Intravesical liposome administration--a novel treatment for hyperactive bladder in the rat

Animal models of interstitial cystitis/bladder pain syndrome

Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS) is a chronic disorder characterized by pelvic and/or bladder pain, along with lower urinary tract symptoms that have a significant impact on an individual's quality of life. The diverse range of symptoms and underlying causes in IC/BPS patients pose a significant challenge for effective disease management and the development of new and effective treatments. To facilitate the development of innovative therapies for IC/BPS, numerous preclinical animal models have been developed, each focusing on distinct pathophysiological components such as localized urothelial permeability or inflammation, psychological stress, autoimmunity, and central sensitization. However, since the precise etiopathophysiology of IC/BPS remains undefined, these animal models have primarily aimed to replicate the key clinical symptoms of bladder hypersensitivity and pain to enhance the translatability of potential therapeutics. Several animal models have now been characterized to mimic the major symptoms of IC/BPS, and significant progress has been made in refining these models to induce chronic symptomatology that more closely resembles the IC/BPS phenotype. Nevertheless, it's important to note that no single model can fully replicate all aspects of the human disease. When selecting an appropriate model for preclinical therapeutic evaluation, consideration must be given to the specific pathology believed to underlie the development of IC/BPS symptoms in a particular patient group, as well as the type and severity of the model, its duration, and the proposed intervention's mechanism of action. Therefore, it is likely that different models will continue to be necessary for preclinical drug development, depending on the unique etiology of IC/BPS being investigated.

Liposome-Encapsulated Botulinum Toxin A in Treatment of Functional Bladder Disorders

Botulinum toxin A (BoNT-A) intravesical injections have been used to treat patients with refractory functional bladder disorders such as overactive bladder (OAB) and interstitial cystitis/bladder pain syndrome (IC/BPS), but the risk of adverse events and the need for repeated injections continue to prevent widespread application of this treatment. Liposomes are vesicles that comprise concentric phospholipid layers and an aqueous core; their flexible compositions enable them to adsorb and fuse with cell membranes and to deliver drugs or proteins into cells. Therefore, liposomes have been considered as promising vehicles for the less invasive delivery of BoNT-A. In previous placebo-controlled trials including patients with OAB refractory to medical treatment, it was shown that liposomal BoNT-A could significantly decrease the frequency and urgency of urination. In patients with IC/BPS, it was shown that liposomal BoNT-A could also improve bladder pain, but the therapeutic efficacy was not superior to that of the placebo. As the therapeutic mechanisms of BoNT-A include the decreased expression of nerve growth factors, P2X3 receptors, and vanilloid receptors on C-fibers, liposomal BoNT-A might play a more promising role in the treatment of bladder oversensitivity. This article features the contemporary literature regarding BoNT-A, liposomes, and liposomal BoNT-A treatment for functional bladder disorders and potential clinical applications in the future.

Nano-Formulation Based Intravesical Drug Delivery Systems: An Overview of Versatile Approaches to Improve Urinary Bladder Diseases

Intravesical drug delivery is a direct drug delivery approach for the treatment of various bladder diseases. The human urinary bladder has distinctive anatomy, making it an effective barrier against any toxic agent seeking entry into the bloodstream. This screening function of the bladder derives from the structure of the urothelium, which acts as a semi-permeable barrier. However, various diseases related to the urinary bladder, such as hyperactive bladder syndrome, interstitial cystitis, cancer, urinary obstructions, or urinary tract infections, can alter the bladder’s natural function. Consequently, the intravesical route of drug delivery can effectively treat such diseases as it offers site-specific drug action with minimum side effects. Intravesical drug delivery is the direct instillation of medicinal drugs into the urinary bladder via a urethral catheter. However, there are some limitations to this method of drug delivery, including the risk of washout of the therapeutic agents with frequent urination. Moreover, due to the limited permeability of the urinary bladder walls, the therapeutic agents are diluted before the process of permeation, and consequently, their efficiency is compromised. Therefore, various types of nanomaterial-based delivery systems are being employed in intravesical drug delivery to enhance the drug penetration and retention at the targeted site. This review article covers the various nanomaterials used for intravesical drug delivery and future aspects of these nanomaterials for intravesical drug delivery.

Nanotechnology as a tool to advance research and treatment of non-oncologic urogenital diseases

Nanotechnology represents an expanding area of research and innovation in almost every field of science, including Medicine, where nanomaterial-based products have been developed for diagnostic and therapeutic applications. Because of their small, nanoscale size, these materials exhibit unique physical and chemical properties that differ from those of each component when considered in bulk. In Nanomedicine, there is an increasing interest in harnessing these unique properties to engineer nanocarriers for the delivery of therapeutic agents. Nano-based drug delivery platforms have many advantages over conventional drug administration routes as this technology allows for local and transdermal applications of therapeutics that can bypass the first-pass metabolism, improves drug efficacy through encapsulation of hydrophobic drugs, and allows for a sustained and controlled release of encapsulated agents. In Urology, nano-based drug delivery platforms have been extensively investigated and implemented for cancer treatment. However, there is also great potential for use of nanotechnology to treat non-oncologic urogenital diseases. We provide an update on research that is paving the way for clinical translation of nanotechnology in the areas of erectile dysfunction (ED), overactive bladder (OAB), interstitial cystitis/bladder pain syndrome (IC/BPS), and catheter-associated urinary tract infections (CAUTIs). Overall, preclinical and clinical studies have proven the utility of nanomaterials both as vehicles for transdermal and intravesical delivery of therapeutic agents and for urinary catheter formulation with antimicrobial agents to treat non-oncologic urogenital diseases. Although clinical translation will be dependent on overcoming regulatory challenges, it is inevitable before there is universal adoption of this technology to treat non-oncologic urogenital diseases.

Nano-BTA: A New Strategy for Intravesical Delivery of Botulinum Toxin A

Botulinum neurotoxin subtype A (BoNT-A) has been part of the urology treatment arsenal since it was first used in the treatment of detrusor-sphincter dyssynergia more than 30 years ago. BoNT-A has been recommended as an effective treatment for neurogenic detrusor overactivity and overactive bladder. However, direct intradetrusor injection of BoNT-A using cystoscopy after anesthesia may cause hematuria, pain, and infection; these adverse events have motivated urologists to find less invasive and more convenient ways to administer BoNT-A. The development of nanotechnology has led to the advancement of intravesical drug delivery. Using versatile nanocarriers to transport BoNT-A across the impermeable urothelium is a promising therapeutic option. In this review, we discuss the effectiveness and feasibility of liposomes, thermosensitive polymeric hydrogels, and hyaluronan-phosphatidylethanolamine as carriers of BoNT-A for intravesical instillation. To date, these carriers have not reached a similar efficacy as intradetrusor injections in long-term observations. Hopefully, researchers will make a breakthrough with new nanomaterials to develop clinical applications in the future.

