Excretion of collagen derived peptides is increased in women with stress urinary incontinence

Molecular Processes in Stress Urinary Incontinence: A Systematic Review of Human and Animal Studies

Stress urinary incontinence (SUI) is a common and burdensome condition. Because of the large knowledge gap around the molecular processes involved in its pathophysiology, the aim of this review was to provide a systematic overview of genetic variants, gene and protein expression changes related to SUI in human and animal studies. On 5 January 2021, a systematic search was performed in Pubmed, Embase, Web of Science, and the Cochrane library. The screening process and quality assessment were performed in duplicate, using predefined inclusion criteria and different quality assessment tools for human and animal studies respectively. The extracted data were grouped in themes per outcome measure, according to their functions in cellular processes, and synthesized in a narrative review. Finally, 107 studies were included, of which 35 used animal models (rats and mice). Resulting from the most examined processes, the evidence suggests that SUI is associated with altered extracellular matrix metabolism, estrogen receptors, oxidative stress, apoptosis, inflammation, neurodegenerative processes, and muscle cell differentiation and contractility. Due to heterogeneity in the studies (e.g., in examined tissues), the precise contribution of the associated genes and proteins in relation to SUI pathophysiology remained unclear. Future research should focus on possible contributors to these alterations.

Expression of COX-2 and Nrf2/GPx3 in the anterior vaginal wall tissues of women with pelvic organ prolapse

PURPOSE

To evaluate COX-2 and Nrf2/GPx3 expressions in the lamina propria of the anterior vaginal wall tissues of women with and without pelvic organ prolapse (POP).

METHODS

Tissue samples of anterior vaginal wall were examined using HE staining, immuohistochemical staining and Western blot for the expressions of COX-2/PGE2, Nrf2/GPx3, MMP2, TIMP1, collagen I and collagen III (n = 35, per group).

RESULTS

Compared with control group, collagen fibers of the anterior vaginal wall were disorganized and discontinuous. Expressions of Nrf2, GPx3, TIMP1, collagen I and collagen III were found significantly lower in POP group (P < 0.05); while, expressions of COX-2, PGE2, and MMP2 were found significantly higher in POP group (P < 0.05). Statistically significant correlations of COX-2 and Nrf2/GPx3 were showed (P < 0.01).

CONCLUSION

We found that the interaction between inflammation and oxidative stress was closely related to the development of POP. This study demonstrates that COX-2 and Nrf2 pathways may be involved in pathogenesis of POP, as promising potential therapeutic targets and agents.

Muscle Precursor Cells for the Restoration of Irreversibly Damaged Sphincter Function

Multiple modalities, including injectable bulking agents and surgery, have been used to treat stress urinary incontinence. However, none of these methods is able to fully restore normal striated sphincter muscle function. In this study, we explored the possibility of achieving functional recovery of the urinary sphincter muscle using autologous muscle precursor cells (MPCs) as an injectable, cell-based therapy. A canine model of striated urinary sphincter insufficiency was created by microsurgically removing part of the sphincter muscle in 24 dogs. Autologous MPCs were obtained, expanded in culture, and injected into the damaged sphincter muscles of 12 animals. The animals were followed for up to 6 months after injection, and urodynamic studies, functional organ bath studies, ultrastructural and histological examinations were performed. Animals receiving MPC injections demonstrated sphincter pressures of approximately 80% of normal values, while the pressures in the control animals without cells dropped and remained at 20% of normal values. Histological analysis indicated that the implanted cells survived and formed tissue, including new innervated muscle fibers, within the injected region of the sphincter. These results indicate that autologous muscle precursor cells may be able to restore otherwise irreversibly damaged urinary sphincter function clinically.

