Hypoxia and an angiogenic response in the partially obstructed rat bladder

Enzyme-induced hypoxia leads to inflammation in urothelial cells in vitro

PURPOSE

To determine the contributions of different durations of hypoxia to NLRP3 inflammasome activation in urothelial cells and how ischemic changes in bladder tissues is an important chemical que that leads to pathological changes seen in BOO.

METHODS

A rat urothelial cell line (MYP3) was exposed to either a short duration (2 h) or long duration (6 h) of enzyme-induced hypoxia. Following exposure to a short duration of hypoxia, NO and ATP concentrations were measured from supernatant media and caspase-1 levels were measured from cell lysates. In a separate experiment, cells were fixed following hypoxia exposure and immunostained for HIF-1α stabilization.

RESULTS

Although short exposure of low oxygen conditions resulted in a hypoxic response in MYP3 cells, as indicated by HIF-1α stabilization and increased NO activity, NLRP3 inflammasome activation was not observed as caspase-1 activity remained unchanged. However, exposure of MYP3 cells to a longer duration of hypoxia resulted in an increase in intracellular caspase-1 activity. Furthermore, treatment with antioxidant (GSH) or TXNIP inhibitor (verapamil) attenuated the hypoxia-induced increase in caspase-1 levels indicating that hypoxia primarily drives inflammation through a ROS-mediated TXNIP/NLRP3 pathway.

CONCLUSION

We conclude that hypoxia induced bladder damage requires a duration that is more likely related to elevated storage pressures/hypoxia, seen in later stages of BOO, as compared to shorter duration pressure elevation/hypoxia that is encountered in normal micturition cycles or early in the BOO pathology where storage pressures are still normal.

Ultrasound-Estimated Bladder Weight Correlates With Videourodynamic Studies in Neurogenic Bladder Dysfunction

PURPOSE

This retrospective study was designed to evaluate which lower urinary tract ultrasound parameter(s) could predict the results of invasive urodynamic testing which are the current reference standard in the evaluation of bladder dysfunction in children with spina bifida.

MATERIALS AND METHODS

Fifty eight children with spina bifida undergoing video urodynamic evaluation and a renal bladder ultrasound as their standard of care were evaluated. Quantitative and qualitative ultrasound parameters were then correlated with the videourodynamic study results which served as the reference standard.

RESULTS

For bladders with ending storage pressures above 15 cm H₂ O, there were increases in these ultrasound measured parameters: 1) bladder mass (P = .00019), 2) bladder/body mass ratio (P = .0059), and 3) wall thickness (P = .01). We defined the storage cost as the final storage pressure divided by the percentage of expected bladder capacity attained. These data were analyzed to compute receiver operating curves with assuming end storage pressures cutoff points of 15, 20, 30, and 40 cm H₂ O. The optimal area under the curve was found for a bladder weight of 65 g and a pressure cutoff of 30 cm H₂ O with a sensitivity of 75% with a specificity of 84%.

CONCLUSION

Bladder weight is independent of luminal volume, can be normalized to body weight, and may serve as a clinically valuable tool for noninvasive screening to define a subset of patients with neurogenic bladder with a higher likelihood of having abnormal videourodynamic results.

Inhibition of DNA methylation during chronic obstructive bladder disease (COBD) improves function, pathology and expression

Partial bladder outlet obstruction due to prostate hyperplasia or posterior urethral valves, is a widespread cause of urinary dysfunction, patient discomfort and also responsible for immense health care costs. Even after removal or relief of obstruction, the functional and pathologic aspects of obstruction remain as a chronic obstructive bladder disease (COBD). Epigenetic changes, such as DNA methylation, contribute to the persistent character of many chronic diseases, and may be altered in COBD. We tested whether candidate genes and pathways and the pathophysiology of COBD were affected by a hypomethylating agent, decitabine (DAC). COBD was created in female Sprague-Dawley rats by surgical ligation of the urethra for 6 weeks, followed by removal of the suture. Sham ligations were performed by passing the suture behind the urethra. After removal of the obstruction or sham removal, animals were randomized to DAC treatment (1 mg/kg/3-times/week intraperitoneally) or vehicle (normal saline). Bladder function was non-invasively tested using metabolic cages, both one day prior to de-obstruction at 6 weeks and prior to sacrifice at 10 weeks. Residual volume and bladder mass were measured for each bladder. Bladders were examined by immunostaining as well as qPCR. The effects of DNA methyltransferase (DNMT)-3A knockout or overexpression on smooth muscle cell (SMC) function and phenotype were also examined in bladder SMC and ex vivo culture. Residual volumes of the DAC treated group were not significantly different from the NS group. Compared to COBD NS, COBD DAC treatment helped preserve micturition volume with a significant recovery of the voiding efficiency (ratio of the maximum voided volume/maximum bladder capacity) by one third (Fig. 1, p > 0.05). Brain-derived neurotrophic factor (BDNF) variants 1 and 5 were upregulated by COBD and significantly reduced by DAC treatment. Deposition of collagen in the COBD bladder was reduced by DAC, but gross hypertrophy remained. In bladder SMC, DNMT3A overexpression led to a loss of contractile function and phenotype. In bladders, persistently altered by COBD, inhibition of DNA-methylation enhances functional recovery, unlike treatment during partial obstruction, which exacerbates obstructive pathology. The underlying mechanisms may relate to the gene expression changes in BDNF and their effects on signaling in the bladder.

Dietary reversal reverts diet-induced alterations in obstructed bladders of Wistar rats

OBJECTIVES

The aim of this study was to investigate the effects of diet reversal to standard chow on diet-induced changes in structure and function of normal and obstructed bladders in male Wistar rats.

METHODS

Eighty animals were equally divided into sham-surgery and bladder outlet obstruction (BOO) dietary groups and fed standard chow (control), high-carbohydrate, high-fat, and high-protein diets. BOO groups had surgically induced BOO, whereas sham surgery was performed on sham groups at the end of week 8. Animals were continued on the treatment diets for 4 wk after surgery, then the diets were all changed to standard chow for the remainder of the study period. Bladder weight, detrusor contractility, Rho-associated protein kinase (Rho-kinase), and myosin light chain kinase were determined. Polymerase chain reaction was used to assay for transforming growth factor-β, connecting tissue growth factor, hypoxia-inducible factor-1α, and platelet-derived growth factor subunit A levels in the bladder. C-reactive protein, insulin-like growth factor-1, nerve growth factor, and C-X-C motif chemokine ligand 12 concentrations were determined by enzyme-linked immunosorbent assay. The collagen content of the bladder was estimated by liquid chromatography/mass spectrometry.

RESULTS

Reversal of diet to standard chow resulted in reversal of diet-induced changes in all variables measured in obstructed bladders. High-fat-diet-induced alterations in normal bladders were also reversed.

CONCLUSION

The results suggested that in obstructed bladders of animals, reversal of the diet could reverse all diet-associated changes that increase inflammation and fibrosis in obstructed bladders. This is especially important in changes related to high consumption of fatty diets and associated lower urinary tract symptoms.

Evaluation of a rat model of functional urinary bladder outlet obstruction produced by chronic inhibition of nitric oxide synthase

AIMS

Ligation of the urethra to create partial bladder outlet obstruction has widely been used as an animal model of bladder obstruction, although obstructive bladder dysfunction may be due to both mechanical and functional obstruction. Previous studies in rodents have demonstrated that long-term nitric oxide (NO) deficiency can lead to detrusor overactivity, and lack of NO may thus cause impairment of bladder outlet relaxation. The aim of this study was to define the characteristics of bladder and urethral dysfunction induced by chronic NO deficiency through both in vivo and in vitro investigations.

MAIN METHODS

Rats were divided into two groups, and one group received an NO synthase inhibitor (N_ω-nitro-L-arginine methyl ester hydrochloride: L-NAME) in the drinking water for 4 weeks. Bladder and urethral function were evaluated by continuous cystometry and isovolumetric cystometry. In vitro functional studies of detrusor strips and measurement of the mRNA and protein expression of an ischemic marker and a gap junction protein were also performed in separate rats.

KEY FINDINGS

L-NAME administration raised blood pressure and decreased plasma nitrite/nitrate level compared to the control group. L-NAME treatment increased the frequency of bladder contractions and the residual volume, and elevated urethral pressure and bladder contraction pressure. In addition, carbachol-induced contraction was reduced in isolated detrusor strips from the L-NAME group, and bladder expression of HIF-1 and connexin 43 showed upregulation.

