Reversible Unilateral Ureteral Obstruction Research Articles

Establishment and Application a Novel Reversible Unilateral Ureteral Obstruction (RUUO) Mouse Model and in Mechanism Study of AKI to CKD

Establishment and Application a Novel Reversible Unilateral Ureteral Obstruction (RUUO) Mouse Model and in Mechanism Study of AKI to CKD

Cells of the renin lineage promote kidney regeneration post-release of ureteral obstruction in neonatal mice.

Ureteral obstruction leads to significant changes in kidney renin expression. It is unclear whether those changes are responsible for the progression of kidney damage, repair, or regeneration. In the current study, we aimed to elucidate the contribution of renin-producing cells (RPCs) and the cells of the renin lineage (CoRL) towards kidney damage and regeneration using a model of partial and reversible unilateral ureteral obstruction (pUUO) in neonatal mice. Renin cells are progenitors for other renal cell types collectively called CoRL. We labeled the CoRL with green fluorescent protein (GFP) using genetic approaches. We performed lineage tracing to analyze the changes in the distribution of CoRL during and after the release of obstruction. We also ablated the RPCs and CoRL by cell-specific expression of Diphtheria Toxin Sub-unit A (DTA). Finally, we evaluated the kidney damage and regeneration during and after the release of obstruction in the absence of CoRL. In the obstructed kidneys, there was a 163% increase in the renin-positive area and a remarkable increase in the distribution of GFP+ CoRL. Relief of obstruction abrogated these changes. In addition, DTA-expressing animals did not respond to pUUO with increased RPCs and CoRL. Moreover, reduction in CoRL significantly compromised the kidney's ability to recover from the damage after the release of obstruction. CoRL play a role in the regeneration of the kidneys post-relief of obstruction.

Current kidney function parameters overestimate kidney tissue repair in reversible experimental kidney disease

Although underlying mechanisms and the clinical course of kidney disease progression are well described, less is known about potential disease reversibility. Therefore, to analyze kidney recovery, we adapted a commonly used murine chronic kidney disease (CKD) model of 2,8- dihydroxyadenine (2,8-DHA) crystal-induced nephropathy to study disease recovery and efficacy of disease-modifying interventions. The recovery phase after CKD was characterized by improved kidney function after two weeks which remained stable thereafter. By contrast, even after eight weeks recovery, tubular injury and inflammation were only partially reduced, and fibrosis persisted. Deep-learning-based histologic analysis of 8,604 glomeruli and 596,614 tubular cross sections revealed numerous tubules had undergone either prominent dilation or complete atrophy, leading to atubular glomeruli and irreversible nephron loss. We confirmed these findings in a second CKD model, reversible unilateral ureteral obstruction, in which a rapid improvement of glomerular filtration rate during recovery also did not reflect the permanent histologic kidney injury. In 2,8-DHA nephropathy, increased drinking volume was highly effective in disease prevention. However, in therapeutic approaches, high fluid intake was only effective in moderate but not severe CKD and established tissue injury was again poorly reflective of kidney function parameters. The injury was particularly localized in the medulla, which is often not analyzed. Thus, recovery after crystal- or obstruction-induced CKD is characterized by ongoing tissue injury, fibrosis, and nephron loss, but not reflected by standard measures of kidney function. Hence, our data might aid in designing kidney recovery studies and suggest the need for biomarkers specifically monitoring intra-kidney tissue injury.

