Smooth muscle myosin heavy chain and caldesmon expression in the anterior vaginal wall of women with and without pelvic organ prolapse

Strains induced in the vagina by smooth muscle contractions

The ability of the vagina to contract gives rise to a set of active mechanical properties that contribute to the complex function of this organ in-vivo. Regional differences in the morphology of the vagina have been long recognized, but the large heterogeneous deformations that the vagina experiences during contractions have never been quantified. Furthermore, there is no consensus regarding differences in contractility along the two primary anatomical directions of the vagina: the longitudinal direction (LD) and the circumferential direction (CD). In this study, square vaginal specimens from healthy virgin rats (n=15) were subjected to isometric planar biaxial tests at four equi-biaxial stretches of 1.0, 1.1, 1.2, and 1.3. Contractions were induced at each stretch by a high concentration potassium solution. The digital image correlation method was used to perform full-field strain measurements during contractions. The vagina was found to undergo significantly higher compressive strains, tensile strains, and contractile forces along the LD than along the CD during contractions. Specifically, when computed over all the applied equi-biaxial stretches, mean (± std. dev.) absolute maximum compressive strains were -(13.43 ± 1.56)% along the LD and -(3.19 ± 0.25)% along the CD, mean absolute maximum tensile strains were (10.92 ± 1.73)% along the LD and (3.62 ± 0.57)% along the CD, and mean maximum contractile forces were 6.24 ± 0.55 mN along the LD and 3.35 ± 0.56 mN along the CD. Moreover, the vaginal tissue appeared to undergo compression in the proximal region and tension in the distal region while kept at constant equi-biaxial stretches. The active mechanical properties of the healthy vagina need to be fully investigated so that detrimental alterations in vaginal contractility, such as those caused by pelvic floor disorders and current treatment strategies, can be prevented. STATEMENT OF SIGNIFICANCE: Contractile forces of the vagina have been measured by several investigators using uniaxial tensile testing methods. Unlike previous studies, in this study planar-biaxial tests of vaginal specimens were performed while the full-field strains of the vagina, as induced by smooth muscle contraction, were measured. The vagina was found to generate significantly larger contractile strains and forces in the longitudinal direction than in the circumferential direction. Knowledge of the contractile mechanics of the healthy vagina is essential to understand the detrimental effects that pelvic organ prolapse and the use of surgical meshes have on the functionality of smooth muscle in the vagina.

Altered mechanics of vaginal smooth muscle cells due to the lysyl oxidase-like1 knockout

The remodeling mechanisms that cause connective tissue of the vaginal wall, consisting mostly of smooth muscle, to weaken after vaginal delivery are not fully understood. Abnormal remodeling after delivery can contribute to development of pelvic organ prolapse and other pelvic floor disorders. The present study used vaginal smooth muscle cells (vSMCs) isolated from knockout mice lacking the expression of the lysyl oxidase-like1 (LOXL1) enzyme, a well-characterized animal model for pelvic organ prolapse. We tested if vaginal smooth muscle cells from LOXL1 knockout mice have altered mechanics including stiffness and surface adhesion. Using atomic force microscopy, we performed nanoindentations on both isolated and confluent cells to evaluate the effect of LOXL1 knockout on in vitro cultures of vSMCs cells from nulliparous mice. The results show that LOXL1 knockout vSMCs have increased stiffness in pre-confluent but decreased stiffness in confluent cultures (p* < 0.05) and significant decreased surface adhesion in pre-confluent cultures (p* < 0.05). This study provides evidence that the weakening of vaginal connective tissue in the absense of LOXL1 changes the mechanical properties of the vSMCs. STATEMENT OF SIGNIFICANCE: Pelvic organ prolapse is a common condition affecting millions of women worldwide, which significantly impacts their quality of life. Alterations in vaginal and pelvic floor mechanical properties can change their ability to support the pelvic organs. This study provides evidence of altered stiffness of vaginal smooth muscle cells from mice resembling pelvic organ prolapse. The results from this study set a foundation to develop pathophysiology-driven therapies focused on the interplay between smooth muscle mechanics and extracellular matrix remodeling.

Role of sex steroid hormones in pelvic organ prolapse

OBJECTIVE

Pelvic organ prolapse (POP) affects a significant percentage of women and contributes to major healthcare costs both in the United States and worldwide. This review examines the current understanding of the role of sex steroid hormones (estrogens, androgens, and progesterone) in POP in premenopausal, perimenopausal, and postmenopausal women.

METHODS

We reviewed the relevant studies on POP related to estrogens, androgens, and progesterone in both animal models and humans.

RESULTS

Estrogen has a profound influence on the synthesis and metabolism of pelvic connective tissues, and may have the ability to both prevent POP and improve prognosis if used therapeutically. There is limited research regarding the role of androgens and progesterone and their receptors in POP and results so far have been contradictory, warranting further study to determine whether changes in androgen and progesterone receptor expression are a cause or effect of POP.

CONCLUSIONS

Because of the role that estrogen plays in maintaining the integrity of pelvic floor connective tissues, we propose that rigorous and well-controlled studies are needed on the role of exogenous estrogen administration as a form of POP prevention. : Video Summary:http://links.lww.com/MENO/A583.

Towards rebuilding vaginal support utilizing an extracellular matrix bioscaffold

As an alternative to polypropylene mesh, we explored an extracellular matrix (ECM) bioscaffold derived from urinary bladder matrix (MatriStem™) in the repair of vaginal prolapse. We aimed to restore disrupted vaginal support simulating application via transvaginal and transabdominal approaches in a macaque model focusing on the impact on vaginal structure, function, and the host immune response. In 16 macaques, after laparotomy, the uterosacral ligaments and paravaginal attachments to pelvic side wall were completely transected (IACUC# 13081928). 6-ply MatriStem was cut into posterior and anterior templates with a portion covering the vagina and arms simulating uterosacral ligaments and paravaginal attachments, respectively. After surgically exposing the correct anatomical sites, in 8 animals, a vaginal incision was made on the anterior and posterior vagina and the respective scaffolds were passed into the vagina via these incisions (transvaginal insertion) prior to placement. The remaining 8 animals underwent the same surgery without vaginal incisions (transabdominal insertion). Three months post implantation, firm tissue bands extending from vagina to pelvic side wall appeared in both MatriStem groups. Experimental endpoints examining impact of MatriStem on the vagina demonstrated that vaginal biochemical and biomechanical parameters, smooth muscle thickness and contractility, and immune responses were similar in the MatriStem no incision group and sham-operated controls. In the MatriStem incision group, a 41% decrease in vaginal stiffness (P=0.042), a 22% decrease in collagen content (P=0.008) and a 25% increase in collagen subtypes III/I was observed vs. Sham. Active MMP2 was increased in both Matristem groups vs. Sham (both P=0.002). This study presents a novel application of ECM bioscaffolds as a first step towards the rebuilding of vaginal support.

