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Huang W, Hong S, Zhu X, Alsaeedi MH, Tang H, Krier JD, Gandhi D, Jordan KL, Saadiq IM, Jiang Y, Eirin A, Lerman LO. Obesity Blunts the Effect of Mesenchymal Stem Cell-Derived Extracellular Vesicles. Kidney Int Rep 2023; 8:1841-1851. [PMID: 37705914 PMCID: PMC10496020 DOI: 10.1016/j.ekir.2023.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 06/02/2023] [Accepted: 06/12/2023] [Indexed: 09/15/2023] Open
Abstract
Introduction Mesenchymal stem/stromal cell-derived extracellular vesicles (MSC-EVs) are paracrine vectors with therapeutic functions comparable to their parent cells. However, it remains unclear if donor obesity affects their therapeutic functions. We tested the hypothesis that the curative effect of human adipose tissue-derived MSC-EVs (A-MSC-EVs) is blunted by obesity. Methods MSC-EVs were isolated by ultracentrifugation from mesenchymal stem/stromal cells (MSCs) collected from abdominal subcutaneous fat of obese and lean human subjects (obese and lean-MSC-EVs, respectively) and injected into the aorta of mice 2 weeks after renal artery stenosis (RAS) induction. Magnetic resonance imaging studies were conducted 2 weeks after MSC-EVs delivery to determine renal function. The effect of MSC-EVs on tissue injury was assessed by histology and gene expression of inflammatory factors, including interleukin (IL)-1β, IL-6, monocyte chemotactic protein-1 (MCP-1), and tumor necrosis factor alpha (TNF-α). Oxidative damage, macrophage infiltration, plasma renin, and hypoxia inducible factor-1α (HIF-1α) were also assessed. Results Tracking showed that MSC-EVs localized in the kidney tissue, including glomeruli and tubules. All MSC-EVs decreased systolic blood pressure (SBP) and plasma renin and improved the poststenotic kidney (STK) volume, but obese-MSC-EVs were less effective than lean-MSC-EVs in improving medullary hypoxia, fibrosis, and tubular injury. Lean-MSC-EVs decreased inflammation, whereas obesity attenuated this effect. Only lean-MSC-EVs decreased STK cortical HIF-1α expression. Conclusion Obesity attenuates the antihypoxia, antifibrosis, antiinflammation, and tubular repair functions of human MSC-EVs in chronic ischemic kidney disease. These observations may have implications for the self-repair potency of obese subjects and for the use of autologous MSC-EVs in regenerative medicine.
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Affiliation(s)
- Weijun Huang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
- Key Laboratory of Chinese Internal Medicine of Ministry of Education and Beijing, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Siting Hong
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Xiangyang Zhu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Mina H. Alsaeedi
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Hui Tang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - James D. Krier
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Deep Gandhi
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Kyra L. Jordan
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Ishran M. Saadiq
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Yamei Jiang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Alfonso Eirin
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Lilach O. Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
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Hong S, Huang W, Zhu X, Tang H, Krier JD, Xing L, Lu B, Gandhi D, Jordan KL, Saadiq IM, Lerman A, Eirin A, Lerman LO. Obesity blunts amelioration of cardiac hypertrophy and fibrosis by human mesenchymal stem/stromal cell-derived extracellular vesicles. Am J Physiol Heart Circ Physiol 2023. [PMID: 37294895 DOI: 10.1152/ajpheart.00676.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 06/01/2023] [Indexed: 06/11/2023]
Abstract
Renovascular hypertension (RVH) can induce cardiac damage that is reversible using adipose tissue-derived mesenchymal stromal/stem cells (A-MSC). However, A-MSCs isolated from obese patients are less effective than lean-A-MSC in blunting hypertensive cardiomyopathy in mice with RVH. We tested the hypothesis that this impairment extends to their obese-A-MSC-extracellular vesicles (EVs) progeny. MSCs were harvested from the subcutaneous fat of obese and lean human subjects, and their EVs were collected and injected into the aorta of mice two weeks after renal artery stenosis or sham surgery. Cardiac left ventricular (LV) function was studied with MRI two weeks later, and myocardial tissue ex-vivo. Blood pressure, LV myocardial wall thickness, mass, and fibrosis that were elevated in RVH mice were suppressed only by lean-EVs. Hence, human A-MSC-derived lean-EVs are more effective than obese-EVs in blunting hypertensive cardiac injury in RVH mice. These observations highlight impaired paracrine repair potency of endogenous MSC in obese patients.
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Affiliation(s)
- Siting Hong
- Division of Nephrology and Hypertension, Mayo Clinic; Department of Cardiology, First Affiliated Hospital of Harbin Medical University, Rochester, United States
| | - Weijun Huang
- Division of Nephrology and Hypertension, Mayo Clinic; Key Laboratory of Chinese Internal Medicine of Ministry of Education and Beijing, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine
| | - Xiangyang Zhu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, United States
| | - Hui Tang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, United States
| | - James D Krier
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, United States
| | - Li Xing
- Division of Nephrology and Hypertension, Mayo Clinic, United States
| | - Bo Lu
- Division of Nephrology and Hypertension, Mayo Clinic, United States
| | - Deep Gandhi
- Division of Nephrology and Hypertension, Mayo Clinic, United States
| | - Kyra L Jordan
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, United States
| | - Ishran M Saadiq
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, United States
| | - Amir Lerman
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, United States
| | - Alfonso Eirin
- The Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, United States
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, United States
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Gandhi DB, Al Saeedi M, Krier JD, Jiang K, Glockner JF, Lerman LO. Evaluation of Renal Fibrosis Using Magnetization Transfer Imaging at 1.5T and 3T in a Porcine Model of Renal Artery Stenosis. J Clin Med 2023; 12:jcm12082956. [PMID: 37109291 PMCID: PMC10140905 DOI: 10.3390/jcm12082956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/13/2023] [Accepted: 04/15/2023] [Indexed: 04/29/2023] Open
Abstract
Renal fibrosis is an important marker in the progression of chronic kidney disease, and renal biopsy is the current reference standard for detecting its presence. Currently, non-invasive methods have only been partially successful in detecting renal fibrosis. Magnetization transfer imaging (MTI) allows estimates of renal fibrosis but may vary with scanning conditions. We hypothesized that MTI-derived renal fibrosis would be reproducible at 1.5T and 3T MRI and over time in fibrotic kidneys. Fifteen pigs with unilateral renal artery stenosis (RAS, n = 9) or age-matched sham controls (n = 6) underwent MTI-MRI at both 1.5T and 3T 6 weeks post-surgery and again 4 weeks later. Magnetization transfer ratio (MTR) measurements of fibrosis in both kidneys were compared between 1.5T and 3T, and the reproducibility of MTI at the two timepoints was evaluated at 1.5T and 3T. MTR at 3T with 600 Hz offset frequency successfully distinguished between normal, stenotic, and contralateral kidneys. There was excellent reproducibility of MTI at 1.5T and 3T over the two timepoints and no significant differences between MTR measurements at 1.5T and 3T. Therefore, MTI is a highly reproducible technique which is sensitive to detect changes in fibrotic compared to normal kidneys in the RAS porcine model at 3T.
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Affiliation(s)
- Deep B Gandhi
- Division of Nephrology and Hypertension, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Mina Al Saeedi
- Division of Nephrology and Hypertension, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - James D Krier
- Division of Nephrology and Hypertension, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Kai Jiang
- Division of Nephrology and Hypertension, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - James F Glockner
- Department of Diagnostic Radiology, Mayo Clinic, Rochester, MN 55905, USA
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Song T, Zhu XY, Eirin A, Jiang Y, Krier JD, Tang H, Jordan KL, Lerman A, Lerman LO. Exogenous pericyte delivery protects the mouse kidney from chronic ischemic injury. Am J Physiol Renal Physiol 2022; 323:F527-F538. [PMID: 36049063 PMCID: PMC9602803 DOI: 10.1152/ajprenal.00064.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 08/19/2022] [Accepted: 08/19/2022] [Indexed: 12/14/2022] Open
Abstract
Pericytes are considered reparative mesenchymal stem cell-like cells, but their ability to ameliorate chronic ischemic kidney injury is unknown. We hypothesized that pericytes would exhibit renoprotective effects in murine renal artery stenosis (RAS). Porcine kidney-derived pericytes (5 × 105) or vehicle were injected into the carotid artery 2 wk after the induction of unilateral RAS in mice. The stenotic kidney glomerular filtration rate and tissue oxygenation were measured 2 wk later using magnetic resonance imaging. We subsequently compared kidney oxidative stress, inflammation, apoptosis, fibrosis, and systemic levels of oxidative and inflammatory cytokines. Treatment of xenogeneic pericytes ameliorated the RAS-induced loss of perfusion, glomerular filtration rate, and atrophy in stenotic kidneys and restored cortical and medullary oxygenation but did not blunt hypertension. Ex vivo, pericytes injection partially mitigated RAS-induced renal inflammation, fibrosis, oxidative stress, apoptosis, and senescence. Furthermore, coculture with pericytes in vitro protected pig kidney-1 tubular cells from injury. In conclusion, exogenous delivery of renal pericytes protects the poststenotic mouse kidney from ischemic injury, underscoring the therapeutic potential role of pericytes in subjects with ischemic kidney disease.NEW & NOTEWORTHY Our study demonstrates a novel pericyte-based therapy for the injured kidney. The beneficial effect of pericyte delivery appears to be mediated by ameliorating oxidative stress, inflammation, cellular apoptosis, and senescence in the stenotic kidney and improved tissue hypoxia, vascular loss, fibrosis, and tubular atrophy. Our data may form the basis for pericyte-based therapy, and additional research studies are needed to gain further insight into their role in improving renal function.
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Affiliation(s)
- Turun Song
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
- Urology Department, Urology Research Institute, Organ Transplantation Center, West China Hospital, Sichuan University, Sichuan, China
| | - Xiang-Yang Zhu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Alfonso Eirin
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Yamei Jiang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - James D Krier
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Hui Tang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Kyra L Jordan
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Amir Lerman
- Department of Cardiovascular diseases, Mayo Clinic, Rochester, Minnesota
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
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Song T, Zhao Y, Zhu X, Eirin A, Krier JD, Tang H, Jordan KL, Lerman A, Lerman LO. Superimposition of metabolic syndrome magnifies post-stenotic kidney injury in dyslipidemic pigs. Am J Transl Res 2021; 13:8965-8976. [PMID: 34540008 PMCID: PMC8430139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 05/12/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Dyslipidemia aggravates kidney injury distal to atherosclerotic renal artery stenosis (ARAS). Besides dyslipidemia, metabolic syndrome (MetS) also involves development of obesity and insulin-resistance (IR). We hypothesized that concurrent obesity and IR magnify swine stenotic-kidney damage beyond dyslipidemia. METHODS Pigs with unilateral RAS were studied after 16 weeks of atherogenic diets without (ARAS) or with (MetS + RAS) development of obesity/IR (n=6 each). Additional pigs on normal diet served as normal or non-dyslipidemic RAS controls (n=6 each). Stenotic-kidney renal blood flow (RBF), glomerular filtration rate (GFR), and microvascular architecture were studied using CT, and oxygenation was studied using blood oxygen level-dependent magnetic-resonance-imaging. We further compared kidney adiposity, oxidative stress, inflammation, apoptosis, fibrosis, and systemic levels of oxidative and inflammatory cytokines. RESULTS ARAS and MetS + RAS developed hypertension and dyslipidemia, and MetS + RAS also developed obesity and IR. RBF and GFR were similarly decreased in all post-stenotic pig kidneys compared to normal pig kidneys, yet MetS + RAS aggravated and expanded medullary hypoxia and microvascular loss. RAS and ARAS increased systemic levels of tumor necrosis factor (TNF)-α, which were further elevated in MetS + RAS. Renal oxidative stress and TNF-α expression increased in ARAS and further in MetS + RAS, which also upregulated expression of anti-angiogenic angiostatin, and magnified apoptosis, tubular injury, and fibrosis. CONCLUSION Beyond dyslipidemia, obesity and insulin-resistance aggravate damage in the post-stenotic kidney in MetS, despite relative hyperfiltration-related preservation of renal function. These observations underscore the need to control systemic metabolic disturbances in order to curb renal damage in subjects with ischemic kidney disease.
