Mayo Clinic, Rochester, MN
| | - John R Woollard
- From the Department of Internal Medicine, Division of Nephrology and Hypertension (A.E., A.S., H.T., S.M.H., J.R.W., S.C.T., L.O.L.) and Division of Cardiovascular Diseases (A.L., L.O.L.), Mayo Clinic, Rochester, MN
| | - Amir Lerman
- From the Department of Internal Medicine, Division of Nephrology and Hypertension (A.E., A.S., H.T., S.M.H., J.R.W., S.C.T., L.O.L.) and Division of Cardiovascular Diseases (A.L., L.O.L.), Mayo Clinic, Rochester, MN
| | - Stephen C Textor
- From the Department of Internal Medicine, Division of Nephrology and Hypertension (A.E., A.S., H.T., S.M.H., J.R.W., S.C.T., L.O.L.) and Division of Cardiovascular Diseases (A.L., L.O.L.), Mayo Clinic, Rochester, MN
| | - Lilach O Lerman
- From the Department of Internal Medicine, Division of Nephrology and Hypertension (A.E., A.S., H.T., S.M.H., J.R.W., S.C.T., L.O.L.) and Division of Cardiovascular Diseases (A.L., L.O.L.), Mayo Clinic, Rochester, MN.
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Grenier N, Merville P, Combe C. Radiologic imaging of the renal parenchyma structure and function. Nat Rev Nephrol 2016; 12:348-59. [DOI: 10.1038/nrneph.2016.44] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Saad A, Herrmann SM, Textor SC. Chronic renal ischemia in humans: can cell therapy repair the kidney in occlusive renovascular disease? Physiology (Bethesda) 2016; 30:175-82. [PMID: 25933818 DOI: 10.1152/physiol.00065.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Occlusive renovascular disease caused by atherosclerotic renal artery stenosis (ARAS) elicits complex biological responses that eventually lead to loss of kidney function. Recent studies indicate a complex interplay of oxidative stress, endothelial dysfunction, and activation of fibrogenic and inflammatory cytokines as a result of atherosclerosis, hypoxia, and renal hypoperfusion in this disorder. Human studies emphasize the limits of the kidney adaptation to reduced blood flow, eventually leading to renal hypoxia with activation of inflammatory and fibrogenic pathways. Several randomized prospective clinical trials show that stent revascularization alone in patients with atherosclerotic renal artery stenosis provides little additional benefit to medical therapy once these processes have developed and solidified. Experimental data now support developing adjunctive cell-based measures to support angiogenesis and anti-inflammatory renal repair mechanisms. These data encourage the study of endothelial progenitor cells and/or mesenchymal stem/stromal cells for the repair of damaged kidney tissue.
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Affiliation(s)
- Ahmed Saad
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Sandra M Herrmann
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Stephen C Textor
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
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Abstract
PURPOSE OF REVIEW Over the past decade, a variety of MRI methods have been developed and applied to many kidney diseases. These MRI techniques show great promise, enabling the noninvasive assessment of renal structure, function and injury in individuals. This review will highlight the current applications of functional MRI techniques for the assessment of renal disease and discuss future directions. RECENT FINDINGS Many pathological (functional and structural) changes or factors in renal disease can be assessed by advanced MRI techniques. These include renal vascular structure and function (contrast-enhanced MRI, arterial spin labelling), tissue oxygenation (blood oxygen level dependent MRI), renal tissue injury and fibrosis (diffusion or magnetization transfer imaging, magnetic resonance elastography), renal metabolism (chemical exchange saturation transfer, spectroscopic imaging), nephron endowment (cationic-contrast imaging), sodium concentration (23Na-MRI) and molecular events (targeted-contrast imaging). SUMMARY Current advances in MRI techniques have enabled the noninvasive investigation of renal disease. Further development, evaluation and application of the MRI techniques should facilitate better understanding and assessment of renal disease, and the development of new imaging biomarkers, enabling the intensified treatment of high-risk populations and a more rapid interrogation of novel therapeutic agents and protocols.