Mesh complications in female pelvic floor reconstructive surgery and their management: A systematic review

We reviewed the incidence, predisposing factors, presentation and management of complications related to the use of synthetic mesh in the management of stress urinary incontinence and pelvic organ prolapse repair. Immediate complications, such as bleeding, hematoma, injury to adjacent organs during placement of mesh and complication of voiding dysfunction are not discussed in this review, since they are primarily related to technique. A PubMed search of related articles published in English was done from April 2008 to March 2011. Key words used were urinary incontinence, mesh, complications, midurethral sling, anterior prolapse, anterior vaginal repair, pelvic organ prolapse, transvaginal mesh, vault prolapse, midurethral slings, female stress urinary incontinence, mesh erosion, vaginal mesh complications, and posterior vaginal wall prolapse. Since there were very few articles dealing with the management of mesh-related complications in the period covered in the search we extended the search from January 2005 onwards. Articles were selected to fit the scope of the topic. In addition, landmark publications and Manufacturer and User Facility Device Experience (MAUDE) data (FDA website) were included on the present topic. A total of 170 articles were identified. The use of synthetic mesh in sub-urethral sling procedures is now considered the standard for the surgical management of stress urinary incontinence. Synthetic mesh is being increasingly used in the management of pelvic organ prolapse. While the incidence of extrusion and erosion with mid-urethral sling is low, the extrusion rate in prolapse repair is somewhat higher and the use in posterior compartment remains controversial. When used through the abdominal approach the extrusion and erosion rates are lower. The management of mesh complication is an individualized approach. The choice of the technique should be based on the type of mesh complication, location of the extrusion and/or erosion, its magnitude, severity and potential recurrence of pelvic floor defect.

Is tissue engineering and biomaterials the future for lower urinary tract dysfunction (LUTD)/pelvic organ prolapse (POP)?

The fields of tissue engineering and regenerative medicine have seen major advances over the span of the past two decades, with biomaterials playing a central role. Although the term "regenerative medicine" has been applied to encompass most fields of medicine, in fact urology has been one of the most progressive. Many urological applications have been investigated over the past decades, with the culmination of these technologies in the introduction of the first laboratory-produced organ to be placed in a human body.1 With the quality of life issues associated with urinary incontinence, there is a strong driver to identify and introduce new technologies and the potential exists for further major advancements from regenerative medicine approaches using biomaterials, cells or a combination of both. A central question is why use biomaterials? The answer rests on the need to make up for inadequate or lack of autologous tissue, to decrease morbidity and to improve long-term efficacy. Thus, the ideal biomaterial needs to meet the following criteria: (1) Provide mechanical and structural support, (2) Maintain compliance and be biocompatible with surrounding tissues, and (3) Be "fit for purpose" by meeting specific application needs ranging from static support to bioactive cell signaling. In essence, this represents a wide range of biomaterials with a spectrum of potential applications, from use as a supportive or bulking implant alone, to implanted biomaterials that promote integration and eventual replacement by infiltrating host cells, or scaffolds pre-seeded with cells prior to implant. In this review we shall discuss the structural versus the integrative uses of biomaterials by referring to two key areas in urology of (1) pelvic organ support for prolapse and stress urinary incontinence, and (2) bladder replacement/augmentation.

Alterations in connective tissue metabolism in stress incontinence and prolapse

PURPOSE

We describe current knowledge about collagen/elastin and extracellular matrix metabolism in the genitourinary tract with special emphasis on stress urinary incontinence. We also explored the influence of genetics and reproductive hormones on extracellular matrix metabolism.

MATERIALS AND METHODS

We performed a MEDLINE® search from 1995 to February 2011 using the key words stress urinary incontinence, pelvic organ prolapse, extracellular matrix, collagen, elastin, matrix metalloproteinase, collagenase, tissue inhibitors of matrix metalloproteinase, elastin metabolism, elastase, connective tissue, supportive tissue, mechanical stress, biomechanical properties, selective estrogen receptor modulators, transforming growth factor-β and wound healing.

