Gene Therapy for Overactive Bladder: A Review of BK-Channel α-Subunit Gene Transfer.

A need exists for local (ie, bladder-specific) interventions to treat overactive bladder (OAB) with low risk of unwanted postprocedural outcomes. Gene therapy targeted to leverage endogenous physiology in bladder cells may assist in restoring normal cell and organ function. Herein, we review the potential promise of gene therapy for treating OAB, focusing on gene transfer of URO-902, a non-viral naked plasmid DNA expressing the big potassium (BK) channel.

Evaluating the safety and potential activity of URO-902 (hMaxi-K) gene transfer by intravesical instillation or direct injection into the bladder wall in female participants with idiopathic (non-neurogenic) overactive bladder syndrome and detrusor overactivity from two double-blind, imbalanced, placebo-controlled randomized phase 1 trials.

Aims: Two phase 1 trials were performed in healthy women with the overactive bladder (OAB) syndrome and urodynamically demonstrated detrusor overactivity (DO), with the aim to demonstrate the safety and potential efficacy of URO-902, which comprises a gene therapy plasmid vector expressing the human big potassium channel α subunit.

Methods: ION-02 (intravesical instillation) and ION-03 (direct injection) were double-blind, placebo-controlled, multicenter studies without overlap in enrollment between studies. Active doses were administered and evaluated sequentially (lowest dose first) for safety.

Diabetes attenuates urothelial modulation of detrusor contractility and spontaneous activity.

Objectives: To investigate the effect of diabetes on urothelial modulation of bladder contractility.

Methods: Bladder strips (urothelium intact or denuded) were prepared from 8-week-old streptozotocin-induced diabetic (n = 19) and non-diabetic control rats (n = 10). The effect of modulators of MaxiK (iberiotoxin and tetraethylammonium) and Kv7 (XE991 and retigabine) potassium channel activity were investigated for their effects on both carbachol-induced force generation and spontaneous contractile activity.

Opiorphin is a master regulator of the hypoxic response in corporal smooth muscle cells.

Men with sickle cell disease (SCD) risk developing priapism. Recognizing that SCD is a disease of hypoxia, we investigated the effect of hypoxia on gene expression in corporal smooth muscle (CSM) cells. Rat CSM cells in vitro were treated with CoCl2 or low oxygen tension to mimic hypoxia.

Large-conductance calcium-activated potassium channel activity, as determined by whole-cell patch clamp recording, is decreased in urinary bladder smooth muscle cells from male rats with partial urethral obstruction.

Objectives: To examine the effect of partial urethral obstruction (PUO) on bladder smooth muscle outward potassium current and the contribution of the large-conductance calcium-activated potassium (Maxi-K, BKCa) channel to this activity in smooth muscle cells isolated from bladders of sham-operated and PUO male rats using whole-cell patch clamp recording techniques. To determine the effect of PUO on the expression of the Maxi-K channel α and β1 subunits and in vitro detrusor contractility.

Materials And Methods: Twenty adult male Sprague-Dawley rats were divided equally into two groups and subjected to surgical ligation of the urethra (PUO) or sham surgery (SHAM).

The bar sinister: does handlebar level damage the pelvic floor in female cyclists?

Introduction: Cycling is associated with genital neuropathies and erectile dysfunction in males. Women riders also have decreased genital sensation; however, sparse information exists addressing the effects of modifiable risks on neurological injuries in females.

Aim: This study assesses the effects of bicycle setup and cyclists' attributes on GS and saddle pressures among female cyclists.

Novel therapeutic targets for erectile dysfunction.

Erectile dysfunction (ED) is a neurovascular phenomenon modulated by hormonal, local biochemical, and biomechanical/structural factors of the penis. The success of the orally active phosphodiesterase inhibitors for the treatment of ED has boosted research activities into the physiology of the erectile mechanism. Peripheral intracellular signal transduction in the penis as well as central brain and spinal cord pathways controlling penile erection have been investigated and are now better understood.

Smooth muscle myosin expression, isoform composition, and functional activities in rat corpus cavernosum altered by the streptozotocin-induced type 1 diabetes.

Diabetes mellitus (DM) is a quite common chronic disease, and the prevalence of erectile dysfunction (ED) is three times higher in this large population. Although diabetes-related ED has been studied extensively, the actin-myosin contractile apparatus was not examined. The mRNAs encoding smooth muscle myosin (SMM) heavy chains (MHC) and essential light chains (LC(17)) exist as several different alternatively spliced isoforms with distinct contractile properties.

