Injectable agents: present and future

Surgical Management of Stress Incontinence

The aim was to describe contemporary surgical procedures for the treatment of stress urinary incontinence (SUI) in women. The 4 most commonly performed surgical procedures for the treatment of SUI were reviewed using standardized terminology. We addressed the history and evolution of the procedures as well as the mechanisms of action by which they work. Efficacy and safety data were also presented. Midurethral Sling, Pubovaginal Sling, Retropubic Colposuspension, and Urethral Bulking are safe and effective procedures. Midurethral Sling, Pubovaginal Sling, Retropubic Colposuspension, and Urethral Bulking are contemporary procedures for the treatment of SUI in women.

Joint Report on Terminology for Surgical Procedures to Treat Stress Urinary Incontinence in Women

INTRODUCTION AND HYPOTHESIS

Standardized terminology for surgical procedures commonly performed to treat stress urinary incontinence in women is needed to facilitate research, clinical care, and teaching in female pelvic medicine and reconstructive surgery.

METHODS

This report combines the input of members of the American Urogynecologic Society and the International Urogynecological Association, assisted by external referees. Extensive searches of the literature were performed, including Instructions for Use brochures and original source documents where possible. Historical context was considered along with procedural modifications, and expert opinion was included when appropriate.

RESULTS

A terminology report for the procedures commonly performed to treat stress urinary incontinence in women was produced. Included procedures are midurethral sling, retropubic colposuspension, pubovaginal sling, urethral bulking, and artificial urinary sphincter. Appropriate figures have been included to supplement and help clarify the text. Ongoing review will be performed periodically to keep the document updated and widely acceptable.

CONCLUSIONS

This document is a literature and consensus-based terminology report for surgical procedures to treat stress urinary incontinence in women. Future publications in female pelvic medicine and reconstructive surgery should use this standardized terminology whenever possible.

Advances in stem cell therapy for male stress urinary incontinence

INTRODUCTION

Among the several options that have been proposed in recent years for the management of male stress urinary incontinence (SUI), stem cell therapy represents a new frontier in treatment. The aim of this paper is to update the current status of stem cell therapy in animal and human studies for the management of iatrogenic male SUI.

AREAS COVERED

A literature review was conducted based on MEDLINE/PubMed searches for English articles using a combination of the following keywords: stem cell therapy, urinary incontinence, prostatectomy, regenerative medicine, mesenchymal stem cells.

EXPERT OPINION

The few studies reported in the literature have demonstrated short-term safety and promising results of stem cell therapy in treating male SUI. However, many aspects need to be clarified before stem cell therapy can be introduced into daily urologic practice. In fact, important issues such as the limitations of these studies in terms of small sample sizes and short follow-ups, the incomplete knowledge of the mechanism of action of stem cells, the technical details regarding the delivery method and the best sources of stem cells, the safety risks regarding genomic or epigenetic changes and potential immune reactions in the longer term need to be identified in more stringent clinical trials.

Structure and rheology of dual-associative protein hydrogels under nonlinear shear flow

Dual-associative protein di- and triblock copolymers composed of sticker-decorated midblocks and micelle-forming elastin-like polypeptide (ELP) endblocks form shear-thinning, thermoresponsively reinforceable hydrogels that are potentially useful as injectable materials for a variety of applications. Here, the combination of rheological and in situ scattering measurements under shear on these dual-associative gels is employed in order to better understand how block architecture plays a role in controlling microscopic structural rearrangement and the resulting macroscopic mechanical responses. These gels, which form a disordered sphere phase due to endblock aggregation under quiescent conditions with the midblock domains physically crosslinked by protein associations, exhibit both viscoelastic and thixotropic signatures with relative magnitudes dependent upon gel concentration and block architecture. In situ SAXS measurements during flow indicate that these thixotropic responses correspond to the development of ordered domains following start-up of shear. For both architectures, the rate of alignment increases with increasing concentration. However, the rate of domain formation when increasing the temperature from 35 to 50 °C depends on the interplay between thermoresponsive toughening of the endblocks and softening of the coiled-coil domains such that rate of rearrangement decreases in the triblock while it increases in the diblock. Following a step-down in shear flow, structural rearrangement within the samples results in a thixotropic stress response. Upon cessation of flow, gel recovery is characterized by a concentration-dependent restoration of the micellar network over time, with two timescales observed that correspond to two different length scales of network relaxation.

Stem Cell Therapy for Male Urinary Incontinence

INTRODUCTION

Among the medical and surgical options which have been proposed in the last years for the management of male stress urinary incontinence (SUI), stem cell therapy represents a new frontier treatment. The aim of this paper is to update the current status of stem cell therapy in animal and human studies for the management of iatrogenic male SUI.