Imatinib Mesylate Reduces Voiding Frequency in Female Mice With Acute Cyclophosphamide-Induced Cystitis

Lamina propria interstitial cells that express the tyrosine kinase receptor, platelet-derived growth factor receptor alpha (PDGFRα) may play a role in urinary sensory signaling. Imatinib mesylate, also referred to as imatinib, is a tyrosine kinase inhibitor that can inhibit PDGFRα and has been widely used in urological research. We evaluated the functional effects of imatinib administration (via oral gavage or intravesical infusion) with two different experimental designs (prevention and treatment), in a cyclophosphamide (CYP)-induced cystitis (acute, intermediate, and chronic), male and female rodent model using conscious cystometry and somatic sensitivity testing. Imatinib significantly (0.0001 ≤ p ≤ 0.05) decreased voiding frequency and increased bladder capacity in acute CYP-induced cystitis, by the prevention (females) and treatment (females and males) designs. Imatinib was not effective in preventing or treating intermediate or chronic CYP-induced cystitis in either sex. Interestingly, in the prevention experiments, imatinib administration increased (0.0001 ≤ p ≤ 0.01) voiding frequency and decreased bladder capacity in control mice. However, in the treatment experiments, imatinib administration decreased (0.01 ≤ p ≤ 0.05) voiding frequency and increased bladder capacity in control mice. Bladder function improvements observed with imatinib treatment in acute CYP-induced cystitis mice remained and additionally improved with a second dose of imatinib 24 hours after CYP treatment. Imatinib administration did not affect pelvic somatic sensitivity in female mice with acute CYP-induced cystitis. Our studies suggest that (1) imatinib improves bladder function in mice with acute CYP-induced cystitis with a prevention and treatment design and (2) interstitial cells may be a useful target to improve bladder function in cystitis.

Emerging molecular mechanisms and genetic targets for developing novel therapeutic strategies for treating bladder diseases

Bladder diseases affect millions of patients worldwide and compromise their quality of life with a substantial economic impact. The not fully understood aetiologies of bladder diseases limit the current diagnosis and therapeutic options to primarily symptomatic treatment. In addition, bladder targeted drug delivery is challenging due to its unique anatomical features and its natural physiological function of urine storage and frequent voiding. Therefore, current treatment options often fail to provide a highly effective, precisely targeted and long-lasting treatment. With the growing maturity of gene therapy, comprehensive studies are needed to provide a better understanding of the molecular mechanisms underpinning bladder diseases and help to identify novel gene therapeutic targets and biomarkers for treating bladder diseases. In this review, molecular mechanisms involved in pathology of bladder cancer, interstitial cystitis and overactive bladder syndrome are reviewed, with focus on establishing potential novel treatment options. Proposed novel therapies, including gene therapy combined with nanotechnology, localised drug delivery by nanoparticles, and probiotics, are discussed in regard to their safety profiles, efficacy, treatment lenght, precise targeting, and in comparison to conventional treatment methods.

An indirect comparison meta-analysis of noninvasive intravesical instillation and intravesical injection of botulinum toxin-A in bladder disorders

BACKGROUND

Botulinum toxin type A (BTX-A) intravesical instillation and BTX-A intravesical injection are both effective treatments or overactive bladder (OAB) and interstitial cystitis/bladder pain syndrome (IC/BPS), but direct comparative studies of the two treatments are lacking.

METHODS

We conducted a pairs-comparison meta-analysis and an adjusted indirect comparison meta-analysis extracting published data from randomized controlled trials in literature databases from the inception of each database to Aug. 31, 2021, evaluating efficacy and safety of BTX-A intravesical instillation and BTX-A intravesical injection. We also carried out a subgroup analysis.

RESULTS

We identified 24 trials in 21 studies were included in our study, of which 18 trials in 17 studies were BTX-A intravesical injections, 6 trials in 4 studies were BTX-A intravesical instillation. Compared with the normal saline injection, BTX-A intravesical injections for patients with OAB and IC/ BPS can obviously improve the symptoms of urinary frequency, urgency episode, UI and UUI, but BTX-A significantly increased the rate of urinary retention and urinary tract infection and increased PVR (p < 0.05). Adjusted indirect comparison meta-analysis showed that BTX-A intravesical injections was more effective than BTX-A intravesical instillation (p > 0.05). Surprisingly, BTX-A intravesical instillation had fewer side effects than BTX-A intravesical injections (p < 0.05).

CONCLUSIONS

Although BTX-A intravesical injections of OAB and IC/BPS has been significantly superior the BTX-A intravesical instillation, it has major side effects, but this needs to be confirmed by more large-scale, multicenter, direct comparison randomized controlled trials.

BoNT/A in the Urinary Bladder-More to the Story than Silencing of Cholinergic Nerves

Botulinum neurotoxin (BoNT/A) is an FDA and NICE approved second-line treatment for overactive bladder (OAB) in patients either not responsive or intolerant to anti-cholinergic drugs. BoNT/A acts to weaken muscle contraction by blocking release of the neurotransmitter acetyl choline (ACh) at neuromuscular junctions. However, this biological activity does not easily explain all the observed effects in clinical and non-clinical studies. There are also conflicting reports of expression of the BoNT/A protein receptor, SV2, and intracellular target protein, SNAP-25, in the urothelium and bladder. This review presents the current evidence of BoNT/A's effect on bladder sensation, potential mechanisms by which it might exert these effects and discusses recent advances in understanding the action of BoNT in bladder tissue.