Women's bike seats: a pressing matter for competitive female cyclists.

Introduction: There are numerous genital complaints in women cyclists, including pain, numbness, and edema of pelvic floor structures. Debate ensues about the best saddle design for protection of the pelvic floor.

Aim: To investigate the relationships between saddle design, seat pressures, and genital nerve function in female, competitive cyclists.

Reversal of diabetic vasculopathy in a rat model of type 1 diabetes by opiorphin-related peptides.

Diabetes results in a myriad of vascular complications, often referred to as diabetic vasculopathy, which encompasses both microvascular [erectile dysfunction (ED), retinopathy, neuropathy, and nephropathy] and macrovascular complications (hypertension, coronary heart disease, and myocardial infarction). In diabetic animals and patients with ED, there is decreased opiorphin or opiorphin-related gene expression in corporal tissue. Both opiorphin and the rat homologous peptide sialorphin are found circulating in the plasma.

Oxidative stress status accompanying diabetic bladder cystopathy results in the activation of protein degradation pathways.

Objective: • To investigate the role that oxidative stress plays in the development of diabetic cystopathy.

Materials And Methods: • Comparative gene expression in the bladder of non-diabetic and streptozotocin (STZ)-induced 2-month- old diabetic rats was carried out using microarray analysis. • Evidence of oxidative stress was investigated in the bladder by analyzing glutathione S-transferase activity, lipid peroxidation, and carbonylation and nitrosylation of proteins.

Update on corpus cavernosum smooth muscle contractile pathways in erectile function: a role for testosterone?

Introduction: Normal erectile function (EF) involves a coordinated relaxation of the arteries that supply the penis and the corpus cavernosum smooth muscle (CCSM), resulting in expansion of the sinusoids and increased intracavernous pressure. But the CCSM spends the majority of its time in the contracted state which is mediated by norepinephrine released from nerve endings and other vasoconstrictors like endothelins released from the endothelium. These agents cause smooth muscle myosin (SMM) phosphorylation by elevating intracellular calcium.

Silencing MaxiK activity in corporal smooth muscle cells initiates compensatory mechanisms to maintain calcium homeostasis.

Introduction: The MaxiK potassium channel is regulated by voltage and intracellular calcium, and plays a critical role in regulating intracellular calcium concentration ([Ca(2+) ](i)), which is the ultimate determinant of smooth muscle tone. Tight control of corpus cavernosum smooth muscle (CCSM) tone is critically important and misregulation can result in erectile dysfunction.

Aim: Because of the tight functional linkage of MaxiK and calcium channel activity, the aim of this study was to determine the effects of silencing and pharmacological inhibition of MaxiK on calcium homeostasis and intercellular calcium signaling in CCSM cells.

Gene therapy for erectile dysfunction: what is the future?

Gene transfer for the treatment of erectile dysfunction has completed phase 1 safety testing and has shown the necessary safety to proceed to the next level of clinical trial. This review focuses on the background of the components of that have led to US Food and Drug Administration acceptance of human gene transfer trials for nonlethal disease.

In vitro and in vivo relaxation of urinary bladder smooth muscle by the selective myosin II inhibitor, blebbistatin.

OBJECTIVE To investigate the in vitro and in vivo effects of blebbistatin (a small cell-permeable molecule with high affinity and selectivity toward the myosin II contractile molecule) on bladder smooth muscle (SM) contractility, as antimuscarinic therapy is only 65-75% effective in treating overactive bladder (OAB) and is associated with considerable side-effects, with a < 25% continuation rate at 1 year. MATERIALS AND METHODS Bladder and aortic strips from adult male rats, and human bladder strips obtained from open prostatectomy, were used for organ-bath studies of blebbistatin. Awake cystometry was also used in rats in both the presence and absence of intravesically delivered blebbistatin.

The sphingosine-1-phosphate pathway is upregulated in response to partial urethral obstruction in male rats and activates RhoA/Rho-kinase signalling.

Objectives: To examine the effect of partial urethral obstruction (PUO) on the sphingosine-1-phosphate (S1P, a bioactive lipid shown to modulate smooth muscle, SM) pathway in the bladders of male rats, and to determine the effect of PUO on the RhoA/Rho-kinase (ROK) pathway, and whether there is a molecular cross-talk with the S1P pathways associated with bladder overactivity (S1P1-S1P3, where S1P1 is associated with nitric oxide-mediated SM relaxation, and S1P2 and S1P3 receptors are associated more with SM contraction via the ROK pathway).

