Karel Dewulf

Addressing challenges in underactive bladder: recommendations and insights from the Congress on Underactive Bladder (CURE-UAB)

Underactive bladder (UAB) is an expanding troublesome health issue, exerting a major influence on the health and independence of older people with a disproportionally low level of attention received. The 2nd International Congress on Underactive Bladder (CURE-UAB 2) convened in Denver, CO on December 3 and 4, 2015, and comprised of top clinicians, scientists, and other stakeholders to address the challenges in UAB. A series of workshops aimed to define UAB and its phenotype, define detrusor underactivity (DU) and create a subtyping of DU, evaluate existing animal models for DU, and lastly to establish research priorities for UAB.

Adipose-derived Stem Cells Counteract Urethral Stricture Formation in Rats

BACKGROUND A medical treatment for urethral stricture (US) is not yet available. OBJECTIVE To evaluate if local injection of human adipose tissue-derived stem cells (hADSC) prevents urethral fibrosis in a rat model of US. DESIGN, SETTING, AND PARTICIPANTS Male rats were divided into three groups: sham, US, and hADSC (n=12 each). Sham rats received a vehicle injection in the urethral wall. US and hADSCs were incised and injected with the fibrosis-inducer transforming growth factor-β1 in the urethral wall. INTERVENTION One day later, hADSCs were injected in the urethral wall of hADSC rats whereas sham and US rats were injected with the vehicle. After 4 wk, the rats underwent cystometries and tissues were then harvested for functional and molecular analyses. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Cystometry, microultrasound, histochemistry, organ bath studies, reverse transcription polymerase chain reaction, and western blot. RESULTS AND LIMITATIONS US rats exhibited 49-51% shorter micturition intervals, 35-51% smaller micturition volumes and bladder capacity, 33-62% higher threshold pressures and flow pressures, and 35-37% lower bladder filling compliance compared with hADSC-treated rats and sham rats (p<0.05). By ultrasound, US rats had hyperechogenic and thick urethral walls with narrowed lumen compared with sham rats, whereas hADSC rats displayed less extensive urethral changes. Isolated detrusor from US rats exhibited 34-55% smaller contractions than detrusor from sham rats (p<0.05). Corresponding values were 11-35% for isolated detrusors from hADSC rats. Collagen and elastin protein expression were increased in the penile urethras of US rats compared with sham and hADSC groups (p<0.05). Endothelial and inducible nitric oxide synthase expressions were higher (p<0.05) in the hADSC group. Compared with US rats, hADSC rats demonstrated decreased expression of several fibrosis-related genes. Administration of hADSCs was performed at an early stage of US development, which we consider a limitation of the study. CONCLUSIONS Local injection of hADSCs prevents stricture formation and urodynamic complications in a new rat model for US. PATIENT SUMMARY Stem cell therapy is effective for preventing urethral stricture in an experimental setting.

Intravesical Activation of the Cation Channel TRPV4 Improves Bladder Function in a Rat Model for Detrusor Underactivity

BACKGROUND Improvement of bladder emptying by modulating afferent nerve activity is an attractive therapeutic strategy for detrusor underactivity. Transient receptor potential vanilloid 4 (TRPV4) is a sensory ion channel in urothelial cells that contribute to the detection of bladder filling. OBJECTIVE To investigate the potential benefit of intravesical TRPV4 agonists in a pelvic nerve injury rat model for detrusor underactivity. DESIGN, SETTING, AND PARTICIPANTS Female wild-type and Trpv4 knockout rats underwent sham surgery or bilateral pelvic nerve injury (bPNI). Four weeks later, rats underwent cystometry with infusion of the TRPV4 agonist GSK1016790A. Bladders were harvested for in vitro pharmacological studies, quantitative reverse polymerase chain reaction and immunohistochemistry. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Data are expressed as median ± interquartile range. Statistical comparisons were made using the Mann-Witney U test and Wilcoxon signed rank test as appropriate. RESULTS AND LIMITATIONS Rats with bPNI showed a phenotype characteristic of detrusor underactivity with lower-amplitude voiding contractions, decreased voiding frequency, and increased postvoid residual. Intravesical application of GSK1016790A increased voiding frequency and reduced postvoid residual in wild-type, but not Trpv4-/-, rats. In isolated bladder strips, GSK1016790A did not induce relevant contractions, indicating that the observed improvements in bladder function are the result of increased afferent signalling through TRPV4 activation, rather than a local effect on the detrusor. The altered urinary phenotype of Trpv4-/- mice was not apparent in the Trpv4-/- rat model, suggesting species-related functional variations. Our results are limited to the preclinical setting in rodents. CONCLUSIONS Intravesical activation of TRPV4 improves bladder dysfunction after bPNI by increasing afferent signalling. PATIENT SUMMARY We demonstrate that the sensory protein transient receptor potential vanilloid 4 (TRPV4) can be targeted to improve bladder function in animals that have iatrogenic injury to the nerves innervating the bladder. Further research is required to determine whether these results can be translated to patients with an underactive bladder.