MATERIAL AND METHODS

A PubMed review of the literature on stem cell therapy for the treatment of male SUI was performed.

RESULTS

Regarding animal studies, bone marrow-, muscle- and adipose-derived stem cells have been widely studied, showing regeneration of the urethral sphincter and recovery of the damaged pelvic nerves. With regard to human studies, only four papers are available in the literature using muscle- and adipose-derived stem cells which reported a significant improvement in sphincteric function and incontinence with no severe side effects.

CONCLUSIONS

In spite of these promising results, further studies are needed with longer follow-ups and larger numbers of patients in order to clarify the potential role of stem cell therapy for the treatment of male SUI.

Autologous Bone Marrow-Derived Cells Regenerate Urethral Sphincters

Regenerative medicine based on tissue engineering and/or stem cell therapy techniques has the potential to improve irreversibly damaged tissues. Surgical injury to the lower urinary tract can occur as a result of radical prostatectomy or bladder neck surgery. Regeneration of urethral sphincters could be an effective treatment for post-surgical intrinsic sphincter deficiency (ISD)-related urinary incontinence. The replacement, enhancement, and/or recovery the urethral sphincter striated and smooth muscles could increase urethral closure pressure to help patients regain continence. Stem cells from muscle-derived satellite or adipose-derived mesenchymal cells provide temporary improvement in urethral closure pressure but do not reconstruct the muscle layer structures. Our strategy to accomplish regeneration of urethral sphincters is the utilization of autologous bone marrow-derived cells. We have developed a freeze injury model of ISD in rabbits. Freezing of the urinary sphincter causes loss of the majority of striated and smooth muscle cells, and causes a significant decrease in leak point pressure. In this review, we show that the autologous bone marrow-derived cells implanted within the freeze-injured sphincters differentiate into striated or smooth muscle cells. These cells then develop to reconstitute muscle layer structures within the sphincter. Furthermore, the leak point pressure of cell-implanted rabbits is significantly higher than that of cell-free injected controls. We conclude that implantation of autologous bone marrow-derived cells could be an effective treatment for human post-surgical ISD-related urinary incontinence.

Implantation of autologous bone-marrow-derived cells reconstructs functional urethral sphincters in rabbits

The purpose of this study was to determine if implantation of autologous bone-marrow-derived cells has the potential to treat stress urinary incontinence caused by intrinsic sphincter deficiency. Bone marrow cells harvested from femurs of New Zealand White rabbits were cultured for 10 days. Seven days before implantation, the urethral sphincters located at the internal urethral orifice were cryo-injured by spraying liquid nitrogen for 15 s. The cultured autologous bone-marrow-derived cells were implanted 7 days after cryo-injury. For controls, cell-free solutions were injected. At 7 and 14 days after implantation, leak point pressures were determined and the urethral sphincters were examined by immunohistochemistry. At 7 and 14 days, the cell-implanted regions contained numerous striated and smooth muscle-like cells expressing myoglobin and smooth muscle actin, respectively. The proportions of myoglobin- and smooth muscle actin-expressing areas in both the 7- and 14-day cell-implanted regions were significantly higher than in controls. By 14 days, these differentiated cells formed contacts with similar cells, creating layered muscle structures. At that time, the leak point pressure of the cell-implanted rabbits was significantly higher than that of the controls. In conclusion, autologous bone-marrow-derived cells can reconstruct functional urethral sphincters.

Slings in iatrogenic male incontinence: Current status

OBJECTIVES

The increasing number of prostatectomies entails an increasing number of patients suffering from iatrogenic incontinence despite improved surgical techniques. The severity of this problem often requires invasive treatments such as periurethral injection of bulking agents, artificial urinary sphincter (AUS) implantation, and sub-urethral sling positioning. The artificial urethral sphincter has represented, until today, the gold standard but, in the recent years, sling systems have been investigated as minimally invasive alternative options. Today, three different sling procedures are commonly performed: bone-anchored, readjustable, and trans-obturator slings systems. The aim of this review is to critically report the current status of sling systems in the treatment of iatrogenic male incontinence.

MATERIALS AND METHODS

MEDLINE and PubMed databases were searched and all articles between 1974 and 2009 were evaluated.

RESULTS

With regard to bone-anchored, readjustable, and trans-obturator slings systems, cure rates ranged between 58.0% and 86.0%, 55.5% and 73.0%, and 40.0% and 63.0%, respectively, while major complication rates ranged between 0 and 14.5%, 10.0 and 22.2%, and 0 and 10.0%, respectively.