Materials And Methods: In all, 20 male rats were divided into two groups and underwent PUO or a sham operation (control). After 2 weeks all rats were killed humanely and bladder specimens used for in vitro organ-bath physiological contractility studies, and for mRNA and protein analyses of major S1P/ROK pathway constituents via real-time polymerase chain reaction and Western blotting, respectively.

Standards for clinical trials in male sexual dysfunctions.

Introduction: Clinical trials in male sexual dysfunction (MSD) are expanding. Consequently, there is a need for consensus standards in this area.

Aim: To develop an evidence-based, state-of-the-art consensus report on standards for clinical trials in MSD.

Nanoparticles as a novel delivery vehicle for therapeutics targeting erectile dysfunction.

Introduction: Nanoparticles represent a potential novel mechanism for transdermal delivery of erectogenic agents directly to the penis.

Aim: To determine if nanoparticles encapsulating known erectogenic agents (tadalafil, sialorphin, and nitric oxide [NO]) can improve erectile function in a rat model of erectile dysfunction (ED) as a result of aging (the Sprague-Dawley retired breeder rat).

Methods: Nanoparticles encapsulating the erectogenic agents were applied as a gel to the glans and penile shaft of anesthetized Sprague-Dawley rats and the intracorporal pressure/blood pressure (ICP/BP) monitored for up to 2 hours with or without stimulation of the cavernous nerve.

Gene transfer for erectile dysfunction: will this novel therapy be accepted by urologists?

Purpose Of Review: The purpose of this review is to update the results of the only phase 1 erectile dysfunction gene transfer trial and based upon those results present the outcome of a web-based survey that studied whether or not knowledgeable in the field urologists would use gene transfer in their patients once approved for use by the US Food and Drug Administration.

Recent Findings: The results of the clinical trials showed no transfer-related serious adverse events. The response to 10 questions of a web-based survey indicates that gene transfer as a first or second-line therapy for practicing urologists would be well accepted.

In vitro and in vivo relaxation of corpus cavernosum smooth muscle by the selective myosin II inhibitor, blebbistatin.

Introduction: Blebbistatin (BLEB) is a small cell permeable molecule originally reported as a selective inhibitor of myosin II isoforms expressed by striated muscle and non-muscle cells (IC(50) = 0.5-5 microM) with poor inhibition of turkey gizzard smooth muscle (SM) myosin II (IC(50) approximately 80 microM). However, recently it was found that BLEB can potently inhibit mammalian arterial SM (IC(50) approximately 5 microM).

The mechanism of opiorphin-induced experimental priapism in rats involves activation of the polyamine synthetic pathway.

Intracorporal injection of plasmids encoding opiorphins into retired breeder rats can result in animals developing a priapic-like condition. Microarray analysis demonstrated that following intracorporal gene transfer of plasmids expressing opiorphins the most significantly upregulated gene in corporal tissue was the ornithine decarboxylase gene (ODC). Quantitative RT-PCR confirmed the upregulation of ODC, as well as other genes involved in polyamine synthesis, such as arginase-I and -II, polyamine oxidase, spermidine synthase, spermidine acetyltransferase (SAT), and S-adenosylmethionine decarboxylase.

Markers of erectile dysfunction.

With the development and marketing of oral pharmacotherapy that is both noninvasive and successful in treating erectile dysfunction (ED), the quest to identify markers of organic ED lost ground. Indeed, the multi-factorial nature of ED may have led many researchers to conclude that searching for a universal marker of ED was futile. However, the realization that ED is strongly correlated with the overall health of men, and may act as a predictor for the development of cardiovascular disease (CVD) and diabetes, has stimulated interest in identifying genes that can distinguish organic ED.

Metrics for evaluation of age-related changes in erectile capacity in a rodent model.

Introduction: Stimulation of the cavernous nerve elicits increases in intracavernosal pressure (ICP) and visible penile erection (VPE) in rats. The observed penile erection can be characterized by the change in ICP and the ratio of ICP over blood pressure (BP; systemic blood pressure).

Aim: We evaluated correlations between ICP, BP, ICP/BP, and VPE, and the magnitude of the nerve stimulation required to elicit those responses in order to evaluate age-related changes in erectile function in a rodent model.