Characterization of voiding function and structural bladder changes in a rat model of neurogenic underactive bladder disease

To create an animal model for neurogenic underactive bladder disease (UAB) and identify markers to describe secondary myogenic changes in the bladder wall.

MP26-10 NEUROGENIC DETRUSOR UNDERACTIVITY: SHOULD WE TARGET THE BLADDER?

alteration of histopathology and expression of TLR4 and NLRP3 inflammasome-related molecules in the bladder using spontaneously hypertensive rats (SHRs) as an OAB model. METHODS: Twenty-weeks-old male SHRs and Wistar Kyoto rats (control) were used. After voiding function was analyzed by using metabolic cages, the bladder was excised for analysis of histopathology and mRNA expression. Hematoxylin eosin and Masson0s trichrome stain were performed to analyze bladder inflammatory condition and fibrosis. Immunohistostaining for NLRP3, TLR4 was also performed. Expression levels of NLRP3, IL1b, IL-18, IL6, IL8 and TGFb mRNA in the bladder were investigated by real-time PCR. Statistical analysis was performed using Mann-Whitney U test. P value less than 0.05 was considered statistically significant. RESULTS: In voiding function analyses, single urine volume was significantly decreased and voiding frequency was significantly increased in SHRs compared to control rats. In histological evaluation, suburothelial fibrosis was shown in SHRs compared to controls. Furthermore, immunohistostaining showed localized expression of NLRP3 and TLR4 in the bladder urothelium in both groups. In RT-qPCR analyses, mRNA expression levels of NLRP3, TLR4, IL1b, IL-18, IL6, IL8 and TGFb were significantly increased in SHRs in the bladder compared to controls. CONCLUSIONS: These results suggest that activation of TLR4 associated with oxidative stress is implicated in bladder chronic inflammation, which leads to frequent urination through NLRP3 inflammasome pathways. Therefore, further clarification of interactions between TLR4 and inflammasome pathways may offer new therapeutic targets for OAB associated with chronic inflammation.

MP82-16 BLADDER SMOOTH MUSCLE CONTRACTILITY IS INHIBITED BY HC030031 INDEPENDENTLY OF TRPA1

INTRODUCTION AND OBJECTIVES: The exact etiology of LUTS in human is still poorly understood. Alpha1-blockers are widely used in the treatment of LUTS associated with BPH. Tamsulosin has been reported to possess a potential of increasing blood flow in bladder microcirculation. Using a characterized rat model of chronic pelvic ischemia, we have studied the ameliorating potential of tamsulosin on the changes in bladder function caused by chronic ischemia. METHODS: Chronic pelvic ischemia (CPI) was induced by causing bilateral endothelial injury of both iliac arteries and feeding a 2% cholesterol diet. A total of 60 male Sprague Dawley rats (18 weeks old) were divided into three groups: Control, CPI, and CPI-tamsulosin. The Control group received a regular diet and the CPI-tamsulosin group received tamsulosin (10 mg/kg/day) for 8 weeks. Eight weeks after surgery, half of the rats in the Control, CPI and CPI-tamsulosin groups were examined by cystometry and sacrificed for organ bath study. The other half of the rats from each group was examined 16 weeks after surgery (the CPI-tamsulosin group were continued treatment in the latter half of 8 weeks). RESULTS: The iliac arteries from the AI showed neo-intimal proliferation and vascular occlusion. This was not prevented by tamsulosin treatment. After 8 weeks, there was no difference between CPI and CPI-tamsulosin groups in micturition interval (MI), bladder capacity (Bcap), and voiding volume (VV). Those parameters in both groups were significantly less than in the Control group (P<0.05). After 16 weeks, those parameters were improved in CPI-tamsulosin group without changing other parameters. CONCLUSIONS: Tamsulosin treatment improved voiding function in rats with established chronic pelvic ischemia. The translational impact of this finding would be worth further study for improving the bladder function.