CONCLUSIONS

Suburethral slings are the only alternative techniques which can be favorably compared with the AUS, showing more advantages with respect to AUS implantations which are mainly represented by a quick and less invasive approach, low morbidity, and low costs. In spite of the difficulty in identifying the most effective sling procedure, overall, sling systems can be recommended for patients with persistent mild or moderate incontinence. However, the indication can also be extended to patients with severe incontinence, after appropriate counseling, allowing AUS implantation in the event of sling failure.

Comparison of the precision of transurethral endoscopic versus ultrasound-guided application of injectables

OBJECTIVE

To compare the precision of transurethral endoscopic- vs ultrasound (US)-guided injections, as transurethral application of various injectables under endoscopic view are widely used to treat urinary incontinence.

MATERIAL AND METHODS

Bovine collagen was injected into the lower urinary tract in 20 dead female pigs. In each pig five depots of collagen were injected and there were five pigs in each group. In group I collagen was injected into the urethral wall under endoscopic control. In group II collagen depots were injected periurethrally under endosocopic guidance. In group III collagen was injected into the urethral wall under US control. In group IV collagen depots were injected periurethrally under US guidance. A transurethral US probe (6 F, 15 MHz) and injection device were used for transurethral US-guided injections. In all pigs the urethra and the periurethral tissue were removed after injection and investigated using anatomical preparations and histological sections.

RESULTS

In group I only two collagen depots were actually located in the urethral wall in two pigs (two of 25 depots, 8%). In group II five depots in two pigs were located in the urethral wall (five of 25 depots, 20%). The periurethral collagen depots were found to spread out in the loose connective and fat tissue around the urethra. In group III all US-guided injections of collagen were situated in the urethral wall and in group IV they were all located periurethrally.

CONCLUSIONS

The present study shows that endoscopic application of injectables is an inaccurate technique, while US-guided injections are precise. US-guided injection enables excellent control of the therapeutic procedure.

Emerging periurethral bulking agents for female stress urinary incontinence: is new necessarily better?

Bulking therapy for stress urinary incontinence in women continues to evolve from the standpoint of material science. Several new materials have recently been subjected to clinical trials with the aim of assessing efficacy and safety of these agents for possible device registration. These new additions run the gamut of biologic to synthetic materials, including re-engineered carbon-coated zirconium beads, ethylene vinyl copolymer, calcium hydroxylapatite, silicone, and hyaluronic acid. Trial design and results reporting for bulking agents has also evolved, with the addition of quality-of-life and patient approbation assessments now being included with outcomes for incontinence reduction and adverse events recording. The new agents and recent studies are reviewed within a context of the prior evidence that has supported the use of the bulking strategy for management of symptomatic stress incontinence. Several recent trials have also compared bulking agents with surgical interventions from effectiveness, approbation, and cost vantage points so as to better determine the reasonability of bulking agent use in an era of minimally invasive incontinence surgery.

Radio-Opaque and Surface-Functionalized Polymer Microparticles: Potentially Safer Biomaterials for Different Injection Therapies

Injectable polymer particles with a diameter in the range of 30-300 microm find applications as a biomaterial in different clinical fields, such as cosmetic surgery, reconstructive surgery, and urology. However, clinical effects tend to disappear after several months, either due to migration of the particles away from the injection site (caused by weak adherence with the surrounding soft tissues) or due to fibrosis (caused by excessive encapsulation of the particles by fibrous tissue). Little is known about the fate of injected microparticles, due to the fact that they are extremely difficult to trace in a noninvasive manner. Design, synthesis, and characterization of new polymeric microspheres with two additional features that can enhance safety and can help to overcome drawbacks of existing products are reported. First, the new microparticles feature clear radio-opacity (X-ray visibility) as they are prepared on the basis of a reactive methacrylic monomer that contains covalently bound iodine. Model experiments reveal that the level of X-ray contrast is sufficient for clinical monitoring; they can be visualized both during the injection and afterward. The particles feature excellent cytocompatibility in vitro and in vivo. Second, a method is explored to functionalize the surface of the particles, for example, through immobilization of collagen. Other extracellular matrix proteins can also be immobilized, and this provides a mechanism to control anchoring of the particles in soft tissue. The results are briefly discussed in the context of improved biomaterials, contemporary X-ray imaging, and control over biomaterial-soft tissue interactions in vivo.