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Wang C, Zhang R, Wang R, Jiang L, Zhang X, Wang H, Zhao K, Jin L, Zhang J, Wang X, Fang J. Noninvasive measurement of renal oxygen extraction fraction under the influence of respiratory challenge. J Magn Reson Imaging 2016; 44:230-7. [PMID: 26800848 DOI: 10.1002/jmri.25163] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/04/2016] [Indexed: 12/12/2022] Open
Affiliation(s)
- Chengyan Wang
- Academy for Advanced Interdisciplinary Studies; Peking University; Beijing PR China
| | - Rui Zhang
- College of Engineering; Peking University; Beijing PR China
| | - Rui Wang
- Department of Radiology; Peking University First Hospital; Beijing PR China
| | - Li Jiang
- Philips Healthcare; Suzhou Jiangsu PR China
| | - Xiaodong Zhang
- Department of Radiology; Peking University First Hospital; Beijing PR China
| | - He Wang
- Philips Healthcare; Suzhou Jiangsu PR China
| | - Kai Zhao
- Department of Radiology; Peking University First Hospital; Beijing PR China
| | - Lixin Jin
- Philips Healthcare; Suzhou Jiangsu PR China
| | - Jue Zhang
- Academy for Advanced Interdisciplinary Studies; Peking University; Beijing PR China
- College of Engineering; Peking University; Beijing PR China
| | - Xiaoying Wang
- Academy for Advanced Interdisciplinary Studies; Peking University; Beijing PR China
- Department of Radiology; Peking University First Hospital; Beijing PR China
| | - Jing Fang
- Academy for Advanced Interdisciplinary Studies; Peking University; Beijing PR China
- College of Engineering; Peking University; Beijing PR China
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Herrmann SMS, Saad A, Eirin A, Woollard J, Tang H, McKusick MA, Misra S, Glockner JF, Lerman LO, Textor SC. Differences in GFR and Tissue Oxygenation, and Interactions between Stenotic and Contralateral Kidneys in Unilateral Atherosclerotic Renovascular Disease. Clin J Am Soc Nephrol 2016; 11:458-69. [PMID: 26787779 DOI: 10.2215/cjn.03620415] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 11/26/2015] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND OBJECTIVES Atherosclerotic renal artery stenosis (ARAS) can reduce renal blood flow, tissue oxygenation, and GFR. In this study, we sought to examine associations between renal hemodynamics and tissue oxygenation with single-kidney function, pressor hormones, and inflammatory biomarkers in patients with unilateral ARAS undergoing medical therapy alone or stent revascularization. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Nonrandomized inpatient studies were performed in patients with unilateral ARAS (>60% occlusion) before and 3 months after revascularization (n=10) or medical therapy (n=20) or patients with essential hypertension (n=32) under identical conditions. The primary study outcome was change in single-kidney GFR. Individual kidney hemodynamics and volume were measured using multidetector computed tomography. Tissue oxygenation (using R(2)* as a measure of deoxyhemoglobin) was determined by blood oxygen level-dependent magnetic resonance imaging at 3 T. Renal vein neutrophil gelatinase-associated lipocalin (NGAL), monocyte chemoattractant protein-1 (MCP-1), and plasma renin activity were measured. RESULTS Total GFR did not change over 3 months in either group, but the stenotic kidney (STK) GFR rose over time in the stent compared with the medical group (+2.2[-1.8 to 10.5] versus -5.3[-7.3 to -0.3] ml/min; P=0.03). Contralateral kidney (CLK) GFR declined in the stent group (43.6±19.7 to 36.6±19.5 ml/min; P=0.03). Fractional tissue hypoxia fell in the STK (fraction R(2)* >30/s: 22.1%±20% versus 14.9%±18.3%; P<0.01) after stenting. Renal vein biomarkers correlated with the degree of hypoxia in the STK: NGAL(r=0.3; P=0.01) and MCP-1(r=0.3; P=0.02; more so after stenting). Renal vein NGAL was inversely related to renal blood flow in the STK (r=-0.65; P<0.001). Biomarkers were highly correlated between STK and CLK, NGAL (r=0.94; P<0.001), and MCP-1 (r=0.96; P<0.001). CONCLUSIONS These results showed changes over time in single-kidney GFR that were not evident in parameters of total GFR. Furthermore, they delineate the relationship of measurable tissue hypoxia within the STK and markers of inflammation in human ARAS. Renal vein NGAL and MCP-1 indicated persistent interactions between the ischemic kidney and both CLK and systemic levels of inflammatory cytokines.