O45: DEFINING CELL-ENRICHED MICRORNAS TO SUPPORT RATIONAL BIOMARKER SELECTION IN HUMAN RENAL TRANSPLANTATION

Abstract Introduction MicroRNAs are promising biomarkers of renal disease, however the cellular origin of their expression is usually unclear limiting their interpretation when measured in renal biopsies and urine. We hypothesised that by first defining renal cell-enriched microRNAs, we could select biomarkers based on the expected histopathological profile. Method Small RNA-sequencing of cortical, proximal tubular (LTL), macrophage (F480), endothelial (CD31) and fibroblast (PDGFRb) populations from the reversible unilateral ureteric obstruction (rUUO) murine model was performed. Hierarchical clustering was used to identify clusters. Findings were translated into an ischaemia reperfusion injury (IRI) model and then into urine samples from renal transplant recipients (n=16) with delayed graft function (DGF) vs. those with primary function. Result Kidney injury resulted in significant macrophage infiltration and tubular injury which improved upon reversal. We characterised novel microRNA clusters enriched for each cell type. With injury there was a significant increase in macrophage (p<0.0001), fibroblast (p<0.01) and decrease in proximal tubule (p<0.0001) enriched microRNAs vs. non-enriched microRNAs. We validated macrophage enriched miR-18a, miR-16 and tubular enriched miR-194 in the IRI model, demonstrating that microRNA expression reflected the histological profile. In humans, urinary miR-16 (FC 16.9; p<0.05) and miR-18a (FC 10: p=0.06) were upregulated at day 2 in patients with DGF; outperforming the traditional injury marker KIM1. Conclusion This is the first study to characterise cell-enriched microRNAs during renal injury and repair. By defining the source of microRNA expression we were able to rationally select miR-16 and miR-18a as promising urinary biomarkers of renal injury. Take-home message We have found that microRNAs have differences in expression between cell types and renal injury states which is important when considering microRNA expression in samples composed of varying cellular composition. By defining the cellular origins of microRNA expression we were able to rationally select microRNA biomarkers of human renal injury.

Identifying cell-enriched miRNAs in kidney injury and repair.

Small noncoding RNAs, miRNAs (miRNAs), are emerging as important modulators in the pathogenesis of kidney disease, with potential as biomarkers of kidney disease onset, progression, or therapeutic efficacy. Bulk tissue small RNA-sequencing (sRNA-Seq) and microarrays are widely used to identify dysregulated miRNA expression but are limited by the lack of precision regarding the cellular origin of the miRNA. In this study, we performed cell-specific sRNA-Seq on tubular cells, endothelial cells, PDGFR-β+ cells, and macrophages isolated from injured and repairing kidneys in the murine reversible unilateral ureteric obstruction model. We devised an unbiased bioinformatics pipeline to define the miRNA enrichment within these cell populations, constructing a miRNA catalog of injury and repair. Our analysis revealed that a significant proportion of cell-specific miRNAs in healthy animals were no longer specific following injury. We then applied this knowledge of the relative cell specificity of miRNAs to deconvolute bulk miRNA expression profiles in the renal cortex in murine models and human kidney disease. Finally, we used our data-driven approach to rationally select macrophage-enriched miR-16-5p and miR-18a-5p and demonstrate that they are promising urinary biomarkers of acute kidney injury in renal transplant recipients.

SiRNA-silencing of CD40 attenuates unilateral ureteral obstruction-induced kidney injury in mice.

BackgroundThe costimulatory CD40-CD40L pathway plays a role in kidney inflammation. We have previously reported that renal CD40 upregulation precedes cellular interstitial infiltrate and fibrosis in the unilateral ureteral obstruction (UUO) model. Here we sought to evaluate whether the administration of siRNA-CD40 has a therapeutic effect in a reversible unilateral ureteral obstruction (D-UUO) mice model.MethodsEight week-old C57BL6J male mice were divided into four groups: Vehicle (Phosphate-buffered saline) (n = 8); siRNA SC (non-specific siRNA) (n = 6); siRNA-CD40 (n = 8) and WT (wild type) (n = 6) mice. UUO was performed with a microvascular clamp. At day 3 after surgery, the ureteral clamp was removed and nephrectomy of the contralateral kidney was performed. Immediately, PBS, siRNA SC (50μg) or siRNA-CD40 (50μg) was administrated via the tail vein. Mice were killed 48h hours after the siRNA or saline administration. Wild type (WT) mice were used as controls. Blood samples were collected for measuring creatinine and blood urea nitrogen (BUN). Histology and kidney mRNA expression were performed.ResultsThe administration of siRNA-CD40 reduced significantly the severity of acute renal failure associated with UUO. Pathologic analysis showed reduction of tubular dilation, interstitial fibrosis, F4/80 macrophage and CD3 (T cell) infiltration in animals treated with siRNA-CD40. Furthermore, kidney mRNA gene expression analysis showed significantly lower levels of macrophage markers (F4/80 and Mannose receptor), fibrosis matrix proteins (Fibronectin, MMP-9, Collagen IV and α-SMA), pro-inflammatory cytokines (iNOS and MCP-1) and the pro-fibrotic molecule TGF-β1 in siRNA-CD40.ConclusionsThe administration of siRNA-CD40 therapy reduces the severity of the acute kidney injury induced by obstructive uropathy and promotes kidney repair. This strategy seems suitable to be tested in humans.