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Affiliation(s)
- Turun Song
- Division of Nephrology and Hypertension, Mayo ClinicRochester, MN 55905, The United States
- Urology Department, Urology Research Institute, Organ Transplantation Center, West China Hospital, Sichuan UniversitySichuan, China
| | - Yu Zhao
- Division of Nephrology and Hypertension, Mayo ClinicRochester, MN 55905, The United States
| | - Xiangyang Zhu
- Division of Nephrology and Hypertension, Mayo ClinicRochester, MN 55905, The United States
| | - Alfonso Eirin
- Division of Nephrology and Hypertension, Mayo ClinicRochester, MN 55905, The United States
| | - James D Krier
- Division of Nephrology and Hypertension, Mayo ClinicRochester, MN 55905, The United States
| | - Hui Tang
- Division of Nephrology and Hypertension, Mayo ClinicRochester, MN 55905, The United States
| | - Kyra L Jordan
- Division of Nephrology and Hypertension, Mayo ClinicRochester, MN 55905, The United States
| | - Amir Lerman
- Department of Cardiovascular Diseases, Mayo ClinicRochester, MN 55905, The United States
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo ClinicRochester, MN 55905, The United States
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Isik B, Thaler R, Goksu BB, Conley SM, Al-Khafaji H, Mohan A, Afarideh M, Abumoawad AM, Zhu XY, Krier JD, Saadiq IM, Tang H, Eirin A, Hickson LJ, van Wijnen AJ, Textor SC, Lerman LO, Herrmann SM. Hypoxic preconditioning induces epigenetic changes and modifies swine mesenchymal stem cell angiogenesis and senescence in experimental atherosclerotic renal artery stenosis. Stem Cell Res Ther 2021; 12:240. [PMID: 33853680 PMCID: PMC8048283 DOI: 10.1186/s13287-021-02310-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 03/25/2021] [Indexed: 12/13/2022] Open
Abstract
Background Atherosclerotic renal artery stenosis (ARAS) is a risk factor for ischemic and hypertensive kidney disease (HKD) for which autologous mesenchymal stem cell (MSC) appears to be a promising therapy. However, MSCs from ARAS patients exhibit impaired function, senescence, and DNA damage, possibly due to epigenetic mechanisms. Hypoxia preconditioning (HPC) exerts beneficial effects on cellular proliferation, differentiation, and gene and protein expression. We hypothesized that HPC could influence MSC function and senescence in ARAS by epigenetic mechanisms and modulating gene expression of chromatin-modifying enzymes. Methods Adipose-derived MSC harvested from healthy control (N = 8) and ARAS (N = 8) pigs were cultured under normoxia (20%O2) or hypoxia (1%O2) conditions. MSC function was assessed by migration, proliferation, and cytokine release in conditioned media. MSC senescence was evaluated by SA-β-gal activity. Specific pro-angiogenic and senescence genes were assessed by reverse transcription polymerase chain reaction (RT-PCR). Dot blotting was used to measure global genome 5-hydroxymethylcytosine (5hmC) levels on DNA and Western blotting of modified histone 3 (H3) proteins to quantify tri-methylated lysine-4 (H3K4me3), lysine-9 (H3K9me3), and lysine-27 (H3K27me3) residues. Results Specific pro-angiogenic genes in ARAS assessed by RT-PCR were lower at baseline but increased under HPC, while pro-senescence genes were higher in ARAS at baseline as compared healthy MSCs. ARAS MSCs under basal conditions, displayed higher H3K4me3, H3K27me3, and 5hmC levels compared to healthy MSCs. During HPC, global 5hmC levels were decreased while no appreciable changes occurred in histone H3 tri-methylation. ARAS MSCs cultured under HPC had higher migratory and proliferative capacity as well as increased vascular endothelial growth factor and epidermal growth factor expression compared to normoxia, and SA-β-gal activity decreased in both animal groups. Conclusions These data demonstrate that swine ARAS MSCs have decreased angiogenesis and increased senescence compared to healthy MSCs and that HPC mitigates MSC dysfunction, senescence, and DNA hydroxymethylation in ARAS MSC. Thus, HPC for MSCs may be considered for their optimization to improve autologous cell therapy in patients with nephropathies. Supplementary Information The online version contains supplementary material available at 10.1186/s13287-021-02310-z.
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Affiliation(s)
- Busra Isik
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - Roman Thaler
- Department of Biochemistry and Molecular Biology, Rochester, USA.,Department of Orthopedics, Rochester, USA
| | - Busra B Goksu
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - Sabena M Conley
- Division of Nephrology and Hypertension, Mayo Clinic, Jacksonville, FL, USA
| | - Hayder Al-Khafaji
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - Arjunmohan Mohan
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - Mohsen Afarideh
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - Abdelrhman M Abumoawad
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - Xiang Y Zhu
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - James D Krier
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - Ishran M Saadiq
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - Hui Tang
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - Alfonso Eirin
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - LaTonya J Hickson
- Division of Nephrology and Hypertension, Mayo Clinic, Jacksonville, FL, USA
| | - Andre J van Wijnen
- Department of Biochemistry and Molecular Biology, Rochester, USA.,Department of Orthopedics, Rochester, USA
| | - Stephen C Textor
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA
| | - Sandra M Herrmann
- Division of Nephrology and Hypertension, Mayo Clinic, 200, First Street SW, Rochester, MN, 55902, USA.
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Yu S, Jiang K, Zhu XY, Ferguson CM, Krier JD, Lerman A, Lerman LO. Endovascular reversal of renovascular hypertension blunts cardiac dysfunction and deformation in swine. J Hypertens 2021; 39:556-562. [PMID: 33399301 PMCID: PMC8400925 DOI: 10.1097/hjh.0000000000002654] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Renovascular hypertension (RVH) induces hemodynamic and humoral aberrations that may impair cardiac function, structure and mechanics, including cardiac twist and deformation. Revascularization of a stenotic renal artery can decrease blood pressure (BP), but its ability to restore cardiac mechanics in RVH remains unclear. We hypothesized that percutaneous transluminal renal angioplasty (PTRA) would improve cardiac function and left ventricular (LV) deformation in swine RVH. METHODS Seventeen domestic pigs were studied for 16 weeks: RVH, RVH + PTRA and normal controls (n = 5-6 each). Global LV function was estimated by multidetector computed-tomography, and LV deformation by electrocardiographically triggered MRI tagging at the apical, mid, and basal LV levels. Cardiomyocyte hypertrophy, myocardial capillary density, and fibrosis were evaluated ex vivo. RESULTS BP and wall thickness were elevated in RVH and decreased by PTRA, yet remained higher than in controls. LV myocardial muscle mass increased in RVH pigs, which also developed diastolic dysfunction, whereas cardiac output increased. Furthermore, both apical rotation and peak torsion angle increased in RVH compared with controls. Ex vivo, RVH induced myocardial fibrosis and vascular rarefaction. PTRA restored cardiac function and alleviated hypertrophy, vascular rarefaction, and fibrosis. PTRA also normalized apical rotation and peak torsion angle, and elevated basal peak radial strain and apical peak radial strain compared with RVH. CONCLUSION In addition to cardiac LV adaptive hypertrophy and diastolic dysfunction, short-term RVH causes cardiac deformation. Despite only partial improvement in BP, PTRA effectively restored cardiac function and reversed abnormal mechanics. Hence, renal revascularization may be a useful strategy to preserve cardiac function in RVH.
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Affiliation(s)
- Shasha Yu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
- Department of Cardiology, First Hospital of China Medical University, Shenyang, Liaoning, China
| | - Kai Jiang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Xiang Y. Zhu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | | | - James D. Krier
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Amir Lerman
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
| | - Lilach O. Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
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Zhao Y, Zhu X, Zhang L, Ferguson CM, Song T, Jiang K, Conley SM, Krier JD, Tang H, Saadiq I, Jordan KL, Lerman A, Lerman LO. Mesenchymal Stem/Stromal Cells and their Extracellular Vesicle Progeny Decrease Injury in Poststenotic Swine Kidney Through Different Mechanisms. Stem Cells Dev 2020; 29:1190-1200. [PMID: 32657229 DOI: 10.1089/scd.2020.0030] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Novel therapies are needed to address the increasing prevalence of chronic kidney disease. Mesenchymal stem/stromal cells (MSCs) and MSC-derived extracellular vesicles (EVs) augment tissue repair. We tested the hypothesis that EVs are as effective as MSCs in protecting the stenotic kidney, but target different injury pathways. Pigs were studied after 16 weeks of renal injury achieved by diet-induced metabolic syndrome (MetS) and renal artery stenosis (RAS). Pigs were untreated or treated 4 weeks earlier with intrarenal delivery of autologous adipose tissue-derived MSCs (107) or their EVs (1011). Lean pigs and sham RAS served as controls (n = 6 each). Stenotic-kidney function was studied in vivo using computed tomography and magnetic resonance imaging. Histopathology and expression of necroptosis markers [receptor-interacting protein kinase (RIPK)-1 and RIPK-3], inflammatory, and growth factors (angiopoietin-1 and vascular endothelial growth factor) were studied ex vivo. Stenotic-kidney glomerular filtration rate and blood flow in MetS + RAS were both lower than Lean and increased in both MetS + RAS + MSC and MetS + RAS + EV. Both MSCs and EV improved renal function and decreased renal hypoxia, fibrosis, and apoptosis. MSCs were slightly more effective in preserving microvascular (0.02-0.2 mm diameters) density and prominently attenuated renal inflammation. However, EV more significantly upregulated growth factor expression and decreased necroptosis. In conclusion, adipose tissue-derived MSCs and their EV both improve stenotic kidney function and decrease tissue injury in MetS + RAS by slightly different mechanisms. MSCs more effectively preserved the microcirculation, while EV bestowed better preservation of renal cellular integrity. These findings encourage further exploration of this novel approach to attenuate renal injury.
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Affiliation(s)
- Yu Zhao
- Institute of Nephrology, Zhong Da Hospital, Southeast University, School of Medicine, Nanjing, China.,Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Xiangyang Zhu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Lei Zhang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA.,Institute of Urology, Zhong Da Hospital, Southeast University, School of Medicine, Nanjing, China
| | | | - Turun Song
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Kai Jiang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Sabena M Conley
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - James D Krier
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Hui Tang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Ishran Saadiq
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Kyra L Jordan
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Amir Lerman
- Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
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10
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Chen XJ, Zhang X, Jiang K, Krier JD, Zhu X, Conley S, Lerman A, Lerman LO. Adjunctive mesenchymal stem/stromal cells augment microvascular function in poststenotic kidneys treated with low-energy shockwave therapy. J Cell Physiol 2020; 235:9806-9818. [PMID: 32430932 DOI: 10.1002/jcp.29794] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/05/2020] [Accepted: 05/05/2020] [Indexed: 12/21/2022]
Abstract
Effective therapeutic strategies are needed to preserve renal function in patients with atherosclerotic renal artery stenosis (ARAS). Low-energy shockwave therapy (SW) and adipose tissue-derived mesenchymal stem/stromal cells (MSCs) both stimulate angiogenesis repair of stenotic kidney injury. This study tested the hypothesis that intrarenal delivery of adipose tissue-derived MSCs would enhance the capability of SW to preserve stenotic kidney function and structure. Twenty-two pigs were studied after 16 weeks of ARAS, ARAS treated with a SW regimen (bi-weekly for 3 weeks) with or without subsequent intrarenal delivery of adipose tissue-derived MSCs and controls. Four weeks after treatment, single-kidney renal blood flow (RBF) before and after infusion of acetylcholine, glomerular filtration rate (GFR), and oxygenation were assessed in vivo and the renal microcirculation, fibrosis, and oxidative stress ex vivo. Mean arterial pressure remained higher in ARAS, ARAS + SW, and ARAS + SW + MSC compared with normal. Both SW and SW + MSC similarly elevated the decreased stenotic kidney GFR and RBF observed in ARAS to normal levels. Yet, SW + MSC significantly improved RBF response to acetylcholine in ARAS, and attenuated capillary loss and oxidative stress more than SW alone. Density of larger microvessels was similarly increased by both interventions. Therefore, although significant changes in functional outcomes were not observed in a short period of time, adjunct MSCs enhanced pro-angiogenic effect of SW to improve renal microvascular outcomes, suggesting this as an effective stratege for long-term management of renovascular disease.