SIGNIFICANCE

These findings suggest that chronic administration of L-NAME to rats induces bladder hyperactivity with residual urine, and may provide a useful model of functional bladder obstruction.

Administration of human umbilical cord blood mononuclear cells restores bladder dysfunction in streptozotocin-induced diabetic rats

OBJECTIVE

This study evaluated the effect of human umbilical cord blood mononuclear cells (HUCB-MNCs) on bladder dysfunction in streptozotocin (STZ; 35 mg/kg, i.v.)-induced diabetic rats.

METHODS

Adult male Sprague-Dawley rats (n = 30) were equally divided into three groups: control group, STZ-diabetic group, and HUCB-MNC-treated group (1 × 10⁶ cells). HUCB-MNCs were isolated by density gradient centrifugation from eight healthy donors and injected into the corpus cavenosum in STZ-diabetic rats 4 weeks after the induction of diabetes. Studies were performed 4 weeks after HUCB-MNC or vehicle injection. In vitro organ bath studies were performed on bladder strips, whereas protein expression of hypoxia-inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), and α-smooth muscle actin (SMA) in the bladder and the ratio of smooth muscle cells (SMCs) to collagen were determined using western blotting and Masson trichrome staining.

RESULTS

Neurogenic contractions of detrusor smooth muscle strips were 55% smaller in the diabetic group than control group (P < 0.05); these contractions were normalized by HUCB-MNC treatment. In addition, HUCB-MNC treatment restored the impaired maximal carbachol-induced contractile response in detrusor strips in the diabetic group (29%; P < 0.05). HUCB-MNC treatment improved the KCl-induced contractile response in the diabetic bladder (68%; P < 0.05), but had no effect on ATP-induced contractile responses. Increased expression of HIF-1α and VEGF protein and decreased expression of α-SMA protein and the SMC/collagen ratio in diabetic rats were reversed by HUCB-MNC.

CONCLUSION

Administration of HUCB-MNCs facilitates bladder function recovery, which is likely related to downregulation of HIF-1α expression and attenuation of fibrosis in STZ-diabetic rats.

Hypoxic changes to the urothelium as a bystander of end-stage bladder disease

INTRODUCTION

Urothelial cells harvested from benign diseased bladders have a compromised capacity to propagate or differentiate in vitro, potentially limiting their application in autologous tissue engineering approaches. The causative pathways behind this altered phenotype are unknown. The hypothesis is that hypoxic damage to the urothelium occurs as a bystander to chronic or recurrent episodes of infection and inflammation.

OBJECTIVE

The aim of this study was to assess immunohistochemically detected nuclear hypoxia-inducible factor 1 alpha (HIF-1α) and vascular endothelial growth factor in the urothelium when exposed to hypoxia.

STUDY DESIGN

Human bladder sections from a total of 29 adult and paediatric patients, representing a variety of different pathologies including neuropathy (n = 15), were analysed. Tissues from adults with bladder outlet obstruction secondary to prostatic disease (n = 1), urothelial carcinoma (n = 1) and tonsil (n = 1) were used as positive tissue controls for immunohistochemistry. Hypoxia-inducible factor 1 alpha-labelled sections were scanned using a Zeiss AxioScan Z1 slide scanner. Analysis of urothelial nuclear HIF-1α labelling was performed using HistoQuest image analysis software (TissueGnostics). Comparison of nuclear HIF-1α labelling between neuropathic and non-neuropathic sections was performed using one-way analysis of variance with the post hoc Tukey honestly significant difference (HSD) test. Patient urodynamic studies performed before tissue sample harvest were evaluated and correlated to the HIF-1α intensity using Spearman's rank correlation.

RESULTS

Hypoxia-inducible factor 1 alpha appeared more intense in the urothelial compartment from neuropathic bladder samples (n = 15) than in the control tissues, including non-obstructed samples (n = 9). Image analysis supported this; median nuclear HIF-1α labelling was 29.98 ± 3.10 (standard deviation [SD]) (n = 9) in controls and 74.29 ± 7.55 (SD) in neuropathic samples (n = 15). A statistically significant difference between the control and neuropathic tissue groups was shown (P < 0.05). Of the 15 neuropathic samples, 11 had traceable urodynamic studies. Both initial and maximum detrusor pressures indicated a positive relationship when plotted against HIF-1α labelling. Spearman's rank correlation, with no missing events, confirmed significant correlations between both initial or maximum detrusor pressure and nuclear HIF-1α labelling intensity (median score); P ≤ 0.046 and P ≤ 0.05, respectively. The null hypothesis was accordingly rejected.

CONCLUSIONS

This study indicates that urothelial nuclear HIF-1α may be a biomarker of hypoxia and a common feature in end-stage bladder disease associated with high-pressure systems.

Effects of varying degrees of partial bladder outlet obstruction on urinary bladder function of rats: A novel link to inflammation, oxidative stress and hypoxia

OBJECTIVES

The aim of the present study was to investigate the effects of different degrees of obstruction, and the roles of inflammation, oxidative stress, and hypoxia parameters on bladder function.

METHODS

Thirty male Sprague-Dawley rats were divided into 3 groups (n = 10 in each group): (i) sham-operated control; (ii) severe partial bladder outlet obstruction (PBOO); and (iii) moderate PBOO. Severe and moderate PBOO were induced by urethral ligation using 3-Fr and 4-Fr catheters, respectively, for 6 weeks. After 6 weeks, the in vitro contractile responses to carbachol, electrical field stimulation, ATP and KCl were measured in bladder strips. In addition, mRNA and protein expression of nuclear factor kappa B (NF-κB) hypoxia-inducible factor (HIF) and nuclear factor, erythroid 2-like 2 (Nrf2) in bladder were determined by real-time polymerase chain reaction and western blotting. Malondialdehyde (MDA) levels in bladder tissues were also determined.

RESULTS

Rats in the severe PBOO group had the highest bladder weight. Detrusor strips from rats in the severe PBOO group exhibited 61%-82% smaller contractile responses to all four stimuli than those from the sham-operated group. Activity of NF-κB as an inflammatory marker was increased in the severe PBOO group, whereas HIF-1α and HIF-2β protein levels were increased significantly in the moderate PBOO group. A master regulator of oxidative stress, Nrf2 expression was increased in all obstructed rats. MDA levels were higher in the severe PBOO group than in sham-operated group.

CONCLUSION

The results of the present study reveal the importance of oxidative stress-induced NF-κB signaling in bladder dysfunction with severe obstruction. Altered HIF signaling may contribute to the functional impairment after PBOO. Novel and evolving therapies targeting oxidative and/or inflammatory pathways may be a reasonable strategy for the management of lower urinary tract symptoms or benign prostatic hyperplasia.

Murine social stress results in long lasting voiding dysfunction

Repeated exposure to social stress shifts the voiding phenotype in male mice leading to bladder wall remodeling and is associated with increased expression of the stress neuropeptide, corticotropin-releasing factor (CRF) in Barrington's nucleus neurons. In these studies, we set out to determine if the voiding phenotype could recover upon removal from the stressor. Male mice were exposed for 1h daily to an aggressor and the voiding phenotype was assessed at one month followed by randomization to three groups. One group underwent immediate sacrifice. Two groups were allowed a one month recovery from the social stress exposure with or without the addition of fluoxetine (1.2mg/ml) in their drinking water and repeat voiding patterns were measured prior to sacrifice. Social stress significantly increased bladder mass, bladder mass corrected for body weight, voided volumes, and decreased urinary frequency. The abnormal voiding phenotype persisted after a 1month recovery with no effect from the addition of fluoxetine. CRF mRNA in Barrington's nucleus was increased by social stress and remained elevated following recovery with no effect from the addition of fluoxetine. The mRNA and protein expression for the alpha 1 chains of type 1 and type III collagen was unchanged across all groups suggesting that changes in the extracellular matrix of the bladder are not responsible for the voiding phenotype. This persisting voiding dysfunction correlates with the persistent elevation of CRF mRNA expression in Barrington's nucleus.

Identification of novel non-invasive biomarkers of urinary chronic pelvic pain syndrome: findings from the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network

OBJECTIVE

To examine a series of candidate markers for urological chronic pelvic pain syndrome (UCPPS), selected based on their proposed involvement in underlying biological processes so as to provide new insights into pathophysiology and suggest targets for expanded clinical and mechanistic studies.