Reversal Unilateral Ureteral Obstruction: A Mice Experimental Model

Background/Aims: Reversible unilateral ureteral obstruction (R-UUO) is a model of renal injury used to study the structural and functional recovery of the kidneys after relief of the obstruction. This model has a prominent potential for the study of inflammatory and immune processes, cellular and tissue regeneration. Here we sought to describe a model of renal injury and repair R-UUO in mice. Methods: Eight week-old C57BL/6J male mice were divided into 5 groups (n = 5 each): UUO day 1, 2, 3, 4 and 5. R-UUO was performed with a microvascular clamp. At day 3, the ureteral clamp was removed and nephrectomy of the contralateral kidney was performed. Mice were sacrificed 48 h afterwards (day 5). An extra group with unilateral nephrectomy without UUO was added. Wild type mice were used as controls. Blood and tissue samples were collected for creatinine, immunohistochemistry and kidney mRNA gene expression analysis. Results: In the analysis of the obstructed kidney, we observed acute kidney injury with creatinine that doubled its baseline value; histological signs of tubular damage; increased inflammatory response evaluated by F4/80 macrophage; upregulation of pro-inflammatory and pro-fibrotic cytokines such as IL-2, MCP-1, CD40 and TGF-β1 and increased α-smooth muscle actin staining and mild fibrosis. Once the clamp was removed, we observed the amelioration of the kidney function, pathological lesions and the inflammatory response. Conclusion: This R-UUO model is an easy, reproducible and reliable method to assess kidney recovery after obstructive uropathy. In this setting, the use of this model may help to a better understanding of the process of kidney repair.

The Effect of Arabic Gum on Renal Function in Reversible Unilateral Ureteric Obstruction.

Arabic gum (AG) has antioxidant and anti-inflammatory properties. However, the effect of AG in ureteric obstruction (UO) has not been investigated yet. Male rats underwent reversible left unilateral UO (UUO) for 72 h. Group AG-1 (n = 12) received AG 15 g/kg/day dissolved in drinking water starting seven days before and continuing throughout the period of the UUO, whereas group Vx-1 (n = 8) had only water. Group AG-2 (n = 12) and Vx-2 (n = 8) had similar protocols as AG-1 and Vx-1, respectively, but underwent terminal experiments to measure renal functions, six days post-UUO reversal. Arabic gum significantly attenuated the UUO-induced increase in the tissue level of malonedialdehyde and superoxide dismutase and the rise in the gene expression of TNF-α, TGF-β1, and p53 in AG-1 compared to Vx-1. It also attenuated the severity of tubular dilatation. However, AG did not affect the alterations in the renal blood flow or glomerular filtration rate. The fractional sodium excretion was lower in AG-2 but did not reach statistical significance (0.40 ± 0.11 vs 0.74 ± 0.12, p = 0.07). AG attenuated the UUO-induced rise in oxidative stress markers and proinflammatory and profibrotic cytokines and the degree of renal tubular dilatation, indicating a protective effect in obstructive nephropathy.

The Effect of Estradiol on Renal Function in Reversible and Irreversible Unilateral Ureteral Obstruction in Rats