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Affiliation(s)
- Xiao-Jun Chen
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota.,Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Xin Zhang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Kai Jiang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - James D Krier
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Xiangyang Zhu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Sabena Conley
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Amir Lerman
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota.,Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
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11
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Song T, Eirin A, Zhu X, Zhao Y, Krier JD, Tang H, Jordan KL, Woollard JR, Taner T, Lerman A, Lerman LO. Mesenchymal Stem Cell-Derived Extracellular Vesicles Induce Regulatory T Cells to Ameliorate Chronic Kidney Injury. Hypertension 2020; 75:1223-1232. [PMID: 32223383 DOI: 10.1161/hypertensionaha.119.14546] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Metabolic syndrome (MetS) profoundly changes the contents of mesenchymal stem cells and mesenchymal stem cells-derived extracellular vesicles (EVs). The anti-inflammatory TGF-β (transforming growth factor-β) is selectively enriched in EVs from Lean but not from MetS pigs, but the functional impact of this endowment remains unknown. We hypothesized that Lean-EVs more effectively induce regulatory T cells in injured kidneys. Five groups of pigs (n=7 each) were studied after 16 weeks of diet-induced MetS and unilateral renal artery stenosis (RAS; MetS+RAS). Two groups of MetS+RAS were treated 4 weeks earlier with an intrarenal injection of either Lean-EVs or MetS-EVs. MetS+RAS had lower renal volume, renal blood flow, and glomerular filtration rate than MetS pigs. Compared with Lean-EVs, MetS-EVs were less effective in improving renal function and decreasing tubular injury and fibrosis in MetS+RAS. Lean-EVs upregulated TGF-β expression in stenotic kidney and increased regulatory T cells numbers more prominently. Furthermore, markedly upregulated anti-inflammatory M2 macrophages reduced proinflammatory M1 macrophages, and CD8+ T cells were detected in stenotic kidneys treated with Lean-EVs compared with MetS-EVs, and renal vein levels of interleukin-1β were reduced. In vitro, coculture of Lean-EVs with activated T cells led to greater TGF-β-dependent regulatory T cells induction than did MetS-EVs. Therefore, the beneficial effects of mesenchymal stem cells-derived EVs on injured kidneys might be partly mediated by their content of TGF-β signaling components, which permitting increased Treg preponderance. Modulating EV cargo and transforming their functionality might be useful for renal repair.
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Affiliation(s)
- Turun Song
- From the Division of Nephrology and Hypertension (T.S., A.E., X.Z., Y.Z., J.D.K., H.T., K.L.J., J.R.W., L.O.L.), Mayo Clinic, Rochester, MN
| | - Alfonso Eirin
- From the Division of Nephrology and Hypertension (T.S., A.E., X.Z., Y.Z., J.D.K., H.T., K.L.J., J.R.W., L.O.L.), Mayo Clinic, Rochester, MN
| | - Xiangyang Zhu
- From the Division of Nephrology and Hypertension (T.S., A.E., X.Z., Y.Z., J.D.K., H.T., K.L.J., J.R.W., L.O.L.), Mayo Clinic, Rochester, MN
| | - Yu Zhao
- From the Division of Nephrology and Hypertension (T.S., A.E., X.Z., Y.Z., J.D.K., H.T., K.L.J., J.R.W., L.O.L.), Mayo Clinic, Rochester, MN
| | - James D Krier
- From the Division of Nephrology and Hypertension (T.S., A.E., X.Z., Y.Z., J.D.K., H.T., K.L.J., J.R.W., L.O.L.), Mayo Clinic, Rochester, MN
| | - Hui Tang
- From the Division of Nephrology and Hypertension (T.S., A.E., X.Z., Y.Z., J.D.K., H.T., K.L.J., J.R.W., L.O.L.), Mayo Clinic, Rochester, MN
| | - Kyra L Jordan
- From the Division of Nephrology and Hypertension (T.S., A.E., X.Z., Y.Z., J.D.K., H.T., K.L.J., J.R.W., L.O.L.), Mayo Clinic, Rochester, MN
| | - John R Woollard
- From the Division of Nephrology and Hypertension (T.S., A.E., X.Z., Y.Z., J.D.K., H.T., K.L.J., J.R.W., L.O.L.), Mayo Clinic, Rochester, MN
| | - Timucin Taner
- Department of Transplant Surgery and Immunology (T.T.), Mayo Clinic, Rochester, MN
| | - Amir Lerman
- Department of Cardiovascular Diseases (A.L.), Mayo Clinic, Rochester, MN
| | - Lilach O Lerman
- From the Division of Nephrology and Hypertension (T.S., A.E., X.Z., Y.Z., J.D.K., H.T., K.L.J., J.R.W., L.O.L.), Mayo Clinic, Rochester, MN
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12
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Zhang X, Krier JD, Amador Carrascal C, Greenleaf JF, Ebrahimi B, Hedayat AF, Textor SC, Lerman A, Lerman LO. Low-Energy Shockwave Therapy Improves Ischemic Kidney Microcirculation. J Am Soc Nephrol 2016; 27:3715-3724. [PMID: 27297945 DOI: 10.1681/asn.2015060704] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 04/05/2016] [Indexed: 12/12/2022] Open
Abstract
Microvascular rarefaction distal to renal artery stenosis is linked to renal dysfunction and poor outcomes. Low-energy shockwave therapy stimulates angiogenesis, but the effect on the kidney microvasculature is unknown. We hypothesized that low-energy shockwave therapy would restore the microcirculation and alleviate renal dysfunction in renovascular disease. Normal pigs and pigs subjected to 3 weeks of renal artery stenosis were treated with six sessions of low-energy shockwave (biweekly for 3 consecutive weeks) or left untreated. We assessed BP, urinary protein, stenotic renal blood flow, GFR, microvascular structure, and oxygenation in vivo 4 weeks after completion of treatment, and then, we assessed expression of angiogenic factors and mechanotransducers (focal adhesion kinase and β1-integrin) ex vivo A 3-week low-energy shockwave regimen attenuated renovascular hypertension, normalized stenotic kidney microvascular density and oxygenation, stabilized function, and alleviated fibrosis in pigs subjected to renal artery stenosis. These effects associated with elevated renal expression of angiogenic factors and mechanotransducers, particularly in proximal tubular cells. In additional pigs with prolonged (6 weeks) renal artery stenosis, shockwave therapy also decreased BP and improved GFR, microvascular density, and oxygenation in the stenotic kidney. This shockwave regimen did not cause detectable kidney injury in normal pigs. In conclusion, low-energy shockwave therapy improves stenotic kidney function, likely in part by mechanotransduction-mediated expression of angiogenic factors in proximal tubular cells, and it may ameliorate renovascular hypertension. Low-energy shockwave therapy may serve as a novel noninvasive intervention in the management of renovascular disease.
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Affiliation(s)
- Xin Zhang
- Division of Nephrology and Hypertension and
| | | | | | | | | | | | | | - Amir Lerman
- Cardiology, Mayo Clinic, Rochester, Minnesota
| | - Lilach O Lerman
- Division of Nephrology and Hypertension and .,Cardiology, Mayo Clinic, Rochester, Minnesota
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13
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Eirin A, Zhu XY, Ebrahimi B, Krier JD, Riester SM, van Wijnen AJ, Lerman A, Lerman LO. Intrarenal Delivery of Mesenchymal Stem Cells and Endothelial Progenitor Cells Attenuates Hypertensive Cardiomyopathy in Experimental Renovascular Hypertension. Cell Transplant 2014; 24:2041-53. [PMID: 25420012 DOI: 10.3727/096368914x685582] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Renovascular hypertension (RVH) leads to left ventricular (LV) hypertrophy and diastolic dysfunction, associated with increased cardiovascular mortality. Intrarenal delivery of endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) improves kidney function in porcine RVH, and the potent anti-inflammatory properties of MSCs may serve to blunt inflammatory mediators in the cardiorenal axis. However, their relative efficacy in attenuating cardiac injury and dysfunction remains unknown. This study tested the hypothesis that the cardioprotective effect of EPCs and MSCs delivered into the stenotic kidney in experimental RVH are comparable. Pigs (n = 7 per group) were studied after 10 weeks of RVH or control untreated or treated with a single intrarenal infusion of autologous EPCs or MSCs 4 weeks earlier. Cardiac and renal function (fast CT) and stenotic kidney release of inflammatory mediators (ELISA) were assessed in vivo, and myocardial inflammation, remodeling, and fibrosis ex vivo. After 10 weeks of RVH, blood pressure was not altered in cell-treated groups, yet stenotic kidney glomerular filtration rate (GFR), blunted in RVH, improved in RVH + EPC, and normalized in RVH + MSCs. Stenotic kidney release of monocyte chemoattractant protein (MCP)-1 and its myocardial expression were elevated in RVH + EPC, but normalized only in RVH + MSC pigs. RVH-induced LV hypertrophy was normalized in both EPC- and MSC-treated pigs, while diastolic function (E/A ratio) was restored to normal levels exclusively in RVH + MSCs. RVH-induced myocardial fibrosis and collagen deposition decreased in RVH + EPCs but further decreased in RVH + MSC-treated pigs. Intrarenal delivery of EPCs or MSCs attenuates RVH-induced myocardial injury, yet MSCs restore diastolic function more effectively than EPCs, possibly by greater improvement in renal function or reduction of MCP-1 release from the stenotic kidney. These observations suggest a therapeutic potential for EPCs and MSCs in preserving the myocardium in chronic experimental RVH.
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Affiliation(s)
- Alfonso Eirin
- Department of Internal Medicine, Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
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14
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Zhu XY, Urbieta-Caceres V, Krier JD, Textor SC, Lerman A, Lerman LO. Mesenchymal stem cells and endothelial progenitor cells decrease renal injury in experimental swine renal artery stenosis through different mechanisms. Stem Cells 2013; 31:117-25. [PMID: 23097349 DOI: 10.1002/stem.1263] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 09/07/2012] [Accepted: 09/23/2012] [Indexed: 12/28/2022]
Abstract
Endothelial progenitor cells (EPC) and mesenchymal stem cells (MSC) augment tissue repair but possess slightly different properties. How the cellular phenotype affects the efficacy of this approach in renovascular disease is incompletely understood. This study tested the hypothesis that EPC and MSC protect the poststenotic kidney by blunting different disease pathways. Peripheral blood EPC and adipose-derived MSC were expanded and characterized by cell surface markers (e.g., CD34/kinase insert domain receptor, or CD44/CD90). Single-kidney hemodynamics and function were assessed in pigs after 10 weeks of renal artery stenosis (RAS) treated 4 weeks earlier with an intrarenal infusion of vehicle (n = 7), EPC (RAS+EPC) or MSC (RAS+MSC) (both 10 × 10(6), n = 6), and normal controls (n = 7). Kidney disease mechanisms were evaluated ex vivo. The ability of EPC and MSC to attenuate endoplasmic reticulum (ER) stress was also studied in isolated ER and in tubular cells cocultured with EPC and MSC. Glomerular filtration rate in RAS was lower than controls, increased in RAS+EPC, and further improved in RAS+MSC, although both improved renal blood flow similarly. EPC prominently enhanced renal growth factor expression and decreased oxidative stress, while MSC more significantly attenuated renal inflammation, ER stress, and apoptosis. Furthermore, MSC induced a greater decrease in caspase-3 and CHOP expression in cultured tubular cells through mechanisms involving cell contact. EPC and MSC achieve a comparable decrease of kidney injury in RAS by different mechanisms, although MSC elicited slightly superior improvement of renal function. These results support development of cell-based approaches for management of renovascular disease and suggest cell selection based on the underlying pathophysiology of kidney injury.