STATEMENT OF SIGNIFICANCE

Pelvic organ prolapse is a common condition related to failure of the supportive soft tissues of the vagina; particularly at the apex and mid-vagina. Few studies have investigated methods to regenerate these failed structures. The overall goal of the study was to determine the feasibility of utilizing a regenerative bioscaffold in prolapse applications to restore apical (level I) and lateral (level II) support to the vagina without negatively impacting vaginal structure and function. The significance of our findings is two fold: 1. Implantation of properly constructed extracellular matrix grafts promoted rebuilding of level I and level II support to the vagina and did not negatively impact the overall functional, morphological and biochemical properties of the vagina. 2. The presence of vaginal incisions in the transvaginal insertion of bioscaffolds may compromise vaginal structural integrity in the short term.

Microarray gene expression analysis of uterosacral ligaments in uterine prolapse

OBJECTIVES

Pelvic organ prolapse (POP) is a major health problem that impairs the quality of life with a wide clinical spectrum. Since the uterosacral ligaments provide primary support for the uterus and the upper vagina, we hypothesize that the disruption of these ligaments may lead to a loss of support and eventually contribute to POP.

DESIGN AND METHODS

In this study, we therefore investigated whether there are any differences in the transcription profile of uterosacral ligaments in patients with POP when compared to those of the control samples. Seventeen women with POP and 8 non-POP controls undergoing hysterectomy for benign conditions were included in the study. Affymetrix® Gene Chip microarrays (Human Hu 133 plus 2.0) were used for whole genome gene expression profiling analysis.

RESULTS

There was 1 significantly down-regulated gene, NKX2-3 in patients with POP compared to the controls (p=4.28464e-013). KIF11 gene was found to be significantly down-regulated in patients with ≥3 deliveries compared to patients with <3 deliveries (p=0.0156237). UGT1A1 (p=2.43388e-005), SCARB1 (p=1.19001e-006) and NKX2-3 (p=2.17966e-013) genes were found to be significantly down-regulated in the premenopausal patients compared to the premenopausal controls. UGT1A1 gene was also found to be significantly down-regulated in the post menopausal patients compared to the postmenopausal controls (p=0.0005).

CONCLUSION

This study provides evidence for a significant down-regulation of the genes that take role in cell cycle, proliferation and embryonic development along with cell adhesion process on the development of POP for the first time.

The impact of prolapse mesh on vaginal smooth muscle structure and function

OBJECTIVE

To evaluate the impact of prolapse meshes on vaginal smooth muscle structure (VaSM) and function, and to evaluate these outcomes in the context of the mechanical and textile properties of the mesh.

DESIGN

Three months following the implantation of three polypropylene prolapse meshes with distinct textile and mechanical properties, mesh tissue explants were evaluated for smooth muscle contraction, innervation, receptor function, and innervation density.

SETTING

Magee-Womens Research Institute at the University of Pittsburgh.

POPULATION

Thirty-four parous rhesus macaques of similar age, parity, and pelvic organ prolapse quantification (POP-Q) scores.

METHODS

Macaques were implanted with mesh via sacrocolpopexy. The impact of Gynemesh(™)  PS (Ethicon; n = 7), Restorelle(®) (Coloplast; n = 7), UltraPro(™) parallel and UltraPro(™) perpendicular (Ethicon; n = 6 and 7, respectively) were compared with sham-operated controls (n = 7). Outcomes were analysed by Kruskal-Wallis ANOVA, Mann-Whitney U-tests and multiple regression analysis (P < 0.05).

MEAN OUTCOME MEASURES

Vaginal tissue explants were evaluated for the maximum contractile force generated following muscle, nerve, and receptor stimulation, and for peripheral nerve density.

RESULTS

Muscle myofibre, nerve, and receptor-mediated contractions were negatively affected by mesh only in the grafted region (P < 0.001, P = 0.002, and P = 0.008, respectively), whereas cholinergic and adrenergic nerve densities were affected in the grafted (P = 0.090 and P = 0.008, respectively) and non-grafted (P = 0.009 and P = 0.005, respectively) regions. The impact varied by mesh property, as mesh stiffness was a significant predictor of the negative affect on muscle function and nerve density (P < 0.001 and P = 0.013, respectively), whereas mesh and weight was a predictor of receptor function (P < 0.001).

CONCLUSIONS

Mesh has an overall negative impact on VaSM, and the effects are a function of mesh properties, most notably, mesh stiffness.

TWEETABLE ABSTRACT

Prolapse mesh affects vaginal smooth muscle.

The role of smooth muscle cells in the pathophysiology of pelvic organ prolapse

Pelvic organ prolapse (POP) is a prevalent and disabling condition. The pathophysiology of prolapse is multifactorial, and no single mechanism adequately explains all aspects of its development. The pathophysiology of POP is complex and incompletely understood. Smooth muscle (SM), an integral part of the vaginal wall and endopelvic structures that support the pelvic viscera, has also been implicated in the pathophysiology of POP. In this article, we review the role of smooth muscle cells (SMC) in the pathophysiology of POP, also addressing the anatomy of SM in pelvic floor, morphometric analysis, biomechanical properties, and potential mechanisms.

Changes in the rheological behavior of the vagina in women with pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Pelvic organ prolapse is a common condition impacting the quality of life of millions of women worldwide. Although vaginal estrogen is widely used in women with prolapse, little is known regarding estrogen's benefits on the biomechanical properties of vaginal tissue. Here, we aimed to examine the effect of prolapse on the biomechanical properties of the vagina and determine alterations in vaginal mechanics in the presence and absence of hormone therapy (HT).

METHODS

We characterized the viscoelastic properties of vaginal biopsies from age-matched premenopausal women without (n = 12) and with prolapse (n = 8) and postmenopausal women with prolapse on (n = 18) and off HT (n = 9). Utilizing a single-lap shear testing protocol, full-thickness anterior vaginal biopsies were subjected to ±10% shear strain over a range of frequencies (1-90 Hz). This applied energy is either dissipated (viscous) or stored (elastic) as a function of frequency due to compositional or structural differences in the tissue.

RESULTS

Prolapsed tissue was more stiff (higher complex modulus) under shear deformation resulting from increases in both elastic (elastic modulus) and viscous (loss modulus) contributions, with non-prolapsed premenopausal women being the least stiff. Postmenopausal women with prolapse currently on HT were the most stiff of all the groups.

CONCLUSIONS

These data suggest that prolapsed tissue has an increased elastic contribution likely resulting from changes in biochemical constituents, and hormones increase the viscous contribution of prolapsed tissue. Overall, this study design characterized the viscoelastic properties of vaginal biopsies and may be utilized to conduct longitudinal studies to better understand the mechanisms of prolapse development and progression.

