Oxybutynin chloride inhibits proliferation and suppresses gene expression in bladder smooth muscle cells

Video-urodynamic effects of vibegron, a new selective β3-adrenoceptor agonist, on antimuscarinic-resistant neurogenic bladder dysfunction in patients with spina bifida

OBJECTIVES

To evaluate the efficacy, safety and tolerability of vibegron for the treatment of antimuscarinic-resistant neurogenic bladder dysfunction in patients with spina bifida.

METHODS

In this retrospective study, 15 patients with antimuscarinic-resistant neurogenic bladder dysfunction due to spina bifida underwent a video-urodynamic study before and during the administration of vibegron 50 mg once daily instead of antimuscarinic agents from February 2019 through April 2021. The video-urodynamic study was carried out to evaluate bladder compliance, maximum cystometric bladder capacity, detrusor overactivity, detrusor leak point pressure and vesicoureteral reflux before and >3 months after the beginning of vibegron administration.

RESULTS

Treatment with vibegron significantly improved bladder compliance and maximum cystometric bladder capacity compared with antimuscarinic agents, respectively (7.4 ± 4.2 vs 30.4 ± 48.2 mL/cmH₂ O, P = 0.0001; 231.4 ± 81.2 vs 325.2 ± 106.5 mL, P = 0.0005). Detrusor overactivity did not change after the administration of vibegron. Bladder deformity, which was confirmed in 12 patients, improved in half of the patients after taking vibegron. Vesicoureteral reflux, which was confirmed in two patients, was extinguished after taking vibegron. Newly occurring adverse events were not observed, and all patients continued to take vibegron during the treatment period.

CONCLUSIONS

Favorable efficacy of vibegron for antimuscarinic-resistant neurogenic bladder dysfunction due to spina bifida was shown video-urodynamically without apparent adverse events. Vibegron is a favorable option for the treatment of antimuscarinic-resistant neurogenic bladder dysfunction in patients with spina bifida.

Early Vs. Expectant Management of Spina Bifida Patients-Are We All Talking About a Risk Stratified Approach?

PURPOSE OF REVIEW

Advancements in the care of patients affected by myelomeningocele have flourished in recent years especially with respect to renal preservation and continence. Involvement of urologists both prenatally and early in life has driven many developments in preventative care and early intervention. As of yet, however, the ideal management algorithm that offers these patients the least invasive diagnostic testing and interventions while still preserving renal and bladder function remains ill defined.

RECENT FINDINGS

In a shift from prior years where the use of surgical intervention and intermittent catheterization were more liberally employed, some providers have more recently advocated for monitoring patients in a more conservative manner with a variety of diagnostic tests until radiographic or clinical changes are discovered. The criteria used to define the need for catheterization and the timing to initiate CIC or more invasive interventions is disparate across pediatric urology and there is published data to support several approaches. This review presents some of these criteria for use of CIC and some newer evidence to support different approaches along with supporting the trend toward individualized medicine and use of risk stratification in developing clinical treatment algorithms.

The effect of oxybutynin on structural changes of the obstructed guinea pig bladder

PURPOSE

Oxybutynin is used clinically to lower intravesical pressure and detrusor overactivity. In vitro it inhibits stretch induced bladder smooth muscle cell proliferation. We tested whether oxybutynin also prevents hypertrophic bladder changes in vivo in a model of partial bladder obstruction.

MATERIALS AND METHODS

Subvesical obstruction was induced in immature guinea pigs by a silver ring around the urethra. Eight animals received 0.4 mg oxybutynin per kg body weight per day in 2 doses. Control groups were obstructed without oxybutynin treatment or sham operated. Urodynamic pressure flow studies were performed at 1-week intervals for 10 weeks in all animals under anesthesia with ketamine/xylazine. After 10 weeks the animals were sacrificed and the bladder was removed for structural analysis with periodic acid-Schiff stain, in which the number of glycogen granules was also scored as a measure of previous ischemia.

RESULTS

Compared to the sham treated group obstructed animals had significantly higher intravesical pressure and detrusor overactivity, lower compliance and increased contractility. Obstructed animals that received oxybutynin retained normal intravesical pressure, detrusor overactivity and compliance. Their bladder contractility increased as in obstructed animals. The oxybutynin group showed less collagen infiltration in the detrusor and fewer glycogen granules compared to those in obstructed animals.