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Affiliation(s)
| | - Ahmed Saad
- Division of Nephrology and Hypertension and
| | | | | | - Hui Tang
- Division of Nephrology and Hypertension and
| | | | - Sanjay Misra
- Department of Radiology, Mayo Clinic, Rochester, Minnesota
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Odudu A, Vassallo D, Kalra PA. From anatomy to function: diagnosis of atherosclerotic renal artery stenosis. Expert Rev Cardiovasc Ther 2015; 13:1357-75. [DOI: 10.1586/14779072.2015.1100077] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
PURPOSE OF REVIEW Over the past decade, a variety of MRI methods have been developed and applied to many kidney diseases. These MRI techniques show great promise, enabling the noninvasive assessment of renal structure, function and injury in individuals. This review will highlight the current applications of functional MRI techniques for the assessment of renal disease and discuss future directions. RECENT FINDINGS Many pathological (functional and structural) changes or factors in renal disease can be assessed by advanced MRI techniques. These include renal vascular structure and function (contrast-enhanced MRI, arterial spin labelling), tissue oxygenation (blood oxygen level dependent MRI), renal tissue injury and fibrosis (diffusion or magnetization transfer imaging, magnetic resonance elastography), renal metabolism (chemical exchange saturation transfer, spectroscopic imaging), nephron endowment (cationic-contrast imaging), sodium concentration (23Na-MRI) and molecular events (targeted-contrast imaging). SUMMARY Current advances in MRI techniques have enabled the noninvasive investigation of renal disease. Further development, evaluation and application of the MRI techniques should facilitate better understanding and assessment of renal disease, and the development of new imaging biomarkers, enabling the intensified treatment of high-risk populations and a more rapid interrogation of novel therapeutic agents and protocols.
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Affiliation(s)
- Takamune Takahashi
- aDivision of Nephrology and Hypertension bDepartment of Radiology and Radiological Sciences cVanderbilt University Institute of Imaging Science, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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Kwon SH, Lerman LO. Atherosclerotic renal artery stenosis: current status. Adv Chronic Kidney Dis 2015; 22:224-31. [PMID: 25908472 DOI: 10.1053/j.ackd.2014.10.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 10/14/2014] [Accepted: 10/15/2014] [Indexed: 12/29/2022]
Abstract
Atherosclerotic renal artery stenosis (ARAS) remains a major cause of secondary hypertension and kidney failure. Randomized prospective trials show that medical treatment should constitute the main therapeutic approach in ARAS. Regardless of intensive treatment and adequate blood pressure control, however, renal and extrarenal complications are not uncommon. Yet, the precise mechanisms, accurate detection, and optimal treatment in ARAS remain elusive. Strategies oriented to early detection and targeting these pathogenic pathways might prevent development of clinical end points. Here, we review the results of recent clinical trials, current understanding of the pathogenic mechanisms, novel imaging techniques to assess kidney damage in ARAS, and treatment options.