Effect of estrogen on molecular and functional characteristics of the rodent vaginal muscularis

INTRODUCTION

Vaginal atrophy is a consequence of menopause; however, little is known concerning the effect of a decrease in systemic estrogen on vaginal smooth muscle structure and function. As the incidence of pelvic floor disorders increases with age, it is important to determine if estrogen regulates the molecular composition and contractility of the vaginal muscularis.

AIM

The goal of this study was to determine the effect of estrogen on molecular and functional characteristics of the vaginal muscularis utilizing a rodent model of surgical menopause.

METHODS

Three- to 4-month old Sprague-Dawley rats underwent sham laparotomy (Sham, N = 18) or ovariectomy (Ovx, N = 39). Two weeks following surgery, animals received a subcutaneous osmotic pump containing vehicle (Sham, Ovx) or 17β-estradiol (Ovx). Animals were euthanized 1 week later, and the proximal vagina was collected for analysis of contractile protein expression and in vitro studies of contractility. Measurements were analyzed using a one-way analysis of variance followed by Tukey's post hoc analysis (α = 0.05).

MAIN OUTCOME MEASURES

Protein and mRNA transcript expression levels of contractile proteins, in vitro measurements of vaginal contractility.

RESULTS

Ovariectomy decreased the expression of carboxyl-terminal myosin heavy chain isoform (SM1) and h-caldesmon and reduced the amplitude of contraction of the vaginal muscularis in response to KCl. Estradiol replacement reversed these changes. No differences were detected in the % vaginal muscularis, mRNA transcript expression of amino-terminal MHC isoforms, l-caldesmon expression, and maximal velocity of shortening.

CONCLUSION

Systemic estrogen replacement restores functional and molecular characteristics of the vaginal muscularis of ovariectomized rats. Our results indicate that menopause is associated with changes in the vaginal muscularis, which may contribute to the increased incidence of pelvic floor disorders with age.

Comparative analysis of pelvic ligaments: a biomechanics study

INTRODUCTION AND HYPOTHESIS

Pelvic organ prolapse (POP) affects one third of women of all ages and is a major concern for gynecological surgeons. In pelvic reconstructive surgery, native ligaments are widely used as a corrective support, while their biomechanical properties are unknown. We hypothesized differences in the strength of various pelvic ligaments and therefore, aimed to evaluate and compare their biomechanical properties.

MATERIALS AND METHODS

Samples from the left and right broad, round, and uterosacral ligaments from 13 fresh female cadavers without pelvic organ prolapse were collected. Uniaxial tension tests at a constant rate of deformation were performed and stress-strain curves were obtained.

RESULTS

We observed a non-linear stress-strain relationship and a hyperelastic mechanical behavior of the tissues. The uterosacral ligaments were the most rigid whether at low or high deformation, while the round ligament was more rigid than the broad ligament.

CONCLUSION

Pelvic ligaments differ in their biomechanical properties and there is fairly good evidence that the uterosacral ligaments play an important role in the maintenance of pelvic support from a biomechanical point of view.

Expression of genes encoding smooth muscle contractile proteins in vaginal tissue of women with and without pelvic organ prolapse

AIMS

We hypothesize that the expression of genes encoding vaginal smooth muscle (SM) contractile proteins is altered in patients with pelvic organ prolapse (POP) and is influenced by age and menopausal status. We aim to analyze the expression of SM-myosin heavy chain (MHY11), caldesmon (CALD1), SM gamma-actin (ACTG2), and tropomyosin (TPM1), in premenopausal and postmenopausal women with advanced POP and asymptomatic controls.

METHODS

During total hysterectomy we collected anterior vaginal wall biopsy samples from 55 women, 37 premenopausal (23 patients and 14 controls), and 18 postmenopausal women (13 patients and 5 controls). Total mRNA from the tissues was quantified by real-time RT-PCR.

RESULTS

MHY11 gene expression was down-regulated in premenopausal POP patients compared to premenopausal controls (fivefold, P = 0.002). In the postmenopausal groups, we observed a sixfold increase in the CALD1 gene expression in POP patients compared to asymptomatic controls (P = 0.03). The gene expression of CALD1, ACTG2, and TPM1 was significantly down-regulated in vaginal tissue of healthy women after menopause (P < 0.05).

CONCLUSION

Dysregulation of the vaginal SM content in POP patients involves alteration of different cellular pathways according to age and menopausal status.

The calpain system as a potential target for pelvic muscle reinforcement

The fascial and muscular components within the pelvic floor create a support mechanism that facilitates storage and voiding of urine. Their constituents are mainly fibrillar collagens I and III, which are responsible for maintaining tensile strength. Stretching and recoiling is enabled by the elastic fibers consisting of elastin on a scaffold of microfibrils, fibrillin-1 and -2. Calpains are intracellular Ca2+ -dependent cysteine proteases found in almost all eukaryotes and some bacteria. Calpains display limited proteolytic activity at neutral pH, proteolyzing substrates to transform and modulate their structures and activities, and are therefore called “modulator proteases”. By making selective limited proteolytic cleavages, they modulate the activity of enzymes, including key signaling molecules, and induce specific cytoskeletal rearrangements, accounting for their roles in signal transduction and structural stabilization. Understanding these mechanisms should provide avenues for novel therapeutic strategies to treat pathological processes such as urinary incontinence and pelvic prolapse.

Genetics of pelvic organ prolapse: crossing the bridge between bench and bedside in urogynecologic research

An increasing number of scientists have studied the molecular and biochemical basis of pelvic organ prolapse (POP). The extracellular matrix content of the pelvic floor is the major focus of those investigations and pointed for potential molecular markers of the dysfunction. The identification of women predisposed to develop POP would help in the patients' management and care. This article includes a critical analysis of the literature up to now; discusses implications for future research and the role of the genetics in POP.

Contractile response of human anterior vaginal muscularis in women with and without pelvic organ prolapse

The aim of this study was to compare the contractility of the anterior vaginal muscularis (AVM) from women with and without pelvic organ prolapse (POP). In vitro experiments were performed to measure the peak force generated in response to potassium chloride (KCl; 125 mmol/L) and phenylephrine by AVM tissue from women with and without POP. Cross-sectional areas and co-localization of α(1A) adrenergic receptor protein with smooth muscle α-actin in AVM strips were determined by histology and immunofluorescence, respectively. There were no differences in the mean amplitude of force generated in response to KCl normalized to either wet weight or muscle cross-sectional area (mN/mm(2)) between women with and without POP (P > .30). However, AVM from women with prolapse produced a significantly higher mean force to KCl normalized to total cross-sectional area compared to controls (P = .007). While the control samples demonstrated a consistent response to phenylephrine, there was no response to this stimulant generated by AVM tissue from women with POP. The proportion of co-localized α(1A) adrenergic receptors with smooth muscle α actin in AVM tissue was significantly less in women with POP compared to normal controls (P < .0001). Although there was significantly greater tissue stress generated by AVM from women with prolapse compared to controls, there were no differences in muscle stress. Absent response to phenylephrine by AVM from women with prolapse may be related to a lower expression of α(1A) adrenergic receptors in vaginal smooth muscle.