METHODS

Baseline urine samples from Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network study participants with UCPPS (n = 259), positive controls (PCs; chronic pain without pelvic pain, n = 107) and healthy controls (HCs, n = 125) were analysed for the presence of proteins that are suggested in the literature to be associated with UCPPS. Matrix metalloproteinase (MMP)-2, MMP-9, MMP-9/neutrophil gelatinase-associated lipocalin (NGAL) complex (also known as Lipocalin 2), vascular endothelial growth factor (VEGF), VEGF receptor 1 (VEGF-R1) and NGAL were assayed and quantitated using mono-specific enzyme-linked immunosorbent assays for each protein. Log-transformed concentration (pg/mL or ng/mL) and concentration normalized to total protein (pg/μg) values were compared among the UCPPS, PC and HC groups within sex using the Student's t-test, with P values adjusted for multiple comparisons. Multivariable logistic regression and receiver-operating characteristic curves assessed the utility of the biomarkers in distinguishing participants with UCPPS and control participants. Associations of protein with symptom severity were assessed by linear regression.

RESULTS

Significantly higher normalized concentrations (pg/μg) of VEGF, VEGF-R1 and MMP-9 in men and VEGF concentration (pg/mL) in women were associated with UCPPS vs HC. These proteins provided only marginal discrimination between UCPPS participants and HCs. In men with UCCPS, pain severity was significantly positively associated with concentrations of MMP-9 and MMP-9/NGAL complex, and urinary severity was significantly positively associated with MMP-9, MMP-9/NGAL complex and VEGF-R1. In women with UCPPS, pain and urinary symptom severity were associated with increased normalized concentrations of MMP-9/NGAL complex, while pain severity alone was associated with increased normalized concentrations of VEGF, and urinary severity alone was associated with increased normalized concentrations of MMP-2. Pain severity in women with UCPPS was significantly positively associated with concentrations of all biomarkers except NGAL, and urinary severity with all concentrations except VEGF-R1.

CONCLUSION

Altered levels of MMP-9, MMP-9/NGAL complex and VEGF-R1 in men, and all biomarkers in women, were associated with clinical symptoms of UCPPS. None of the evaluated candidate markers usefully discriminated UCPPS patients from controls. Elevated VEGF, MMP-9 and VEGF-R1 levels in men and VEGF levels in women may provide potential new insights into the pathophysiology of UCPPS.

The Obstructed Bladder: Expression of Collagen, Matrix Metalloproteinases, Muscarinic Receptors, and Angiogenic and Neurotrophic Factors in Patients With Benign Prostatic Hyperplasia

OBJECTIVE

To evaluate the gene expression of collagen, matrix metalloproteinases (MMPs) and inhibitors, cholinergic muscarinic receptors (CHRMs), and angiogenic and nerve growth factors (NGFs) in the bladder of patients with bladder outlet obstruction caused by benign prostatic hyperplasia (BPH).

METHODS

We analyzed bladder specimens from 43 patients with obstructive BPH undergoing transurethral resection of the prostate as compared to 10 age-matched controls with an International Prostatic Symptom Score of <8 and a prostate volume of <30 g. A bladder biopsy was performed for relative gene expression analysis with quantitative real-time polymerase chain reaction of collagens I and III, MMP-1, MMP-2, and MMP-9; tissue inhibitors of metalloproteinases (TIMPs) TIMP-1, TIMP-2, and reversion-inducing cysteine-rich protein with kazal motifs (RECK); CHRM2 and CHRM3; VEGF and CD105; and NGF and nerve growth factor receptor (NGFr).

RESULTS

Patients with bladder outlet obstruction presented a statistically significant overexpression of collagens I and III, VEGF, CHRM2, and CHRM3. CD105, MMP-9, and TIMP-1 were underexpressed. Expressions of NGF, NGFr, MMP-1, MMP-2, TIMP-2, and RECK were heterogeneous. CHRM2 and CHRM3 were overexpressed in patients with persistent detrusor overactivity. Smokers presented an upregulation of NGFr and VEGF; dyslipidemic patients had an overexpression of NGFr.

CONCLUSION

Bladder upregulation of collagens I and III on transcriptional level appears to be relevant in BPH. Muscarinic receptors CHRM2 and CHRM3 are also overexpressed, more so in patients with persistent detrusor overactivity. Upregulation of VEGF and NGFr, particularly in subjects with risk factors for atherosclerosis, reinforces the role of ischemia in BPH-induced modifications of the bladder.

Deletion of neuropilin 2 enhances detrusor contractility following bladder outlet obstruction

Chronic urethral obstruction and the ensuing bladder wall remodeling can lead to diminished bladder smooth muscle (BSM) contractility and debilitating lower urinary tract symptoms. No effective pharmacotherapy exists to restore BSM contractile function. Neuropilin 2 (Nrp2) is a transmembrane protein that is highly expressed in BSM. Nrp2 deletion in mice leads to increased BSM contraction. We determined whether genetic ablation of Nrp2 could restore BSM contractility following obstruction. Partial bladder outlet obstruction (pBOO) was created by urethral occlusion in mice with either constitutive and ubiquitous, or inducible smooth muscle-specific deletion of Nrp2, and Nrp2-intact littermates. Mice without obstruction served as additional controls. Contractility was measured by isometric tension testing. Nrp2 deletion prior to pBOO increased force generation in BSM 4 weeks following surgery. Deletion of Nrp2 in mice already subjected to pBOO for 4 weeks showed increased contractility of tissues tested 6 weeks after surgery compared with nondeleted controls. Assessment of tissues from patients with urodynamically defined bladder outlet obstruction revealed reduced NRP2 levels in obstructed bladders with compensated compared with decompensated function, relative to asymptomatic controls. We conclude that downregulation of Nrp2 promotes BSM force generation. Neuropilin 2 may represent a novel target to restore contractility following obstruction.

Inhibition of vascular smooth muscle inward-rectifier K+ channels restores myogenic tone in mouse urinary bladder arterioles

Prolonged decreases in urinary bladder blood flow are linked to overactive and underactive bladder pathologies. However, the mechanisms regulating bladder vascular reactivity are largely unknown. To investigate these mechanisms, we examined myogenic and vasoactive properties of mouse bladder feed arterioles (BFAs). Unlike similar-sized arterioles from other vascular beds, BFAs failed to constrict in response to increases in intraluminal pressure (5-80 mmHg). Consistent with this lack of myogenic tone, arteriolar smooth muscle cell membrane potential was hyperpolarized (-72.8 ± 1.4 mV) at 20 mmHg and unaffected by increasing pressure to 80 mmHg (-74.3 ± 2.2 mV). In contrast, BFAs constricted to the thromboxane analog U-46619 (100 nM), the adrenergic agonist phenylephrine (10 µM), and KCl (60 mM). Inhibition of nitric oxide synthase or intermediate- and small-conductance Ca²⁺-activated K⁺ channels did not alter arteriolar diameter, indicating that the dilated state of BFAs is not attributable to overactive endothelium-dependent dilatory influences. Myocytes isolated from BFAs exhibited BaCl₂ (100 µM)-sensitive K⁺ currents consistent with strong inward-rectifier K⁺ (K_IR) channels. Notably, block of these K_IR channels "restored" pressure-induced constriction and membrane depolarization. This suggests that these channels, in part, account for hyperpolarization and associated absence of tone in BFAs. Furthermore, smooth muscle-specific knockout of K_IR2.1 caused significant myogenic tone to develop at physiological pressures. This suggests that 1) the regulation of vascular tone in the bladder is independent of pressure, insofar as pressure-induced depolarizing conductances cannot overcome K_IR2.1-mediated hyperpolarization; and 2) maintenance of bladder blood flow during bladder filling is likely controlled by neurohumoral influences.