Intravesical drug delivery approaches for improved therapy of urinary bladder diseases

Diseases of the urinary bladder have high incidence rates and burden healthcare costs. Their pharmacological treatment involves systemic and local drug administration. The latter is generally accomplished through instillation of liquid formulations and requires repeated or long-term catheterization that is associated with discomfort, inflammation and bacterial infections. Consequently, compliance issues and dropouts are frequently reported. Moreover, instilled drugs are progressively diluted as the urine volume increases and rapidly excreted. When penetration of drugs into the bladder wall is needed, the poor permeability of the urothelium has also to be accounted for. Therefore, much research effort is spent to overcome these hurdles, thereby improving the efficacy of available therapies. Particularly, indwelling delivery systems suited for i) insertion into the bladder through the urethra, ii) intra-organ retention and prolonged release for the desired time lapse, iii) final elimination, either spontaneous or by manual removal, have been proposed to reduce the number of catheterization procedures and reach higher drug levels at the target site. Vesical retention of such devices is allowed by the relevant expansion that can either be triggered from the outside or achieved exploiting elastic and purposely 4D printed shape memory materials. In this article, the main rationales and strategies for improved intravesical delivery are reviewed.

Optimization of a floating poloxamer 407-based hydrogel using the Box-Behnken design: in vitro characterization and in vivo buoyancy evaluation for intravesical instillation

Intravesical instillation of a poloxamer 407 (PLX)-based hydrogel offers advantages such as thermo-sensitivity and sol-to-gel transition, but its utility is limited by urinary obstruction and insufficient bladder residence time. To overcome these obstacles, a floating PLX-hydrogel (FPH) was developed using sodium bicarbonate (BC) as a floating agent and hyaluronic acid (HA) as a gel strength modulator. The FPH composition was optimized using the Box-Behnken design with three independent variables: X₁ [PLX concentration, 23.91%], X₂ [BC concentration, 5.15%], and X₃ [HA concentration, 3.49%]. The quadratic model was the best fit (desirability function, 0.623), resulting in response parameters of Y₁ [floating time, 53.7 s], Y₂ [gelation temperature gap, 20.3°C], and Y₃ [duration time of gel, 396.7 min]. Rheological observations revealed the mechanical rigidity (storage modulus > loss modulus at elevated temperature) of the optimized FPH (phase transition temperature, 15.08°C). Gel erosion and drug release studies were performed using the gravimetric method; the remaining FPH fraction decreased exponentially with time, and gemcitabine release was biphasic and surface erosion-controlled. In vivo buoyancy was evaluated in rats using ultrasonography; these results were similar to those of the in vitro floating behavior. Thus, optimized FPH for intravesical instillation is a prospective option for bladder cancer treatment.

A Systematic Review of Therapeutic Approaches Used in Experimental Models of Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a multifactorial, chronic bladder disorder with limited therapeutic options currently available. The present review provides an extensive overview of therapeutic approaches used in in vitro, ex vivo, and in vivo experimental models of IC/BPS. Publications were identified by electronic search of three online databases. Data were extracted for study design, type of treatment, main findings, and outcome, as well as for methodological quality and the reporting of measures to avoid bias. A total of 100 full-text articles were included. The majority of identified articles evaluated therapeutic agents currently recommended to treat IC/BPS by the American Urological Association guidelines (21%) and therapeutic agents currently approved to treat other diseases (11%). More recently published articles assessed therapeutic approaches using stem cells (11%) and plant-derived agents (10%), while novel potential drug targets identified were proteinase-activated (6%) and purinergic (4%) receptors, transient receptor potential channels (3%), microRNAs (2%), and activation of the cannabinoid system (7%). Our results show that the reported methodological quality of animal studies could be substantially improved, and measures to avoid bias should be more consistently reported in order to increase the value of preclinical research in IC/BPS for potential translation to a clinical setting.

Local drug delivery systems for inflammatory diseases: Status quo, challenges, and opportunities

Inflammation that is not resolved in due course becomes a chronic disease. The treatment of chronic inflammatory diseases involves a long-term use of anti-inflammatory drugs such as corticosteroids and nonsteroidal anti-inflammatory drugs, often accompanied by dose-dependent side effects. Local drug delivery systems have been widely explored to reduce their off-target side effects and the medication frequency, with several products making to the market or in development over the years. However, numerous challenges remain, and drug delivery technology is underutilized in some applications. This review showcases local drug delivery systems in different inflammatory diseases, including the targets well-known to drug delivery scientists (e.g., joints, eyes, and teeth) and other applications with untapped opportunities (e.g., sinus, bladder, and colon). In each section, we start with a brief description of the disease and commonly used therapy, introduce local drug delivery systems currently on the market or in the development stage, focusing on polymeric systems, and discuss the remaining challenges and opportunities in future product development.

Therapeutic Effect of Botulinum Toxin A on Sensory Bladder Disorders-From Bench to Bedside

Bladder oversensitivity arises from several different conditions involving the bladder, bladder outlet, systemic or central nervous system diseases. Increase of the bladder sensation results from activation of the sensory receptors in the urothelial cells or suburothelial tissues. Medical treatment targeting the overactive bladder (OAB) or interstitial cystitis (IC) might relieve oversensitive bladder symptoms (frequency, urgency and pain) in a portion of patients, but a certain percentage of patients still need active management. Botulinum toxin A (BoNT-A) has been demonstrated to have anti-inflammatory and antinociceptive effects in bladder sensory disorders and has been shown effective in the reduction of bladder oversensitivity and the increase of functional bladder capacity. For patients with OAB, urgency and urinary incontinence improved, while in patients with IC, bladder pain could be relieved in association with reduction of bladder oversensitivity after BoNT-A intravesical injection. Histological evidence has confirmed the therapeutic mechanism and clinical efficacy of intravesical BoNT-A injection on patients with OAB or IC. Bladder oversensitivity can also be relieved with the instillation of liposome encapsulated BoNT-A or low energy show waves (LESWs), which enable the BoNT-A molecule to penetrate into the urothelium and suburothelial space without affecting the detrusor contractility. Liposome encapsulated BoNT-A or combined LESWs and BoNT-A instillation might be future treatment alternatives for bladder oversensitivity in sensory bladder disorders.