CONCLUSIONS

Our results demonstrate that oxybutynin has a protective effect on bladder function and structure. Prevention of hypertrophic and ischemic bladder changes is an argument for an early start of oxybutynin treatment in children with inborn neurogenic bladder dysfunction, such as spina bifida, or in patients with urethral valves.

Botulinum-A toxin injection into the detrusor: a safe alternative in the treatment of children with myelomeningocele with detrusor hyperreflexia

PURPOSE

We prospectively evaluated the efficacy and durability of botulinum-A toxin in the treatment of detrusor hyperreflexia in children with myelomeningocele (MMC).

MATERIALS AND METHODS

This study involved 15 patients with MMC (10 male and 5 female, mean age 5.8 years), all nonresponders to orally and intravesically administered anticholinergic medication and all on clean intermittent catheterization. Pretreatment assessment included a videourodynamic evaluation, an incontinence score and a mercaptoacetyltriglycine-3 renal scan. We injected 10 U/kg to a maximum of 360 U of botulinum-A toxin into the detrusor at 25 to 40 sites, sparing the trigone. Followup lasted between 12 and 30 months. All children underwent a urodynamic reevaluation, an assessment of the bladder capacity and an incontinence score at 3, 9 and 12 months after the first injection. A second intravesical injection was administered after 12 months and followup repeated as in the first year.

RESULTS

After the first injection treatment mean bladder reflex volume increased from 72.00 +/- 28.12 ml to 298 +/- 32.45 ml (mean +/- SD, p <0.001). Maximum detrusor pressure decreased from 78.76 +/- 23.14 cm H2O to 42.76 +/- 24.34 cm H2O (p <0.001). Maximum bladder capacity increased from 136.34 +/- 45.71 ml to 297.02 +/- 87.17 ml (p <0.001). Detrusor compliance increased from 18.29 +/- 27.19 ml/cm H2O to 51.17 +/- 38.17 ml/cm H2O (p <0.001). Of the 15 patients 13 became completely dry with CIC. The remaining 2 patients improved from score 3 to 1. Results after 9 months were similar to those obtained after 3 months. Mean durability of the effect of the drug was 10.5 months after the first as well as after the second intravesical injection.

CONCLUSIONS

Botulinum-A toxin is a safe alternative in the management of detrusor hyperreflexia in children with MMC. The preliminary results regarding urodynamic parameters and continence have been promising.

Effects of 4-Ethylamino-2-butynyl(2-cyclohexyl-2-phenyl)glycolate Hydrochloride, a Metabolite of Oxybutynin, on Bladder Specimens and Rhythmic Bladder Contraction in Rats in Comparison With Oxybutynin

Oxybutynin has been used for neurogenic bladder disorders and is known to have anti-cholinergic and antispasmodic properties. However, the anti-cholinergic and antispasmodic properties of 4-ethylamino-2-butynyl(2-cyclohexyl-2-phenyl)glycolate hydrochloride (N-desethyloxybutynin: DEOB), a metabolite of oxybutynin, have not been clarified. Therefore, in the present study, we studied these properties by using rat urinary bladder specimens in comparison with oxybutynin. Moreover, the effect of DEOB on rhythmic urinary bladder contraction was also evaluated using anesthetized rats. DEOB and oxybutynin concentration-dependently inhibited the carbachol-induced contraction, the pA(2) values being 7.19 and 7.11, respectively. DEOB and oxybutynin also concentration-dependently inhibited the 100 mM KCl-induced contraction, the ED(50) values being 12.1 and 10.4 microM, respectively. Intravenously administered DEOB and oxybutynin dose-dependently (0.03 - 0.3 mg/kg) inhibited the amplitude of the rhythmic bladder contraction to similar degrees, but had no affect on the frequency. From the above results, it was determined that DEOB has anti-cholinergic and antispasmodic properties and that these activities were almost equal to those of oxybutynin. Therefore, DEOB may play an important role during oxybutynin therapy for neurogenic bladder disorder.