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Mark PB, Schiffrin EL, Jennings GL, Dominiczak AF, Wang JG, De Buyzere M, Staessen JA. Renovascular Hypertension. Hypertension 2014; 64:1165-8. [DOI: 10.1161/hypertensionaha.114.04497] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Patrick B. Mark
- From the Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK (P.B.M., A.F.D.); Lady Davis Institute for Medical Research and Department of Medicine, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, PQ, Canada (E.L.S.); Director’s Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia (G.L.J.); Center for Epidemiological Studies and Clinical Trials, Shanghai Institute of
| | - Ernesto L. Schiffrin
- From the Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK (P.B.M., A.F.D.); Lady Davis Institute for Medical Research and Department of Medicine, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, PQ, Canada (E.L.S.); Director’s Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia (G.L.J.); Center for Epidemiological Studies and Clinical Trials, Shanghai Institute of
| | - Garry L. Jennings
- From the Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK (P.B.M., A.F.D.); Lady Davis Institute for Medical Research and Department of Medicine, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, PQ, Canada (E.L.S.); Director’s Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia (G.L.J.); Center for Epidemiological Studies and Clinical Trials, Shanghai Institute of
| | - Anna F. Dominiczak
- From the Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK (P.B.M., A.F.D.); Lady Davis Institute for Medical Research and Department of Medicine, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, PQ, Canada (E.L.S.); Director’s Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia (G.L.J.); Center for Epidemiological Studies and Clinical Trials, Shanghai Institute of
| | - Ji-Guang Wang
- From the Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK (P.B.M., A.F.D.); Lady Davis Institute for Medical Research and Department of Medicine, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, PQ, Canada (E.L.S.); Director’s Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia (G.L.J.); Center for Epidemiological Studies and Clinical Trials, Shanghai Institute of
| | - Marc De Buyzere
- From the Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK (P.B.M., A.F.D.); Lady Davis Institute for Medical Research and Department of Medicine, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, PQ, Canada (E.L.S.); Director’s Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia (G.L.J.); Center for Epidemiological Studies and Clinical Trials, Shanghai Institute of
| | - Jan A. Staessen
- From the Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK (P.B.M., A.F.D.); Lady Davis Institute for Medical Research and Department of Medicine, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, PQ, Canada (E.L.S.); Director’s Research Group, Baker IDI Heart and Diabetes Institute, Melbourne, Australia (G.L.J.); Center for Epidemiological Studies and Clinical Trials, Shanghai Institute of
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Zheng Z, Shi H, Ma H, Li F, Zhang J, Zhang Y. Renal Oxygenation Characteristics in Healthy Native Kidneys: Assessment with Blood Oxygen Level-Dependent Magnetic Resonance Imaging. Nephron Clin Pract 2014; 128:47-54. [PMID: 25471091 DOI: 10.1159/000366448] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 08/04/2014] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE To explore the characteristics of blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) in healthy native kidneys. METHODS Seventy-nine patients without chronic kidney disease underwent BOLD-MRI with T2* spoiled gradient recalled echo sequences. BOLD images were analyzed using R2*map software to produce an R2* pseudo-color map. Cortical and medullary R2* values were analyzed in both kidneys and in both sexes. Different regional R2* values in the cortex and medulla were also analyzed. Physiological indices including age, height, weight, body mass index, body surface area, and estimated glomerular filtration rate (eGFR) were recorded. Correlations between R2* value and physiological indices were determined. RESULTS Renal cortical R2* values were lower than values in the medulla (p < 0.001). Female and male cortical R2* values were also lower than the corresponding values in the medulla (p < 0.001). Renal medullary R2* values in the lower renal pole were lower than values in the middle and upper poles (p = 0.001). Age was positively correlated with R2* values in the medulla (r = 0.32, p = 0.004). eGFR was negatively correlated with both cortical R2* values (r = -0.26, p = 0.02) and medullary R2* values (r = -0.29, p = 0.009). CONCLUSIONS BOLD-MRI can directly visualize renal oxygenation. There was variation in the oxygenation of different regions of the kidney. Renal cortical and medullary oxygenation in healthy kidneys decreased with patient age. eGFR also decreased with patient age.
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Affiliation(s)
- Zhenfeng Zheng
- Department of Nephrology, General Hospital of Tianjin Medical University, Tianjin, PR China
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Neugarten J, Golestaneh L. Blood oxygenation level-dependent MRI for assessment of renal oxygenation. Int J Nephrol Renovasc Dis 2014; 7:421-35. [PMID: 25473304 PMCID: PMC4247132 DOI: 10.2147/ijnrd.s42924] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) has recently emerged as an important noninvasive technique to assess intrarenal oxygenation under physiologic and pathophysiologic conditions. Although this tool represents a major addition to our armamentarium of methodologies to investigate the role of hypoxia in the pathogenesis of acute kidney injury and progressive chronic kidney disease, numerous technical limitations confound interpretation of data derived from this approach. BOLD MRI has been utilized to assess intrarenal oxygenation in numerous experimental models of kidney disease and in human subjects with diabetic and nondiabetic chronic kidney disease, acute kidney injury, renal allograft rejection, contrast-associated nephropathy, and obstructive uropathy. However, confidence in conclusions based on data derived from BOLD MRI measurements will require continuing advances and technical refinements in the use of this technique.