RESULTS

The literature searched produced data on 4 areas of significance for extracellular matrix metabolism in patients with stress urinary incontinence and prolapse, including collagen, elastin and transforming growth factor-β. Data on collagen metabolism continue to support the hypothesis of increased turnover involving matrix metalloproteinases and serine proteases in pelvic tissues of affected individuals. Elastin metabolism studies suggest increased degradation but also abnormal elastin fiber synthesis. Epidemiological data indicate a genetic predisposition to abnormal extracellular matrix in affected individuals while human tissue and animal models reveal differential expression of candidate genes involved in structural proteins. Transforming growth factor-β pathways have been documented to be involved in stress urinary incontinence in human tissues and animal models. Finally, these extracellular matrix metabolisms are modulated by reproductive hormones and selective estrogen receptor modulators.

CONCLUSIONS

Pelvic tissue from women with stress urinary incontinence and pelvic organ prolapse show a genetic predisposition to abnormal extracellular matrix remodeling, which is modulated by reproductive hormones, trauma, mechanical stress load and aging. This progressive remodeling contributes to stress urinary incontinence/pelvic organ prolapse by altering normal tissue architecture and mechanical properties.

Pelvic floor disorders: linking genetic risk factors to biochemical changes

Pelvic floor disorders (PFDs) such as stress urinary incontinence (SUI) and pelvic organ prolapse (POP) may share a common pathophysiological process related to pelvic floor tissue laxity and loss of support. We reviewed recent literature on observed biochemical changes in women with SUI and POP, linking them to genetic predisposition. We found that studies of pelvic tissues showed differences between control subjects and women with POP and SUI in collagen and elastin structure at a molecular and fibrillar level. Studies were heterogeneous but showed a trend towards decreased collagen and elastin content. The contribution of matrix metalloproteinases to increased collagenolysis can be related to genetic polymorphisms present in higher frequency in women with PFD. Extracellular matrix (ECM) protein turnover plays a role in the development of POP and SUI, but much remains to be understood of this complex dynamic interplay of enzymes, proteins and molecules. Genotyping of candidate genes participating in ECM formation will elucidate the missing link between the manifestation of the disease and the biochemical changes observed systematically, in addition to those in the pelvic floor.

Pelvic organ prolapse and stress urinary incontinence: A review of etiological factors

Although they may present with significant morbidity, pelvic organ prolapse and stress urinary incontinence are mainly afflictions that affect quality of life. To appropriately treat these entities, comprehension of the various theories of the pathophysiology is paramount. Utilizing a Medline search, this article reviews recent data concerning intrinsic (i.e., genetics, postmenopausal status) and extrinsic factors (i.e., previous hysterectomy, childbirth) leading to organ prolapse or stress incontinence.

Stem cells for stress urinary incontinence: the adipose promise

Stress urinary incontinence (SUI), the most common type of incontinence in women, is a frequent and costly ailment responsible for an alteration in the quality of life. Although medical treatment gives some rather deceiving results, surgical techniques that include colposuspension or tension-free vaginal tape, employed in cases of urethral support defect, give a 5-year cure rate of more than 80%. However, these techniques could lead to complications or recurrence of symptoms. Recently, the initiation of urethral cell therapy has been undertaken by doctors and researchers. One principal source of autologous adult stem cells is generally used: muscle precursor cells (MPCs) which are the progenitors of skeletal muscle cells. Recently, a few research groups have shown interest in the MPCs and their potential for the treatment of urinary incontinence. However, using MPCs or fibroblasts isolated from a striated muscle biopsy could be questionable on several points. One of them is the in vitro cultivation of cells, which raises issues over the potential cost of the technique. Besides, numerous studies have shown the multipotent or even the pluripotent nature of stromal vascular fraction (SVF) or adipose-derived stem cells (ASCs) from adipose tissue. These cells are capable of acquiring in vitro many different phenotypes. Furthermore, recent animal studies have highlighted the potential interest of SVF cells or ASCs in cell therapy, in particular for mesodermal tissue repair and revascularization. Moreover, the potential interest of SVF cells or ASCs for the treatment of urinary incontinence in women is supported by many other characteristics of these cells that are discussed here. Because access to these cells via lipoaspiration is simple, and because they are found in very large numbers in adipose tissue, their future potential as a stem cell reservoir for use in urethral or other types of cell therapy is enormous.