Mechanical stretch regulates cell survival in human bladder smooth muscle cells in vitro

Our understanding of the pathophysiology of the overactive bladder is poor. It has been proposed that localized contractions result in the abnormal stretching of bladder smooth muscle. We hypothesize that stretch regulates the cellular processes that determine tissue size. The purpose of this study was to investigate the effect of stretch on apoptosis, proliferation, cell hypertrophy, and growth factor production in human bladder smooth muscle cells in vitro. Normal human detrusor muscle was obtained from patients undergoing radical cystectomy for invasive bladder cancer, and primary cultures were established. Cells were mechanically stretched on flexible plates at a range of pressures and times. Apoptosis was assessed by propidium iodide incorporation and flow cytometry. Radiolabeled thymidine and amino acid incorporation were used to assess proliferation and cell hypertrophy. ELISA and RT-PCR were used to assess growth factor production. Mechanical stretch inhibits apoptosis in a time- and dose-dependent manner and was associated with increases in the antiapoptotic proteins heat shock protein-70 and cIAP-1. Stretch also increases smooth muscle cell proliferation and hypertrophy, but hypertrophy is the more dominant response. These changes were associated with increases in IGF-1 and basic FGF and a decrease in transforming growth factor-beta1. Mechanical stretch regulates apoptosis, proliferation, and cell hypertrophy in human bladder smooth muscle cells.

Preliminary study of the safety and efficacy of extended-release oxybutynin in children

OBJECTIVES

To test the safety and efficacy of extended-release oxybutynin in children with bladder dysfunction. The efficacy of oxybutynin in children has been limited by side effects. A new extended-release formulation of oxybutynin has some benefits versus traditional oxybutynin but has never been evaluated in children.

METHODS

A retrospective study was performed on 25 children who had been treated with extended-release oxybutynin. Fourteen had neurogenic bladder dysfunction and 11 had urinary frequency and urgency and urge incontinence but no neurologic abnormalities. Patients and families were asked to semiquantitatively (0 to 10 grading with 10 = severe) assess the effects of the medication on efficacy, as well as side effects and compliance with medication schedules.

RESULTS

All 25 patients had improvement in incontinence and/or voiding dysfunction on extended-release oxybutynin. Twelve (48%) experienced no side effects. Of the 13 who did, 10 complained of dry mouth (grade 4.6 plus minus 0.5), 4 had constipation (grade 5.8 plus minus 1.8), 4 had heat intolerance (grade 5.1 plus minus 0.9), and 3 had drowsiness (grade 5.3 plus minus 2.4). Of patients previously treated with oxybutynin, the extended-release oxybutynin was equally or more efficacious and had the same or fewer side effects, especially less dry mouth. Families reported much better patient compliance with the medication regimen using extended-release oxybutynin compared with oxybutynin. Patient and family satisfaction was very high, and 21 of 25 have continued using the medication.

CONCLUSIONS

Extended-release oxybutynin is safe and efficacious in children. In this preliminary evaluation, it had benefits over traditional, immediate-release oxybutynin.

Long-term followup of newborns with myelodysplasia and normal urodynamic findings: Is followup necessary?

PURPOSE

A subset of newborns with myelodysplasia have normal bladder function on urodynamic assessment. We analyzed long-term followup in this population to determine the necessity for subsequent urological surveillance.

MATERIALS AND METHODS

We retrospectively analyzed the records of 25 of 204 newborns (12%) with myelodysplasia in whom neurourological evaluation was normal after surgical repair of the spinal defect. Initial assessment included complete urodynamic study, renal ultrasound, urinalysis and urine culture. These patients were reevaluated every 3 months until age 3 years, semiannually until age 6 years and yearly thereafter. The longest followup was 18.6 years.

RESULTS

Of the 25 newborns 22 had myelomeningocele and 3 had meningocele. During a mean followup of 9.1 years urodynamics subsequently showed neurourological deterioration in 8 children (32%). No changes in urodynamics were observed in any patient older than 6 years. All children with neurourological deterioration underwent magnetic resonance imaging, which confirmed a tethered spinal cord that was then surgically corrected. After the untethering procedure 2 patients (25%) regained normal voiding function, whereas in 6 (75%) mild or moderate neurogenic bladder dysfunction persisted.

CONCLUSIONS

Newborns with myelodysplasia and initially normal urodynamic studies are at risk for neurological deterioration secondary to spinal cord tethering, especially during the first 6 years of life. Close followup of these children is important for the early diagnosis and timely surgical correction of tethered spinal cord, and for the prevention of progressive urinary tract deterioration.