BACKGROUND: The ureteral obstruction (UO) is the most common clinical disorders. This study was designed to investigate the renoprotective effect of estradiol in unilateral UO (UUO) and reversible UUO (RUUO).METHODS: Eighty-four ovareictomized Wistar rats were assigned into 14 groups. Group 1 was sham operated group. All the groups 2-14 were subject to UUO, however they received additional treatments. Group 2-4 received test substances (vehicle, 0.1 or 0.05 mg/kg of estradiol) and sacrificed after 3 days. Group 5-7 received test substances and after 3 days followed by RUUO (obstruction removal) and after one day post RUUO were sacrificed. Group 8-9 followed by RUUO after 3 days and simultaneously received estradiol and after one day post RUUO were sacrificed. Group 10-12 followed by RUUO after 3 days and simultaneously received test substances and after 3 days post RUUO were sacrificed. Group 13-14 received test substances followed by RUUO and received test substances again and after 3 days post RUUO were sacrificed.RESULTS: The estradiol reduced body weight significantly (p<0.05) in UUO, and the uterus weight (UW) increased significantly by estradiol (p<0.05). The increased serum levels of blood urea nitrogen (BUN) and creatinine (Cr), and kidney weight (KW) induced by UUO (p<0.05) were not attenuated by estradiol. Estradiol treatment did not alter the levels of BUN, Cr, KW, Cr clearance (CrCl), urine sodium excretion and urine flow when compared with control.CONCLUSION: Although the protective role of estradiol in cardiovascular system is well accepted, however our findings suggest that its protection during UUO or after RUUO in renal system cannot be certain.KEYWORDS: estradiol, ureteral obstruction, renal function, rat

Intravoxel Incoherent Motion and Arterial Spin Labeling MRI Analysis of Reversible Unilateral Ureteral Obstruction in Rats.

Renal fibrosis is a common consequence of chronic kidney disease (CKD) and is the mechanism by which various forms of CKD progress to endstage renal failure. Accurate assessment of renal fibrosis is important for treatment. To measure longitudinal changes of intravoxel incoherent motion (IVIM) and arterial spin labeling (ASL) before and after reversible unilateral ureteral obstruction in an animal model. Self-controlled animal study. Surgical obstruction of the ureters was performed and then removed after 5 days. Rats were scanned on Days 0, 1, 3, and 5 after creating the obstruction and on Days 4, 7, and 12 after releasing the obstruction. 3.0T/IVIM/ASL. The apparent diffusion coefficient (ADC), pure molecular diffusion (D), perfusion fraction (f), pseudodiffusion (D*), and renal blood flow (RBF) obtained from the ASL were measured. Using SPSS v. 20.0 software, P < 0.05 were considered statistically significant. The data from each timepoint were compared using one-way analysis of variance and correlation analysis was applied to various parameters. The postobstruction kidneys showed renal tubule swelling and increased collagen fiber content. Renal tubule swelling was relieved after reversing the obstruction, but Masson staining and cell density analysis revealed progressive changes that were primarily localized to the medulla. In general, ADC, D, f, D*, and RBF decreased with time during the 5 days of obstruction, and increased after release of the obstruction. ADC positively correlated with D, f, D*, and RBF (r = 0.415, r = 0.634, r = 0.465 r = 0.586, P < 0.001, respectively) in the cortex in this study. Also, ADC showed a positive correlation with D, f, and D* (r = 0.724, r = 0.749, r = 0.151, P < 0.001, respectively) in the medulla. Kidney perfusion was the major factor affecting ADC. Functional imaging may be useful for following progression of CKD. 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:288-296.

The Role of Mas Receptor on Renal Hemodynamic Responses to Angiotensin 1-7 in Both Irreversible and Reversible Unilateral Ureteral Obstruction Rats.

Background:Unilateral ureteral obstruction (UUO) alters the expression of renin-angiotensin system (RAS) components and angiotensin 1-7 (Ang 1-7) as a main arm of RAS is affected by UUO. The role of Mas receptor antagonist (A779) was examined in renal hemodynamic responses to Ang 1-7 in 3-day UUO and UUO removal (RUUO) in rats.Materials and Methods:Forty-five male Wistar rats were randomly divided into three groups of sham operated, UUO, and RUUO, while each group was divided into two subgroups treated with vehicle or A779. Renal blood flow (RBF) and renal vascular resistance (RVR) responses to graded Ang 1-7 infusion were measured at controlled renal perfusion pressure.Results:Mean arterial pressure response to Ang 1-7 was increased in vehicle-treated subgroup significantly (P < 0.05) when compared with A779-treated subgroup. However, such observation was not seen in UUO and RUUO rats. The graded Ang 1-7 infusion increased RBF and decreased RVR significantly in vehicle-treated rats (P < 0.005). Furthermore, a significant difference was found between vehicle and A779-treated subgroups in sham, UUO, and RUUO groups (P < 0.005).Conclusion:Ang 1-7 could alter the kidney hemodynamics responses in ureteral obstruction models.