Neuromuscular morphometry of the vaginal wall in women with anterior vaginal wall prolapse

INTRODUCTION AND HYPOTHESIS

The aim of this study was to compare the changes in hystomorphometry and innervation of the anterior vaginal wall in women with and without anterior vaginal wall prolapse.

METHODS

Eighty-nine biopsy specimens were obtained from the anterior vaginal wall of women having a cystocele repaired (stage >or=II; prolapse group, 49) and the same location in patients with no prolapse (stage <II; control group, 40). Routine H&E staining and immunohistochemical staining for protein gene product 9.5 (PGP-9.5) and smooth muscle alpha-actin (SMA) were performed for all specimens.

RESULTS

Number and diameter of the submucosal nerve fibers were significantly lower, submucosal distance to muscular region was significantly higher in the vaginal wall of patients with cystocele than in women with normal vaginal support. We found that there was a negative correlation between the vaginal delivery and the nerve number and diameter measurements, and positive correlation between the vaginal delivery and submucosal distance of muscular level.

CONCLUSIONS

Results indicate that women with a cystocele have a significantly lower total innervation and higher muscular distance of the anterior vaginal epithelium than the control subjects.

[Connective tissue and prolapse genesis]

The pathophysiology of pelvic floor disorders still remains not well understood. Increasing age as well as vaginal multiparity are the main commonly accepted factors. The hypothesis of a defect of connective tissues of the pelvic floor with aging due to collagen deficiency and/or elastic fiber degradation is often highlighted. The issue of a potential protective role of HRT is also discussed although the recent results from the WHI would suggest a negative impact of HRT on urinary incontinence, especially when HRT is initiated in elderly women, far from the menopause. Nevertheless, environmental factors cannot explain the full pathogenesis of pelvic organ prolapse (POP) and the contribution of genetic factors to the development of pelvic floor disorders is widely recognized. Support for a genetic influence on POP derives from reports suggesting that heritability is a strong contributing factor and a familial history of POP is considered as a classical risk factor. However, the characterization of the underlying molecular mechanisms remains limited, since POP may be considered the end result of a multifactorial process leading to destruction of vaginal wall connective tissue. Experimental studies in mice with null mutations in the genes encoding different putative factors involved in elastic fibers remodeling and homeostasis are crucial in the understanding of the pathogenesis of POP. Mice with null mutation in the gene encoding lysyl oxidase-like 1 (LOXL1) or fibulin-5, demonstrate signs of elastinopathy including the development of a POP in the postpartum. Likewise, homeobox genes such as HOXA11, which are essential in the embryonic development of the urogenital tract might also be involved in the pathogenesis of POP. The better understanding of the underlying determinants of pelvic floor disorders with a special focus on genetic factors may offer new therapeutic strategies, in addition to or replacement of surgical procedures.

Differential expression of smooth muscle regulatory proteins in the uterosacral ligaments of women with uterine prolapse

OBJECTIVE

To compare smooth muscle regulatory protein expression in the uterosacral ligament (USL) of women with and without uterine prolapse.

STUDY DESIGN

USLs ligament were sampled in women with (n = 9) or without (n = 9) uterine prolapse. Caldesmon, smooth muscle actin (SMA), myosin heavy chain, and zinc finger protein messenger RNA expression was assessed by quantitative real-time polymerase chain reaction. Immunohistochemistry and digital image analysis were used to determine protein expression.

RESULTS

Caldesmon messenger RNA expression and the ratio of caldesmon-SMA messenger RNA expression was significantly increased in the USL from women with uterine prolapse compared with women without prolapse (caldesmon mean +/- standard deviation messenger RNA, 0.81 +/- 0.46 vs 0.39 +/- 0.16; P = .01 and caldesmon-SMA messenger RNA ratio, mean +/- standard deviation, 0.11 +/- 0.04 vs 0.07 +/- 0.02; P = .01). In addition, the ratio of caldesmon-SMA staining was significantly increased in women with uterine prolapse compared with women without prolapse (mean +/- standard deviation, 0.44 +/- 0.28 vs 0.28 +/- 0.16; P = .03).

CONCLUSION

Uterine prolapse is associated with an increased ratio of caldesmon-SMA actin expression.

The role of calpain-calpastatin system in the development of stress urinary incontinence

INTRODUCTION AND HYPOTHESIS

The objective of this study is to investigate the expression of calpain-1, calpain-2, and calpastatin in the human periurethral vaginal tissues and to show the potential link between calpain system and stress urinary incontinence (SUI).

METHODS

The periurethral vaginal tissues of 39 women with SUI and 31 women without SUI were collected to detect the expressions of calpains and calpastatin by using semi-quantitative competitive reverse transcription-polymerase chain reaction and Western blotting.

RESULTS

There were no significant differences on the expressions of calpain-1 at the levels of messenger RNA (mRNA) and protein in both groups (P > 0.05), but the patients with SUI had significantly higher levels of calpain-2 mRNA and protein than the control (P < 0.05); and the mRNA expressions of calpastatin in women with SUI were significantly higher than the control (P < 0.05), while the protein expressions were significantly lower when compared to the control (P < 0.01).

CONCLUSIONS

Overexpression of calpain-2 and low expression of calpastatin may involve in the pathological development of SUI.

COL3A1 2209G>A is a predictor of pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

A familial tendency has been demonstrated in the etiology of pelvic organ prolapse (POP), but the specific genetic defects have not been identified. Type III collagen is an important factor in the repair of connective tissue, and gene polymorphisms may impair the tensile strength. We hypothesized that polymorphisms in the alpha I chain of the type III collagen protein-encoding gene (COL3A1) pose women at risk for POP.

METHODS

In this case-control study, the prevalence of type III collagen polymorphisms was compared in women with and without signs and symptoms of POP.

RESULTS

Two hundred and two POP patients and 102 normal parous controls were included. A homozygous single-nucleotide substitution in the coding region of type III collagen (COL3A1 2209G>A, rs1800255) was identified in 27 (13%) POP patients and three (3%) controls (odds ratio, 5.0; 95% confidence interval, 1.4-17.1).

CONCLUSIONS

The probability of POP was higher in women with COL3A1 2209G>A. This polymorphism showed to be a relevant risk factor for POP.

Caldesmon expression is decreased in women with anterior vaginal wall prolapse: a pilot study

INTRODUCTION AND HYPOTHESIS

The purpose of this study is to compare vaginal caldesmon expression in women with and without anterior vaginal wall prolapse.

METHODS

Vaginal tissues were sampled in women with (n = 11) or without (n = 11) vaginal wall prolapse. Caldesmon messenger RNA (mRNA) expression was assessed by quantitative real-time polymerase chain reaction. Immunohistochemistry and digital image analysis were used to determine caldesmon protein expression in the histologic sections.