Lower urinary tract physiology and pharmacology

This review focuses on what we consider to be the most important findings of the last year relating to the smooth muscle of the lower urogenital system and the different levels of regulation that control its contraction and relaxation. One level is through modulation of the smooth muscle itself or its environment. Recent findings examining myosin isoform composition and collagen content as well as mechanisms that appear to be involved in inducing hyperplasia/hypertrophy of smooth muscle are described. Another method of regulation is via calcium-dependent phosphorylation of the regulatory light chain of myosin, which increases its activity. Interesting results indicating an uncoupling of force from calcium in the bladder are discussed. A third level of regulation is pharmacologic. Thus, the most recent findings related to receptor subtypes, including muscarinic, endothelin, alpha-adrenergic and nicotinic receptors, are presented. In addition, the effects of diabetes, incontinence, and partial bladder outlet obstruction on these modes of contractile regulation are also discussed.

Coculture of bladder urothelial and smooth muscle cells on small intestinal submucosa: potential applications for tissue engineering technology

PURPOSE

Small intestinal submucosa is a xenogenic, acellular, collagen rich membrane with inherent growth factors that has previously been shown to promote in vivo bladder regeneration. We evaluate in vitro use of small intestinal submucosa to support the individual and combined growth of bladder urothelial cells and smooth muscle cells for potential use in tissue engineering techniques, and in vitro study of the cellular mechanisms involved in bladder regeneration.

MATERIALS AND METHODS

Primary cultures of human bladder urothelial cells and smooth muscle cells were established using standard enzymatic digestion or explant techniques. Cultured cells were then seeded on small intestinal submucosa at a density of 1 x 105 cells per cm.2, incubated and harvested at 3, 7, 14 and 28 days. The 5 separate culture methods evaluated were urothelial cells seeded alone on the mucosal surface of small intestinal submucosa, smooth muscle cells seeded alone on the mucosal surface, layered coculture of smooth muscle cells seeded on the mucosal surface followed by urothelial cells 1 hour later, sandwich coculture of smooth muscle cells seeded on the serosal surface followed by seeding of urothelial cells on the mucosal surface 24 hours later, and mixed coculture of urothelial cells and smooth muscle cells mixed and seeded together on the mucosal surface. Following harvesting at the designated time points small intestinal submucosa cell constructs were formalin fixed and processed for routine histology including Masson trichrome staining. Specific cell growth characteristics were studied with particular attention to cell morphology, cell proliferation and layering, cell sorting, presence of a pseudostratified urothelium and matrix penetrance. To aid in the identification of smooth muscle cells and urothelial cells in the coculture groups, immunohistochemical analysis was performed with antibodies to alpha-smooth muscle actin and cytokeratins AE1/AE3.

RESULTS

Progressive 3-dimensional growth of urothelial cells and smooth muscle cells occurred in vitro on small intestinal submucosa. When seeded alone urothelial cells and smooth muscle cells grew in several layers with minimal to no matrix penetration. In contrast, layered, mixed and sandwich coculture methods demonstrated significant enhancement of smooth muscle cell penetration of the membrane. The layered and sandwich coculture techniques resulted in organized cell sorting, formation of a well-defined pseudostratified urothelium and multilayered smooth muscle cells with enhanced matrix penetration. With the mixed coculture technique there was no evidence of cell sorting although matrix penetrance by the smooth muscle cells was evident. Immunohistochemical studies demonstrated that urothelial cells and smooth muscle cells maintain the expression of the phenotypic markers of differentiation alpha-smooth muscle actin and cytokeratins AE1/AE3.

CONCLUSIONS

Small intestinal submucosa supports the 3-dimensional growth of human bladder cells in vitro. Successful combined growth of bladder cells on small intestinal submucosa with different seeding techniques has important future clinical implications with respect to tissue engineering technology. The results of our study demonstrate that there are important smooth muscle cell-epithelial cell interactions involved in determining the type of in vitro cell growth that occurs on small intestinal submucosa. Small intestinal submucosa is a valuable tool for in vitro study of the cell-cell and cell-matrix interactions that are involved in regeneration and various disease processes of the bladder.