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Affiliation(s)
- Xiang-Yang Zhu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota 55905, USA
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15
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Zhang X, Li ZL, Woollard JR, Eirin A, Ebrahimi B, Crane JA, Zhu XY, Pawar AS, Krier JD, Jordan KL, Tang H, Textor SC, Lerman A, Lerman LO. Obesity-metabolic derangement preserves hemodynamics but promotes intrarenal adiposity and macrophage infiltration in swine renovascular disease. Am J Physiol Renal Physiol 2013; 305:F265-76. [PMID: 23657852 DOI: 10.1152/ajprenal.00043.2013] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Obesity-metabolic disorders (ObM) often accompany renal artery stenosis (RAS). We hypothesized that the coexistence of ObM and RAS magnifies inflammation and microvascular remodeling in the stenotic kidney (STK) and aggravates renal scarring. Twenty-eight obesity-prone Ossabaw pigs were studied after 16 wk of a high-fat/high-fructose diet or standard chow including ObM-sham, ObM-RAS, Lean-RAS, or Lean-sham (normal control) groups. Single-kidney renal blood flow (RBF) and glomerular filtration rate (GFR) were assessed by multidetector computed tomography (CT), renal oxygenation and tubular transport capability by blood-oxygen-level-dependent MRI, and microcirculation by micro-CT for vessel density, and Western blotting for protein expressions of angiogenic factors (VEGF/FLK-1). Renal vein and inferior vena cava levels of inflammatory cytokines were measured to evaluate systemic and kidney inflammation. Macrophage (MØ) infiltration and subpopulations, fat deposition in the kidney, and inflammation in perirenal and abdominal fat were also examined. GFR and RBF were decreased in Lean-STK but relatively preserved in ObM-STK. However, ObM-STK showed impaired tubular transport function, suppressed microcirculation, and stimulated glomerulosclerosis. ObM diet interacted with RAS to blunt angiogenesis in the STK, facilitated the release of inflammatory cytokines, and led to greater oxidative stress than Lean-STK. The ObM diet also induced fat deposition in the kidney and infiltration of proinflammatory M1-MØ, as also in perirenal and abdominal fat. Coexistence of ObM and RAS amplifies renal inflammation, aggravates microvascular remodeling, and accelerates glomerulosclerosis. Increased adiposity and MØ-accentuated inflammation induced by an ObM diet may contribute to structural injury in the post-STK kidney.
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Affiliation(s)
- Xin Zhang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
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16
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Zhang X, Eirin A, Li ZL, Crane JA, Krier JD, Ebrahimi B, Pawar AS, Zhu XY, Tang H, Jordan KL, Lerman A, Textor SC, Lerman LO. Angiotensin receptor blockade has protective effects on the poststenotic porcine kidney. Kidney Int 2013; 84:767-75. [PMID: 23615504 PMCID: PMC3732527 DOI: 10.1038/ki.2013.144] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 01/14/2013] [Accepted: 02/14/2013] [Indexed: 12/19/2022]
Abstract
Angiotensin converting enzyme inhibitors (ACEI)/ angiotensin-II receptor blockers (ARBs) may induce an acute decrease of glomerular filtration rate (GFR) in the stenotic kidney in renal artery stenosis, but most patients tolerate these drugs well. We hypothesized that ACEI/ARBs stabilize stenotic kidney function during prolonged treatment by conferring protective effects. We tested this in control domestic pigs and pigs with renal artery stenosis untreated or treated with valsartan, or triple therapy (7 pigs in each group) for 4 weeks starting 6 weeks after stenosis induction. Renal function, oxygenation, tubular function, and microcirculation were assessed by multi-detector computed tomography (CT), blood-oxygen-level-dependent magnetic-resonance imaging, and micro-CT. Valsartan and triple therapy decreased blood pressure similarly, however, valsartan did not change the GFR of the stenotic kidney compared to renal artery stenosis and was similar to triple therapy. Both valsartan and triple therapy stimulated microvascular density, and improved tubular function. Valsartan also caused a greater increase of angiogenic factors and a decrease in oxidative stress, which were related to higher cortical perfusion and tubular response than triple therapy. Thus, valsartan did not decrease stenotic kidney GFR, but improved cortical perfusion and microcirculation. These beneficial effects may partly offset the hemodynamic GFR reduction in renal artery stenosis and preserve kidney function.
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Affiliation(s)
- Xin Zhang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
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17
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Krier JD, Crane JA, Eirin A, Zhu XY, Lerman A, Lerman LO. Hemodynamic determinants of perivascular collateral development in swine renal artery stenosis. Am J Hypertens 2013; 26:209-17. [PMID: 23382405 DOI: 10.1093/ajh/hps010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Renal artery stenosis (RAS) resulting in reduced renal blood flow (RBF) is a common cause of secondary hypertension and deterioration of renal function, which may lead to end-stage renal disease. Recruitment and formation of periarterial collateral vessels may serve to bypass RAS and restore distal blood supply. We hypothesized that development of collaterals around RAS may preserve kidney function. METHODS Collateral formation index (CI) was assessed using multidetector computed tomography as fractional vascular volume surrounding the stenosis in 31 pigs with unilateral RAS. Single kidney RBF and glomerular filtration rate (GFR) were also measured. RESULTS Of 25 pigs that developed significant stenosis (≥65%), 8 demonstrated minor collateral development (CI < 0.3), and 17 showed major collateral development (CI ≥ 0.3). The degree of RAS was significantly higher in pigs with major collaterals compared with pigs with minor collaterals, and poststenotic kidney cortical volume, perfusion, RBF, and GFR were significantly lower. In a subset of pigs matched for the degree of RAS, RBF and GFR remained lower in pigs with major collaterals. CONCLUSIONS We conclude that collaterals develop in animals with significant RAS in proportion to its severity and might be triggered by distal injury, such as decreases in cortical volume and perfusion. However, development of collaterals was unable to confer measurable benefits for stenotic kidney function distal to severe RAS.
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Affiliation(s)
- James D Krier
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
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18
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Eirin A, Li Z, Zhang X, Krier JD, Woollard JR, Zhu XY, Tang H, Herrmann SM, Lerman A, Textor SC, Lerman LO. A mitochondrial permeability transition pore inhibitor improves renal outcomes after revascularization in experimental atherosclerotic renal artery stenosis. Hypertension 2012; 60:1242-9. [PMID: 23045468 DOI: 10.1161/hypertensionaha.112.199919] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Revascularization improves blood pressure but not renal function in most patients with atherosclerotic renal artery stenosis (ARAS), possibly related to injury incurred during renal reperfusion. Bendavia, a novel tetrapeptide that inhibits mitochondrial permeability transition pore opening, reduces apoptosis, oxidative stress, and ischemia-reperfusion injury in experimental models. However, its potential for improving renal response to revascularization of chronic ARAS is unknown. We hypothesized that adjunct Bendavia would improve renal structure and function after percutaneous transluminal renal angioplasty (PTRA). Pigs were treated after 6 weeks of ARAS or control with PTRA+stenting (or sham), adjunct continuous 4-hour infusion of Bendavia (0.05 mg/kg IV) or vehicle (n=7 each) during PTRA. Single-kidney renal blood flow and glomerular filtration rate were studied 4 weeks later and renal mitochondrial biogenesis, microvascular architecture, and injurious pathways evaluated ex vivo. Monocyte chemoattractant protein-1 levels rose after PTRA, suggesting inflammatory injury. Bendavia did not immediately affect inflammatory cytokine levels, yet 4 weeks later, stenotic kidney renal blood flow and glomerular filtration rate both improved (44.00 ± 0.21% and 36.40 ± 10.21%, respectively) in ARAS+PTRA+Bendavia compared with ARAS+PTRA+vehicle. Renal mitochondrial biogenesis was restored after PTRA+Bendavia, and microvascular rarefaction, apoptosis, oxidative stress, tubular injury, and fibrosis decreased. Infusion of Bendavia during PTRA preserved mitochondrial biogenesis, renal hemodynamics, and function, and attenuated tissue injury in swine ARAS. Thus, functional mitochondrial injury during renal reperfusion may sustain renal inflammatory injury and limit kidney recovery after PTRA. Potent antiapoptotic and antioxidant effects provide Bendavia a novel therapeutic potential for improving kidney outcomes after PTRA in experimental ARAS.
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Affiliation(s)
- Alfonso Eirin
- Division of Nephrology and Hypertension, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
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19
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Eirin A, Zhu XY, Krier JD, Tang H, Jordan KL, Grande JP, Lerman A, Textor SC, Lerman LO. Adipose tissue-derived mesenchymal stem cells improve revascularization outcomes to restore renal function in swine atherosclerotic renal artery stenosis. Stem Cells 2012; 30:1030-41. [PMID: 22290832 DOI: 10.1002/stem.1047] [Citation(s) in RCA: 180] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Reno-protective strategies are needed to improve renal outcomes in patients with atherosclerotic renal artery stenosis (ARAS). Adipose tissue-derived mesenchymal stem cells (MSCs) can promote renal regeneration, but their potential for attenuating cellular injury and restoring kidney repair in ARAS has not been explored. We hypothesized that replenishment of MSC as an adjunct to percutaneous transluminal renal angioplasty (PTRA) would restore renal cellular integrity and improve renal function in ARAS pigs. Four groups of pigs (n = 7 each) were studied after 16 weeks of ARAS, ARAS 4 weeks after PTRA and stenting with or without adjunct intrarenal delivery of MSC (10 × 10(6) cells), and controls. Stenotic kidney blood flow (renal blood flow [RBF]) and glomerular filtration rate (GFR) were measured using multidetector computer tomography (CT). Renal microvascular architecture (micro-CT), fibrosis, inflammation, and oxidative stress were evaluated ex vivo. Four weeks after successful PTRA, mean arterial pressure fell to a similar level in all revascularized groups. Stenotic kidney GFR and RBF remained decreased in ARAS (p = .01 and p = .02) and ARAS + PTRA (p = .02 and p = .03) compared with normal but rose to normal levels in ARAS + PTRA + MSC (p = .34 and p = .46 vs. normal). Interstitial fibrosis, inflammation, microvascular rarefaction, and oxidative stress were attenuated only in PTRA + MSC-treated pigs. A single intrarenal delivery of MSC in conjunction with renal revascularization restored renal hemodynamics and function and decreased inflammation, apoptosis, oxidative stress, microvascular loss, and fibrosis. This study suggests a unique and novel therapeutic potential for MSC in restoring renal function when combined with PTRA in chronic experimental renovascular disease.
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Affiliation(s)
- Alfonso Eirin
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota 55905, USA
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Korsmo MJ, Ebrahimi B, Woollard JR, Crane JA, Eirin A, Krier JD, Ehman RL, Lerman LO. Magnetic resonance elastography (MRE) detects medullary renal fibrosis. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.523.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Behzad Ebrahimi
- Department of Nephrology & HypertensionMayo ClinicRochesterMN
| | | | - John A. Crane
- Department of Nephrology & HypertensionMayo ClinicRochesterMN
| | - Alfonso Eirin
- Department of Nephrology & HypertensionMayo ClinicRochesterMN
| | - James D. Krier
- Department of Nephrology & HypertensionMayo ClinicRochesterMN
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Chade AR, Zhu XY, Krier JD, Jordan KL, Textor SC, Grande JP, Lerman A, Lerman LO. Endothelial progenitor cells homing and renal repair in experimental renovascular disease. Stem Cells 2010; 28:1039-47. [PMID: 20506499 DOI: 10.1002/stem.426] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Tissue injury triggers reparative processes that often involve endothelial progenitor cells (EPCs) recruitment. We hypothesized that atherosclerotic renal artery stenosis (ARAS) activates homing signals that would be detectable in both the kidney and EPCs, and attenuated on renal repair using selective cell-based therapy. Pigs were treated with intrarenal autologous EPC after 6 weeks of ARAS. Four weeks later, expression of homing-related signals in EPC and kidney, single kidney function, microvascular (MV) density, and morphology were compared with untreated ARAS and normal control pigs (n = 7 each). Compared with normal EPC, EPC from ARAS pigs showed increased stromal cell-derived factor (SDF)-1, angiopoietin-1, Tie-2, and c-kit expression, but downregulation of erythropoietin (EPO) and its receptor. The ARAS kidney released the c-kit-ligand stem cell factor, uric acid, and EPO, and upregulated integrin beta2, suggesting activation of corresponding homing signaling. However, angiopoietin-1 and SDF-1/CXCR4 were not elevated. Administration of EPC into the stenotic kidney restored angiogenic activity, improved MV density, renal hemodynamics and function, decreased fibrosis and oxidative stress, and attenuated endogenous injury signals. The ARAS kidney releases specific homing signals corresponding to cognate receptors expressed by EPC. EPC show plasticity for organ-specific recruitment strategies, which are upregulated in early atherosclerosis. EPC are renoprotective as they attenuated renal dysfunction and damage in chronic ARAS, and consequently decreased the injury signals. Importantly, manipulation of homing signals may potentially allow therapeutic opportunities to increase endogenous EPC recruitment.
