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Hultborn R, Weiss L, Tveit E, Lange S, Jennische E, Erlandsson MC, Johansson ME. Ex Vivo Vascular Imaging and Perfusion Studies of Normal Kidney and Tumor Vasculature. Cancers (Basel) 2024; 16:1939. [PMID: 38792017 PMCID: PMC11119251 DOI: 10.3390/cancers16101939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/10/2024] [Accepted: 05/15/2024] [Indexed: 05/26/2024] Open
Abstract
This work describes a comprehensive study of the vascular tree and perfusion characteristics of normal kidney and renal cell carcinoma. Methods: Nephrectomy specimens were perfused ex-vivo, and the regional blood flow was determined by infusion of radioactive microspheres. The vascular architecture was characterized by micronized barium sulphate infusion. Kidneys were subsequently sagitally sectioned, and autoradiograms were obtained to show the perfusate flow in relation to adjacent contact X-ray angiograms. Vascular resistance in defined tissue compartments was quantified, and finally, the tumor vasculature was 3D reconstructed via the micro-CT technique. Results show that the vascular tree of the kidney could be distinctly defined, and autoradiograms disclosed a high cortical flow. The peripheral resistance unit of the whole perfused specimen was 0.78 ± 0.40 (n = 26), while that of the renal cortex was 0.17 ± 0.07 (n = 15 with 114 samples). Micro-CT images from both cortex and medulla defined the vascular architecture. Angiograms from the renal tumors demonstrated a significant vascular heterogeneity within and between different tumors. A dense and irregular capillary network characterized peripheral tumor areas, whereas central parts of the tumors were less vascularized. Despite the dense capillarity, low perfusion through vessels with a diameter below 15 µm was seen on the autoradiograms. We conclude that micronized barium sulphate infusion may be used to demonstrate the vascular architecture in a complex organ. The vascular resistance was low, with little variation in the cortex of the normal kidney. Tumor tissue showed a considerable vascular structural heterogeneity with low perfusion through the peripheral nutritive capillaries and very poor perfusion of the central tumor, indicating intratumoral pressure exceeding the perfusion pressure. The merits and shortcomings of the various techniques used are discussed.
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Affiliation(s)
- Ragnar Hultborn
- Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden;
| | - Lilian Weiss
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden;
| | - Egil Tveit
- Department of Surgery, Sahlgrenska University Hospital, 413 45 Gothenburg, Sweden;
| | - Stefan Lange
- Department of Microbiology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden;
| | - Eva Jennische
- Department of Medical Chemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden;
| | - Malin C. Erlandsson
- Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden;
| | - Martin E. Johansson
- Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Center for Cancer Research, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden
- Department of Clinical Pathology, Sahlgrenska University Hospital, 413 45 Gothenburg, Sweden
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Kumaran GK, Hanukoglu I. Mapping the cytoskeletal architecture of renal tubules and surrounding peritubular capillaries in the kidney. Cytoskeleton (Hoboken) 2024; 81:227-237. [PMID: 37937511 DOI: 10.1002/cm.21809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 11/02/2023] [Accepted: 11/06/2023] [Indexed: 11/09/2023]
Abstract
The human kidney includes ~1 million nephrons which are long U-shaped tubules with convoluted segments that serve as filtration units. During the passage of the ultrafiltrate through a nephron, electrolytes and nutrients are re-absorbed into peritubular capillaries. The fluid remaining in the distal end of the renal tubules flows through the collecting ducts into the ureter. In this study, we generated high-resolution images of mouse kidney sections using confocal microscopy with only two fluorescently tagged biomarkers, F-actin binding phalloidin and CD34 antibodies as a marker for blood vessels. In tile-scan images of entire sections of mouse kidney (composed of >1000 images), the tubule segments are easily identifiable by their F-actin bundles on cell borders and the outlines of the peritubular capillaries by CD34 immunofluorescence. In the inner stripe of the medulla, the vascular bundles composed of vasa recta (straight vessels) could be easily distinguished from the peritubular capillaries by their full circular shapes. The highly vascular inner medulla and the papilla similarly have straight capillaries. About 95% of kidney volume is composed of renal tubules and blood vessels. Thus, our results show that relatively simple cytoskeletal mapping can be used to visualize the structural organization of the kidney. This method can also be applied to examine pathological changes in the kidney.