Cerebral and extracerebral vulnerability to hypoxic insults after diffuse traumatic brain injury in rats

The post-traumatic brain vulnerability suggests that after traumatic brain injury (TBI), the brain may be more susceptible to posttraumatic hypoxic insults. This concept could be extended to 'peripheral' organs, as non-neurologic organ failure is common after TBI. This study aims to characterize and quantify cerebral and extracerebral tissue hypoxia with pimonidazole resulting from a standardized hypoxia-hypotension (HH) phase occurring after a diffuse experimental TBI in rats. Rats were allocated to Sham (n=5), TBI (n=7), HH (n=7) and TBI+HH (n=7) groups. Then, pimonidazole was injected and brain, liver, heart and kidneys were analysed. In the cerebral cortex, post-treatment hypoxia was higher in TBI+HH group than Sham group (p=0.003), HH group (p=0.003) and TBI group (p=0.002). Large trends in thalamus, hippocampus and striatum for the TBI+HH group compared to the other groups were observed. For the heart and liver, the 4 groups were comparable. For the kidneys, post-treatment hypoxia was higher in the TBI group compared to the Sham and HH groups, but not more than TBI+HH group. This study reveals that a posttraumatic hypoxic insult occurring after a severe TBI has major hypoxic consequences on brain structures. However, TBI by itself appears to induce renal hypoxia that is not enhanced by posttraumatic hypoxic insult.

Inhibition of HIF Reduces Bladder Hypertrophy and Improves Bladder Function in Murine Model of Partial Bladder Outlet Obstruction

PURPOSE

Posterior urethral valves are the most common cause of partial bladder outlet obstruction in the pediatric population. However, to our knowledge the etiology and the detailed mechanisms underlying pathological changes in the bladder following partial bladder outlet obstruction remain to be elucidated. Recent findings suggest that hypoxia and associated up-regulation of HIFs (hypoxia-inducible factors) have a key role in partial bladder outlet obstruction induced pathology in the bladder. We examined the effects of pharmacological inhibition of HIF pathways by 17-DMAG (17-(dimethylaminoethylamino)-17-demethoxygeldanamycin) in pathophysiological phenotypes after partial bladder outlet obstruction.

MATERIALS AND METHODS

Partial bladder outlet obstruction was surgically created in male C57BL/6J mice. The animals received oral administration of 17-DMAG or vehicle daily starting from the initiation of obstruction up to 5 days. Sham operated mice served as controls. Bladders were harvested from each group 2, 4 and 7 days postoperatively, and analyzed for histological and biochemical changes. Bladder function was assessed by in vitro muscle contractility recordings.

RESULTS

Partial bladder outlet obstruction caused a significant increase in the bladder mass accompanying enhanced collagen deposition in the bladder wall while 17-DMAG treatment suppressed those increases. Treatment with 17-DMAG attenuated the degree of up-regulation of HIFs and their target genes involving the development of tissue fibrosis in obstructed bladders. Treatment with 17-DMAG improved the decreased responses of obstructed bladder strips to electrical field stimulation and KCl.

CONCLUSIONS

In vivo 17-DMAG treatment decreased partial bladder outlet obstruction induced pathophysiological changes in the bladder. HIF pathway inhibition has a potential clinical implication for the development of novel pharmacological therapies to treat bladder pathology associated with partial bladder outlet obstruction.

Activation of common signaling pathways during remodeling of the heart and the bladder

The heart and the urinary bladder are hollow muscular organs, which can be afflicted by pressure overload injury due to pathological conditions such as hypertension and bladder outlet obstruction. This increased outflow resistance induces hypertrophy, marked by dramatic changes in the organs' phenotype and function. The end result in both the heart and the bladder can be acute organ failure due to advanced fibrosis and the subsequent loss of contractility. There is emerging evidence that microRNAs (miRNAs) play an important role in the pathogenesis of heart failure and bladder dysfunction. MiRNAs are endogenous non-coding single-stranded RNAs, which regulate gene expression and control adaptive and maladaptive organ remodeling processes. This Review summarizes the current knowledge of molecular alterations in the heart and the bladder and highlights common signaling pathways and regulatory events. The miRNA expression analysis and experimental target validation done in the heart provide a valuable source of information for investigators working on the bladder and other organs undergoing the process of fibrotic remodeling. Aberrantly expressed miRNA are amendable to pharmacological manipulation, offering an opportunity for development of new therapies for cardiac and bladder hypertrophy and failure.

HIF-mediated metabolic switching in bladder outlet obstruction mitigates the relaxing effect of mitochondrial inhibition

Prior work demonstrated increased levels of hypoxia-inducible factor-1α (HIF-1α) in the bladder following outlet obstruction, associated with bladder growth and fibrosis. Here we hypothesized that HIF induction in outlet obstruction also switches energetic support of contraction from mitochondrial respiration to glycolysis. To address this hypothesis, we created infravesical outlet obstruction in female Sprague-Dawley rats and examined HIF induction and transcriptional activation. HIF-1α increased after 6 weeks of outlet obstruction as assessed by western blotting and yet transcription factor-binding site analysis indicated HIF activation already at 10 days of obstruction. Accumulation HIF-2α and of Arnt2 proteins were found at 10 days, providing an explanation for the lack of correlation between HIF-1α protein and transcriptional activation. HIF signature targets, including Slc2a1, Tpi1, Eno1 and Ldha increased in obstructed compared with sham-operated bladders. The autophagy markers Bnip3 and LC3B-II were also increased at 6 week of obstruction, but electron microscopy did not support mitophagy. Mitochondria were, however, remodeled with increased expression of Cox4 compared with other markers. In keeping with a switch toward glycolytic support of contraction, we found that relaxation by the mitochondrial inhibitor cyanide was reduced in obstructed bladders. This was mimicked by organ culture with the HIF-inducer dimethyloxalylglycine, which also upregulated expression of Ldha. On the basis of these findings, we conclude that HIF activation in outlet obstruction involves mechanisms beyond the accumulation of HIF-1α protein and that it results in a switch of the energetic support of contraction to anaerobic glycolysis. This metabolic adaptation encompasses increased expression of glucose transporters and glycolytic enzymes combined with mitochondrial remodeling. Together, these changes uphold contractility when mitochondrial respiration is limited.

Treatment of bladder dysfunction using stem cell or tissue engineering technique

Tissue engineering and stem cell transplantation are two important options that may help overcome limitations in the current treatment strategy for bladder dysfunction. Stem cell therapy holds great promise for treating pathophysiology, as well as for urological tissue engineering and regeneration. To date, stem cell therapy in urology has mainly focused on oncology and erectile dysfunction. The therapeutic potency of stem cells (SCs) was originally thought to derive from their ability to differentiate into various cell types including smooth muscle. The main mechanisms of SCs in reconstituting or restoring bladder function are migration, differentiation, and paracrine effects. Nowadays, paracrine effects of stem cells are thought to be more prominent because of their stimulating effects on stem cells and adjacent cells. Studies of stem cell therapy for bladder dysfunction have been limited to experimental models and have been less focused on tissue engineering for bladder regeneration. Bladder outlet obstruction is a representative model. Adipose-derived stem cells, bone marrow stem cells (BMSCs), and skeletal muscle-derived stem cells or muscle precursor cells are used for transplantation to treat bladder dysfunction. The aim of this study is to review stem cell therapy and updated tissue regeneration as treatments for bladder dysfunction and to provide the current status of stem cell therapy and tissue engineering for bladder dysfunction including its mechanisms and limitations.

Stem cell therapy in bladder dysfunction: where are we? And where do we have to go?

To date, stem cell therapy for the bladder has been conducted mainly on an experimental basis in the areas of bladder dysfunction. The therapeutic efficacy of stem cells was originally thought to be derived from their ability to differentiate into various cell types. Studies about stem cell therapy for bladder dysfunction have been limited to an experimental basis and have been less focused than bladder regeneration. Bladder dysfunction was listed in MESH as "urinary bladder neck obstruction", "urinary bladder, overactive", and "urinary bladder, neurogenic". Using those keywords, several articles were searched and studied. The bladder dysfunction model includes bladder outlet obstruction, cryoinjured, diabetes, ischemia, and spinal cord injury. Adipose derived stem cells (ADSCs), bone marrow stem cells (BMSCs), and skeletal muscle derived stem cells (SkMSCs) are used for transplantation to treat bladder dysfunction. The main mechanisms of stem cells to reconstitute or restore bladder dysfunction are migration, differentiation, and paracrine effects. The aim of this study is to review the stem cell therapy for bladder dysfunction and to provide the status of stem cell therapy for bladder dysfunction.