Clinical application of intravesical botulinum toxin type A for overactive bladder and interstitial cystitis

After decades of clinical and basic science research, the clinical application of botulinum toxin A (Botox) in urology has been extended to neurogenic detrusor overactivity (NDO), idiopathic detrusor overactivity, refractory overactive bladder (OAB), interstitial cystitis/bladder pain syndrome (IC/BPS), lower urinary tract symptoms, benign prostatic hyperplasia, and neurogenic or non-neurogenic lower urinary tract dysfunction in children. Botox selectively disrupts and modulates neurotransmission, suppresses detrusor overactivity, and modulates sensory function, inflammation, and glandular function. In addition to motor effects, Botox has been found to have sensory inhibitory effects and anti-inflammatory effects; therefore, it has been used to treat IC/BPS and OAB. Currently, Botox has been approved for the treatment of NDO and OAB. Recent clinical trials on Botox for the treatment of IC/BPS have reported promising therapeutic effects, including reduced bladder pain. Additionally, the therapeutic duration was found to be longer with repeated Botox injections than with a single injection. However, the use of Botox for IC/BPS has not been approved. This paper reviews the recent advances in intravesical Botox treatment for OAB and IC/BPS.

Fluorinated Polymer Mediated Transmucosal Peptide Delivery for Intravesical Instillation Therapy of Bladder Cancer

Surgical intervention combined with intravesical instillation of chemotherapeutics to clear residual cancer cells after operation is the current standard treatment method for bladder cancer. However, the poor bioavailability of active pharmaceutical ingredients for bladder cancer cells on account of the biological barriers of bladder mucosa, together with significant side effects of currently used intravesical medicine, have limited the clinical outcomes of localized adjuvant therapy for bladder cancer. Aiming at improved intravesical instillation therapy of bladder cancer, a fluorinated polyethylenimine (F-PEI) is employed here for the transmucosal delivery of an active venom peptide, polybia-mastoparan I (MPI), which shows selective antiproliferative effect against various bladder cancer cell lines. Upon simple mixing, MPI and F-PET would coassemble to form stable nanoparticles, which show greatly improved cross-membrane and transmucosal penetration capacities compared with MPI alone or nonfluorinated MPI/PEI nanoparticles. MPI/F-PEI shows higher in vivo tumor growth inhibition efficacy for local treatment of a subcutaneous tumor model. More excitingly, as further demonstrated in an orthotopic bladder cancer model, MPI/F-PEI offers remarkably improved therapeutic effects compared to those achieved by free MPI or the first-line bladder cancer drug mitomycin C. This work presents a new transmucosal delivery carrier particularly promising for intravesical instillation therapy of bladder cancer.

Efficacy and Safety of Noninvasive Intravesical Instillation of Onabotulinum Toxin-A for Overactive Bladder and Interstitial Cystitis/Bladder Pain Syndrome: Systematic Review and Meta-analysis

OBJECTIVE

To investigate the efficacy and safety of noninvasive intravesical instillation of onabotulinum toxin-A (OBTX-A) through systematic review and meta-analysis. Recently, several studies of noninvasive intravesical instillation of OBTX-A have been published. However, its efficacy is not well validated yet compared to well-known efficacy of minimally invasive intravesical injection of OBTX-A.

METHOD

Systematic review and meta-analysis were performed to evaluate the efficacy of noninvasive intravesical instillation of OBTX-A in patients with overactive bladder and interstitial cystitis/bladder pain syndrome by measuring outcomes such as urgency episode per 72 hours, frequency per 72 hours, urgency urinary incontinence, voided volume (VV), postvoided residual volume, maximum flow rate, and patient perception of bladder condition.

RESULT

Six trials in 4 studies that compared instillation of OBTX-A and placebo involving 248 patients (121 experimental and 127 controls) were included for final data extraction. Instillation of OBTX-A significantly increased VV, with a mean difference of 38.48 (95% confidence interval: 76.05, 0.92) compared to the placebo group. However, other outcomes showed statistically insignificant changes. Major adverse events were not reported in the group receiving intravesical instillation of OBTX-A.

CONCLUSION

Intravesical instillation of OBTX-A showed limited efficacy with improvement of VV for treatment of overactive bladder or interstitial cystitis/bladder pain syndrome. More studies are needed to overcome the efficacy of current noninvasive bladder instillation of OBTX-A regarding effective drug transport.

Neonatal Bladder Irritation Is Associated With Vanilloid Receptor TRPV1 Expression in Adult Rats

PURPOSE

To evaluate whether mild chemical irritation of the bladder in neonatal rats is associated with persistent vanilloid receptor transient receptor potential vanilloid subfamily 1 (TRPV1) activity in adult rats.

METHODS

Female Sprague-Dawley rats were used. Ten-day-old rat pups underwent bladder sensitization via intravesical infusion of 0.2% acetic acid in saline with or without prior bladder desensitization with capsaicin. After 8 weeks, 3 groups of rats (control [group 1], bladder sensitization [group 2], and bladder desensitization [group 3]) underwent cystometry. Inflammation of bladder tissue and the expression of TRPV1 in bladder tissue and dorsal root ganglia (DRG) were also evaluated.

RESULTS

The bladder sensitization group showed more frequent voiding contractions. TRPV1 expression in adult bladder tissue was elevated in group 2. TRPV1 mRNA levels in the bladder and DRG were significantly higher in group 2 than in group 1. Moreover, group 2 had significantly more DRG neurons (identified by uptake of the retrograde label Fast Blue) that exhibited TRPV1 immunoreactivity.

CONCLUSION

We found a significant association between neonatal bladder sensitization and persistent TRPV1 activity in adult rats. This is the first study to focus on the underlying pathogenesis of bladder overactivity from childhood to adulthood. Our findings could lead to the development of new strategies for the treatment and prevention of adult urinary symptoms arising from childhood urinary tract dysfunction.

Effects of liposome-based local suppression of nerve growth factor in the bladder on autonomic dysreflexia during urinary bladder distention in rats with spinal cord injury

PURPOSE

To examine (1) whether spinal cord injury (SCI) time-dependently increases the severity of autonomic dysreflexia (AD) and expression levels of bladder nerve growth factor (NGF) protein, and (2) whether local suppression of NGF in the bladder improves SCI-induced AD in rats.

MATERIALS AND METHODS

SCI was produced by the transection of the T2/3 spinal cord in female Sprague-Dawley rats. At 4 or 8weeks after SCI, differences in the mean arterial blood pressure (ΔMAP) and heart rate (ΔMHR) during graded increases in intravesical pressure to 20, 40 and 60cm H₂O from those before bladder distention and NGF protein levels in the bladder wall were evaluated in spinal intact and SCI rats under urethane anesthesia. Seven weeks after SCI liposome-NGF antisense conjugates were administered intravesically to the animals. At 1week after intravesical treatment (8weeks after SCI), ΔMAP and ΔMHR during bladder distention and bladder NGF protein expression were evaluated.