Renal blood flow and vascular resistance responses to angiotensin II in irreversible and reversible unilateral ureteral obstruction rats; the role of angiotensin II type 1 &amp; 2 receptors

Background: Unilateral ureteral obstruction (UUO) alters the expression of renin-angiotensin system (RAS) components and angiotensin II (Ang II) as the main arm of RAS is affected by UUO. Objectives: In this study the role of Ang II subtypes 1 and 2 receptors (AT1R and AT2R) antagonists (losartan and PD123319) was examined in renal hemodynamic responses to graded Ang II infusion in sham, 3-day UUO and removal UUO (RUUO) models in rats. Materials and Methods: Seventy-one male Wistar rats randomly divided into three different sets of animal models; sham-operated, UUO and RUUO that each set contains three groups treated with vehicle, losartan, and PD123319. Renal vascular responses to Ang II infusion were measured at controlled renal perfusion pressure (RPP). Results: The graded Ang II infusion decreased renal blood flow (RBF), increased renal vascular resistance (RVR) and mean arterial pressure (MAP) in vehicle or PD123319 treated groups significantly (P<0.005), but no significant difference was found between these treated groups. However, RBF, RVR and MAP responses to graded Ang II infusion in losartan-treated rats were attenuated significantly when compared with vehicle or PD123319 treated groups (P<0.05). In addition, the RBF, RVR and MAP responses to Ang II were not similar in sham, UUO and RUUO rats treated with losartan. Conclusions: Vascular responses to Ang II in UUO and RUUO rat model treated with losartan is not as the normal pattern.

Establishment and observation of a new and ideal reversible model of PUUO

Objective: We established a novel procedure to generate a reversible partial unilateral ureteral obstruction (PUUO) in rabbit. The method allows us to reliably measure the degree of ureteral obstruction in live animals, and thus could be a useful tool for studying kidney diseases.Methods: Thirty rabbits of clean grade were divided randomly into sham control group and obstruction (PUUO) group. Each rabbit in this study received the same blocking surgery, in which the upper ureter was curvilinearly incised and inserted with two F6 ureteral catheters that were connected with a tee joint valve. Ureteral obstruction was created and released through the valve adjustment. Serum creatinine and ultrasonographic measurements were performed preoperatively, on the fifth and tenth days after obstruction surgery, and on the 10th and 20th day, respectively, after the relief of the obstruction. Pathological measurements were taken in two randomly chosen rabbits of each group on the 10th day after surgery and on the 20th day after obstruction relief.Results: Data showed that the serum creatinine went transiently up and down in the early days and then remained a little bit higher in the following days after obstruction surgery. The morphology in obstructed kidney changed significantly on the 10th day postoperatively, compared to the sham control group. The obvious differences were also observed in pathology tests. After the relief of obstruction, the volume of renal pelvis (V), renal cortical thickness (RCT), and pathological impairment were partially reversed.Conclusions: Those findings indicate our procedure generate a successful and reversible PUUO animal model. It is a reliable and simple procedure for generating an animal model for reversible PUUO. The feasibility and significance of the new method was confirmed through ultrasonographic and pathological results.