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Affiliation(s)
- Alejandro R Chade
- Divisions of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
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Warner L, Woollard JR, Glockner JD, Krier JD, Zhu XY, Textor S, Lerman LO. Improved Renal Tubular Function Detected by Magnetic Resonance Imaging after Revascularization of Experimental Renal Artery Stenosis. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.1025.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Liu X, Primak AN, Krier JD, Yu L, Lerman LO, McCollough CH. Renal perfusion and hemodynamics: accurate in vivo determination at CT with a 10-fold decrease in radiation dose and HYPR noise reduction. Radiology 2009; 253:98-105. [PMID: 19789255 DOI: 10.1148/radiol.2531081677] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE To prospectively evaluate the accuracy of computed tomographic (CT) perfusion measurements of renal hemodynamics and function obtained by using images acquired with one-tenth the typical radiation dose and postprocessed with a highly constrained back-projection (HYPR)-local reconstruction (LR) noise-reduction technique. MATERIALS AND METHODS This study was approved by the institutional Animal Care and Use Committee. Two consecutive CT perfusion acquisitions were performed in 10 anesthetized pigs over 180 seconds by using routine (80 kV, 160 mAs) and one-tenth (80 kV, 16 mAs) dose levels. Images obtained with each acquisition were reconstructed with identical parameters, and the one-tenth dose images were also processed with a HYPR-LR algorithm. Attenuation changes in kidneys were determined as a function of time to form time-attenuation curves (TACs). Extended gamma-variate curve-fitting was performed, and regional perfusion, glomerular filtration rate, and renal blood flow were calculated. Image quality was evaluated (in 10 pigs), and the agreement for renal perfusion and function between the routine dose and the one-tenth dose HYPR-LR images was determined (for 20 kidneys) by using statistical methods. Statistical analysis was performed by using the paired t test, linear regression, and Bland-Altman analysis. RESULTS TACs obtained with the one-tenth dose were similar to those obtained with the routine dose. Statistical analysis showed that there were no significant differences between the routine dose and the one-tenth dose acquisitions in renal perfusion and hemodynamic values and that there were slight but statistically significant differences in some values with the one-tenth dose HYPR-LR-processed acquisition. The image quality of the one-tenth dose acquisition was improved by using the HYPR-LR algorithm. Linear regression and Bland-Altman plots showed agreement between the images acquired by using the routine dose and those acquired by using the one-tenth dose with HYPR-LR processing. CONCLUSION A 10-fold dose reduction at renal perfusion CT imaging can be achieved in vivo, without loss of accuracy. The image quality of the one-tenth dose images could be improved to be near that of the routine dose images by using the HYPR-LR noise-reduction algorithm. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.2531081677/-/DC1.
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Affiliation(s)
- Xin Liu
- Department of Radiology, Divisions of Nephrology and Hypertension, CT Clinical Innovation Center, Mayo Clinic, Rochester, MN 55905, USA
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Zhu XY, Daghini E, Chade AR, Versari D, Krier JD, Textor KB, Lerman A, Lerman LO. Myocardial microvascular function during acute coronary artery stenosis: effect of hypertension and hypercholesterolaemia. Cardiovasc Res 2009; 83:371-80. [PMID: 19423617 DOI: 10.1093/cvr/cvp140] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS Coronary collateral arteries (CCA) reduce cardiovascular events. We tested the hypothesis that new microvessels that proliferate in early atherosclerosis may be associated with myocardial protection during acute subtotal coronary artery obstruction (CAO). METHODS AND RESULTS Acute left anterior descending CAO was induced by a balloon catheter in pigs after 12 weeks of high-cholesterol (HC) diet, renovascular hypertension (HTN), or normal control. Cardiac structure, myocardial perfusion, and functional response to iv adenosine and CAO were studied in vivo using electron beam computed tomography (CT). The intra-myocardial microvessels were subsequently evaluated ex vivo using micro-CT, and myocardial expression of growth factors using immunoblotting. Basal myocardial perfusion and microvascular permeability were similar among the groups, whereas their responses to adenosine were attenuated in HC and HTN. A significant decline in myocardial perfusion in normal pigs during acute CAO was attenuated in HC and abolished in HTN. CAO also elicited an increase in normal anterior wall microvascular permeability (+202 +/- 59%, P < 0.05), which was attenuated in HC and HTN (+55 +/- 9 and +31 +/- 8%, respectively, P < 0.05 vs. normal). Microvascular (<200 microm) spatial density was significantly elevated in HC and HTN, accompanied by increased myocardial growth factor expression. CONCLUSION This study demonstrates that early exposure to the cardiovascular risk factors HC and HTN protects the heart from decreases in myocardial perfusion during acute subtotal CAO. This protective effect is associated with and potentially mediated by pre-emptive development of intra-myocardial microvessels that might serve as recruitable CCA.
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Affiliation(s)
- Xiang-Yang Zhu
- Division of Nephrology and Hypertension, Department of Internal Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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Urbieta VH, Zhu X, Chade A, Krier JD, Lerman A, Lerman LO. Intra‐Renal Delivery of Progenitor Cells Improves Systemic Inflammation, Oxidative Stress, and Myocardial Microvascular Function in Experimental Renovascular Disease. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.969.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | - Amir Lerman
- Cardiovascular DiseasesMayo ClinicRochesterMN
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Chade AR, Zhu X, Lavi R, Krier JD, Pislaru S, Simari RD, Napoli C, Lerman A, Lerman LO. Endothelial progenitor cells restore renal function in chronic experimental renovascular disease. Circulation 2009; 119:547-57. [PMID: 19153272 DOI: 10.1161/circulationaha.108.788653] [Citation(s) in RCA: 168] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND Endothelial progenitor cells (EPCs) promote neovascularization and endothelial repair. Renal artery stenosis (RAS) may impair renal function by inducing intrarenal microvascular injury and remodeling. We investigated whether replenishment with EPCs would protect the renal microcirculation in chronic experimental renovascular disease. METHODS AND RESULTS Single-kidney hemodynamics and function were assessed with the use of multidetector computed tomography in vivo in pigs with RAS, pigs with RAS 4 weeks after intrarenal infusion of autologous EPCs, and controls. Renal microvascular remodeling and angiogenic pathways were investigated ex vivo with the use of micro-computed tomography, histology, and Western blotting. EPCs increased renal expression of angiogenic factors, stimulated proliferation and maturation of new vessels, and attenuated renal microvascular remodeling and fibrosis in RAS. Furthermore, EPCs normalized the blunted renal microvascular and filtration function. CONCLUSIONS The present study shows that a single intrarenal infusion of autologous EPCs preserved microvascular architecture and function and decreased microvascular remodeling in experimental chronic RAS. It is likely that restoration of the angiogenic cascade by autologous EPCs involved not only generation of new vessels but also acceleration of their maturation and stabilization. This contributed to preserving the blood supply, hemodynamics, and function of the RAS kidney, supporting EPCs as a promising therapeutic intervention for preserving the kidney in renovascular disease.
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Affiliation(s)
- Alejandro R Chade
- Division of Nephrology and Hypertension, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
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Abstract
Hypercholesterolemia induces renal inflammation and neovascularization, associated with renal endothelial dysfunction and injury. Neovascularization might conceivably represent a defense mechanism to sustain renal perfusion. Therefore, the present study was designed to test the hypothesis that preventing neovascularization using thalidomide, a potent anti-inflammatory and antiangiogenic agent, would impair basal renal hemodynamics in experimental hypercholesterolemia. Single-kidney function and hemodynamic responses to endothelium-dependent challenge were assessed in pigs after 12 weeks of hypercholesterolemia, hypercholesterolemia chronically supplemented with thalidomide (4 mg/kg per day), and normal controls. Renal microvascular architecture was then studied ex vivo using 3D microcomputed tomography imaging and inflammation, angiogenesis, and oxidative stress explored in renal tissue. The density of larger microvessels (200 to 500 microm) was selectively decreased in hypercholesterolemia plus thalidomide and accompanied by a decreased fraction of angiogenic, integrin beta(3)-positive microvessels (9.9%+/-0.9% versus 25.5%+/-1.7%; P<0.05 versus hypercholesterolemia), implying decreased angiogenic activity. Furthermore, thalidomide increased renal expression of endothelial NO synthase and decreased tumor necrosis factor-alpha and renal inflammation but did not decrease oxidative stress. Thalidomide also decreased basal renal blood flow and glomerular filtration rate but normalized the blunted renal hemodynamic responses in hypercholesterolemia. Attenuated inflammation and pathological angiogenesis achieved in hypercholesterolemia by thalidomide are accompanied by restoration of renovascular endothelial function but decreased basal renal hemodynamics. This study, therefore, suggests that neovascularization in the hypercholesterolemic kidney is a compensatory mechanism that sustains basal renal vascular function.
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Affiliation(s)
- Alejandro R Chade
- Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Daghini E, Primak AN, Chade AR, Krier JD, Zhu XY, Ritman EL, McCollough CH, Lerman LO. Assessment of renal hemodynamics and function in pigs with 64-section multidetector CT: comparison with electron-beam CT. Radiology 2007; 243:405-12. [PMID: 17456868 DOI: 10.1148/radiol.2432060655] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To prospectively evaluate the feasibility of obtaining reliable measurements of renal hemodynamics and function by using 64-section multidetector CT. MATERIALS AND METHODS This study was approved by the Institutional Animal Care and Use Committee. Eight pigs (two with induced unilateral renal artery stenosis) were studied with both electron-beam CT and 64-section multidetector CT at 1-week intervals in randomized order. Both kidneys were scanned repeatedly, without table movement, for about 3 minutes after intravenous (IV) administration of a bolus of contrast medium and again during vasodilator challenge (acetylcholine). Images were reconstructed on each CT console but were analyzed on the same independent workstation. Attenuation changes in the kidneys were plotted as function of time, and time-attenuation curves (TACs) were subsequently analyzed to determine regional perfusion and volume, glomerular filtration rate (GFR), and renal blood flow (RBF). Statistical analysis utilized Student t test, analysis of variance (ANOVA), linear regression, and Bland-Altman analysis. RESULTS TACs obtained with multidetector CT were qualitatively similar to those obtained with electron-beam CT, as were the quantitative values of renal perfusion and function. RBF correlated significantly between the two techniques (RBF(MD) = 0.96 . RBF(EB) mL/min; R = 0.77, P < .01). GFR(MD) was also similar to GFR(EB) (77.6 +/- 8.3 vs 79.8 +/- 8.8 mL/min, p > .05). Bland-Altman plots showed good agreement between the two techniques. Both techniques similarly detected the differences between stenotic and contralateral kidneys. CONCLUSION The clinical multidetector CT scanner provides reliable measurements of single-kidney hemodynamics and function, which are similar to those obtained with previously validated electron-beam CT.
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Affiliation(s)
- Elena Daghini
- Department of Medicine, Division of Nephrology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Daghini E, Juillard L, Haas JA, Krier JD, Romero JC, Lerman LO. Comparison of Mathematic Models for Assessment of Glomerular Filtration Rate with Electron-Beam CT in Pigs. Radiology 2007; 242:417-24. [PMID: 17255413 DOI: 10.1148/radiol.2422052144] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To prospectively compare in pigs three mathematic models for assessment of glomerular filtration rate (GFR) on electron-beam (EB) computed tomographic (CT) images, with concurrent inulin clearance serving as the reference standard. MATERIALS AND METHODS This study was approved by the institutional animal care and use committee. Inulin clearance was measured in nine pigs (18 kidneys) and compared with single-kidney GFR assessed from renal time-attenuation curves (TACs) obtained with EB CT before and after infusion of the vasodilator acetylcholine. CT-derived GFR was calculated with the original and modified Patlak methods and with previously validated extended gamma variate modeling of first-pass cortical TACs. Statistical analysis was performed to assess correlation between CT methods and inulin clearance for estimation of GFR with least-squares regression analysis and Bland-Altman graphical representation. Comparisons within groups were performed with a paired t test. RESULTS GFR assessed with the original Patlak method indicated poor correlation with inulin clearance, whereas GFR assessed with the modified Patlak method (P < .001, r = 0.75) and with gamma variate modeling (P < .001, r = 0.79) correlated significantly with inulin clearance and indicated an increase in response to acetylcholine. CONCLUSION CT-derived estimates of GFR can be significantly improved by modifications in image analysis methods (eg, use of a cortical region of interest).