RESULTS

The ΔMAP and ΔMHR were increased in a graded manner in response to bladder distention at intravesical pressures of 20, 40 and 60cm H₂O in SCI rats. These AD-like cardiovascular responses and NGF protein expression in the bladder mucosal and muscle layers were increased after SCI in a time-dependent manner. The liposome-NGF antisense treatment significantly reduced the NGF protein overexpression in the mucosal layer of SCI rat bladder and reduced ΔMAP and ΔMHR elicited by bladder distention.

CONCLUSIONS

These results indicate that the duration of the post-SCI recovery period affects the severity of AD induced by bladder distention as well as the level of bladder NGF protein, and that local suppression of NGF expression in the bladder reduces SCI-induced AD. Thus, Intravesical application of liposome-NGF antisense conjugates can be a new effective therapy for bladder distention-induced AD after SCI.

Investigational drugs for bladder pain syndrome (BPS) / interstitial cystitis (IC)

INTRODUCTION

Bladder pain syndrome (BPS)/interstitial cystitis (IC) is associated with sensory lower urinary tract symptoms. Unfortunately, many of the existing oral treatments are ineffective in most patients of BPS/IC, which is the motivation for developing new drugs and therapeutic approaches. This review covers the latest drugs that have been investigated in BPS/IC patients. Intravesical treatments offer the opportunity to directly target the painful bladder with less systemic side effects.

AREAS COVERED

In this review, the authors analyze the existing literature supporting the treatment of BPS/IC with conventional drugs including heparin, hyaluronic acid, chondroitin sulfate, and dimethylsulfoxide (DMSO). Furthermore, investigational drugs such as tanezumab and adalimumab, capable of sequestering nerve growth factor (NGF), and Tumor necrosis factor-α (TNF- α) are discussed. Investigational treatments such as liposomes, botulinum toxin (BTX), liposomal BTX, PD-0299685 (a Ca(2+) channel ɑ2δ ligand), continuous intravesical lidocaine, and AQX-1125 (a novel SHIP1 activating compound) are also covered.

EXPERT OPINION

New investigational drugs offer promising improvements in clinical outcomes for BPS/IC patients; however, BPS/IC is a chronic pain disorder that is very vulnerable to a strong placebo effect. In addition, BPS/IC is a heterogeneous disorder that can be classified into several phenotypes. Since different phenotypes of BPS/IC respond differently to systemic and intravesical treatments, the authors believe that new drugs developed for BPS/IC are more likely to meet their predetermined clinical endpoints if the inclusion/exclusion criterion is tailored to specific phenotype of BPS/IC patients.

Intravesical liposome drug delivery and IC/BPS

Intravesical therapy has previously shown to be effective in delaying or preventing recurrence of superficial bladder cancer. This local route of drug administration is now demonstrating promise in the treatment of interstitial cystitis/bladder pain syndrome (IC/BPS) with the benefit of minimal systemic side effects. Liposomes (LPs) are lipid vesicles composed of phospholipid bilayers surrounding an aqueous core. They can incorporate drug molecules, both hydrophobic and hydrophilic, and vastly improve cellular uptake of these drug molecules via endocytosis. Intravesical LPs have therapeutic effects on IC/BPS patients, mainly due to their ability to form a protective lipid film on the urothelial surface and repair the damaged urothelium. This review considers the current status of intravesical LPs and LP mediated drug delivery for the treatment of IC/BPS.

Intravesical instillation of onabotulinum toxin A embedded in inert hydrogel in the treatment of idiopathic overactive bladder: A double-blind randomized pilot study

OBJECTIVE

It was hypothesized that increasing the time for which onabotulinum toxin A (OnabotA) is exposed to the urothelium following intravesical instillation will augment its effect. TC-3 is an inert heat-sensitive hydrogel, which creates an intravesical bulk providing a slow release of the embedded drug after instillation. The aim of this study was to evaluate the effect of OnabotA, embedded in inert TC-3 hydrogel, in patients with idiopathic overactive bladder (OAB).

METHODS

In total, 39 female patients (age 30-65, average 53.8 years) with OAB symptoms were randomized for the study into four groups, each receiving 50 ml of the following intravesical instillations: Group A, 0.9% NaCl (placebo, n = 11); Group B, TC-3 gel + 200 U OnabotA (n = 9); Group C, TC-3 gel + 200 U OnabotA + dimethyl sulfoxide (DMSO) (n = 10); and Group D, DMSO (n = 9). The parameters were compared before and 1 month after treatment.

RESULTS

When comparing parameters using conventional statistical methods (Kruskal-Wallis test), no statistically significant changes were observed within the groups. Comparison of the medians using an analysis based on the mathematical gnostics showed the superiority of the method used in Group B over the other groups in the following parameters: number of urgency grade 3 + 4 episodes/72 h, number of leakage episodes/72 h, Overactive Bladder Questionnaire total score and Patient Perception of Bladder Condition total score. Group D showed its superiority over the other groups in respect to the number of nocturia episodes/72 h.

CONCLUSIONS

The results indicate that intravesical instillation of OnabotA, embedded in TC-3 gel, could become an alternative to intramural injection for a well-selected subgroup of patients.

OnabotulinumtoxinA Treatment for Overactive Bladder in the Elderly: Practical Points and Future Prospects

Overactive bladder (OAB) increases with age. OAB in the elderly may be associated with increased risks of falls, fractures and mortality. Degeneration of the central nervous system in the elderly is proposed as one of the pathogenic factors for OAB. Recently, onabotulinumtoxinA (BoNT-A) 100 U has been demonstrated to be well tolerated, and it significantly improves all OAB symptoms and health-related quality of life in patients who are inadequately managed with anticholinergics. However, an increased risk of a large post-void residual volume and a lower long-term success rate were noted in frail elderly patients. Careful patient selection for BoNT-A injection treatment is important in elderly OAB patients. Patients who are frail, are elderly, have comorbidity or have a post-void residual volume >100 mL should be monitored carefully after BoNT-A injection treatment to prevent urinary retention and subsequent urinary tract infection. Use of liposomes to carry BoNT-A across the urothelial barrier decreases urgency-frequency episodes without compromising detrusor contractility and might avoid urinary tract infection. This treatment might prevent undesired detrusor underactivity after BoNT-A injection treatment, especially in elderly patients who have low detrusor contractility. For treatment of OAB in the elderly, clinicians should be aware of the balance between therapeutic efficacy and safety.