Patient-perceived outcomes in the treatment of stress urinary incontinence: focus on urethral injection therapy

Intervention for stress urinary incontinence (SUI) is generally focused on minimizing urinary leakage. However, the overall impact of SUI therapy on patients' quality of life is, arguably, more important than leakage outcomes. We performed a literature search to investigate the effect of urethral injection therapy on quality of life. Significant quality-of-life improvements have been observed with a number of injectable agents, while there is a distinct lack of correlation between subjective and objective outcomes. Two studies comparing urethral injection therapy with surgical intervention found superior objective efficacy with surgery, but no significant differences in quality-of-life improvements. Personal goals of patients undergoing urethral injection are yet to be explored, but there may be willingness to trade a lower success rate in favor of a more minor treatment procedure. In conclusion, quality-of-life improvements after urethral injection appear significant and comparable to those obtained with surgery. Further study of patients' own perceptions, pre- and posttreatment, would be valuable.

Stress incontinence injection therapy: what is best for our patients?

OBJECTIVE

Urethral injection (periurethral/intraurethral bulking) is an established, minimally invasive therapy for stress urinary incontinence (SUI). This review aims to determine which women should potentially benefit from, and be considered as candidates for, injection therapy and to elucidate what we are trying to achieve.

METHODS

Based on MEDLINE database searches, all aspects of urethral injection were examined, including patient selection, safety, injection technique, efficacy, quality of life, goals and cost.

RESULTS

Such therapy has a low complication rate, improves or cures about 3 out of 4 women, as shown in mainly short-term studies, and improves patients' quality of life. It can be used in the majority of patients with uncomplicated SUI. Therefore, injection therapy may be considered as a first-line treatment option for patients who have failed conservative therapy such as pelvic floor exercises and who decline or have a contraindication for pharmacological treatment. However, the decision of whether to use this type of treatment must be based on an informed discussion between the physician and patient--this dialogue should incorporate questions about patients' own treatment goals. Injection therapy appears to have the profile required to meet patients' goals, based on the findings that a procedure with an improvement in incontinence, minimal short-term risk, no long-term risk, and performed in a clinic, would be acceptable.

CONCLUSION

Investigating and trying to achieve patients' own treatment goals will ultimately enable us to do what is best for our patients, but current evidence suggests that injection therapy is a valid option worth discussing with many patients.

An open, multicentre study of NASHA/Dx Gel (Zuidex) for the treatment of stress urinary incontinence

OBJECTIVE

The Zuidex system facilitates non-endoscopic urethral injection for stress urinary incontinence (SUI). It comprises four pre-filled syringes of non-animal stabilised hyaluronic acid/dextranomer (NASHA/Dx) gel and an Implacer device. This open, 12-month study was performed to evaluate the safety and efficacy of this system in women with SUI.

METHODS

Patients were aged > or =18 years with a history of SUI for > or =12 months (hypermobility and/or intrinsic sphincter deficiency), had failed prior non-invasive therapy and were invasive-therapy naïve. Up to two treatments with NASHA/Dx gel were permissible (re-treatment was offered at week 8). Positive response to treatment was defined as a reduction in provocation test leakage of > or =50% compared with baseline. Efficacy was also measured by 24-hour pad weight test leakage, and number of incontinence episodes/24 hours.

RESULTS

A total of 142 patients were enrolled, with a mean age of 55.7 years. The response rate was 78% at week 12, and 77% at month 12. Significant reductions in median provocation test leakage, 24-hour pad-weight test leakage and number of incontinence episodes/24 hours were observed at all time-points. At month 12, the median decreases from baseline in these three variables were 93%, 89% and 67%, respectively. Treatment-related adverse events were of a nature expected with urethral injection - most were transient, and of mild or moderate intensity.

CONCLUSIONS

Treatment with NASHA/Dx gel produced large, statistically significant reductions in urinary leakage sustained over 12 months and was well tolerated. These findings suggest that NASHA/Dx gel could be considered as an early intervention in treatment-naïve cases of SUI.

A critical review of diagnostic criteria for evaluating patients with symptomatic stress urinary incontinence

The first paper in this section is a review by several highly respected authors of diagnostic criteria for evaluating patients with symptomatic stress urinary incontinence, and is followed by a review of the role of urgency and its measurement in the overactive bladder symptom syndrome, with emphasis on current concepts and future prospects. These are two important papers, which point the reader in the direction of a greater understanding of these conditions. The concept of alpha-blockade before a trial without catheter after acute urinary retention is revisited by authors from the UK, who used tamsulosin in a randomized controlled trial. They found that it is appropriate to recommend tamsulosin for such use in this condition.