Phenotypic switching induced by damaged matrix is associated with DNA methyltransferase 3A (DNMT3A) activity and nuclear localization in smooth muscle cells (SMC)

Extracellular matrix changes are often crucial inciting events for fibroproliferative disease. Epigenetic changes, specifically DNA methylation, are critical factors underlying differentiated phenotypes. We examined the dependency of matrix-induced fibroproliferation and SMC phenotype on DNA methyltransferases. The cooperativity of matrix with growth factors, cell density and hypoxia was also examined. Primary rat visceral SMC of early passage (0–2) were plated on native collagen or damaged/heat-denatured collagen. Hypoxia was induced with 3% O₂ (balanced 5% CO₂ and 95% N₂) over 48 hours. Inhibitors were applied 2–3 hours after cells were plated on matrix, or immediately before hypoxia. Cells were fixed and stained for DNMT3A and smooth muscle actin (SMA) or smooth muscle myosin heavy chain. Illumina 450 K array of CpG sites was performed on bisulfite-converted DNA from smooth muscle cells on damaged matrix vs native collagen. Matrix exquisitely regulates DNMT3A localization and expression, and influences differentiation in SMCs exposed to denatured matrix +/− hypoxia. Analysis of DNA methylation signatures showed that Matrix caused significant DNA methylation alterations in a discrete number of CpG sites proximal to genes related to SMC differentiation. Matrix has a profound effect on the regulation of SMC phenotype, which is associated with altered expression, localization of DNMTs and discrete changes DNA methylation.

PDE5-Is for the Treatment of Concomitant ED and LUTS/BPH

Epidemiologic data in adult men exhibit a strong relationship between erectile dysfunction (ED) and lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH), indicating that men affected by ED should also be investigated for LUTS/BPH and those presenting with storage or voiding LUTS should be investigated for co-morbid ED. Common pathophysiolgical mechanisms underlying both LUTS/BPH and ED, including alteration of NO/cGMP or RhoA/Rho-kinase signaling and/or vascular or neurogenic dysfunction, are potential targets for proposed phosphodiesterase type 5 inhibitors (PDE5-Is). Several randomized controlled trials and only a few reviews including all commercially available PDE5-Is demonstrated the safety and efficacy of these drugs in the improvement of erectile function and urinary symptoms, in patients affected either by ED, LUTS, or both conditions.

Persistent fibrosis in the liver of choline-deficient and iron-supplemented L-amino acid-defined diet-induced nonalcoholic steatohepatitis rat due to continuing oxidative stress after choline supplementation

Nonalcoholic steatohepatitis (NASH) is characterized by combined pathology of steatosis, lobular inflammation, fibrosis, and hepatocellular degeneration, with systemic symptoms of diabetes or hyperlipidemia, all in the absence of alcohol abuse. Given the therapeutic importance and conflicting findings regarding the potential for healing the histopathologic features of NASH in humans, particularly fibrosis, we investigated the reversibility of NASH-related findings in Wistar rats fed a choline-deficient and iron-supplemented l-amino acid-defined (CDAA) diet for 12weeks, with a recovery period of 7weeks, during which the diets were switched to a choline-sufficient and iron-supplemented l-amino acid-defined (CSAA) one. Analysis showed that steatosis and inflammation were significantly resolved by the end of the recovery period, along with decreases in AST and ALT activities within 4weeks. In contrast, fibrosis remained even after the recovery period, to an extent similar to that in continuously CDAA-fed animals. Real-time reverse transcriptase-polymerase chain reaction, Western blot, and immunohistochemical investigations revealed that expression of some factors indicating oxidative stress (CYP2E1, 4-HNE, and iNOS) were elevated, whereas catalase and SOD1 were decreased, and a hypoxic state and CD34-positive neovascularization were evident even after the recovery period, although the fibrogenesis pathway by activated α-SMA-positive hepatic stellate cells via TGF-β and TIMPs decreased to the CSAA group level. In conclusion, persistent fibrosis was noted after the recovery period of 7weeks, possibly due to sustained hypoxia and oxidative stress supposedly caused by capillarization. Otherwise, histopathological features of steatosis and inflammation, as well as serum AST and ALT activities, were recovered.

Stromal Cell-Derived Factor 1α Induces Accumulation of Intraveneously Administered Marrow-Derived Stromal Cells in the Partially Obstructed Rat Bladder

OBJECTIVES

We investigated the time course of the stromal cell-derived factor 1α (SDF1α) expression and behavior of intravenously administered bone marrow-derived stromal (BMS) cells in the urinary bladder of partial bladder outlet obstruction (PBOO) rats.

METHODS

Study 1: Recombinant SDF1α or saline was directly injected into the bladder wall of female rats followed by intravenous administration of BMS cells isolated from green fluorescent protein (GFP) transgenic rats. The bladder was examined with immunohistochemistry to determine whether SDF1α would enhance migration of BMS cells to the bladder. Study 2: Following surgery of PBOO or sham in female rats, bladders were removed on days 1-14, and expression of hypoxia inducible factor 1α (HIF1α) and SDF1α were examined with real-time polymerase chain reaction (PCR) to determine if PBOO preferentially increased their expression. Study 3: Female rats underwent PBOO or sham surgery followed by intravenous administration of GFP-positive BMS cells. Bladders were examined with immunohistochemistry on days 1-14 to determine whether BMS cells preferentially accumulated in the bladder.

RESULTS

BMS cells were accumulated in the injection site of SDF1α but not saline in the bladder. SDF1α and HIF1α increased at day 1 after PBOO compared to sham. More BMS cells accumulated in the bladder of PBOO on day 1, and some BMS cells expressed smooth muscle phenotypes by day 14.

CONCLUSION

SDF1α induced with ischemia/hypoxia due to PBOO is implicated in the accumulation of BMS cells in the bladder and regeneration of the bladder for PBOO.

Should we screen for and treat lower urinary tract dysfunction after major pelvic surgery? ICI-RS 2011

AIMS

Given the relative frequency of lower urinary tract dysfunction (LUTD) after major pelvic surgery, the main question for this debate is: "Should we [actively] screen for LUTD after major pelvic surgery," with the intention to treat and improve patient care.

METHODS

The discussants selected relevant papers from a limited review of the literature [PubMed/Medline database (January 1966 to May 2011)] and prepared the YES versus NO presentations.

RESULTS

The evidence was presented for the following major pelvic procedures: colorectal surgery, hysterectomy, and surgery for other benign gynecologic conditions, radical prostatectomy, brachytherapy, and primary cryotherapy for prostate cancer. Based on the presentations, the audience voted in favor of screening for LUTD after major pelvic surgery.

CONCLUSIONS

Irreversible treatment should be delayed in case of LUTD after major pelvic surgery. In fact, most symptoms spontaneously subside within 6 months after the surgery. Once the period of 6-12 months of conservative management has been completed and if LUTD persists, a new urodynamic screening should be followed by appropriate treatment.

Molecular reactions and ultrastructural damage in the chronically ischemic bladder

PURPOSE

Clinical and basic research data suggest that pelvic ischemia may contribute to bladder overactivity. We characterized the molecular and ultrastructural reactions of the chronically ischemic bladder.

MATERIALS AND METHOD

A model of pelvic ischemia was developed by creating iliohypogastric/pudendal arterial atherosclerosis in rabbits. At 12 weeks conscious urinary frequency was examined, bladder blood flow was recorded and cystometrograms were done using general anesthesia. Bladder tissue was processed for molecular and ultrastructural analysis using quantitative real-time polymerase chain reaction, Western blot and transmission electron microscopy.

RESULTS

Conscious urinary frequency and the frequency of spontaneous bladder contractions significantly increased in animals with pelvic ischemia. Bladder ischemia up-regulated the gene and protein expression of hypoxia inducible factor-1α, transforming growth factor-β and nerve growth factor B. Vascular endothelial growth factor gene expression also increased but protein levels were unchanged. Transmission electron microscopy of ischemic bladder samples showed swollen mitochondria with degraded granules, thickened epithelium, deformed muscle fascicles, collagen deposition and impaired microvasculature with thickened intima and disrupted endothelial cell junctions. Degenerating axonal and Schwann cell profiles, and myelin sheath splitting around axons and Schwann cells were evident in ischemic bladders.

CONCLUSIONS

Interrupting pelvic blood flow resulted in an ischemic overactive bladder and significant increase in conscious urinary frequency. Molecular responses involving hypoxia inducible factor, transforming growth factor-β, vascular endothelial growth factor and nerve growth factor were associated with mitochondrial injury, fibrosis, microvasculature damage and neurodegeneration. Ischemia may have a key role in bladder overactivity and lower urinary tract symptoms.