Novel targeted bladder drug-delivery systems: a review

The objective of pharmaceutics is the development of drugs with increased efficacy and reduced side effects. Prolonged exposure of the diseased tissue to the drug is of crucial importance. Drug-delivery systems (DDSs) have been introduced to control rate, time, and place of release. Drugs can easily reach the bladder through a catheter, while systemically administered agents may undergo extensive metabolism. Continuous urine filling and subsequent washout hinder intravesical drug delivery (IDD). Moreover, the low permeability of the urothelium, also described as the bladder permeability barrier, poses a major challenge in the development of the IDD. DDSs increase bioavailability of drugs, therefore improving therapeutic effect and patient compliance. This review focuses on novel DDSs to treat bladder conditions such as overactive bladder, interstitial cystitis, bladder cancer, and recurrent urinary tract infections. The rationale and strategies for both systemic and local delivery methods are discussed, with emphasis on new formulations of well-known drugs (oxybutynin), nanocarriers, polymeric hydrogels, intravesical devices, encapsulated DDSs, and gene therapy. We give an overview of current and future prospects of DDSs for bladder disorders, including nanotechnology and gene therapy.

Presence of Cleaved Synaptosomal-Associated Protein-25 and Decrease of Purinergic Receptors P2X3 in the Bladder Urothelium Influence Efficacy of Botulinum Toxin Treatment for Overactive Bladder Syndrome

OBJECTIVES

To evaluate whether botulinum toxin A (BoNT-A) injection and Lipotoxin (liposomes with 200 U of BoNT-A) instillation target different proteins, including P2X3, synaptic vesicle glycoprotein 2A, and SNAP-25, in the bladder mucosa, leading to different treatment outcomes.

MATERIALS AND METHODS

This was a retrospective study performed in a tertiary teaching hospital. We evaluated the clinical results of 27 OAB patients treated with intravesical BoNT-A injection (n = 16) or Lipotoxin instillation (n = 11). Seven controls were treated with saline. Patients were injected with 100 U of BoNT-A or Lipotoxinin a single intravesical instillation. The patients enrolled in this study all had bladder biopsies performed at baseline and one month after BoNT-A therapy. Treatment outcome was measured by the decreases in urgency and frequency episodes at 1 month. The functional protein expressions in the urothelium were measured at baseline and after 1 month. The Wilcoxon signed-rank test and ordinal logistic regression were used to compare the treatment outcomes.

RESULTS

Both BoNT-A injection and Lipotoxin instillation treatments effectively decreased the frequency of urgency episodes in OAB patients. Lipotoxin instillation did not increase post-void residual volume. BoNT-A injection effectively cleaved SNAP-25 (p < 0.01). Liposome encapsulated BoNT-A decreased urothelial P2X3 expression in the five responders (p = 0.04), while SNAP-25 was not significantly cleaved.

CONCLUSIONS

The results of this study provide a possible mechanism for the therapeutic effects of BoNT-A for the treatment of OAB via different treatment forms. BoNT-A and Lipotoxin treatments effectively decreased the frequency of urgency episodes in patients with OAB.

Current recommendations for bladder instillation therapy in the treatment of interstitial cystitis/bladder pain syndrome

Bladder instillation therapy refers to the direct introduction of medication into the bladder and is a common treatment modality for patients with interstitial cystitis/bladder pain syndrome (IC/BPS) who have failed conservative and oral therapies. The current American Urological Association (AUA) recommendations list three medications as options for IC/BPS instillation therapy: dimethyl sulfoxide, heparin, and lidocaine. The purpose of this review is to examine the evidence behind the recommendations for these medications. We also examine several historical or experimental therapies that do not hold recommendations but are still used on rare occasion. Finally, we discuss our bladder instillation strategies as well as potential future research and development in intravesicular therapy.

Functionalized mesoporous silica nanoparticles with mucoadhesive and sustained drug release properties for potential bladder cancer therapy

The synthesis of a series of β-cyclodextrin modified mesoporous silica nanoparticles with hydroxyl, amino, and thiol groups was described. A comparison of their mucoadhesive properties and potential as a drug delivery system for superficial bladder cancer therapy was made. The thiol-functionalized nanoparticles exhibit significantly higher mucoadhesivity on the urothelium as compared to the hydroxyl- and amino-functionalized nanoparticles. This is attributed to the formation of disulfide bonds between the thiol-functionalized nanoparticles and cysteine-rich subdomains of mucus glycoproteins. An anticancer drug, doxorubicin, was loaded into the mesopores of the thiol-functionalized nanoparticles, and sustained drug release triggered by acidic pH was achieved. The present study demonstrates that thiol-functionalized mesoporous silica nanoparticles are promising as a mucoadhesive and sustained drug delivery system for superficial bladder cancer therapy.

Liposomal inhibition of acrolein-induced injury in rat cultured urothelial cells

PURPOSE

To study the protection offered by empty liposomes (LPs) alone against acrolein-induced changes in urothelial cell viability and explored uptake of LPs by primary (rat) urothelial cells.

METHODS

Acrolein was used as a means to induce cellular damage and reduce urothelial cellular viability. The effect of acrolein or liposomal treatment on cellular proliferation was studied using 5-bromo-2'-deoxy-uridine assay. Cytokine release was measured after urothelial cells were exposed to acrolein. Temperature-dependent uptake study was carried out for fluorescent-labeled LPs using confocal microscopy.

RESULTS

Liposome pretreatment protected against acrolein-induced decrease in urothelial cell proliferation. LPs also significantly affected the acrolein-induced cytokine (interferon-gamma) release offering protection to the urothelial cells against acrolein damage. We also observed a temperature-dependent urothelial uptake of fluorescent-labeled LPs occurred at 37 °C (but not at 4 °C).

CONCLUSIONS

Empty LPs alone provide a therapeutic efficacy against acrolein-induced changes in urothelial cell viability and may be a promising local therapy for bladder diseases. Hence, our preliminary evidence provides support for liposome-therapy for urothelial protection and possible repair.