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Affiliation(s)
| | - Israel Hanukoglu
- Laboratory of Cell Biology, Ariel University, Ariel, Israel
- Etgar College of Engineering and Technology, Tel Aviv, Israel
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Ulpiano Trillig A, Damianaki A, Hendriks-Balk M, Brito W, Garessus J, Burnier M, Wuerzner G, Pruijm M. Determinants of Renal Micro-Perfusion as Assessed with Contrast-Enhanced Ultrasound in Healthy Males and Females. J Clin Med 2023; 12:4141. [PMID: 37373834 DOI: 10.3390/jcm12124141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/09/2023] [Accepted: 06/16/2023] [Indexed: 06/29/2023] Open
Abstract
(1) Background: The renal microcirculation is essential to maintain the renal function, but its determinants in humans have been poorly studied. Contrast-enhanced ultrasound (CEUS) allows the non-invasive quantification of the cortical micro-perfusion at the bedside using the perfusion index (PI). The aims of this study were to assess whether differences exist in PI between healthy males and females and to identify clinical determinants associated with cortical micro-perfusion. (2) Methods: Healthy, normotensive volunteers (eGFR > 60 mL/min/1.73 m2, no albuminuria) underwent CEUS under standardized conditions with the destruction-reperfusion (DR) technique. The mean PI of four DR sequences was reported as the primary outcome measure (3) Results: A total of 115 subjects (77 females and 38 males) completed the study; the mean ± SD age was, respectively, 37.1 ± 12.2 and 37.1 ± 12.7 years in females and males, and the mean eGFR was 105.9 ± 15.1 and 91.0 ± 17.4 mL/min/1.73 m2. The PI (median) was higher in females than in males, i.e., 2705 (IQR 1641-3777) vs. 1965 (IQR 1294-3346) arbitrary units (a.u), p = 0.02). A correlation analysis showed positive associations between PI and eGFR, female sex, heart rate, plasma renin activity (PRA) and plasma aldosterone concentrations (PAC), negative associations with potassium, bicarbonate and systolic blood pressure, and no associations with age, body mass index and renal resistive index (RRI). In a multivariate linear regression analysis, only PRA remained significantly associated with PI. (4) Conclusions: Although the PI was higher among females, this association was no longer significant after adjustment for covariates. There was no difference in females tested during the follicular or the luteal phases. In conclusion, the PI was only weakly influenced by classic clinical variables, but was positively associated with PRA, suggesting that the renin-angiotensin system plays a role in the regulation of the cortical micro-perfusion in humans. Identifying which other factors contribute to the large variations in micro-perfusion across individuals needs further study.
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Affiliation(s)
- Antonio Ulpiano Trillig
- Service of Nephrology and Hypertension, Lausanne University Hospital and University of Lausanne, Rue du Bugnon 17, 1005 Lausanne, Switzerland
| | - Aikaterini Damianaki
- Service of Nephrology and Hypertension, Lausanne University Hospital and University of Lausanne, Rue du Bugnon 17, 1005 Lausanne, Switzerland
| | - Mariëlle Hendriks-Balk
- Service of Nephrology and Hypertension, Lausanne University Hospital and University of Lausanne, Rue du Bugnon 17, 1005 Lausanne, Switzerland
| | - Wendy Brito
- Service of Nephrology and Hypertension, Lausanne University Hospital and University of Lausanne, Rue du Bugnon 17, 1005 Lausanne, Switzerland
| | - Jonas Garessus
- Service of Nephrology and Hypertension, Lausanne University Hospital and University of Lausanne, Rue du Bugnon 17, 1005 Lausanne, Switzerland
| | - Michel Burnier
- Service of Nephrology and Hypertension, Lausanne University Hospital and University of Lausanne, Rue du Bugnon 17, 1005 Lausanne, Switzerland
| | - Grégoire Wuerzner
- Service of Nephrology and Hypertension, Lausanne University Hospital and University of Lausanne, Rue du Bugnon 17, 1005 Lausanne, Switzerland
| | - Menno Pruijm
- Service of Nephrology and Hypertension, Lausanne University Hospital and University of Lausanne, Rue du Bugnon 17, 1005 Lausanne, Switzerland
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Lilley RJ, Taylor KD, Wildman SSP, Peppiatt-Wildman CM. Inflammatory mediators act at renal pericytes to elicit contraction of vasa recta and reduce pericyte density along the kidney medullary vascular network. Front Physiol 2023; 14:1194803. [PMID: 37362447 PMCID: PMC10288992 DOI: 10.3389/fphys.2023.1194803] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 06/01/2023] [Indexed: 06/28/2023] Open
Abstract
Introduction: Regardless of initiating cause, renal injury promotes a potent pro-inflammatory environment in the outer medulla and a concomitant sustained decrease in medullary blood flow (MBF). This decline in MBF is believed to be one of the critical events in the pathogenesis of acute kidney injury (AKI), yet the precise cellular mechanism underlying this are still to be fully elucidated. MBF is regulated by contractile pericyte cells that reside on the descending vasa recta (DVR) capillaries, which are the primary source of blood flow to the medulla. Methods: Using the rat and murine live kidney slice models, we investigated the acute effects of key medullary inflammatory mediators TNF-α, IL-1β, IL-33, IL-18, C3a and C5a on vasa recta pericytes, the effect of AT1-R blocker Losartan on pro-inflammatory mediator activity at vasa recta pericytes, and the effect of 4-hour sustained exposure on immunolabelled NG2+ pericytes. Results and discussion: Exposure of rat and mouse kidney slices to TNF-α, IL-18, IL-33, and C5a demonstrated a real-time pericyte-mediated constriction of DVR. When pro-inflammatory mediators were applied in the presence of Losartan the inflammatory mediator-mediated constriction that had previously been observed was significantly attenuated. When live kidney slices were exposed to inflammatory mediators for 4-h, we noted a significant reduction in the number of NG2+ positive pericytes along vasa recta capillaries in both rat and murine kidney slices. Data collected in this study demonstrate that inflammatory mediators can dysregulate pericytes to constrict DVR diameter and reduce the density of pericytes along vasa recta vessels, further diminishing the regulatory capacity of the capillary network. We postulate that preliminary findings here suggest pericytes play a role in AKI.