Mesenchymal stem cell recruitment and improved bladder function after bladder outlet obstruction: preliminary data

PURPOSE

Mesenchymal stem cells have various therapeutic benefits in various organ injury models. Bladder outlet obstruction causes smooth muscle hypertrophy and fibrosis, leading to lowered compliance, increased storage pressures and renal injury. Decreased blood flow and hypoxia may contribute to obstruction related bladder decompensation. We used a mouse model to determine whether mesenchymal stem cell recruitment occurred after bladder outlet obstruction and whether this was associated with changes in bladder hypoxia, histology and function. We also identified potential chemokines involved in mesenchymal stem cell recruitment.

MATERIALS AND METHODS

A total of 20 female mice underwent bladder outlet obstruction. Three days later 2 million green fluorescent protein labeled mesenchymal stem cells were intravenously administered. After 4 weeks urodynamic and histological evaluation was performed. Quantitative reverse transcriptase-polymerase chain reaction was done to determine relative expression of the chemokines CCL2, CCL20, CCL25, CXCL9 and CXCL16. We simultaneously studied mice with bladder outlet obstruction only without mesenchymal stem cell injection and a control group.

RESULTS

In 10 of 15 surviving mesenchymal stem cell injected mice mesenchymal stem cells were identified in the detrusor, and decreased hypoxia, hypertrophy and fibrosis was seen. Nine of 10 mice with mesenchymal stem cell engraftment had improved compliance compared to those without engraftment (mean±SD 9.6±5.1 vs 3.9±2.6 μl/cm H2O, p=0.012). Polymerase chain reaction revealed a 2-fold increase in CCL2 expression but there were no significant changes in other chemokine levels.

CONCLUSIONS

Mesenchymal stem cell recruitment to the bladder after bladder outlet obstruction appears to be associated with increased blood flow and decreased tissue hypoxia, which may contribute to improvement in histopathological and functional parameters. Mesenchymal stem cell recruitment may be related to CCL2 over expression. Additional studies in larger samples are needed but these initial results suggest a potential role for mesenchymal stem cell based therapy for bladder outlet obstruction related bladder injury.

Engineering endostatin-producing cartilaginous constructs for cartilage repair using nonviral transfection of chondrocyte-seeded and mesenchymal-stem-cell-seeded collagen scaffolds

Although there is widespread recognition of the importance of angiogenesis in tissue repair, there is little work on the inhibition of angiogenesis in the context of tissue engineering of naturally avascular tissues, like articular cartilage. The objective was to engineer a collagen-scaffold-based cartilaginous construct overexpressing a potent antiangiogenic factor, endostatin, using nonviral transfection. Endostatin-plasmid-supplemented collagen scaffolds were seeded with mesenchymal stem cells and chondrocytes and cultured for 20&#x2013;22 days. The effects of the following variables on endostatin expression and chondrogenesis were examined: collagen scaffold material, method of nonviral vector incorporation, plasmid load, culture medium, and oxygen tension. An increase and peak of endostatin protein was observed during the first week of culture, followed by a decrease to low levels, suggesting that overexpression of endostatin could be sustained for several days using the nonviral vector. The amount of endostatin produced was tunable with the external factors. Chondrogenesis was observed in the engineered constructs cultured in chondrogenic medium at the 3-week time point, demonstrating that endostatin did not inhibit the chondrogenic potential of mesenchymal stem cells or the general viability of the cells. The ability to engineer endostatin-expressing cartilaginous constructs will be of value for future work exercising regulatory control of angiogenesis in cartilage repair.

Gastroprotective activity of atractylenolide III from Atractylodes ovata on ethanol-induced gastric ulcer in vitro and in vivo

Objectives

The rhizome of Atractylodes ovata De Candolle is popularly used in traditional Chinese medicine to treat gastrointestinal diseases. However, the major gastroprotective compounds of A. ovata have not been identified. This study reports on the principal gastro- protective component of A. ovata.

Methods

Five sesquiterpenoids (atractylon, atractylenolides I, II, III and biatractylolide) were isolated from the extracts of A. ovata rhizome via silica gel column chromatography. The gastroprotective effects of these five sesquiterpenoids were measured in in-vitro ethanol-induced primary culture rat gastric mucosal (PRGM) cell damage and in-vivo ethanol-induced acute rat gastric ulcer models.

Key findings

Atractylon, atractylenolide I and biatractylolide were strongly toxic in PRGM cells, whilst atractylenolides II and III were not. Atractylenolide II did not show cytoprotective effects, but oral administration of atractylenolide III dose-dependently prevented ethanol-induced PRGM cell death and cell membrane damage. The EC50 values were 0.27 and 0.34 mm, respectively. In the in-vivo assay, atractylenolide III 10 mg/kg significantly reduced 70% ethanol-induced Wistar rat gastric ulcer. Atractylenolide III could inhibit matrix metalloproteinase (MMP)-2 and MMP-9 expression through upregulation of tissue inhibitors of metalloproteinase from the gastric ulcerated tissues.

Conclusions

Atractylenolide III was the major gastroprotective component of A. ovata in ethanol-induced acute gastric ulcer. It is suggested that the gastroprotective mechanism of atractylenolide III was via inhibition of the MMP-2 and MMP-9 pathway.

Preliminary study on the effect of trauma-induced secondary cellular hypoxia in brain injury

Secondary cerebral hypoxia has recently been shown to play an important role in the outcome of patients suffering from traumatic brain injury (TBI). However, the precise mechanisms underlying secondary cerebral hypoxia are complex and interrelated. In this study, we investigate the effect of hypoxia within a rat model of trauma-induced late cerebral cortex injury. Using the hypoxia marker pimonidazole, we verified and isolated areas of the cortex that had suffered hypoxic damage. Using subsequent reverse-transcriptase PCR analyses, we found that the expressions of both transforming growth factor beta1 (TGF-beta1) and hypoxia-inducible factor-1alpha (HIF-1alpha) increased significantly under hypoxic conditions induced by TBI compared with uninjured control animals. In addition, the maximum mRNA expression of TGF-beta1 and HIF-1alpha was found at 3 days and 12h after TBI, respectively. Our data suggest that secondary cerebral hypoxia injury involves various cytokines including TGF-beta1 and HIF-1alpha. Furthermore, upon immunohistochemical analysis, both TGF-beta1 and HIF-1alpha expression were almost localized in the same types of cells by using immunohistochemical study. These results may have important implications in the understanding of trauma-induced secondary cerebral hypoxia injury.

The bladder extracellular matrix. Part I: architecture, development and disease

From the earliest studies with epithelial cells implanted into detrusor muscle to later experiments on smooth muscle in defined collagen gels, cell niche and extracellular matrix (ECM) have been clearly shown to orchestrate cellular behavior and fate whether quiescent, migratory, or proliferative. Normal matrix can revert transformed cells to quiescence, and damaged matrix can trigger malignancy or dedifferentiation. ECM influence in disease, development, healing and regeneration has been demonstrated in many other fields of study, but a thorough examination of the roles of ECM in bladder cell activity has not yet been undertaken. Structural ECM proteins, in concert with adhesive proteins, provide crucial structural support to the bladder. Both structural and nonstructural components of the bladder have major effects on smooth muscle function, through effects on matrix rigidity and signaling through ECM receptors. While many ECM components and receptors identified in the bladder have specific known functions in the vascular smooth musculature, their function in the bladder is often less well defined. In cancer and obstructive disease, the ECM has a critical role in pathogenesis. The challenge in these settings will be to find therapies that prevent hyperproliferation and encourage proper differentiation, through an understanding of matrix effects on cell biology and susceptibility to therapeutics.

Vascular endothelial growth factor and bladder from a different perspective: not only an angiogenic factor

Angiogenesis has a key role for embryonic development and is crucial in several major diseases. Molecular basis of angiogenesis has been widely investigated (J Biochem Mol Biol. 2006;39:469-478, Oncogene. 2000;19:5598-5605). In this review, vascular endothelial growth factor (VEGF) and related receptors and their key roles in embryonic bladder development are discussed. The normal VEGF expression and related angiogenesis pattern of embryonic bladder are highlighted. The VEGF family especially VEGF-A is the major player in angiogenesis as well as many other angiogenic factors and activates 2 tyrosine kinase receptors, VEGFR-1 and VEGFR-2 (J Biochem Mol Biol. 2006;39:469-478). Besides its worthy role in angiogenesis, VEGF-A also seems to participate in normal bladder development (J Urol. 2007;177:1552-1557, Br J Urol Int. 2006;98:217-225). In previous studies, we have shown that exogenous VEGF or hypoxia-induced endogenous upregulation of this protein accelerates the growth of the bladder by detrusor and urothelium hypertrophy and hyperplasia (J Urol. 2007;177:1552-1557, Br J Urol Int. 2006;98:217-225, Dev Biol. 1997;183:139-149, Neurourol Urodyn. 2004;23:342-348). This abrupt role of VEGF on detrusor muscle through a hypoxic pathway may potentially be a part of the solution for many urologic conditions such as remodeling of detrusor muscle in antenatal bladder outlet obstruction.