Glycan-targeted drug delivery for intravesical therapy: in the footsteps of uropathogenic bacteria

The human urothelium belongs to the most efficient biobarriers, and represents a highly rewarding but challenging target for local drug administration. Inadequate urothelial bioavailability is a major obstacle for successful treatment of bladder cancer and other diseases, yet little research has addressed the development of advanced delivery concepts for the intravesical route. A prominent example of how to overcome the urothelial barrier by means of specific biorecognition is the efficient cytoinvasion of UPEC bacteria, mediated by the mannose-targeted lectin domain FimH. Similar mechanisms of non-bacterial origin may be exploited for enhancing drug uptake from the bladder cavity. This review covers the current status in the development of lectin-based delivery strategies for the urinary tract. Different concepts for preparing and optimizing carbohydrate-targeted delivery systems are presented, along with important design parameters, benefits and shortcomings. Bioconjugate- and nano-/microparticle-based systems are discussed in further detail with regard to their performance in preclinical testing.

How are we going to make progress treating bladder pain syndrome? ICI-RS 2013

AIMS

To look at the current state of knowledge in bladder pain syndrome and ascertain how we can make advances in the near term.

METHODS

A compendium of the ideas presented at the International Consultation on Incontinence Research Society 2013 meeting of clinicians and basic scientists.

RESULTS

The meeting included the following topics: potential connection between defined and undefined IC/BPS; association between psychiatric disorders and IC/BPS; rationale for multimodal therapy approach in IC/BPS; and issues of a placebo control in human studies.

CONCLUSIONS

Translational research studies are still in need of improved animal models to study IC/BPS mechanisms and development of novel methods to objectively measure bladder pain in rodents. The need to try and develop better clinical therapies will best be met by proper phenotyping of this heterogeneous population and avoiding premature publication of clinical trials that are anecdotal and do not include randomized placebo control populations. Patients with Hunner's lesions should be identified prior to or in the course of clinical trials so that results in this subgroup can be evaluated.

Pilot study of liposome-encapsulated onabotulinumtoxina for patients with overactive bladder: a single-center study

BACKGROUND

Intradetrusor onabotulinumtoxinA (BoNT-A) injection benefits overactive bladder (OAB) patients, but increased postvoid residual (PVR) urine volume and urinary tract infection (UTI) remain risks. Intravesical instillation of liposomal BoNT-A instead of injection could prevent such adverse events.

OBJECTIVE

To evaluate instillation of liquid liposomal BoNT-A (Lipotoxin) for the treatment of OAB and to determine its mechanism of action.

DESIGN, SETTING, AND PARTICIPANTS

A double-blind randomized parallel controlled pilot trial in 24 OAB patients at a single tertiary center.

INTERVENTION

Patients were randomly assigned to intravesical instillation of Lipotoxin containing 80 mg liposomes and 200 U BoNT-A or normal saline (N/S). Patients were retreated with Lipotoxin 1 mo later if they failed the first treatment.

OUTCOME MEASUREMENT AND STATISTICAL ANALYSIS

Voiding diaries, OAB symptom scores, urodynamic studies, and adverse events were monitored. The primary end point was change of total urinary frequency per 3 d at 1 mo after treatment. Immunohistochemistry and Western blotting for synaptic vesicle glycoprotein 2A (SV2A) and synaptosomal-associated protein, 25 kDa (SNAP25) were performed at baseline and 3 mo after treatment. The Wilcoxon rank sum test and Wilcoxon signed rank test were used for statistical analysis.

RESULTS AND LIMITATIONS

At 1 mo after treatment, the change of urinary frequency per 3 d significantly improved in the Lipotoxin group (n=12; median: -6.50; interquartile range [IQR]: -18.3 to -0.25; p=0.008) but not in the N/S group. (n=12.0; IQR: -7.75 to 8.0; p=0.792). Urgency episodes also showed a significant decrease in the Lipotoxin group (-12.0; IQR: -20.3 to -2.75; p=0.012) but not in the N/S group (-1.0; IQR: -11.0 to 2.5; p=0.196). SV2A and SNAP25 were expressed in urothelial cells and suburothelial tissues. However, the protein expression did not significantly differ between responders and nonresponders at 3 mo after treatment.

CONCLUSIONS

Intravesical Lipotoxin instillation effectively reduced frequency episodes 1 mo after treatment in OAB patients without any increase in PVR or risk of UTI.

PATIENT SUMMARY

We demonstrated that intravesical Lipotoxin instillation reduced frequency episodes at 1 mo in overactive bladder patients. This procedure is safe, without an increase in postvoid residual or the risk of urinary tract infection.

Intravesical liposome and antisense treatment for detrusor overactivity and interstitial cystitis/painful bladder syndrome

Purpose. The following review focuses on the recent advancements in intravesical drug delivery, which brings added benefit to the therapy of detrusor overactivity and interstitial cystitis/painful bladder syndrome (IC/PBS). Results. Intravesical route is a preferred route of administration for restricting the action of extremely potent drugs like DMSO for patients of interstitial cystitis/painful bladder syndrome (IC/PBS) and botulinum toxin for detrusor overactivity. Patients who are either refractory to oral treatment or need to mitigate the adverse effects encountered with conventional routes of administration also chose this route. Its usefulness in some cases can be limited by vehicle (carrier) toxicity or short duration of action. Efforts have been underway to overcome these limitations by developing liposome platform for intravesical delivery of biotechnological products including antisense oligonucleotides. Conclusions. Adoption of forward-thinking approaches can achieve advancements in drug delivery systems targeted to future improvement in pharmacotherapy of bladder diseases. Latest developments in the field of nanotechnology can bring this mode of therapy from second line of treatment for refractory cases to the forefront of disease management.

Urothelial signaling

The urothelium, which lines the inner surface of the renal pelvis, the ureters, and the urinary bladder, not only forms a high-resistance barrier to ion, solute and water flux, and pathogens, but also functions as an integral part of a sensory web which receives, amplifies, and transmits information about its external milieu. Urothelial cells have the ability to sense changes in their extracellular environment, and respond to chemical, mechanical and thermal stimuli by releasing various factors such as ATP, nitric oxide, and acetylcholine. They express a variety of receptors and ion channels, including P2X3 purinergic receptors, nicotinic and muscarinic receptors, and TRP channels, which all have been implicated in urothelial-neuronal interactions, and involved in signals that via components in the underlying lamina propria, such as interstitial cells, can be amplified and conveyed to nerves, detrusor muscle cells, and ultimately the central nervous system. The specialized anatomy of the urothelium and underlying structures, and the possible communication mechanisms from urothelial cells to various cell types within the bladder wall are described. Changes in the urothelium/lamina propria ("mucosa") produced by different bladder disorders are discussed, as well as the mucosa as a target for therapeutic interventions.