MP67-19 ALISKIREN PROVIDES INCOMPLETE PROTECTION OF THE KIDNEY IN UNILATERAL URETERIC OBSTRUCTION IN THE RAT

You have accessJournal of UrologyStone Disease: Basic Research & Pathophysiology II1 Apr 2016MP67-19 ALISKIREN PROVIDES INCOMPLETE PROTECTION OF THE KIDNEY IN UNILATERAL URETERIC OBSTRUCTION IN THE RAT Fayez Hammad and Loay Lubbad Fayez HammadFayez Hammad More articles by this author and Loay LubbadLoay Lubbad More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.1335AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Ureteric obstruction (UO) is a common urological condition caused by several conditions such as urolithiasis and might lead to renal impairment. UO induces alterations in renin angiotensin system (RAS) which plays an important role in obstruction-induced renal dysfunction. Renin catalyzes the first and rate limiting step of RAS. However, until recently, direct renin inhibitors were not used effectively in clinical practice due to toxicity, poor bioavailability and limited efficacy. Aliskiren is the first commercially available FDA-approved oral direct renin inhibitor. Very few studies showed that aliskiren ameliorates some of the UO-induced markers of acute renal injury. However, these protective effects do not necessarily imply an improvement in the UO-induced alterations in some of the clinically more relevant parameters such as the glomerular filtration rate (GFR), renal blood flow (RBF) and tubular functions. Indeed, the effect of aliskiren on these parameters in the post-obstruction period has not been studied yet. Thus, the aim of this study was to investigate the effect of aliskiren on the alterations in renal dysfunction following reversible unilateral UO in the rat. METHODS Male Wistar rats underwent reversible left UO for 72 hours. Group-1 (n=10) received aliskiren (60 mg/kg/day) dissolved in water by oral gavage starting one day before and continued throughout the period of UO until the terminal experiment 5 days post reversal when the renal functions were measured using clearance techniques. Group-2 (n=10) underwent similar protocol but had drinking water only. In addition, gene expression of some markers of kidney injury was measured in the kidney tissue using PCR technique. RESULTS The mean arterial blood pressure and heart rate in both groups were similar. UO affected all hemodynamic and tubular parameters in the affected kidney. So in Group-2, left RBF, was 57% of the right RBF (1.82±0.12 vs. 3.19±0.40, P<0.01). Similarly, left GFR was 55% that of the right GFR (0.81±0.08 vs. 1.44±0.09, P<0.01). On the other hand, the left fractional excretion of sodium (FENa) was higher than the right FENa (0.76±0.17 vs. 0.56±0.09, P<0.05). Aliskiren attenuated the UO-related alterations in hemodynamic parameters; so when the left obstructed kidney in Group-2 and Group-1 were compared, RBF was significantly higher in Group-1 (2.44±0.30 vs. 1.82±0.12, P=0.049). GFR was also higher in Group-1 (1.02±0.10 vs. 0.81±0.08, P=0.07) but did not reach statistical significance. On the other hand, the left renal FENa was similar in both groups (0.53±0.08 vs. 0.76±0.17, P=0.12). Aliskiren also decreased the gene expressions of some of the markers of kidney injury such as Lipocalin-2 (2.7±0.2 vs. 5.5±1.2, P=0.03). CONCLUSIONS Aliskiren attenuated the UO-induced alterations in the hemodynamic renal parameters and some of the markers of kidney injury but not the tubular alterations indicating an incomplete protective effect of this renin inhibitor © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e888 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Fayez Hammad More articles by this author Loay Lubbad More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

A Murine Model of Irreversible and Reversible Unilateral Ureteric Obstruction

Obstruction of the kidney may affect native or transplanted kidneys and results in kidney injury and scarring. Presented here is a model of obstructive nephropathy induced by unilateral ureteric obstruction (UUO), which can either be irreversible (UUO) or reversible (R-UUO). In the irreversible UUO model, the ureter may be obstructed for variable periods of time in order to induce increasingly severe renal inflammation and interstitial fibrotic scarring. In the reversible R-UUO model the ureter is obstructed to induce hydronephrosis, tubular dilation and inflammation. After a suitable period of time the ureteric obstruction is then surgically reversed by anastomosis of the severed previously obstructed ureter to the bladder in order to allow complete decompression of the kidney and restoration of urinary flow to the bladder. The irreversible UUO model has been used to investigate various aspects of renal inflammation and scarring including the pathogenesis of disease and the testing of potential anti-inflammatory or anti-fibrotic therapies. The more challenging model of R-UUO has been used by some investigators and does offer significant research potential as it allows the study of inflammatory and immune processes and tissue remodeling in an injured and scarred kidney following the removal of the injurious stimulus. As a result, the R-UUO model offers investigators the opportunity to explore the resolution of kidney inflammation together with key aspects of tissue repair. These experimental models are of relevance to human disease as patients often present with obstruction of the renal tract that requires decompression and are commonly left with significant residual kidney impairment that has no current treatment options and may lead to eventual end stage kidney failure.

A murine model of irreversible and reversible unilateral ureteric obstruction.