Signs of herniosis in women with vaginal prolapse and/or stress incontinence

Gynecological literature pertaining to prolapse or stress urinary incontinence published over the past four decades was reviewed to determine whether signs of herniosis, the systemic connective tissue co-morbidity known to play a significant role in abdominal herniation, were present and differed from controls. A total of eight indications were reported: (1) Genetic factors, i.e., family history and race, were predictive. (2) An increase in the incidence was observed in association with heritable diseases of collagen and their formes frustes (e.g., joint laxity). (3) Recurrence rate after repair was high (30%). (4) Fragmentation and degeneration of smooth muscle and collagen fibers were observed histologically. (5) Biochemistry demonstrated a decline of 24-40% in collagen content of skin, round ligament, cardinal ligament, periurethral vaginal wall, cervix, pubocervical, cervicococcygeal, and vesicovaginal fasciae. (6) In patients with stress urinary incontinence, collagen content decreased 60%. This change was independent of age, parity, menopausal status, and weight. (7) Matrix metalloproteinase (MMP-2 and MMP-9) activity increased fourfold and that of their inhibitor TIMP-1 decreased. (8) Cigarette smoking, an acquired factor, increased the incidence of stress urinary incontinence. This commonality with the etiology of abdominal herniae explains why gynecologists have decreased their emphasis on childbirth injury and, like herniologists, have moved to discard the dogma "prolapse" as a designate for extraperitoneal herniation in the pelvis.

The use of synthetic sub-urethral slings in the treatment of female stress urinary incontinence

We set out to review the existing literature regarding the use of synthetic suburethral sling products for the treatment of female stress urinary incontinence. Products currently implanted are examined and scrutinized, and evidence regarding their efficacy and complication rates is noted. Additionally, specifics of presently utilized synthetic materials, including construction method and biocompatibility, are explored and directly correlated to currently marketed products. This investigation was undertaken with the use of the Medline database. Studies pertaining to synthetic or surgical mesh, as well as each specific suburethral sling product, are included. Our findings and ultimately our recommendations stem from the preponderance of evidence supporting the continued use of knitted, macroporous polypropelene mesh slings. Several existing marketed products detailed in the study fit this description. Specific reference is made to recent reports of vaginal erosions and deep space infections related to several specific products. A cautionary note is also made regarding the implantation of transobturator sling products currently marketed without the necessary pre-market testing, potentially placing the public at risk. From the currently available literature on biomaterials, it seems clear that knitted macroporous polypropylene is the material of choice for suburethral implantation. With respect to the means and techniques by which these mesh materials are suburethrally implanted, the surgeon's choice often dictates which method is used, but recent experience has demonstrated that the transobturator approach can be equally as effective as the traditional tension-free vaginal tape, with less-associated morbidity. Ongoing randomized controlled trials will further clarify and distinguish between methods.

Pelvic organ prolapse: demographics and future growth prospects

Pelvic Organ Prolapse (POP) is the hidden epidemic. Demographic studies have shown that women over the age of eighty are the fastest growing population segment in the United States and Canada. Over the next thirty years the rate of women who will seek treatment for POP will double. Risks for the development of POP have been categorized into factors that predispose, incite, promote, and decompensate. Connective tissue disorders may play a role in the pathogenesis which may involve a reduction in total collagen content secondary to increased collagenolytic activity. Eventually clinicians may be able to identify women who may be genetically predetermined to develop POP. The role of adjuvant materials in performing reconstructive pelvic surgery may improve success rates, but evidence based medicine and randomized controlled trials are currently lacking.