Pharmacotherapy of interstitial cystitis in women

Interstitial cystitis is a condition that affects the urinary bladder and may be more prevalent than commonly thought. Symptoms range widely in severity and typically include urinary urgency, frequency and pelvic pain. Therapies usually target the known pathophysiology of this condition. Oral agents commonly include bladder surface mucin analogues, antihistamines, narcotics, tricyclic antidepressants and anticonvulsants. Intravesical therapy is usually used as second-line treatment. Multiple forms of pharmacotherapy are often provided simultaneously to improve efficacy and time to response.

Sensory dysfunction of bladder mucosa and bladder oversensitivity in a rat model of metabolic syndrome

Purpose

To study the role of sensory dysfunction of bladder mucosa in bladder oversensitivity of rats with metabolic syndrome.

Materials and Methods

Female Wistar rats were fed a fructose-rich diet (60%) or a normal diet for 3 months. Based on cystometry, the fructose-fed rats (FFRs) were divided into a group with normal detrusor function or detrusor overactivity (DO). Acidic adenosine triphosphate (ATP) solution (5mM, pH 3.3) was used to elicit reflex micturition. Cystometric parameters were evaluated before and after drug administration. Functional proteins of the bladder mucosa were assessed by western blotting.

Results

Compared to the controls, intravesical acidic ATP solution instillation induced a significant increase in provoked phasic contractions in both FFR groups and a significant decrease in the mean functional bladder capacity of group DO. Pretreatment with capsaicin for C-fiber desentization, intravesical liposome for mucosal protection, or intravenous pyridoxal 5-phosphate 6-azophenyl-2′,4′-disulfonic acid for antagonized purinergic receptors can interfere with the urodynamic effects of intravesical ATP in FFRs and controls. Over-expression of TRPV1, P2X₃, and iNOS proteins, and down-regulation of eNOS proteins were observed in the bladder mucosa of both fructose-fed groups.

Conclusions

Alterations of sensory receptors and enzymes in the bladder mucosa, including over-expression of TRPV1, P2X₃, and iNOS proteins, can precipitate the emergence of bladder phasic contractions and oversensitivity through the activation of C-afferents during acidic ATP solution stimulation in FFRs. The down-regulation of eNOS protein in the bladder mucosa of FFRs may lead to a failure to suppress bladder oversensitivity and phasic contractions. Sensory dysfunction of bladder mucosa and DO causing by metabolic syndrome are easier to elicit bladder oversensitivity to certain urothelium stimuli.

Novel Therapy with Intravesical Liposomes for Ulcerative Interstitial Cystitis/Painful Bladder Syndrome

OBJECTIVES

A Federal Drug Administration-approved, compassionate-use, investigational new drug single-subject trial was conducted to evaluate the safety and clinical outcomes of intravesical instillation of liposomes in a woman with ulcerative interstitial cystitis/painful bladder syndrome (IC/PBS).

METHODS

After obtaining informed consent, the 48-year-old woman, diagnosed with ulcerative IC/PBS, received four weekly instillations of intravesical liposomes. Subsequently she was evaluated for 8 weeks post bladder instillation.

RESULTS

No side effects or adverse events were reported during the 12 week study period. Voids per day decreased from a baseline of 18 voids per 24 h to 11.3 voids per 24 h at week 3, and 12.6 voids per 24 h at 8 weeks after final instillation. Urgency score also decreased from a pre-instillation mean of 1.75 (out of 10) to 1.07 8 weeks after the final instillation. Bladder ulcers noted by cystoscopy at baseline were absent at the 8 weeks post-treatment and no evidence of bladder inflammation was noted.

CONCLUSION

Intravesical liposome instillation is minimally invasive and presents an appealing new treatment for IC/PBS. Prospective trials are needed to assess intravesical liposomes for IC/PBS.

Safety and dose flexibility clinical evaluation of intravesical liposome in patients with interstitial cystitis or painful bladder syndrome

To present single institution open-label experience with intravesical liposomes (LPs), a mucosal protective agent, in patients with interstitial cystitis/painful bladder syndrome (IC/PBS) and to assess the safety and efficacy on IC/PBS symptoms. A total of 17 symptomatic IC/PBS patients were treated with intravesical LPs (80mg/40mL distilled water) once a week for 4 weeks (n=12) or twice a week treatment for 4 weeks (n=5). The primary outcome was the change in the O'Leary-Sant Symptom/Problem score and O'Leary-Sant total Score from baseline to Week 4 and Week 8. Other outcome measurements included the changes in pain scale, urgency scale, voiding log, and patient global assessment. Both weekly and biweekly LP instillation regiments were well tolerated. The incidence of urinary incontinence, retention, or unanticipated adverse changes was not noted at any dose either during the treatment or at the 4-week follow-up. The O'Leary-Sant Symptom/Problem score, O'Leary-Sant total Score, and pain score were significantly improved from baseline at both dose regimens with added benefit with the biweekly regimen. Intravesical LPs treatment is safe and its efficacy has sustained duration. Furthermore large-scale, placebo-controlled studies are warranted to assess the efficacy for this promising new treatment for IC/PBS.

Models of inflammation of the lower urinary tract

Inflammation of the lower urinary tract occurs frequently in people. The causes remain obscure, with the exception of urinary tract infection. Animal models have proven useful for investigating and assessing mechanisms underlying symptoms associated with lower urinary tract inflammation and options for suppressing these symptoms. This review will discuss various animal models of lower urinary tract inflammation, including feline spontaneous (interstitial) cystitis, neurogenic cystitis, autoimmune cystitis, cystitis induced by intravesical instillation of chemicals or bacterial products (particularly lipopolysaccharide or LPS), and prostatic inflammation initiated by transurethral instillation of bacteria. Animal models will continue to be of significant value in identifying mechanisms resulting in bladder inflammation, but the relevance of some of these models to the causes underlying clinical disease is unclear. This is primarily because of the lack of understanding of causes of these disorders in people. Comparative and translational studies are required if the full potential of findings obtained with animal models to improve prevention and treatment of lower urinary tract inflammation in people is to be realized.