Obstruction of the kidney may affect native or transplanted kidneys and results in kidney injury and scarring. Presented here is a model of obstructive nephropathy induced by unilateral ureteric obstruction (UUO), which can either be irreversible (UUO) or reversible (R-UUO). In the irreversible UUO model, the ureter may be obstructed for variable periods of time in order to induce increasingly severe renal inflammation and interstitial fibrotic scarring. In the reversible R-UUO model the ureter is obstructed to induce hydronephrosis, tubular dilation and inflammation. After a suitable period of time the ureteric obstruction is then surgically reversed by anastomosis of the severed previously obstructed ureter to the bladder in order to allow complete decompression of the kidney and restoration of urinary flow to the bladder. The irreversible UUO model has been used to investigate various aspects of renal inflammation and scarring including the pathogenesis of disease and the testing of potential anti-inflammatory or anti-fibrotic therapies. The more challenging model of R-UUO has been used by some investigators and does offer significant research potential as it allows the study of inflammatory and immune processes and tissue remodeling in an injured and scarred kidney following the removal of the injurious stimulus. As a result, the R-UUO model offers investigators the opportunity to explore the resolution of kidney inflammation together with key aspects of tissue repair. These experimental models are of relevance to human disease as patients often present with obstruction of the renal tract that requires decompression and are commonly left with significant residual kidney impairment that has no current treatment options and may lead to eventual end stage kidney failure.

Bosentan normalizes the GFR response to renal nerve stimulation following reversible unilateral ureteric obstruction in the rat.

We investigated the renal response to direct renal nerve stimulation, 2 weeks following reversal of 24-h unilateral (left) ureteric obstruction. Renal nerve stimulation caused a 13-15 % fall in renal blood flow, in 4 groups of anesthetized rats following ureteric obstruction (n=9) or a sham operation (n=7) both with (n=9) and without (n=7) treatment with the mixed ET(A/B) receptor antagonist, bosentan. In the sham-operated rats, renal nerve stimulation did not change glomerular filtration rate but reduced urine flow rate (37+/-3 %, P<0.001), and absolute (38+/-4 %, P<0.001) and fractional (35+/-5 %, P<0.01) sodium excretion. Following unilateral ureteric obstruction, renal nerve stimulation increased glomerular filtration rate by 22+/-3 % (P<0.01), but reduced urine flow rate (14+/-2 %, P<0.001) and fractional sodium excretion (23+/-5 %, P<0.01). Bosentan treatment had no effect on baseline or renal responses to renal nerve stimulation in the sham group but normalized the renal response to renal nerve stimulation in the unilateral ureteric obstruction group. We conclude that 14 days after a 24-h period of unilateral ureteric obstruction there is an increase in GFR in response to direct renal nerve stimulation, which is due, in part, to the actions of endothelin at the time of obstruction.

MP25-18 DOES DIABETES MELLITUS AFFECT THE RECOVERY OF RENAL DYSFUNCTION FOLLOWING REVERSIBLE UNILATERAL URETERIC OBSTRUCTION?

You have accessJournal of UrologyStone Disease: Basic Research II1 Apr 2014MP25-18 DOES DIABETES MELLITUS AFFECT THE RECOVERY OF RENAL DYSFUNCTION FOLLOWING REVERSIBLE UNILATERAL URETERIC OBSTRUCTION? Fayez Hammad, Omran Bakoush, and Loay Lubbad Fayez HammadFayez Hammad More articles by this author , Omran BakoushOmran Bakoush More articles by this author , and Loay LubbadLoay Lubbad More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.320AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Following reversal of relatively short periods of unilateral ureteral obstruction (UUO), renal functional parameters such as renal blood flow (RBF), glomerular filtration rate (GFR), urinary volume (UV), total (UNaV) and fractional (FENa) excretion of sodium ultimately recover within a certain time frame. Diabetic mellitus (DM) might result in renal damage. Hence, it is possible that the ability of the diabetic kidney to recover from UUO is impaired. Thus, the aim of this study was to examine the renal functional changes following reversal of UUO in diabetic rats. METHODS Diabetes mellitus (DM) was induced by intraperitoneal injection of streptozotocin in Wistar rats which then received daily insulin for 3 months to maintain blood glucose level between 18-25 mM. All diabetic rats and age-matched controls underwent reversible 24-hour left UUO. The renal functions of right and left kidneys were studied using clearance techniques, 3 hours (Group N-1 and D-1), 7 days (Group N-2 and D-2) and 30 days (Group N-3 and D-3) following reversal of UUO. Group N-1, N-2 and N-3 were normal rats whereas group D-1, D-2 and D-3 were diabetic rats. The right non-obstructed kidney was used as a control for the left obstructed kidney. RESULTS In group N-1, GFR and RBF of the left kidney were 30% and 52% of the right kidney, respectively (P<0.05 for both). However, the FENa was higher in the left kidney (232%, P=0.06). In group N-2, the left GFR was still marginally lower than the right GFR (74%, P=0.052) but all other parameters were similar in both kidneys. In group N-3, all left and right parameters were similar. CONCLUSIONS In this model of 24-hr reversible UUO, all hemodynamic and tubular renal parameters were significantly altered shortly after reversal. In diabetes, although, there was a trend in some of the parameters to deteriorate more significantly shortly after the reversal, all of them returned back to baseline by 30 days post-reversal similar to normal subjects. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e273-e274 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Fayez Hammad More articles by this author Omran Bakoush More articles by this author Loay Lubbad More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Longitudinal changes in MRI markers in a reversible unilateral ureteral obstruction mouse model: Preliminary experience

