Comparison of leak point pressure methods in an animal model of stress urinary incontinence.

We compared three different methods of testing leak point pressure (LPP) in rats with or without the pudendal nerves and nerves to the iliococcygeus/pubococcygeus muscles transected: (1) sneeze induced with a whisker in the nostril (sneeze LPP), (2) manually increased abdominal pressure (Crede LPP), and (3) increased intravesical pressure using the vertical tilt table method (vertical tilt table LPP). In sham rats, passive intravesical pressure rises in Crede and vertical tilt table methods induced active urethral closure mechanisms that contributed to high LPPs (41.4 and 35.5 cm H2O, respectively), which were significantly reduced by nerve transection. During sneezing, leakage was observed in nerve-transected rats, but not in sham rats, indicating that sneezing can activate an additional urethral closure mechanism. Measuring LPP during sneezing or passive intravesical pressure rises in the vertical tilt table and Crede method seems to be useful for assessing the continence mechanisms under different stress conditions in rats.

A tissue-engineered suburethral sling in an animal model of stress urinary incontinence.

OBJECTIVE: To create and evaluate the functional effects of a tissue-engineered sling in an animal model of stress urinary incontinence (SUI). MATERIALS AND METHODS: Twenty female Sprague-Dawley rats were divided into four equal groups: a control group (C) had no intervention before the leak-point pressure (LPP) was measured; a denervated group (D) had bilateral proximal sciatic nerve transection (PSNT) and periurethral dissection with no sling placed; group S had concomitant bilateral PSNT and a suburethral sling of small intestinal submucosa (SIS) placed; and group (M) had concomitant bilateral PSNT with implantation of a tissue-engineered sling. The suburethral sling was placed via a transabdominal approach with the sling sutured to the pubic bone. Tissue-engineered slings were prepared with muscle-derived cells obtained via the pre-plate technique and subsequently seeded for 2 weeks on a SIS scaffold. Suburethral slings were implanted 2 weeks before LPP testing, using the vertical-tilt method. RESULTS: Surgically placing a suburethral sling is feasible in the female rat, with few complications. LPPs from both sling groups (S and M) were not significantly different from untreated controls (C). The S, M and C groups all had significantly higher LPPs than group D. Importantly, no rat from either sling group (S and M) had signs of urinary retention. CONCLUSIONS: Placing tissue-engineered slings in an animal model of SUI resulted in LPP values that were not significantly different from those in untreated control or SIS (S) groups. These data show that incorporating muscle stem cells into SIS slings does not adversely alter the advantageous mechanical properties of the SIS sling in a model of SUI, and provide the basis for future functional studies of tissue-engineered sling materials with long-term retention.

Bladder and sexual function among women with multiple sclerosis.

OBJECTIVE: Genitourinary dysfunction is common in women with multiple sclerosis (MS), yet few studies have evaluated the association between bladder and sexual dysfunction in these women. The aim of this study was to determine factors, including demographic and bladder function, associated with sexual dysfunction in a sample of women with MS. METHODS: One hundred and thirty-three women with MS completed questionnaires related to overall heath status, bladder function and sexual function. Response frequencies and percentages were calculated for questionnaire responses. Multivariate logistic regression analyses were performed to determine predictors of sexual dysfunction. RESULTS: Sixty-one per cent of the sample indicated that they had a problem with bladder control. Forty-seven per cent of respondents indicated that their neurological problems interfered with their sex life. Over 70% of the sample reported that they enjoyed, felt aroused and experienced orgasm during sexual activity. Not having a sexual partner and the indication of bothersome neurological problems were the best predictors of sexual dysfunction. Interestingly, patients bothered by their urge incontinence had higher levels of orgasm compared to women not bothered by urge incontinence. CONCLUSIONS: Although over half of the women reported voiding symptoms, most still enjoyed, felt aroused and could experience orgasm. Neurological symptoms and lacking a sexual partner emerged as the best predictors of sexual dysfunction. Urge incontinence may not be a risk factor for an orgasm. Our findings elucidate the complex nature of sexual dysfunction in women with MS.

Intraurethral muscle-derived cell injections increase leak point pressure in a rat model of intrinsic sphincter deficiency.