RESULTS

There were no significant differences in demographic data between the two groups. Caldesmon mRNA expression was significantly decreased in the vaginal tissue from women with anterior vaginal wall prolapse compared to women without prolapse [(caldesmon mean +/- SD mRNA expression in relative units) 0.03 +/- 0.03 vs 0.17 +/- 0.17, P = 0.02]. The fractional area of nonvascular caldesmon staining in the vagina of women with anterior vaginal wall prolapse was significantly decreased compared to women without prolapse [mean +/- SD (0.09 +/- 0.04 vs 0.16 +/- 0.09, P = 0.03)].

CONCLUSIONS

Vaginal caldesmon expression is significantly decreased in women with anterior vaginal wall prolapse compared to normal subjects.

Tissue mechanics, animal models, and pelvic organ prolapse: a review

Pelvic floor disorders such as pelvic organ prolapse, urinary incontinence, and fecal incontinence affect a large number of women each year. The pelvic floor can be thought of as a biomechanical structure due to the complex interaction between the vagina and its supportive structures that are designed to withstand the downward descent of the pelvic organs in response to increases in abdominal pressure. Although previous work has highlighted the biochemical changes that are associated with specific risk factors (i.e. parity, menopause, and genetics), little work has been done to understand the biomechanical changes that occur within the vagina and its supportive structures to prevent the onset of these pelvic floor disorders. Human studies are often limited due to the challenges of obtaining large tissue samples and ethical concerns. Therefore, it is necessary to investigate the use of animal models and their importance in understanding how different risk factors affect the biomechanical properties of the vagina and its supportive structures. In this review paper, we will discuss the different animal models that have been previously used to characterize the biomechanical properties of the vagina: including non-human primates, rodents, rabbits, and sheep. The anatomy and preliminary biomechanical findings are discussed along with the importance of considering experimental conditions, tissue anisotropy, and viscoelasticity when characterizing the biomechanical properties of vaginal tissue. Although there is not a lot of biomechanics research related to the vagina and pelvic floor, the future is exciting due to the significant potential for scientific findings that will improve our understanding of these conditions and hopefully lead to improvements in the prevention and treatment of pelvic disorders.

Uterosacral ligament smooth muscle cell apoptosis is increased in women with uterine prolapse

PURPOSE

The purpose of this study was to compare the smooth muscle content and apoptosis of the uterosacral ligament in women with and without uterine prolapse.

STUDY DESIGN

Uterosacral ligaments were sampled in women with (n = 9) or without (n = 9) uterine prolapse undergoing hysterectomy. Smooth muscle of the uterosacral ligament was identified by immunohistochemistry. Digital image analysis was used to determine the fractional area of smooth muscle in the histologic cross sections. Apoptosis was assessed by terminal deoxynucelotidyl-transferase-mediated dUTP nick-end-labeling method.

RESULTS

The fractional area of nonvascular smooth muscle in the uterosacral ligament of women with uterine prolapse was significantly decreased compared to women without prolapse (0.32 +/- 0.12 vs. 0.42 +/- 0.03, P = .02) and the apoptotic index was significantly higher compared to women without prolapse (0.20 +/- 0.06 vs. 0.08 +/- 0.04, P < .01).

CONCLUSION

The fraction of smooth muscle in the uterosacral ligaments is significantly decreased, and the rate of apoptosis is higher in women with uterine prolapse compared to women without prolapse.

Fibulin-5 expression is decreased in women with anterior vaginal wall prolapse

The aim of this study was to compare fibulin-5 expression in women with and without anterior vaginal wall prolapse. Vaginal tissues were sampled in a standardized fashion from women with (n = 12) or without (n = 10) anterior vaginal wall prolapse. Quantitative real-time polymerase chain reaction was performed to measure mRNA levels of fibulin-5 (FIB-5). FIB-5 protein expression was assessed by immunohistochemistry. There were no significant differences in demographic data between the two groups. FIB-5 mRNA expression was significantly decreased in women with anterior vaginal wall prolapse compared to women without prolapse [(FIB-5 mean +/- SD mRNA expression in relative units) 0.01 +/- 0.01 vs. 0.09 +/- 0.14, P = 0.04]. Fibulin-5 staining intensity was diminished in women with prolapse compared to women without prolapse [intensity score, median (range), 1 (1-2) vs. 3 (2-3), P = 0.04]. Fibulin-5 expression is decreased in vaginal biopsies from women with prolapse. Changes in fibulin expression may play a role in the development of pelvic organ prolapse.

Quantification of pelvic organ prolapse in mice: vaginal protease activity precedes increased MOPQ scores in fibulin 5 knockout mice

Two mouse models of pelvic organ prolapse have been generated recently, both of which have null mutations in genes involved in elastic fiber synthesis and assembly (fibulin 5 and lysyl oxidase-like 1). Interestingly, although these mice exhibit elastinopathies early in life, pelvic organ prolapse does not develop until later in life. In this investigation we developed and validated a tool to quantify the severity of pelvic organ prolapse in mice, and we used this tool prospectively to study the role of fibulin 5, aging, and vaginal proteases in the development of pelvic organ prolapse. The results indicate that >90% of Fbln5(-/-) mice develop prolapse by 6 mo of age, even in the absence of vaginal delivery, and that increased vaginal protease activity precedes the development of prolapse.

Effect of vaginal distention on elastic fiber synthesis and matrix degradation in the vaginal wall: potential role in the pathogenesis of pelvic organ prolapse

Matrix metalloprotease (MMP) activity is increased in the postpartum vagina of wild-type (WT) animals. This degradative activity is also accompanied by a burst in elastic fiber synthesis and assembly. The mechanisms that precipitate these changes are unclear. The goals of this study were to determine how vaginal distention (such as in parturition) affects elastic fiber homeostasis in the vaginal wall and the potential significance of these changes in the pathogenesis of pelvic organ prolapse. Vaginal distention with a balloon simulating parturition resulted in increased MMP-2 and MMP-9 activity in the vaginal wall of nonpregnant and pregnant animals. This was accompanied by visible fragmented and disrupted elastic fibers in the vaginal wall. In nonpregnant animals, the abundant amounts of tropoelastin and fibulin-5 in the vagina were not increased further by distention. In contrast, in pregnant animals, the suppressed levels of both proteins were increased 3-fold after vaginal distention. Distention performed in fibulin-5-deficient (Fbln5(-/-)) mice with defective elastic fiber synthesis and assembly induced accelerated pelvic organ prolapse, which never recovered. We conclude that, in pregnant mice, vaginal distention results in increased protease activity in the vaginal wall but also increased synthesis of proteins important for elastic fiber assembly. Distention may thereby contribute to the burst of elastic fiber synthesis in the postpartum vagina. The finding that distention results in accelerated pelvic organ prolapse in Fbln5(-/-) animals, but not in WT, indicates that elastic fiber synthesis is crucial for recovery of the vaginal wall from distention-induced increases in vaginal protease activity.