To evaluate longitudinal changes in renal oxygenation and diffusion measurements in a model of reversible unilateral ureteral obstruction (rUUO) which has been shown to induce chronic renal functional deficits in a strain dependent way. C57BL/6 mice show higher degree of functional deficit compared with BALB/c mice. Because hypoxia and development of fibrosis are associated with chronic kidney diseases and are responsible for progression, we hypothesized that MRI measurements would be able to monitor the longitudinal changes in this model and will show strain dependent differences in response. Here blood oxygenation level dependent (BOLD) and diffusion MRI measurements were performed at three time points over a 30 day period in mice with rUUO. The studies were performed on a 4.7T scanner with the mice anesthetized with isoflurane before UUO, 2 and 28 days postrelease of 6 days of obstruction. We found at the early time point (∼2 days after releasing the obstruction), the relative oxygenation in C57Bl/6 mice were lower compared with BALB/c. Diffusion measurements were lower at this time point and reached statistical significance in BALB/c These methods may prove valuable in better understanding the natural progression of kidney diseases and in evaluating novel interventions to limit progression.

Arterially transplanted mesenchymal stem cells in a mouse reversible unilateral ureteral obstruction model: in vivo bioluminescence imaging and effects on renal fibrosis

Background Chronic kidney disease (CDK) is a worldwide health problem, but there is currently no effective treatment that can completely cure this disease. Recently, studies with mesenchymal stem cells (MSCs) on treating various renal diseases have shown breakthroughs. This study is to observe the homing features of MSCs transplanted via kidney artery and effects on renal fibrosis in a reversible unilateral ureteral obstruction (R-UUO) model. Methods Thirty-six Balb/c mice were divided into UUO group, UUO-MSC group, and sham group randomly, with 12 mice in each group. The MSCs had been infected by a lentiviral vector to express stably the luciferase reporter gene and green fluorescence protein genes (Luc-GFP-MSC). Homing of MSCs was tracked using in vivo imaging system (IVIS) 1, 3, 14, and 28 days after transplantation. Imaging results were verified by detecting GFP expression in frozen section under a fluorescence microscope. E-cadherin, α-SMA, TGF-β1, and TNF-α mRNA expression in all groups at 1 and 4 weeks after transplantation were analyzed by quantitative PCR. Results Transplanted Luc-GFP-MSCs showed increased Luciferase expression 3 days after transplantation. The expression decreased from 7 days, weakened thereafter and could not be detected 14 days after transplantation. Quantitative PCR results showed that all gene expressions in UUO group and UUO-MSC group at 1 week had no statistical difference, while at 4 weeks, except TGF-β expression (P&gt;0.05), the expression of E-cadherin, α-SMA, and TNF-α in the above two groups have statistical difference (P&lt;0.01). Conclusion IVIS enables fast, noninvasive, and intuitive tracking of MSC homing in vivo. MSCs can be taken home to kidney tissues of the diseased side in R-UUO model, and renal interstitial fibrosis can be improved as well.