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Affiliation(s)
- Rebecca J. Lilley
- Division of Natural Sciences, University of Kent, Kent, United Kingdom
| | - Kirsti D. Taylor
- Division of Natural Sciences, University of Kent, Kent, United Kingdom
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Prasad PV, Li LP, Hack B, Leloudas N, Sprague SM. Quantitative Blood Oxygenation Level Dependent Magnetic Resonance Imaging for Estimating Intra-renal Oxygen Availability Demonstrates Kidneys Are Hypoxemic in Human CKD. Kidney Int Rep 2023; 8:1057-1067. [PMID: 37180507 PMCID: PMC10166744 DOI: 10.1016/j.ekir.2023.02.1092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/08/2023] [Accepted: 02/27/2023] [Indexed: 03/09/2023] Open
Abstract
Introduction Kidney blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) has shown great promise in evaluating relative oxygen availability. This method is quite efficacious in evaluating acute responses to physiological and pharmacologic maneuvers. Its outcome parameter, R2∗ is defined as the apparent spin-spin relaxation rate measured in the presence of magnetic susceptibility differences and it is measured using gradient echo MRI. Although associations between R2∗ and renal function decline have been described, it remains uncertain to what extent R2∗ is a true reflection of tissue oxygenation. This is primarily because of not taking into account the confounding factors, especially fractional blood volume (fBV) in tissue. Methods This case-control study included 7 healthy controls and 6 patients with diabetes and chronic kidney disease (CKD). Using data before and after administration of ferumoxytol, a blood pool MRI contrast media, the fBVs in kidney cortex and medulla were measured. Results This pilot study independently measured fBV in kidney cortex (0.23 ± 0.03 vs. 0.17 ± 0.03) and medulla (0.36 ± 0.08 vs. 0.25 ± 0.03) in a small number of healthy controls (n = 7) versus CKD (n = 6). These were then combined with BOLD MRI measurements to estimate oxygen saturation of hemoglobin (StO2) (0.87 ± 0.03 vs. 0.72 ± 0.10 in cortex; 0.82 ± 0.05 vs. 0.72 ± 0.06 in medulla) and partial pressure of oxygen in blood (bloodPO2) (55.4 ± 6.5 vs. 38.4 ± 7.6 mm Hg in cortex; 48.4 ± 6.2 vs. 38.1 ± 4.5 mm Hg in medulla) in control versus CKD. The results for the first time demonstrate that cortex is normoxemic in controls and moderately hypoxemic in CKD. In the medulla, it is mildly hypoxemic in controls and moderately hypoxemic in CKD. Whereas fBV, StO2, and bloodPO2 were strongly associated with estimated glomerular filtration rate (eGFR), R2∗ was not. Conclusion Our results support the feasibility of quantitatively assessing oxygen availability using noninvasive quantitative BOLD MRI that could be translated to the clinic.