Combined estrogen and ghrelin administration decreases expression of p27(kip1) and proportion of isomyosin type I in the striated urethral and anal sphincters and levator ani of old ovariectomized rats

We compared estrogen and/or ghrelin effects on pelvic floor muscles in old versus young adult ovariectomized rats. Ovariectomized Fisher 344 rats (18 and 3 months old, n = 24 x 2) received 42 daily intraperitoneal 17-beta estradiol (10 microg kg(-1)), ghrelin (2 microg kg(-1)), both, or vehicle (n = 6 x 4/group). Cytoplasmic p27(kip1) expression and isomyosin I proportion in striated urethral and anal sphincters and levator ani were measured, respectively, by Western blot analysis and gel electrophoresis with immunohistochemistry of muscle ghrelin receptors and radioimmunoassay of circulating growth hormone. In young adult rats, estrogen significantly decreased cytoplasmic p27(kip1) and isomyosin I signal intensities. In old rats, ghrelin and estrogen/ghrelin significantly decreased both intensities with greater estrogen/ghrelin effect. Ghrelin receptors were not immunostained in any muscle. Estrogen and/or ghrelin significantly increased or decreased, respectively, circulating growth hormone in old and young adult rats. Estrogen/ghrelin administration reversed pelvic floor muscle ageing changes in old ovariectomized rats through growth hormone production.

Gene expression in the rectus abdominus muscle of patients with and without pelvic organ prolapse

OBJECTIVE

The objective of the study was to compare gene expression in a group of actin and myosin-related proteins in the rectus muscle of 15 patients with pelvic organ prolapse and 13 controls.

STUDY DESIGN

Six genes previously identified by microarray GeneChip analysis were examined using real-time quantitative reverse transcriptase-polymerase chain reaction analysis, including 2 genes showing differential expression in pubococcygeus muscle. Samples and controls were run in triplicate in multiplexed wells, and levels of gene expression were analyzed using the comparative critical threshold method.

RESULTS

One gene, MYH3, was 3.2 times overexpressed in patients with prolapse (P = .032), but no significant differences in expression were seen for the other genes examined. An age-matched subset of 9 patients and controls showed that MYH3 gene expression was no longer significantly different (P = .058).

CONCLUSION

Differential messenger ribonucleic acid levels of actin and myosin-related genes in patients with pelvic organ prolapse and controls may be limited to skeletal muscle from the pelvic floor.

The role of smooth muscle in the pathogenesis of pelvic organ prolapse—an immunohistochemical and morphometric analysis of the cervical third of the uterosacral ligament

The uterosacral ligament (USL) is part of the pelvic floor connecting the uterus to the dorsal body wall and stabilizing it. In samples obtained from hysterectomy patients, the smooth muscle component of the cervical third of the USL was studied by smooth muscle actin (SMA) immunohistochemistry as indicator for structural abnormalities and by morphometric determination of nuclear size as measure for the functional state. From a total of 40 patients, 18 were matched according to age, parity, and premenopausal status. Immunohistochemistry showed a granular patchy distribution of SMA in the pelvic organ prolapse (POP) group. In patients with POP, the size of smooth muscle cell nuclei was significantly reduced in comparison to patients without POP (25.45+/-1.92 microm(2) vs 28.87+/-2.92 microm(2), p<0.05). We conclude that the smooth muscle component of the USL is impaired in POP patients, indicating a possible role of smooth muscle in the pathogenesis of POP.

Levator ani muscle and connective tissue changes associated with pelvic organ prolapse, parity, and aging in the squirrel monkey: a histologic study

OBJECTIVE

This study was undertaken to evaluate histologically the levator ani muscle and paravaginal attachments in squirrel monkeys with and without pelvic organ prolapse.

STUDY DESIGN

Serial sections from 19 females were processed with routine histology stains. Fiber typing was performed with antifast (type II) and antislow (type I) skeletal myosin antibodies, and apoptotic nuclei were examined by dUTP nick-end labeling (TUNEL).

RESULTS

Gross disruption of the levator ani muscle and its innervation was not observed in animals with or without visible support defects. Myogenic changes occurred more frequently in the pubocaudalis than iliocaudalis muscles, and a significant association was found with aging (P < .05, Fisher exact test) but not with pelvic organ prolapse or parity. Neurogenic changes were observed in 3 of 13 multiparous monkeys. Myocyte diameter increased in animals with pelvic organ prolapse compared with age-, weight-, and parity-matched animals without pelvic organ prolapse (P = .005) and correlated with levator ani muscle wet weight (R = 0.76; P = .0006). In the paravaginal attachments, the numbers of fibroblasts and apoptotic nuclei were not different between animals with and without pelvic organ prolapse, but parity was associated with increased apoptosis (P = .025).

CONCLUSION

Vaginal prolapse in the squirrel monkey does not result from atrophy or gross disruption of the levator ani muscle or its innervation. As in women, myogenic changes are a common finding in the levator ani muscle and increase with aging, whereas denervation with subsequent reinnervation occurs in some multiparous monkeys.

Pelvic organ prolapse in fibulin-5 knockout mice: pregnancy-induced changes in elastic fiber homeostasis in mouse vagina

Pelvic organ prolapse is strongly associated with a history of vaginal delivery. The mechanisms by which pregnancy and parturition lead to failure of pelvic organ support, however, are not known. Recently, it was reported that mice with null mutations in lysyl oxidase-like 1 (LOXL1) develop pelvic organ prolapse. Elastin is a substrate for lysyl oxidase (LOX) and LOXL1, and LOXL1 interacts with fibulin-5 (FBLN5). Therefore, to clarify the potential role of elastic fiber assembly in the pathogenesis of pelvic organ prolapse, pelvic organ support was characterized in Fbln5-/- mice, and changes in elastic fiber homeostasis in the mouse vagina during pregnancy and parturition were determined. Pelvic organ prolapse in Fbln5-/- mice was remarkably similar to that in primates. The temporal relationship between LOX mRNA and protein, processing of LOXL1 protein, FBLN5 and tropoelastin protein, and desmosine content in the vagina suggest that a burst of elastic fiber assembly and cross linking occurs in the vaginal wall postpartum. Together with the phenotype of Fbln5-/- mice, the results suggest that synthesis and assembly of elastic fibers are crucial for recovery of pelvic organ support after vaginal delivery and that disordered elastic fiber homeostasis is a primary event in the pathogenesis of pelvic organ prolapse in mice.