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Affiliation(s)
- Elena Daghini
- Division of Nephrology and Hypertension and Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905, USA
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Chade AR, Krier JD, Textor SC, Lerman A, Lerman LO. Endothelin-a receptor blockade improves renal microvascular architecture and function in experimental hypercholesterolemia. J Am Soc Nephrol 2006; 17:3394-403. [PMID: 17082239 DOI: 10.1681/asn.2006060635] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Hypercholesterolemia (HC) may trigger early renal injury, partly by impairing the function or the structure of renal microvessels (MV). The endothelin (ET) system is upregulated in HC and can have an impact on the renal microcirculation by regulating MV tone, growth factors, and remodeling. It was hypothesized that ET-A blockade would protect the HC kidney by improving the function and attenuating the damage of intrarenal MV. Single-kidney function and hemodynamic responses to endothelium-dependent challenge were assessed in pigs after 12 wk of experimental HC, HC and chronic supplementation with the ET receptor A blocker ABT-627 (HC+ET-A, 0.75 mg/kg per d), and normal controls. Renal MV architecture then was studied ex vivo using three-dimensional microcomputed tomography imaging, and growth factors and remodeling pathways were explored in renal tissue. The HC kidney showed increased MV density compared with normal (77.68 +/- 5.1 versus 62.9 +/- 4.8 vessels/cm(2); P = 0.04) but blunted endothelial function. Chronic ET-A blockade in HC upregulated renal vascular growth factors, further increased renal MV density (139.9 +/- 8.4 vessels/cm(2); P = 0.001 versus normal and HC), and decreased renal tissue and MV remodeling. Furthermore, ET-A blockade in HC decreased MV tortuosity and improved MV endothelial function, suggesting accelerated stabilization and maturation of neo-vessels. Modulation of renal MV architecture and function in HC is mediated partly by the endogenous ET system. Notably, ET-A blockade enhanced the proliferation and facilitated the maturation of renal MV in the HC kidney and improved renal MV remodeling and function. This study suggests novel renoprotective effects of ET-A blockers and supports further exploration of strategies that target the ET pathway in HC and atherosclerosis.
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Affiliation(s)
- Alejandro R Chade
- Department of Internal Medicine, Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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Sattler KJE, Galili O, Rodriguez-Porcel M, Krier JD, Lerman LO, Lerman A. Dietary reversal of experimental hypercholesterolemia improves endothelial dysfunction of epicardial arteries but not of small coronary vessels in pigs. Atherosclerosis 2005; 188:301-8. [PMID: 16343507 DOI: 10.1016/j.atherosclerosis.2005.11.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2005] [Revised: 11/02/2005] [Accepted: 11/03/2005] [Indexed: 11/17/2022]
Abstract
Endothelial dysfunction is characterized by impaired vasodilation, increase of oxidative stress and inflammation. The current study was designed to test the hypothesis that reversal of hypercholesterolemic diet alone does not normalize all the parameters of endothelial dysfunction. After 10 weeks on a high-cholesterol diet, female juvenile pigs were randomized to normal diet (n=5, "Reversals") or continued on the same diet (n=6, "HC") for another 6 weeks. A control group of 11 pigs received a normal diet ("C"). Coronary epicardial and arteriolar endothelial function was tested in vitro. NFkappaB and p47phox expression was analyzed in epicardial arteries and myocardium, respectively. P47phox localization in coronary arteries was demonstrated with immunohistochemistry. Lipid levels normalized in Reversal pigs. Epicardial arteries of Reversals showed a normalized relaxation and NFkappaB expression compared to HC (p<0.05). Small vessel relaxation remained attenuated, and expression of p47phox in myocardial tissue was elevated in Reversals compared to C (p<0.05). Dietary lowering of serum cholesterol and LDL improves vascular function of epicardial arteries but neither of small vessels nor vascular oxidative stress within this time frame. Hence, dietary normalization of serum lipid levels alone may not be synonymous to normalization of the components of endothelial dysfunction.
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Affiliation(s)
- Katherine J E Sattler
- Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, MN, USA
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Daghini E, Chade AR, Krier JD, Versari D, Lerman A, Lerman LO. Acute inhibition of the endogenous xanthine oxidase improves renal hemodynamics in hypercholesterolemic pigs. Am J Physiol Regul Integr Comp Physiol 2005; 290:R609-15. [PMID: 16284087 DOI: 10.1152/ajpregu.00436.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hypercholesterolemia (HC), a major risk factor for onset and progression of renal disease, is associated with increased oxidative stress, potentially causing endothelial dysfunction. One of the sources of superoxide anion is xanthine oxidase (XO), but its contribution to renal endothelial function in HC remains unclear. We tested the hypothesis that XO modulates renal hemodynamics and endothelial function in HC pigs. Four groups (n = 23) of female domestic pigs were studied 12 wk after either normal (n = 11) or HC diet (n = 12). Oxidative stress was assessed by plasma isoprostanes and oxidized LDL, and the XO system by plasma uric acid, urinary xanthine, and renal XO expression (by immunoblotting and immunohistochemistry). Renal hemodynamics and function were studied with electron beam-computed tomography before and after endothelium-dependent (ACh) and -independent (sodium nitroprusside) challenge, during a concurrent intrarenal infusion of either oxypurinol or saline (n = 5-6 in each group). HC showed elevated oxidative stress, higher plasma uric acid (23.8 +/- 3.8 vs. 6.2 +/- 0.8 microM/mM creatinine, P = 0.001), lower urinary xanthine, and greater renal XO expression compared with normal. Inhibition of XO in HC significantly improved the blunted responses to ACh of cortical perfusion (13.5 +/- 12.1 and 37.2 +/- 10.6%, P = 0.01 and P = not significant vs. baseline, respectively), renal blood flow, and glomerular filtration rate; restored medullary perfusion; and improved the blunted cortical perfusion response to sodium nitroprusside. This study demonstrates that the endogenous XO system is activated in swine HC. Furthermore, it suggests an important role for XO in regulation of renal hemodynamics, function, and endothelial function in experimental HC.
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Affiliation(s)
- Elena Daghini
- Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, 200 First St., SW, Rochester, Minnesota 55905, USA
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Chade AR, Herrmann J, Zhu X, Krier JD, Lerman A, Lerman LO. Effects of Proteasome Inhibition on the Kidney in Experimental Hypercholesterolemia. J Am Soc Nephrol 2005; 16:1005-12. [PMID: 15716331 DOI: 10.1681/asn.2004080674] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Hypercholesterolemia (HC) and atherosclerosis often accompany and aggravate renal disease. Proteasome inhibitors (PSI) can decrease proliferation and inflammation, likely by reducing activation of the proinflammatory NF-kappaB. However, chronic proteasome inhibition has never been demonstrated in the HC kidney. Four groups of pigs (n = 7 each) were studied after a 12-wk normal (N) or 2% HC diet alone or supplemented (N+PSI and HC+PSI) with MLN-273 (0.08 mg/kg subcutaneously twice weekly). Renal hemodynamics and function were quantified in vivo using electron-beam computed tomography at baseline and after vasodilator challenge using acetylcholine. Renal tissue was studied ex vivo using immunoblotting, PCR, and immunohistochemistry. Serum cholesterol was similarly elevated in HC and HC+PSI. Basal renal blood flow was similar among the groups, whereas GFR was decreased in both N+PSI and HC+PSI. The blunted renovascular and functional responses to acetylcholine in HC were normalized in HC+PSI (suggesting renal endothelial function improvement), which was accompanied by decreased renal endothelin, NF-kappaB, and augmented endothelial nitric oxide synthase expression. In parallel, HC+PSI animals also showed elevated NAD(P)H oxidase expression and circulating oxidized LDL, suggesting a potential for increased oxidative stress. This study shows that chronic PSI intervention in HC improves renal endothelial functional responses to challenge, possibly by modulating nitric oxide availability and endothelin. Furthermore, PSI may decrease intrarenal inflammation through modulation of the NF-kappaB pathway but may potentially increase oxidative stress, which warrants further investigation. This study may support a role for the ubiquitin/proteasome system in the kidney in HC and early atherosclerosis.
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Affiliation(s)
- Alejandro R Chade
- Department of Internal Medicine, Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA
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Chade AR, Krier JD, Rodriguez-Porcel M, Breen JF, McKusick MA, Lerman A, Lerman LO. Comparison of acute and chronic antioxidant interventions in experimental renovascular disease. Am J Physiol Renal Physiol 2004; 286:F1079-86. [PMID: 14722019 DOI: 10.1152/ajprenal.00385.2003] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Reactive oxygen species (ROS) can modulate renal hemodynamics and function both directly, by leading to vasoconstriction, and indirectly, by inducing renal inflammation and tissue growth. The involvement of oxidative stress in the pathogenesis of renovascular disease (RVD) is increasingly recognized, but the relative contribution of long-term tissue injury to renal dysfunction remains unclear. We hypothesized that functional and structural alterations elicited by oxidative stress in RVD would be more effectively modulated by chronic than by acute antioxidant intervention. Renal hemodynamics and function were quantified in vivo in pigs using electron-beam computed tomography at baseline and after vasoactive challenge (ACh and sodium nitroprusside); after 12 wk of RVD (simulated by concurrent hypercholesterolemia and renal artery stenosis, n = 7); RVD acutely infused with the SOD-mimetic tempol (RVD+tempol, n = 7); RVD chronically supplemented with antioxidant vitamins C (1 g) and E (100 IU/kg; RVD+vitamins, n = 7); or control (normal, n = 7). Renal tissue was studied ex vivo using immunoblotting and immunohistochemistry. Basal renal blood flow (RBF) and glomerular filtration rate were similarly decreased in all RVD groups. ACh-stimulated RBF remained unchanged in RVD, increased in RVD+tempol, but further increased (similarly to normal) in RVD+vitamins ( P < 0.05 vs. RVD). Furthermore, RVD+vitamins also showed a decreased presence of superoxide anion, decreased NAD(P)H-oxidase and nitrotyrosine expression, increased endothelial nitric oxide synthase expression, and attenuated renal fibrosis. Chronic antioxidant intervention in early RVD improved renal hemodynamic responses more effectively than acute intervention, likely due to increased nitric oxide bioavailability and decreased structural injury. These suggest that chronic tissue changes play an important role in renal compromise mediated by oxidative stress in RVD.
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Affiliation(s)
- Alejandro R Chade
- Div. of Hypertension, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA
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Rodriguez-Porcel M, Herrman J, Chade AR, Krier JD, Breen JF, Lerman A, Lerman LO. Long-term antioxidant intervention improves myocardial microvascular function in experimental hypertension. Hypertension 2004; 43:493-8. [PMID: 14718362 DOI: 10.1161/01.hyp.0000111834.03000.e4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hypertension increases oxidative stress, which can impair myocardial microvascular function and integrity. However, it is yet unclear whether long-term antioxidant intervention in early hypertension would preserve myocardial perfusion and vascular permeability responses to challenge. Pigs were studied after 12 weeks of renovascular hypertension without (n=8) or with daily supplementation of antioxidants (100 IU/kg vitamin E and 1 g vitamin C, n=6), and compared with normal controls (n=7). Myocardial perfusion and microvascular permeability were measured in vivo by electron beam computed tomography before and after 2 cardiac challenges (intravenous adenosine and dobutamine). Basal left ventricular muscle mass was also obtained. Mean arterial pressure was significantly increased in both groups of hypertensive animals (without and with antioxidants, 123+/-9 and 126+/-4 mm Hg, respectively, versus normal, 101+/-4 mm Hg; both P<0.05), but muscle mass was not different among the groups. The impaired myocardial perfusion response to adenosine observed in hypertensives (normal, +51+/-14%; P<0.05 versus baseline; hypertension, +14+/-15%; P=0.3 versus baseline) was preserved in hypertensive pigs that received antioxidants (+44+/-15%; P=0.01 compared with baseline). Long-term antioxidant intervention also preserved subendocardial microvascular permeability responses in hypertension. On the other hand, antioxidant intervention had little effect on the hypertension-induced myocardial vascular dysfunction observed in response to dobutamine. This study demonstrates that the impaired myocardial perfusion and permeability responses to increased cardiac demand in early hypertension are significantly improved by long-term antioxidant intervention. These results support the involvement of oxidative stress in myocardial vascular dysfunction in hypertension and suggest a role for antioxidant strategies to preserve the myocardial microvasculature.