OBJECTIVES: To determine whether allogenic muscle-derived cells (MDCs) could restore sphincter function in rats with intrinsic sphincter deficiency (ISD). ISD denotes a malfunction of the urethral sphincter. METHODS: ISD was produced in 25 adult female Sprague-Dawley rats by cauterizing tissues lateral to the mid-urethra. One week after cauterization, 1.5 x 10(6) MDCs, genetically engineered for beta-galactosidase expression, was injected into the mid-urethra in 16 rats. Another 9 rats were injected with Hanks' balanced salt solution after cauterization. As a control, 9 normal rats underwent a sham operation. Sphincter function was studied using the vertical tilt table/intravesical pressure clamp technique to measure leak point pressures (LPPs). The fate of the MDCs was assessed using LacZ staining. RESULTS: The injection of MDCs increased the LPP without affecting bladder function. The mean LPP of the control rats 2, 4, and 6 weeks after the sham operation was 49.8 +/- 1.3, 51.2 +/- 1.5, and 51.6 +/- 2.0 cm H2O, respectively. The mean LPP of the rats 2, 4, and 6 weeks after cauterization and Hanks' balanced salt solution injection was 17.2 +/- 1.4, 26.9 +/- 1.9, and 25.5 +/- 1.3 cm H2O, respectively. The mean LPP of the rats 2, 4, and 6 weeks after cauterization and MDC injection was 38.2 +/- 2.2, 43.1 +/- 2.6, and 51.5 +/- 0.9 cm H2O, respectively. LacZ staining confirmed that MDC had integrated within the striated muscle layer of the cauterized urethra. CONCLUSIONS: The injection of intraurethral MDCs improved sphincter function in rats with ISD and may provide an attractive alternative to current treatments.

The role of bladder-to-urethral reflexes in urinary continence mechanisms in rats.

Urethral closure mechanisms during passive increments in intravesicular pressure (P(ves)) were investigated using microtip transducer catheters in urethane-anesthetized female rats. After a block of reflex bladder contractions by spinal cord transection at T8-T9, abruptly raising P(ves) to 20, 40, or 60 cmH(2)O for 2 min induced a bladder pressure-dependent contractile response in a restricted portion of the middle urethra (12.5-15 mm from the urethral orifice) that was abolished by cutting the pelvic nerves bilaterally. In pelvic nerve-intact rats, the bilateral transection of either the pudendal nerves, the nerves to the iliococcygeous/pubococcygeous muscles, or the hypogastric nerves significantly reduced (49-74%) the urethral reflex response induced by passive P(ves) increases, and combined transection of these three sets of nerves totally abolished the urethra-closing responses. In spinal cord-intact rats, similar urethral contractile responses were elicited during P(ves) elevation (20 or 40 cmH(2)O) and were also eliminated by bilateral pelvic nerve transection. After spinal cord and pelvic nerve transection, leak point pressures, defined as the pressure inducing fluid leakage from the urethral orifice during passive P(ves) elevation by either bladder pressure clamping in 2.5-cmH(2)O steps or direct compression of the bladder, were significantly lowered by 30-35% compared with sham-operated (spinal cord-transected and pelvic nerve-intact) rats. These results indicate that 1) passive elevation of P(ves) can elicit pelvic afferent nerve-mediated contractile reflexes in the restricted portion of the urethra mediated by activation of sympathetic and somatic nerves and 2) bladder-to-urethral reflexes induced by passive P(ves) elevation significantly contribute to the prevention of stress urinary incontinence.

A model of intrinsic sphincteric deficiency in the rat: electrocauterization.

AIMS: Intrinsic sphincteric deficiency (ISD) denotes a malfunction of the distal urethral sphincter. Our objective was to produce a durable model of ISD in the rat. METHODS: Surrounding tissues lateral to the mid-urethra were cauterized to produce sphincteric injury in 24 adult female Sprague-Dawley rats. The rats were divided into four groups of six rats each and followed for 2, 4, 6, and 16 weeks. Sphincteric function was studied by using the vertical tilt table/intravesical pressure clamp model to measure leak point pressures (LPPs). Muscle and nerve damage were assessed with hematoxylin and eosin (H&E) and anti-protein gene product (PGP) 9.5 staining, respectively. As a control, 12 rats underwent a sham operation and subsequent LPP testing at 2, 4, 6, and 16 weeks. RESULTS: The mean LPPs of the rats 2, 4, 6, and 16 weeks after cauterization were 18.7 +/- 0.8 cm H2O, 27.6 +/- 1.6 cm H2O, 24.3 +/- 1.7 cm H2O, and 19.1 +/- 2.2 cm H2O, respectively. The mean LPPs of the rats 2, 4, 6, and 16 weeks after the sham operation were 49.8 +/- 1.3 cm H2O, 51.2 +/- 1.5 cm H2O, 51.6 +/- 2.0 cm H2O, and 49.7 +/- 0.6 cm H2O, respectively. When compared to time-matched control groups, the decreased LPPs in each cauterized group were significantly lower (P < 0.001). Histological analysis showed muscle damage and fewer nerves in all cauterized groups. CONCLUSIONS: Cauterization of tissues lateral to the mid-urethra decreased LPP without affecting bladder function. This electrocauterization model produced low LPPs that, after 2 weeks, were maintained for up to 16 weeks. Histology suggests that damage to striated muscle and nerves might have contributed to the change in LPP in this model for ISD.

Innovations in pharmacotherapy for stress urinary incontinence.