Mammalian target of rapamycin (mTOR) induces proliferation and de-differentiation responses to three coordinate pathophysiologic stimuli (mechanical strain, hypoxia, and extracellular matrix remodeling) in rat bladder smooth muscle

Maladaptive bladder muscle overgrowth and de-differentiation in human bladder obstructive conditions is instigated by coordinate responses to three stimuli: mechanical strain, tissue hypoxia, and extracellular matrix remodeling.( 1,2) Pathway analysis of genes induced by obstructive models of injury in bladder smooth muscle cells (BSMCs) identified a mammalian target of rapamycin (mTOR)-specific inhibitor as a potential pharmacological inhibitor. Strain-induced mTOR-specific S6K activation segregated differently from ERK1/2 activation in intact bladder ex vivo. Though rapamycin's antiproliferative effects in vascular smooth muscle cells are well known, its effects on BSMCs were previously unknown. Rapamycin significantly inhibited proliferation of BSMCs in response to mechanical strain, hypoxia, and denatured collagen. Rapamycin inhibited S6K at mTOR-sensitive phosphorylation sites in response to strain and hypoxia. Rapamycin also supported smooth muscle actin expression in response to strain or hypoxia-induced de-differentiation. Importantly, strain plus hypoxia synergistically augmented mTOR-dependent S6K activation, Mmp7 expression and proliferation. Forced expression of wild-type and constitutively active S6K resulted in loss of smooth muscle actin expression. Decreased smooth muscle actin, increased Mmp7 levels and mTOR pathway activation during in vivo partial bladder obstruction paralleled our in vitro studies. These results point to a coordinate role for mTOR in BSMCs responses to the three stimuli and a potential new therapeutic target for myopathic bladder disease.

Differential expression of vascular endothelial growth factor, and angiopoietin 1 and 2 in functionally divergent experimental rabbit models of bladder hypertrophy

PURPOSE

Partial bladder outlet obstruction or ovariectomy with subsequent estrogen replenishment induces bladder hypertrophy in rabbits and yet the functional outcomes of these procedures differ. We investigated whether these models might be distinguished by differential expression of the genes controlling angiogenesis.

MATERIALS AND METHODS

Groups of male rabbits underwent sham surgery or partial bladder outlet obstruction for 1 or 2 weeks. Groups of females underwent sham surgery, ovariectomy or ovariectomy plus estrogen for 1 or 2 weeks. Bladders from each group were weighed and assayed for the contractile response, smooth muscle content and vascular density. Mucosa and muscle layers were separated and RNA from the fractions was assayed by quantitative real-time polymerase chain reaction to measure the relative expression of vascular endothelial growth factor, and angiopoietin 1 and 2 mRNA.

RESULTS

Male bladders with partial outlet obstruction had attributes that typified hypertrophy with a loss of contractile function. Vascular endothelial growth factor expression was up-regulated in the mucosa and muscle layers but the effect was most pronounced in mucosa. Angiopoietin 1 expression was significantly up-regulated in muscle. Female bladders with ovariectomy plus estrogen had attributes that typified bladder hypertrophy with increased contractile function. Vascular endothelial growth factor expression was up-regulated early in mucosa but more highly and consistently increased in muscle. Angiopoietin 1 and 2 expression was not significantly affected.

CONCLUSIONS

Although these models have similar outcomes with regard to bladder hypertrophy, they have opposite functional outcomes that coincide with compartmental differences in the expression of genes involved in the regulation of angiogenesis. The disparity in gene expression might explain the difference in the functional outcomes.

Increased renal adrenomedullin expression in rats with ureteral obstruction

Ureteral obstruction is characterized by decreased renal blood flow that is associated with hypoxia within the kidney. Adrenomedullin (AM) is a peptide hormone with tissue-protective capacity that is stimulated through hypoxia. We tested the hypothesis that ureteral obstruction stimulates expression of AM and hypoxia-inducible factor-1 (HIF-1α) in kidneys. Rats were exposed to bilateral ureteral obstruction (BUO) for 2, 6, 12, and 24 h or sham operation and compared with unilateral obstruction (UUO). AM mRNA expression was measured by quantitative PCR in cortex and outer medulla (C+OM) and inner medulla (IM). AM and HIF-1α protein abundance and localization were determined in rats subjected to 24-h BUO. AM mRNA expression in C+OM increased significantly after 12-h BUO and further increased after 24 h. In IM, AM mRNA expression increased significantly in response to BUO for 6 h and further increased after 24 h. AM peptide abundance was enhanced in C+OM and IM after 24-h BUO. Immunohistochemical labeling of kidneys showed a wider distribution and more intense AM signal in 24-h BUO compared with Sham. In UUO rats, AM mRNA expression increased significantly in IM of the obstructed kidney compared with nonobstructed and Sham kidney whereas AM peptide increased in IM compared with Sham. HIF-1α protein abundance increased significantly in IM after 24-h BUO compared with Sham and HIF-1α immunoreactive protein colocalized with AM. In summary, AM and HIF-1α expression increases in response to ureteral obstruction in agreement with expected oxygen gradients. Hypoxia acting through HIF-1α accumulation may be an important pathway for the renal response to ureteral obstruction.

Bladder outlet obstruction accelerates bladder carcinogenesis

OBJECTIVE

To examine the correlation between partial bladder outlet obstruction (PBOO) and bladder carcinogenesis.

MATERIALS AND METHODS

Female Wistar rats (6 weeks old) were divided into three groups of 10 each: group 1 was exposed to n-butyl-n-butanol nitrosamine (BBN, a carcinogen) in drinking water for 8 weeks; group 2 had PBOO induced surgically after exposure to BBN for 8 weeks; group 3 had a sham operation and the rats drank normal water (control group). After 20 weeks, all of the rats were killed humanely and their bladders analysed.

RESULTS

There were no significant differences in body weight among the groups. The bladder weight of group 2 was significantly greater than either group 1 or group 3. Histopathologically, bladder smooth muscle hypertrophy was the major cause of the increased bladder weight for group 2. In group 2 there were increases in bladder wall thickness and many nipple-shaped urothelial tumours. Basic fibroblast growth factor and hypoxia-inducible factor-1alpha expression were significantly greater in group 2 than in groups 1 and 3.

CONCLUSIONS

Exposure of the bladder to carcinogens during bladder hyperplasia and hypertrophy induced by PBOO results in a greater incidence of superficial bladder carcinoma.

Mechanical strain activates a program of genes functionally involved in paracrine signaling of angiogenesis

Studies were performed to examine the extent to which mechanical stimuli mediate control of angiogenesis in bladder cells both in vitro and in vivo. Differential gene expression between control nonstretched and cyclically stretched bladder smooth muscle cells was assessed using oligonucleotide microarrays and pathway analysis by the web tool Fast Assignment and Transference of Information (FatiGO). Data showed that a substantial proportion (33 of 86) of mechanically responsive genes were angiogenesis-related and include cytokines, growth-related factors, adhesion proteins, and matricellular, signal transduction, extracellular matrix (ECM), and inflammatory molecules. Integrative knowledge of protein-protein interactions revealed that 12 mechano-sensitive gene-encoded proteins have interacting partner(s) in the vascular system confirming their potential role in paracrine regulation of angiogenesis. Angiogenic genes include matricellular proteins such as Cyr61/CCN1, CTGF/CCN2 and tenascin C, components of the VEGF and IGF systems, ECM proteins such as type I collagen and proteoglycans, and matrix metalloproteinases. In an in vivo model of bladder overdistension, 5 of 11 mechano-responsive angiogenic genes, independently tested by real-time PCR, were upregulated as a result of pressure overload including Cyr61/CCN1, CTGF/CCN2, MCP-1, VEGF-A, MMP-1, and midkine. Meanwhile, the molecular anatomy of angiogenic gene promoters reveals the presence of GA box-binding for the myc-associated zinc finger protein, MAZ, often found adjacent to binding sites for mechano-responsive transcription factors (e.g., NF-kappaB), suggesting that the coordinated activity of these factors may induce selective angiogenic gene transcription. These data suggest that mechanical control of angiogenic genes is an integral part of the adaptive and plasticity responses to mechanical overload.