Changes in the extracellular matrix in the anterior vagina of women with or without prolapse

To investigate the changes in the connective tissues located in the upper portion of the anterior vaginal wall, which are associated with anterior vaginal wall prolapse, 23 women with anterior vaginal wall prolapse were included in the study group and 15 women with normal genital support served as control group. The anterior vaginal wall tissue samples were obtained for immunohistochemical staining of collagen (type I, III, IV, V, VI), elastin, and glycoproteins from the extracellular matrix (fibronectin, vitronectin, laminin). The number of capillaries per arteriole and mitochondria numbers per smooth muscle cell were evaluated for demonstrating whether the anatomical prolapse affect on blood supply to these tissues. Collagen III was significantly less in the anterior vaginal wall of patients with anterior vaginal wall prolapse. Quantitative immunoreactivity of collagen I and III had significant positive correlations with ageing.

Vaginal thickness, cross-sectional area, and perimeter in women with and those without prolapse

OBJECTIVE

Use axial magnetic resonance imaging to test the null hypothesis that no difference exists in apparent vaginal thickness between women with and those without prolapse.

METHODS

Magnetic resonance imaging studies of 24 patients with prolapse at least 2 cm beyond the introitus were selected from an ongoing study comparing women with prolapse with normal control subjects. The magnetic resonance scans of 24 women with prolapse (cases) and 24 women without prolapse (controls) were selected from those of women of similar age, race, and parity. The magnetic resonance files were imported into an experimental modeling program, and 3-dimensional models of each vagina were created. The minimum transverse plane cross-sectional area, mid-sagittal plane diameter, and transverse plane perimeter of each vaginal model were calculated.

RESULTS

Neither the mean age (cases 58.6 years +/- standard deviation [SD] 14.4 versus controls 59.4 years +/- SD 13.2) nor the mean body mass index (cases 24.1 kg/m(2)+/- SD 3.3, controls 25.7 kg/m(2)+/- SD 3.7) differed significantly between groups. Minimum mid-sagittal vaginal diameters did not differ between groups. Patients with prolapse had larger minimum vaginal cross-sectional areas than controls (5.71 cm(2)+/- standard error of the mean [SEM] 0.25 versus 4.76 cm(2)+/- SEM 0.20, respectively; P = .005). The perimeter of the vagina was also larger in the prolapse group (11.10 cm +/- SEM 0.24) compared with controls (9.96 cm +/- SEM 0.22) P = .001. Subgroup analysis of patients with endogenous or exogenous estrogen showed prolapse patients had larger vaginal cross-sectional area (P = .030); in patients without estrogen group differences were not significant (P = .099).

CONCLUSION

Vaginal thickness is similar in women with and those without pelvic organ prolapse. The vaginal perimeter and cross-sectional areas are 11% and 20% larger in prolapse patients, respectively. Estrogen status did not affect differences found between groups.

Basic science and translational research in female pelvic floor disorders: proceedings of an NIH-sponsored meeting

AIMS

To report the findings of a multidisciplinary group of scientists focusing on issues in basic science and translational research related to female pelvic floor disorders, and to produce recommendations for a research agenda for investigators studying female pelvic floor disorders.

METHODS

A National Institutes of Health (NIH)-sponsored meeting was held on November 14-15, 2002, bringing together scientists in diverse fields including obstetrics, gynecology, urogynecology, urology, gastroenterology, biomechanical engineering, neuroscience, endocrinology, and molecular biology. Recent and ongoing studies were presented and discussed, key gaps in knowledge were identified, and recommendations were made for research that would have the highest impact in making advances in the field of female pelvic floor disorders.

RESULTS

The meeting included presentations and discussion on the use of animal models to better understand physiology and pathophysiology; neuromuscular injury (such as at childbirth) as a possible pathogenetic factor and mechanisms for recovery of function after injury; the use of biomechanical concepts and imaging to better understand the relationship between structure and function; and molecular and biochemical mechanisms that may underlie the development of female pelvic floor disorders.

CONCLUSIONS

While the findings of current research will help elucidate the pathophysiologic pathways leading to the development of female pelvic floor disorders, much more research is needed for full understanding that will result in better care for patients through specific rather than empiric therapy, and lead to the potential for prevention on primary and secondary levels.

Different expression of calpains in the anterior vaginal wall of women with and without uterovaginal prolapse

OBJECTIVE

Tissue ischemia-hypoxia can activate the calpain proteolytic system. Mechanical trauma to the upper vaginal wall and pelvic floor could compromise vascular perfusion and could also result in calpain expression. The aims of this investigation were to assess the expression messenger RNA and proteins for m-calpain and micro-calpain in the vaginal walls of women with and without uterovaginal prolapse.

METHODS

The anterior vaginal walls of 22 women with and without uterovaginal prolpase were evaluated using a reverse transcription polymerase chain reaction and western blotting for detecting calpain expression.

RESULTS

The number of messenger RNA transcripts of m- and micro-calpain was significantly less in women with uterovaginal prolapse than in women without uterovaginal prolapse (two of 11 and zero of 11 versus eight of 11 and five of 11, P < .05). All women had m-calpain protein expression in the anterior vaginal wall. However, the concentration of m-calpain protein was less, but not significantly different, in women with uterovaginal prolapse than in the women without uterovaginal prolapse (0.386 +/- 0.018 versus 0.439 +/- 0.011 optical density/mm2, P > .05). None of the women with uterovaginal prolapse had expression of micro-calpain mRNA or protein (zero of 11). Expression of protein of calpains in the anterior vaginal wall is not consistent with mRNA transcripts.

CONCLUSION

Calpain expression may be compromised in the anterior vaginal wall of women with uterovaginal prolapse who have abnormal histologic changes in the vaginal connective tissues or have anterior vaginal laxity.

What's new in prolapse surgery?

PURPOSE OF REVIEW

There are very many types of operation for the correction of symptomatic pelvic floor relaxation, and the pelvic surgeon is faced with a difficult task when selecting the most appropriate procedure(s) for an individual patient. Currently, the lifetime risk of undergoing prolapse or continence surgery in France is one in 11; up to 30% of patients will require repeat prolapse surgery, and 10% will require repeat continence surgery. Reconstructive pelvic surgery for the treatment of vaginal prolapse continues to evolve as surgeons continue their quest for a definitive surgical cure. This review looks at the etiology, presentation and current surgical management of genital prolapse in females.

RECENT FINDINGS

There are three primary routes of access in reconstructive pelvic surgery (abdominal, vaginal and laparoscopic) for the repair of anterior, superior and posterior defects; the choice often depends on the surgeon's experience. Of the abdominal repairs, abdominal sacrocolpopexy with mesh remains the 'gold standard'; the retropubic paravaginal repair and laparoscopic techniques have not gained widespread acceptance. The laparoscopic approach appears to be the least utilized, because of the great degree of technical difficulty associated with laparoscopic suturing. Of the vaginal restorative procedures, uterosacral ligament vault suspension and iliococcygeous and sacrospinous fixation have their proponents. However, there is increasing interest in the use of biological prostheses (allografts/xenografts) and synthetic absorbable meshes.