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Affiliation(s)
- Joel Neugarten
- Renal Division, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Ladan Golestaneh
- Renal Division, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, USA
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48
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Where now in the management of renal artery stenosis? Implications of the ASTRAL and CORAL trials. Curr Opin Nephrol Hypertens 2014; 23:525-32. [DOI: 10.1097/mnh.0000000000000059] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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49
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Zhu XY, Ebrahimi B, Eirin A, Woollard JR, Tang H, Jordan KL, Ofori M, Saad A, Herrmann SMS, Dietz AB, Textor SC, Lerman A, Lerman LO. Renal Vein Levels of MicroRNA-26a Are Lower in the Poststenotic Kidney. J Am Soc Nephrol 2014; 26:1378-88. [PMID: 25270070 DOI: 10.1681/asn.2014030248] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 08/01/2014] [Indexed: 01/06/2023] Open
Abstract
MicroRNA-26a (miR-26a) is a post-transcriptional regulator that inhibits cellular differentiation and apoptosis. Renal vascular disease (RVD) induces ischemic injury characterized by tubular cell apoptosis and interstitial fibrosis. We hypothesized that miR-26a levels are reduced in the poststenotic kidney and that kidney repair achieved by adipose tissue-derived mesenchymal stem cells (ad-MSCs) is associated with restored miR-26a levels. Renal function and renal miR-26a levels were assessed in pigs with RVD not treated (n=7) or 4 weeks after intrarenal infusion of ad-MSC (2.5×10(5) cells/kg; n=6), patients with RVD (n=12) or essential hypertension (n=12), and healthy volunteers (n=12). In addition, the direct effect of miR-26a on apoptosis was evaluated in a renal tubular cell culture. Compared with healthy control kidneys, swine and human poststenotic kidneys had 45.5±4.3% and 90.0±3.5% lower levels of miR-26a, respectively, which in pigs, localized to the proximal tubules. In pigs, ad-MSC delivery restored tubular miR-26a expression, attenuated tubular apoptosis and interstitial fibrosis, and improved renal function and tubular oxygen-dependent function. In vitro, miR-26a inhibition induced proximal tubular cell apoptosis and upregulated proapoptotic protein expression, which were both rescued by ad-MSC. In conclusion, decreased tubular miR-26a expression in the poststenotic kidney may be responsible for tubular cell apoptosis and renal dysfunction but can be restored using ad-MSC. Therefore, miR-26a might be a novel therapeutic target in renovascular disease.
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Affiliation(s)
| | | | | | | | - Hui Tang
- Divisions of Nephrology and Hypertension and
| | | | | | - Ahmed Saad
- Divisions of Nephrology and Hypertension and
| | | | - Allan B Dietz
- Department of Laboratory Medicine, Mayo Clinic, Rochester, Minnesota
| | | | | | - Lilach O Lerman
- Divisions of Nephrology and Hypertension and Cardiovascular Diseases and
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50
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Giannarini G, Kessler TM, Roth B, Vermathen P, Thoeny HC. Functional Multiparametric Magnetic Resonance Imaging of the Kidneys Using Blood Oxygen Level Dependent and Diffusion-Weighted Sequences. J Urol 2014; 192:434-9. [DOI: 10.1016/j.juro.2014.02.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2014] [Indexed: 12/11/2022]
Affiliation(s)
| | - Thomas M. Kessler
- Neuro-Urology, Spinal Cord Injury Centre and Research, University of Zurich, Balgrist University Hospital, Zurich, Switzerland
| | - Beat Roth
- Department of Urology, University of Bern, Inselspital, Bern, Switzerland
| | - Peter Vermathen
- Department of Radiology, Neuroradiology and Nuclear Medicine, Institute of Diagnostic, Interventional and Pediatric Radiology, University of Bern, Inselspital, Bern, Switzerland
| | - Harriet C. Thoeny
- Department of Radiology, Neuroradiology and Nuclear Medicine, Institute of Diagnostic, Interventional and Pediatric Radiology, University of Bern, Inselspital, Bern, Switzerland
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