The purpose of this review article is to highlight new pharmacotherapies on the horizon for the treatment of stress urinary incontinence (SUI). Although behavioral and surgical therapies are currently the mainstay of treating SUI, we believe that medications will take center stage and possibly become first-line therapy. Currently, there are no FDA medications indicated for SUI. However, results are becoming available about an oral medication, duloxetine, which appears to be clinically safe and efficacious for the treatment of SUI. In addition to discussing medications currently under development, we will also discuss exciting pharmacological targets that could be suitable to treat SUI.

Improved sphincter contractility after allogenic muscle-derived progenitor cell injection into the denervated rat urethra.

OBJECTIVES: To study the physiologic outcome of allogenic transplant of muscle-derived progenitor cells (MDPCs) in the denervated female rat urethra. METHODS: MDPCs were isolated from muscle biopsies of normal 6-week-old Sprague-Dawley rats and purified using the preplate technique. Sciatic nerve-transected rats were used as a model of stress urinary incontinence. The experimental group was divided into three subgroups: control, denervated plus 20 microL saline injection, and denervated plus allogenic MDPCs (1 to 1.5 x 10(6) cells) injection. Two weeks after injection, urethral muscle strips were prepared and underwent electrical field stimulation. The pharmacologic effects of d-tubocurare, phentolamine, and tetrodotoxin on the urethral strips were assessed by contractions induced by electrical field stimulation. The urethral tissues also underwent immunohistochemical staining for fast myosin heavy chain and CD4-activated lymphocytes. RESULTS: Urethral denervation resulted in a significant decrease of the maximal fast-twitch muscle contraction amplitude to only 8.77% of the normal urethra and partial impairment of smooth muscle contractility. Injection of MDPCs into the denervated sphincter significantly improved the fast-twitch muscle contraction amplitude to 87.02% of normal animals. Immunohistochemistry revealed a large amount of new skeletal muscle fiber formation at the injection site of the urethra with minimal inflammation. CD4 staining showed minimal lymphocyte infiltration around the MDPC injection sites. CONCLUSIONS: Urethral denervation resulted in near-total abolishment of the skeletal muscle and partial impairment of smooth muscle contractility. Allogenic MDPCs survived 2 weeks in sciatic nerve-transected urethra with minimal inflammation. This is the first report of the restoration of deficient urethral sphincter function through muscle-derived progenitor cell tissue engineering. MDPC-mediated cellular urethral myoplasty warrants additional investigation as a new method to treat stress urinary incontinence.

Muscle-derived stem cells seeded into acellular scaffolds develop calcium-dependent contractile activity that is modulated by nicotinic receptors.

OBJECTIVES: To explore the contractile activity and physiologic properties of muscle-derived stem cells (MDSCs) incorporated into small intestinal submucosa (SIS) scaffolds. METHODS: MDSCs were harvested from mice hind leg muscles using the preplate technique and stably transfected with a plasmid to express the LacZ reporter gene. Fifty different preparations of SIS cultured with MDSCs (MDSC/SIS) or SIS alone were incubated at 37 degrees C for 1, 4, and 8 weeks and also were mounted in a bath to measure the isometric contractions. RESULTS: LacZ and Masson-trichrome staining revealed MDSCs could migrate into and distribute throughout the SIS and form myotubes. In MDSC/SIS, spontaneous contractile activities were noted in the 4-week (five of six specimens) and 8-week (eight of eight specimens) cultures, but not in 1-week cultures (n = 11). All SIS control groups after 1 (n = 11), 4 (n = 6), and 8 (n = 8) weeks of incubation did not show any activity. In most of the 4-week, and all of the 8-week, MDSC/SIS cultures, the frequency and amplitude of spontaneous contractile activities were decreased by succinylcholine 10 microM and 20 microM. Electrical field stimulation, carbachol, and KCl did not alter the frequency, amplitude, or pattern of spontaneous contractile activities in MDSC/SIS. Spontaneous contractile activities were blocked by Ca(32+)-free Krebs solution with ethyleneglycoltetraacetic acid 200 microM and distilled water. CONCLUSIONS: MDSCs could be incorporated into SIS-forming myotubes capable of contracting. The contractile activity of this three-dimensional construct is Ca(2+) dependent and is modulated by nicotinic receptors. MDSC seeding of an acellular matrix may become a functional sling to reengineer the deficient sphincter or as contractile bladder augmentation.

Pharmacotherapy for stress urinary incontinence.

The purpose of this review article is to highlight new pharmacotherapies on the horizon for the treatment of stress urinary incontinence. Although behavioral and surgical therapies are currently the mainstay of treatment for this condition, we are hopeful that pharmacotherapy will one day take center stage of the various treatment options. Currently, there are no medications approved by the US Food and Drug Administration for the treatment of stress urinary incontinence. However, exciting clinical data are becoming available about an oral medication for the treatment of stress urinary incontinence that appears to be clinically safe and efficacious. In addition to discussing medications currently under development, this article also discusses pharmacologic targets that could be suitable future targets to treat stress urinary incontinence.