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Affiliation(s)
- Martin Rodriguez-Porcel
- Department of Internal Medicine, Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, 200 First St SW, Rochester, Minn 55905, USA
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Abstract
Renal artery stenosis (RAS) may lead to renal injury, partly mediated through increased oxidative stress. However, the potential effects of chronic oral antioxidant intervention on the stenotic kidney remain unknown. This study was designed to test the hypothesis that chronic antioxidant vitamin supplementation in RAS would preserve renal function and structure. Single-kidney hemodynamics and function were quantified in vivo in pigs using electron-beam CT after 12 weeks of unilateral RAS (n=7), a similar degree of RAS orally supplemented with vitamins C (1 g) and E (100 IU/kg) (RAS+Vitamins, n=7), or controls (normal, n=7). Renal tissue was studied ex vivo using Western blotting and immunohistochemistry. Mean arterial pressure was similarly elevated in both RAS groups, while ischemic renal volume and glomerular filtration rate were similarly reduced. Renal blood flow was decreased in RAS compared with normal (326.5+/-99.9 versus 553.4+/-48.7 mL/min, respectively, P=0.01), but preserved in RAS+Vitamins (485.2+/-104.1 mL/min, P=0.3 versus normal). The marked increase in the expression of the NADPH-oxidase subunits p47phox and p67phox, nitrotyrosine, endothelial and inducible nitric oxide synthase, and nuclear factor-kappaB observed in RAS (P<0.05 versus normal) was normalized in RAS+Vitamins (P>0.1). Furthermore, trichrome staining and the expression of transforming growth factor-beta and tissue inhibitor of matrix-metalloproteinase-1 were also decreased in RAS+Vitamins. In conclusion, chronic blockade of the oxidative stress pathway in RAS using antioxidant vitamins improved renal hemodynamics and decreased oxidative stress, inflammation, and fibrosis in the ischemic kidney. These observations underscore the involvement of oxidative stress in renal injury in RAS and support a role for antioxidant vitamins in preserving the ischemic kidney.
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Affiliation(s)
- Alejandro R Chade
- Division of Hypertension, Department of Internal Medicine, Mayo Clinic, Rochester, Minn 55905, USA
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37
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Abstract
BACKGROUND Atherosclerotic renovascular disease may augment deterioration of renal function and ischemic nephropathy compared with other causes of renal artery stenosis (RAS), but the underlying mechanisms remain unclear. This study was designed to test the hypothesis that concurrent early atherosclerosis and hypoperfusion might have greater early deleterious effects on the function and structure of the stenotic kidney. METHODS AND RESULTS Regional renal hemodynamics and function at baseline and during vasoactive challenge (acetylcholine or sodium nitroprusside) were quantified in vivo in pigs by electron-beam computed tomography after a 12-week normal (n=7) or hypercholesterolemic (HC, n=7) diet, RAS (n=6), or concurrent HC and a similar degree of RAS (HC+RAS, n=7). Flash-frozen renal tissue was studied ex vivo. Basal cortical perfusion and single-kidney glomerular filtration rate (GFR) were decreased similarly in the stenotic RAS and HC+RAS kidneys, but tubular fluid reabsorption was markedly impaired only in HC+RAS. Perfusion responses to challenge were similarly blunted in the experimental groups. Stimulated GFR increased in normal, HC, and RAS (38.3+/-3.6%, 36.4+/-7.6%, and 60.4+/-9.3%, respectively, P<0.05), but not in HC+RAS (6.5+/-15.1%). These functional abnormalities in HC+RAS were accompanied by augmented perivascular, tubulointerstitial, and glomerular fibrosclerosis, inflammation, systemic and tissue oxidative stress, and tubular expression of nuclear factor-kappaB and inducible nitric oxide synthase. CONCLUSIONS Early chronic HC+RAS imposes distinct detrimental effects on renal function and structure in vivo and in vitro, evident primarily in the tubular and glomerular compartments. Increased oxidative stress may be involved in the proinflammatory and progrowth changes observed in the stenotic HC+RAS kidney, which might potentially facilitate the clinically observed progression to end-stage renal disease.
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Affiliation(s)
- Alejandro R Chade
- Department of Internal Medicine, Division of Hypertension, Mayo Clinic, Rochester, Minn 55905, USA
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Krier JD, Rodriguez-Porcel M, Best PJM, Romero JC, Lerman A, Lerman LO. Vascular responses in vivo to 8-epi PGF(2alpha) in normal and hypercholesterolemic pigs. Am J Physiol Regul Integr Comp Physiol 2002; 283:R303-8. [PMID: 12121841 DOI: 10.1152/ajpregu.00602.2001] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypercholesterolemia (HC) is characterized by increased circulating 8-epi-prostaglandin-F(2alpha) (isoprostane), a vasoconstrictor, marker, and mediator of increased oxidative stress, whose vascular effects might be augmented in HC. Anesthetized pigs were studied in vivo with electron beam computed tomography after a 12-wk normal (n = 8) or HC (n = 8) diet. Mean arterial pressure (MAP), single-kidney perfusion, and glomerular filtration rate (GFR) were quantified before and during unilateral intrarenal infusions of U46619 (10 ng x kg(-1) x min(-1)) or isoprostane (1 microg x kg(-1) x min(-1)). Basal renal perfusion and function were similar, and isoprostane infusion elevated its systemic levels similarly in normal and HC (333 +/- 89 vs. 366 +/- 48 pg/ml, respectively, P < 0.01 vs. baseline). Both drugs markedly and comparably decreased cortical perfusion and GFR in both groups, whereas medullary perfusion decreased significantly only in HC. Moreover, MAP increased significantly only in HC (+9 +/- 3 and +11 +/- 3 mmHg, respectively, P<or= 0.05). Hence, in HC, renal functional responses to high-dose isoprostane are largely similar to normal, but the systemic circulation exhibits augmented sensitivity to pathophysiological levels of isoprostane and U46619, which may potentially play a role in development of hypertension and vascular injury associated with increased oxidative stress.
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Affiliation(s)
- James D Krier
- Department of Internal Medicine, Division of Hypertension, Mayo Clinic, Rochester, Minnesota 55905, USA
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Krier JD, Ritman EL, Bajzer Z, Romero JC, Lerman A, Lerman LO. Noninvasive measurement of concurrent single-kidney perfusion, glomerular filtration, and tubular function. Am J Physiol Renal Physiol 2001; 281:F630-8. [PMID: 11553509 DOI: 10.1152/ajprenal.2001.281.4.f630] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To assess the reliability of electron beam computed tomography (EBCT), measurements of single-kidney renal blood flow (RBF), glomerular filtration rate (GFR), and intratubular contrast medium concentration (ITC) of radiographic contrast media were quantified in anesthetized pigs before and after acetylcholine-induced vasodilation and diuresis. EBCT measurements were compared with those obtained with intravascular Doppler and inulin clearance. The capability of EBCT to detect chronic changes in single-kidney function was evaluated in pigs with unilateral renal artery stenosis, and their long-term reproducibility in normal pigs was studied repeatedly at 1-mo intervals. EBCT-RBF (ml/min) correlated with Doppler-RBF as RBF(EBCT) = 45 + 1.07 * RBF(Doppler), r = 0.81. EBCT-GFR (ml/min) correlated with inulin clearance as GFR(EBCT) = 11.7 + 1.02 * GFR(inulin), r = 0.80. During vasodilation, RBF and GFR increased, whereas ITC decreased along the nephron. In renal artery stenosis, single-kidney GFR decreased linearly with the degree of stenosis, and ITC increased along the nephron, indicating increased fluid reabsorption. EBCT-RBF, GFR, and ITC were similar among repeated measurements. This approach might be invaluable for simultaneous quantification of regional hemodynamics and function in the intact kidneys, in a manner potentially applicable to humans.
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Affiliation(s)
- J D Krier
- Division of Hypertension, Department of Internal Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA
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Rodriguez-Porcel M, Lerman A, Best PJ, Krier JD, Napoli C, Lerman LO. Hypercholesterolemia impairs myocardial perfusion and permeability: role of oxidative stress and endogenous scavenging activity. J Am Coll Cardiol 2001; 37:608-15. [PMID: 11216987 DOI: 10.1016/s0735-1097(00)01139-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES We intended to study the effect of hypercholesterolemia (HC) on myocardial perfusion and permeability response to increased cardiac demand. BACKGROUND Hypercholesterolemia is associated with increased incidence of cardiac events and characterized by impaired coronary vascular function, possibly mediated partly through increased pro-oxidative conditions in plasma and tissue. However, it is yet unclear whether HC is also associated with impaired myocardial perfusion and vascular permeability responses in vivo. METHODS For 12 weeks pigs were fed a normal, HC or HC diet supplemented daily with antioxidants (HC + AO, 100 IU/kg vitamin E and 1 g vitamin C). Myocardial perfusion and vascular permeability were measured in vivo using electron beam computed tomography before and after cardiac challenge with intravenous adenosine. Plasma and tissue oxidative status was determined ex vivo. RESULTS Plasma cholesterol increased in all cholesterol-fed pigs but was associated with increased markers of oxidative stress only in HC pigs. Myocardial perfusion increased in response to adenosine in normal and HC + AO (+37 +/- 13% and +58 +/- 22%, respectively, p < 0.05 vs. baseline) but not in HC, whereas vascular permeability index increased only in HC pigs (+ 92 +/- 25%, p = 0.002). In HC animals, tissue endogenous oxygen radical scavengers and antioxidant vitamins were depleted and LDL oxidizability enhanced, but both were normalized in HC + AO pigs. Myocardial perfusion response was directly, and permeability inversely, associated with plasma and tissue vitamin concentrations. CONCLUSIONS This study demonstrates that experimental HC is associated with blunted myocardial perfusion and increased vascular permeability responses in vivo to increased cardiac demand, which may be partly mediated by a shift in oxidative status.
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Affiliation(s)
- M Rodriguez-Porcel
- Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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Lerman LO, Nath KA, Rodriguez-Porcel M, Krier JD, Schwartz RS, Napoli C, Romero JC. Increased oxidative stress in experimental renovascular hypertension. Hypertension 2001; 37:541-6. [PMID: 11230332 DOI: 10.1161/01.hyp.37.2.541] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The pathophysiological mechanisms responsible for maintenance of chronic renovascular hypertension remain undefined. Excess angiotensin II generation may lead to release of reactive oxygen species and increased vasoconstrictor activity. To examine the potential involvement of oxidation-sensitive mechanisms in the pathophysiology of renovascular hypertension, blood samples were collected and renal blood flow measured with electron-beam computed tomography in pigs 5 and 10 weeks after induction of unilateral renal artery stenosis (n=7) or sham operation (n=7). Five weeks after procedure, plasma renin activity and mean arterial pressure were elevated in hypertensive pigs. Levels of prostaglandin F2alpha (PGF(2alpha))-isoprostanes, vasoconstrictors and markers of oxidative stress, also were significantly increased (157+/-21 versus 99+/-16 pg/mL; P<0.05) and correlated with both plasma renin activity (r=0.83) and arterial pressure (r=0.82). By 10 weeks, plasma renin activity returned to baseline but arterial pressure remained elevated (144+/-10 versus 115+/-5 mm Hg; P:<0.05). Isoprostane levels remained high and still correlated directly with the increase in arterial pressure (r=0.7) but not with plasma renin activity. Stenotic kidney blood flow was decreased at both studies. In shock-frozen cortical tissue, ex vivo endogenous intracellular radical scavengers were significantly decreased in both kidneys. The present study demonstrates, for the first time, that in early renovascular hypertension, an increase in plasma renin activity and arterial pressure is associated with increased systemic oxidative stress. When plasma renin activity later declines, PGF(2alpha)-isoprostanes remain elevated, possibly due to local activation or slow responses to angiotensin II, and may participate in sustenance of arterial pressure. Moreover, oxidation-sensitive mechanisms may influence ischemic and hypertensive parenchymal renal injury.
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Affiliation(s)
- L O Lerman
- Department of Internal Medicine, Division of Hypertension, Mayo Clinic, Rochester, Minnesota, USA.