SUMMARY

Randomized controlled trials are required to evaluate the role of surgical procedures in reconstructive surgery, to determine which type of prosthesis is most suitable.

Differential gene expression in pubococcygeus muscle from patients with pelvic organ prolapse

OBJECTIVE

This study was undertaken to compare differential gene expression in the pubococcygeus muscle in patients with pelvic organ prolapse and controls.

STUDY DESIGN

We performed microarray analysis on individual pubococcygeus muscle biopsy specimens from five patients with stage III or IV pelvic organ prolapse and five control subjects without prolapse. This study received full Institutional Review Board approval. Total RNA was extracted, purified, and probed on the Human Genome U95A Array for each individual sample. RNA from patients and controls was not pooled. For microarray analysis, 7 microg of total RNA was used to synthesize complementary DNA that was then biotinylated. Arrays were hybridized for 16 hours in the GeneChip Fluidics Station 400 and were washed and scanned with the Hewlett-Packard GeneArray Scanner. Affymetrix GeneChip 5.0 software was used for scanning and data analysis.

RESULTS

Of the 12626 total genes compared, 257 genes were more than 2-fold underexpressed, 20 genes were more than 5-fold underexpressed, and 3 genes were more than 10-fold underexpressed in patients with pelvic organ prolapse compared with control subjects. Myosin-binding protein H was 24.7 times underexpressed in patients with prolapse (normalized signal intensity [NSI]: 0.46 [0.2-0.6]) compared with controls (NSI: 11.4 [0.2-31.3]). Skeletal muscle myosin heavy polypeptide 3 was 17.4 times underexpressed in patients with prolapse (NSI: 0.85 [0.7-0.9]) compared with controls (NSI: 14.8 [1.5-38.3]). Of the 12,626 genes compared, 479 genes were more than 2-fold overexpressed, 18 genes were more than 5-fold overexpressed, and 2 genes were more than 10-fold overexpressed in patients with pelvic organ prolapse compared with controls. Many of these overexpressed genes were related to actin and myosin proteins. Smooth muscle myosin heavy chain was 11.8 times overexpressed in patients (NSI: 5.21 [0.25-22.71]) compared with controls (NSI 0.44 [0.11-0.71]). Myosin light-chain kinase was 5.8 times overexpressed in patients (NSI: 7.9 [0.5-36.1]) compared with controls (NSI: 1.37 [0.38-1.8]). Extracellular matrix proteins were also differentially regulated. Cartilage oligomeric matrix protein precursor was found to be 6.0 times underexpressed, whereas tenascin-C (hexabrachion) was 5.1 times overexpressed in prolapse patients.

CONCLUSION

These data suggest that the differences between patients with advanced pelvic organ prolapse and controls may be related to differential gene expression of structural proteins that are related to actin and myosin as well as extracellular matrix proteins in the pubococcygeus muscle. Studies are ongoing to confirm these findings and to further characterize the role of these genes in prolapse.

A technique to evaluate the thickness and density of nonvascular smooth muscle in the suburethral fibromuscular layer

OBJECTIVE

The suburethral fibromuscular layer (SUFML) contains nonvascular smooth muscle that may play an important role in the continence mechanism. This study was undertaken to develop a method to systematically quantify differences in the thickness and density of nonvascular smooth muscle within the SUFML and to demonstrate its use in assessing variation.

STUDY DESIGN

Urethral and anterior vaginal wall sections from the urethrovesical junction of fresh cadavers were stained to define alpha actin in smooth muscle cells. The thickness of the SUFML was microscopically measured and the density of the nonvascular smooth muscle was determined with computer-aided analysis.

RESULTS

The mean thickness of the SUFML was 3.04 mm (range 1.74-3.78 mm, SD +/-0.63 mm). The mean density of nonvascular smooth muscle within it was 17.94% (range 10.48%-42.84%, SD +/-9.4%). The mean age was 55 years (range 36-69 years, SD +/-10.75 years).

CONCLUSION

The thickness and density of the nonvascular smooth muscle within the SUFML can be quantified and there is variation among individuals.

Morphometric properties of the posterior vaginal wall in women with pelvic organ prolapse

OBJECTIVE

Our purpose was to analyze the morphometric properties of the posterior vaginal wall and compare the smooth muscle distribution in the posterior vaginal muscularis in women with and without pelvic organ prolapse.

STUDY DESIGN

Specimens were taken from the apex of the posterior vaginal wall after hysterectomy from 15 women with pelvic organ prolapse and from 8 healthy control subjects. Smooth muscle cells of the posterior vaginal wall were identified by immunohistochemistry with antibodies to smooth muscle alpha-actin. Morphometric analysis was performed on histologic cross-sections of the posterior vaginal wall to determine the fractional area of nonvascular smooth muscle in the muscularis. The innervation pattern of the vaginal wall was determined by use of S100 immunostaining. Statistical comparisons between two groups were conducted by a Student t test. Comparisons between multiple groups were conducted with a one-way analysis of variance followed by a post-hoc Student-Neuman-Keuls test.

RESULTS

The fractional area of nonvascular vaginal smooth muscle in the muscularis of women with posterior wall prolapse was significantly decreased compared with that of healthy control subjects. Nerve bundles were located in the deep vaginal muscularis and adventitia of the posterior vaginal wall. In women with posterior wall prolapse, nerve bundles were smaller and fewer in number.

CONCLUSION

Morphologic features of the posterior vaginal wall are significantly altered in women with posterior wall prolapse compared with asymptomatic control subjects.

Morphometric analysis of smooth muscle in the anterior vaginal wall of women with pelvic organ prolapse

OBJECTIVE

The purpose of this study was to compare the smooth muscle content of the anterior vaginal wall in normal women and women with pelvic organ prolapse.

STUDY DESIGN

Specimens were taken from the apex of the anterior vaginal cuff after abdominal hysterectomy from 28 women with pelvic organ prolapse and 12 control subjects. Smooth muscle cells of the anterior vaginal wall were identified by immunohistochemistry with antibodies to smooth muscle alpha-actin. Morphometric analysis was used to determine the fractional area of nonvascular smooth muscle in the muscularis in histologic cross-sections of the anterior vaginal wall.

RESULTS

The fractional area of nonvascular vaginal smooth muscle in the muscularis of women with prolapse was significantly decreased compared with that of control subjects. This decreased fraction of smooth muscle in the anterior vaginal wall was not related to age, race, or stage of prolapse. In women with prolapse, vaginal smooth muscle content was most diminished in specimens from postmenopausal women with no estrogen replacement. The fractional area of muscularis smooth muscle was also decreased significantly in premenopausal women with prolapse.

CONCLUSION

The fraction of smooth muscle in the muscularis of the anterior vaginal wall is significantly decreased in women with pelvic organ prolapse compared with normal control subjects.