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Affiliation(s)
- Pottumarthi V. Prasad
- Department of Radiology, NorthShore University HealthSystem, Evanston, Illinois, USA
- Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA
| | - Lu-Ping Li
- Department of Radiology, NorthShore University HealthSystem, Evanston, Illinois, USA
- Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA
| | - Bradley Hack
- Department of Radiology, NorthShore University HealthSystem, Evanston, Illinois, USA
| | - Nondas Leloudas
- Department of Radiology, NorthShore University HealthSystem, Evanston, Illinois, USA
| | - Stuart M. Sprague
- Department of Medicine, NorthShore University HealthSystem, Evanston, Illinois, USA
- Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA
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Kuo W, Le NA, Spingler B, Wenger RH, Kipar A, Hetzel U, Schulz G, Müller B, Kurtcuoglu V. Simultaneous Three-Dimensional Vascular and Tubular Imaging of Whole Mouse Kidneys With X-ray μCT. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2020; 26:731-740. [PMID: 32627730 DOI: 10.1017/s1431927620001725] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Concurrent three-dimensional imaging of the renal vascular and tubular systems on the whole-kidney scale with capillary level resolution is labor-intensive and technically difficult. Approaches based on vascular corrosion casting and X-ray micro computed tomography (μCT), for example, suffer from vascular filling artifacts and necessitate imaging with an additional modality to acquire tubules. In this work, we report on a new sample preparation, image acquisition, and quantification protocol for simultaneous vascular and tubular μCT imaging of whole, uncorroded mouse kidneys. The protocol consists of vascular perfusion with the water-soluble, aldehyde-fixable, polymeric X-ray contrast agent XlinCA, followed by laboratory-source μCT imaging and structural analysis using the freely available Fiji/ImageJ software. We achieved consistent filling of the entire capillary bed and staining of the tubules in the cortex and outer medulla. After imaging at isotropic voxel sizes of 3.3 and 4.4 μm, we segmented vascular and tubular systems and quantified luminal volumes, surface areas, diffusion distances, and vessel path lengths. This protocol permits the analysis of vascular and tubular parameters with higher reliability than vascular corrosion casting, less labor than serial sectioning and leaves tissue intact for subsequent histological examination with light and electron microscopy.
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Affiliation(s)
- Willy Kuo
- University of Zurich, Institute of Physiology, Winterthurerstrasse 190, 8057Zurich, Switzerland
- University of Zurich, National Centre of Competence in Research, Kidney. CH, Winterthurerstrasse 190, 8057Zurich, Switzerland
- University of Basel, Biomaterials Science Center, Department of Biomedical Engineering, Gewerbestrasse 14, 4123Allschwil, Switzerland
| | - Ngoc An Le
- University of Zurich, Department of Chemistry, Winterthurerstrasse 190, 8057Zurich, Switzerland
| | - Bernhard Spingler
- University of Zurich, Department of Chemistry, Winterthurerstrasse 190, 8057Zurich, Switzerland
| | - Roland H Wenger
- University of Zurich, Institute of Physiology, Winterthurerstrasse 190, 8057Zurich, Switzerland
- University of Zurich, National Centre of Competence in Research, Kidney. CH, Winterthurerstrasse 190, 8057Zurich, Switzerland
| | - Anja Kipar
- University of Zurich, Laboratory for Animal Model Pathology (LAMP), Institute of Veterinary Pathology, Vetsuisse Faculty, Winterthurerstrasse 268, 8057Zurich, Switzerland
| | - Udo Hetzel
- University of Zurich, Electron Microscopy Unit, Institute of Veterinary Pathology, Vetsuisse Faculty, Winterthurerstrasse 268, 8057Zurich, Switzerland
| | - Georg Schulz
- University of Basel, Biomaterials Science Center, Department of Biomedical Engineering, Gewerbestrasse 14, 4123Allschwil, Switzerland
| | - Bert Müller
- University of Basel, Biomaterials Science Center, Department of Biomedical Engineering, Gewerbestrasse 14, 4123Allschwil, Switzerland
| | - Vartan Kurtcuoglu
- University of Zurich, Institute of Physiology, Winterthurerstrasse 190, 8057Zurich, Switzerland
- University of Zurich, National Centre of Competence in Research, Kidney. CH, Winterthurerstrasse 190, 8057Zurich, Switzerland
- University of Zurich, Zurich Center for Integrative Human Physiology, 8057Zurich, Switzerland
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Le NA, Kuo W, Müller B, Kurtcuoglu V, Spingler B. Crosslinkable polymeric contrast agent for high-resolution X-ray imaging of the vascular system. Chem Commun (Camb) 2020; 56:5885-5888. [DOI: 10.1039/c9cc09883f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A contrast agent for X-ray micro computed tomography (μCT), called XlinCA, that combines reliable perfusion and permanent retention and contrast properties, was developed for ex vivo imaging.
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Affiliation(s)
- Ngoc An Le
- Department of Chemistry
- University of Zurich
- 8057 Zurich
- Switzerland
| | - Willy Kuo
- Institute of Physiology
- University of Zurich
- 8057 Zurich
- Switzerland
- National Centre of Competence in Research
| | - Bert Müller
- Biomaterials Science Center
- Department of Biomedical Engineering
- University of Basel
- 4123 Allschwil
- Switzerland
| | - Vartan Kurtcuoglu
- Institute of Physiology
- University of Zurich
- 8057 Zurich
- Switzerland
- National Centre of Competence in Research
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O'Connor PM. Going with the flow: updating old techniques to gain insight into regional kidney hemodynamics. Physiol Rep 2019; 7:e14103. [PMID: 31090164 PMCID: PMC6517335 DOI: 10.14814/phy2.14103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Paul M. O'Connor
- Department of Physiology Medical College of Georgia Augusta Georgia
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