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Rodriguez-Porcel M, Krier JD, Lerman A, Sheedy PF, Romero JC, Napoli C, Lerman LO. Combination of hypercholesterolemia and hypertension augments renal function abnormalities. Hypertension 2001; 37:774-80. [PMID: 11230372 DOI: 10.1161/01.hyp.37.2.774] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypercholesterolemia and hypertension are both risk factors for end-stage renal disease. This study was designed to examine whether their coexistence augmented impairment in renal function and redox status. Regional renal hemodynamics and function in response to vasoactive challenges with acetylcholine or sodium nitroprusside were quantified by using electron-beam computed tomography in pigs after 12 weeks of either a normal (n=10) or hypercholesterolemic (n=10) diet, renovascular hypertension (n=7), or combined hypercholesterolemia+hypertension (n=6). The hypercholesterolemic and hypercholesterolemic+hypertensive groups had significantly increased serum cholesterol levels, whereas in the hypertensive and hypercholesterolemic+hypertensive groups, mean arterial pressure was significantly elevated compared with the group fed a normal diet. Basal regional renal perfusion and glomerular filtration rates were similar among the groups. In response to acetylcholine, cortical perfusion increased in normal animals (15.6+/-4.7%, P=0.002) but not in hypercholesterolemic or hypertensive animals (8.0+/-7.4% and 8.2+/-5.9%, respectively; P>0.05). Moreover, in the hypercholesterolemic+hypertensive group, cortical perfusion response was further attenuated (2.5+/-4.8%, P=0.02) and significantly different from the group fed a normal diet (P<0.05). The response to sodium nitroprusside followed a similar pattern, and the impairment was augmented in the hypercholesterolemic+hypertensive group. The functional abnormalities in hypercholesterolemia or hypertension were associated with a decrease in systemic and/or renal tissue levels of oxygen radical scavengers that was again accentuated in hypercholesterolemia+hypertension. These results demonstrate that concurrent hypercholesterolemia and hypertension have a greater detrimental effect on renal perfusion responses compared with hypercholesterolemia or hypertension alone, associated with a marked pro-oxidant shift in redox status. These effects may potentially augment renal functional impairment and play a role in the initiation and progression of renal injury in hypertension and atherosclerosis.
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Affiliation(s)
- M Rodriguez-Porcel
- Department of Internal Medicine, Division of Hypertension, Mayo Clinic, Rochester, Minnesota, USA
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Rodriguez-Porcel MG, Krier JD, Lerman A, Romero JC, Lerman LO. A Combination of Hypercholesterolemia and Hypertension Augments an Impairment in Intra-Renal Perfusion Responses. Hypertension 2000. [DOI: 10.1161/hyp.36.suppl_1.712-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
P105
The kidney is a target organ for cardiovascular risk factors, such as atherosclerosis and hypertension (HT), and is particularly susceptible to their combination. Even at an early stage, hypercholesterolemia (HC) and HT are individually associated with impaired renal perfusion responses to challenge with vasodilators. However, the effect of combined HC and HT on renal perfusion remains uncertain. To examine this, regional renal perfusion response to the renal vasodilator acetylcholine (Ach) was quantified in 4 groups of pigs, using electron beam CT, after 12 weeks of either normal (n=6), HC diet (n=6), HT (unilateral renal artery stenosis, n=5), or combined HC and HT (HC+HT, n=6). The HC and HC+HT groups had increased cholesterol levels vs. normal and HT (430±82 and 351±52 vs. 71±6 and 83±4 mg/dl, ANOVA p<0.05, respectively). Mean arterial pressure was significantly elevated in HT and HC+HT vs. normal and HC (132±6 and 127±13 vs. 88±5 and 92±6 mmHg, p<0.05, respectively). The combination of HC and HT was associated with a greater impairment in cortical and papillary perfusion responses than HC or HT alone (Table). Medullary perfusion response was not significantly different among the four groups (Table). These results demonstrate that concurrent HC and HT have a greater detrimental effect on renal perfusion responses than HC or HT alone, and that this effect is regionally heterogeneous. These effects may potentially lead to enhanced renal functional impairment and may play a role in the progression of renal damage in HT and atherosclerosis.
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Feldstein A, Krier JD, Sarafov MH, Lerman A, Best PJ, Wilson SH, Lerman LO. In vivo renal vascular and tubular function in experimental hypercholesterolemia. Hypertension 1999; 34:859-64. [PMID: 10523374 DOI: 10.1161/01.hyp.34.4.859] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypercholesterolemia (HC) is often associated with impaired peripheral and coronary vascular responses to endothelium-dependent vasodilators, which are probably due to low bioavailability of nitric oxide. To examine the effect of HC on renal vascular and tubular function, 22 domestic pigs were studied after being fed a 12-week normal (n=11) or HC (n=11) diet. Renal regional perfusion and intratubular contrast media concentration in each nephron segment (representing fluid reabsorption) were quantified in vivo with electron-beam computed tomography before and after a suprarenal infusion of either acetylcholine (6 pigs of each diet) or sodium nitroprusside (SNP; 5 pigs of each diet). An increase in cortical perfusion, observed in normal pigs with acetylcholine (+35+/-6%, P=0. 002) and SNP (+12+/-4%, P=0.005), was blunted in the HC group (+8. 8+/-4.0, P=0.01, and -4.6+/-4.0%, P=0.1, respectively, P=0.003 and P=0.005 compared with normal) as was an increase in medullary perfusion (+58+/-21 in normal versus +24+/-11% in HC, P=0.04). A decrease in the intratubular contrast media concentration in the distal tubule and collecting duct of normal pigs was observed in all tubular segments (and was significantly enhanced in the proximal tubule and Henle's loop) in the HC group, which was associated with increased sodium excretion. The tubular and renal excretory responses to SNP were similar between the groups. In conclusion, early experimental HC in the pig attenuates renal perfusion response to both endothelium-dependent and -independent vasodilators possibly because of decreased bioavailability or decreased vascular responsiveness to nitric oxide. This vascular impairment may play a role in maladjusted renovascular responses and contribute to renal damage in later stages of atherosclerosis.
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Affiliation(s)
- A Feldstein
- Department of Internal Medicine, the Division of Hypertension, Mayo Clinic, Rochester, MN 55905, USA
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Abstract
Chronic intravenous infusion of subpressor doses of angiotensin II causes blood pressure to increase progressively over the course of several days. The mechanisms underlying this response, however, are poorly understood. Because high-dose angiotensin II increases oxidative stress, and some compounds that result from the increased oxidative stress (eg, isoprostanes) produce vasoconstriction and antinatriuresis, we tested the hypothesis that a subpressor dose of angiotensin II also increases oxidative stress, as measured by 8-epi-prostaglandin F(2alpha) (isoprostanes), which may contribute to the slow pressor response to angiotensin II. To test this hypothesis, we infused angiotensin II (10 ng/kg per minute for 28 days via an osmotic pump) into 6 conscious normotensive female pigs (30 to 35 kg). We recorded mean arterial pressure continuously with a telemetry system and measured plasma isoprostanes before starting the angiotensin II infusion (baseline) and again after 28 days with an enzyme immunoassay. Angiotensin II infusion significantly increased mean arterial pressure from 121+/-4 to 153+/-7 mm Hg (P<0. 05) without altering total plasma isoprostane levels (180.0+/-24.3 versus 147.0+/-29.2 pg/mL; P=NS). However, the plasma concentrations of free isoprostanes increased significantly, from 38.3+/-5.8 to 54.7+/-10.4 pg/mL (P<0.05). These results suggest that subpressor doses of angiotensin II increase oxidative stress, as implied by the increased concentration of free isoprostanes, which accompany the elevation in mean arterial pressure elevation. Thus, isoprostane-induced vasoconstriction and antinatriuresis may contribute to the hypertension induced by the slow pressor responses of angiotensin II.
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Affiliation(s)
- J A Haas
- Department of Physiology and Biophysics, Mayo School of Medicine and Mayo Clinic, Rochester, MN 55905, USA
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Abstract
Nitric oxide (NO) synthesis inhibition with NG-nitro-L-arginine methyl ester (L-NAME) (10 micrograms.kg-1.min-1 i.v.), cyclooxygenase inhibition with meclofenamate (Meclo; 5 mg/kg i.v. bolus), and combination of drugs (L-NAME + Meclo) were used to investigate the roles of NO and prostaglandins (PG) in the hemodynamic and natriuretic responses to isotonic saline volume expansion (VE; 5% body wt over 60 min) in anesthetized dogs. Before VE, L-NAME (n = 6), Meclo (n = 6), and L-NAME + Meclo (n = 6) produced significant increments in mean arterial pressure (MAP) of 12 +/- 2, 15 +/- 3, and 17 +/- 3 mmHg, respectively. VE did not change MAP in Meclo-treated dogs, but produced a significant elevation in the control dogs (14 +/- 6 mmHg), in L-NAME-treated dogs (17 +/- 6 mmHg), and in dogs pretreated with L-NAME + Meclo (12 +/- 5 mmHg). VE alone induced marked natriuretic responses in the control (38 +/- 9 to 562 +/- 86 mumol/min), L-NAME (31 +/- 9 to 664 +/- 65 mumol/min), and Meclo groups (41 +/- 10 to 699 +/- 51 mumol/min). However, this natriuretic response was attenuated in dogs pretreated with L-NAME + Meclo (12 +/- 4 to 185 +/- 52 mumol/ min). These results indicate that 1) blockade of both NO and PGs has significant diminishing effects on volume-induced natriuresis, 2) NO blockade alone impairs volume-induced natriuresis in a manner that requires further increases in MAP to restore the natriuresis, and 3) PG blockade alone does not curtail volume-induced natriuresis.
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Affiliation(s)
- J D Krier
- Department of Physiology and Biophysics, Mayo Medical School, Rochester, Minnesota 55905, USA
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47
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Zachariah PK, Krier JD. Hypertension and ambulatory blood pressure monitoring. Prim Care 1991; 18:651-62. [PMID: 1946792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Advancing technology will develop lighter, less expensive, more compatible, and more reliable ambulatory blood pressure recording devices, which will result in an increased use of the procedure in clinical practice. Future longitudinal prospective studies of normotensive and hypertensive subjects may authenticate the relationship between ambulatory blood pressure values and cardiovascular morbidity and mortality, thus enabling clinicians to generate guidelines for the diagnosis and treatment of hypertension. Until that happens, ambulatory blood pressure monitoring can provide meaningful supplemental information that overcomes the limitations of office blood pressure. In addition, various cardiovascular disorders may only be evaluated by using ambulatory blood pressure monitoring. Finally, ambulatory blood pressure monitoring is valuable in determining the efficacy of antihypertensive medications and improving the research trials of these drugs.
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Affiliation(s)
- P K Zachariah
- Division of Hypertension/Nephrology, Mayo Clinic, Jacksonville, Florida
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48
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Zachariah PK, Krier JD. Clinical uses of ambulatory blood pressure monitoring. J Hypertens Suppl 1991; 9:S7-11; discussion S11-2. [PMID: 2040906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In the past, the diagnosis and management of hypertension has been based on office blood pressure. However, office blood pressure is not always a true reflection of a patient's blood pressure profile. Since ambulatory blood pressure monitoring permits a large number of readings to be taken in the patient's usual environment, it may provide a more representative blood pressure profile. Indeed, ambulatory blood pressure has been better correlated than office blood pressure with the target-organ complications of hypertension. Office or white-coat hypertension (elevated blood pressure only when measured in the physician's office) has been reported in 12-21% of patients in mildly hypertensive sample populations. While office blood pressure and daytime ambulatory blood pressure values are reported to be similar in normotensive subjects, ambulatory systolic and diastolic readings in hypertensive subjects have been reported as, respectively, 4-15 mmHg and 3-10 mmHg lower than office blood pressure readings. In estimating a patient's mean blood pressure and diagnosing hypertension, the greater the number of recording hours the more accurate the estimate is likely to be; in addition, increasing the number of measurements per hour also improves accuracy and increases the sensitivity of the readings. An increased frequency and severity of target-organ damage has been associated with higher 24-h blood pressure variability. Although the diagnosis of hypertension should not be based on ambulatory blood pressure alone, there are many clinical problems for which ambulatory blood pressure can be useful.
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Affiliation(s)
- P K Zachariah
- Division of Hypertension and Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905
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