Pelvic ischemia is measurable and symptomatic in patients with coronary artery disease: a novel application of dynamic contrast-enhanced magnetic resonance imaging

INTRODUCTION

Pelvic ischemia can manifest as vascular-mediated erectile dysfunction (ED) and lower urinary tract symptoms (LUTS), and is associated with cardiac ischemia.

AIMS

We aimed to develop a dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) technique to measure pelvic perfusion in benign tissue.

METHODS

Nine men with coronary artery disease (CAD) were compared with nine without. Images were acquired at 3T with T1-weighted DCE-MRI for perfusion. Two-compartment pharmacokinetic modeling was employed to fit signal enhancement from prostate, corpus cavernosal, and spongiosal tissues.

MAIN OUTCOME MEASURES

Perfusion parameters and validated pelvic symptom scores were compared.

RESULTS

The mean International Index of Erectile Function (IIEF) total score was worse in CAD (41.3 +/- 19.7) vs. controls (59.4 +/- 14.9, P = 0.04). The IIEF erectile function domain score trended to worse in CAD (13.7 +/- 9.7) vs. controls (22.0 +/- 9.9, P = 0.09). The mean total International Prostate Symptom Score (IPSS) trended to worse in CAD patients (13.2) than controls (7.0) (P = 0.10). Magnetic resonance perfusion analysis demonstrated lower mean maximal percent enhancement to P < 0.0001 in the CAD group vs. controls for all the following comparisons: prostate in CAD (22.4 +/- 0.4) vs. controls (26.3 +/- 0.1); cavernosal tissue in CAD (9.3 +/- 0.2) vs. controls (16.6 +/- 0.8); and spongiosal tissue in CAD (20.6 +/- 1.2) vs. controls (24.0 +/- 0.6). Comparison of mean wash-in rates in the unit of 10(-3)/second was also highly significant (P < 0.0001 for all tissues): prostate in CAD (574.0 +/- 18.0) was lower than controls (1,035.0 +/- 29.0); slower wash-in rates were seen in CAD cavernosal (58.0 +/- 4.0 vs. 139.0 +/- 9.0 in controls) and spongiosal tissue (134.0 +/- 6.0 vs. 278.0 +/- 12.0 in controls).

CONCLUSION

These initial data demonstrate that pelvic perfusion can be measured in noncancerous tissues, and that perfusion correlates with validated measures of ED and LUTS.

Endostatin expression in the murine model of ischaemia/reperfusion-induced acute renal failure

BACKGROUND

Renal ischaemia-hypoxia is a leading cause of acute renal failure, a clinical condition associated with rapid loss of renal function and high rates of mortality. Renal proximal tubular cells are the most severely injured during renal ischaemia, caused by the breakdown of the extracellular matrix of the tubular basement membrane. Endostatin is the C-terminal fragment of collagen XVIII generated by proteolytic cleavage and it is well-known as being an inhibitor of angiogenesis. In vitro, endostatin inhibits endothelial cell proliferation and migration, as well as tubule formation. In vivo, it has a potent inhibitory effect on tumour growth. In this study, we analysed endostatin gene expression in C57BL/6 mouse kidneys subjected to ischaemia/reperfusion.

METHODS

Ischaemic renal failure was induced via 45 min of bilateral occlusion of the renal artery and vein, followed by 12 h or 24 h of reperfusion. Whole-kidney homogenate and total RNA were extracted for examination by western blot analysis and quantitative polymerase chain reaction. The immunohistological examination revealed increased endostatin expression in injured kidney, mainly in the proximal tubule and collecting ducts.

RESULTS

Endostatin/collagen XVIII mRNA and protein expression increased during ischaemia and within 12 h of reperfusion. In the western blot assay, we identified increased expression of the 30 kDa endostatin-related fragment and of matrix metalloproteinase-9. CD31 was significantly expressed during reperfusion (P < 0.05). Immunohistological examination revealed glomerular and tubulointerstitial expression of endostatin.

CONCLUSION

These data suggest the local synthesis of a 30 kDa endostatin-related fragment following acute renal failure and suggest its role in the modulation of renal capillary density.

A porcine model of bladder outlet obstruction incorporating radio-telemetered cystometry

OBJECTIVE

To present a novel porcine model of bladder outlet obstruction (BOO) with a standardized bladder outlet resistance and real-time ambulatory radio-telemetered cystometry, as BOO is a common condition with many causes in both adults and children, with significant morbidity and occasional mortality, but attempts to model this condition in many animal models have the fundamental problem of standardising the degree of outlet resistance.

MATERIALS AND METHODS

BOO was created in nine castrated male pigs by dividing the mid-urethra; outflow was allowed through an implanted bladder drainage catheter containing a resistance valve, allowing urine to flow across the valve only when a set pressure differential was generated across the valve. An implantable radio-telemetered pressure sensor monitored the pressure within the bladder and abdominal cavity, and relayed this information to a remote computer. Four control pigs had an occluded bladder drainage catheter and pressure sensor placed, but were allowed to void normally through the native urethra. Intra-vesical pressure was monitored by telemetry, while the resistance valve was increased weekly, beginning with 2 cmH2O and ultimately reaching 10 cmH2O. The pigs were assessed using conventional cystometry under anaesthesia before death, and samples conserved in formalin for haematoxylin and eosin staining.

RESULTS

The pigs had radio-telemetered cystometry for a median of 26 days. All telemetry implants functioned well for the duration of the experiment, but one pig developed a urethral fistula and was excluded from the study. With BOO the bladder mass index (bladder mass/body mass x 10 000) increased from 9.7 to 20 (P = 0.004), with a significant degree of hypertrophy of the detrusor smooth muscle bundles. Obstructed bladders were significantly less compliant than control bladders (8.3 vs 22.1 mL/cmH2O, P = 0.03). Telemetric cystometry showed that there was no statistically significance difference in mean bladder pressure between obstructed and control pigs (4.8 vs 6.7 cmH2O, P = 0.7), but that each void was longer in the pigs with BOO.

CONCLUSION

This new model of BOO provides a method of reliably and precisely defining the bladder outlet resistance; it induces the changes classically seen with BOO, including increased bladder mass, increased smooth muscle bundle size and decreased compliance.

Detrusor glycogen reflects the functional history of bladders with partial outlet obstruction

OBJECTIVE

To assess the relationship between glycogen content in bladder detrusor tissue and historical bladder function in a guinea-pig model of partial bladder outlet obstruction (PBOO).

MATERIALS AND METHODS

In male immature guinea pigs PBOO was created with a silver ring around the proximal urethra; a control group had a sham operation for comparison. Longitudinal individual urodynamic data were obtained weekly, so that guinea pigs were killed at different levels of bladder dysfunction. Bladder sections were stained with periodic acid-Schiff (PAS) to assess overall morphology and glycogen granule density, scored from 0 (no glycogen) to 3. Glycogen scores were related to both the end-stage and historical extremes of bladder function values.

RESULTS

Glycogen granules were seen only in the detrusor; as their number increased their location expanded from only close to the serosa (glycogen score 1), through the detrusor (score 2) up to the urothelium (score 3). A glycogen score of 0 correlated with normal values for all urodynamic variables. Compared with a glycogen score of 0 a score of 1 correlated with significant (P < 0.05) changes in end-stage compliance (decrease) and contractility (increase) and significantly higher historical values for contractility, pressure and number of unstable contractions (NUC). In the group with a glycogen score of 2 there were significant changes in both the end-stage values and historical extremes for compliance, pressure, contractility and NUC (all P < 0.05). In the group with a glycogen score of 3 all these changes were even more dramatic, except for the end-stage contractility, for which the increase was not significant. From glycogen score 0 to score 3 all changes increased in magnitude.

CONCLUSION

A high glycogen content reflects a history of abnormal urodynamic function. This finding exemplifies the added value of structural analysis to urodynamic studies. Further studies are needed to relate bladder structure to the potential for functional recovery.