Changes in connective tissue in patients with pelvic organ prolapse—a review of the current literature

Pelvic floor disorder symptoms and bone strength in postmenopausal women

INTRODUCTION AND HYPOTHESIS

The current study is aimed at characterizing the association between pelvic floor disorder symptoms and bone strength reflecting a potential connective tissue pathophysiology in postmenopausal women.

METHODS

A cross-sectional study was conducted in postmenopausal women undergoing osteoporosis evaluation from 2007 to 2010. Urinary incontinence (UI) was defined as urinary leakage ≥2-3 times/week. UI types were defined using the 3 Incontinence Questionnaire. Fecal incontinence was defined as stool leakage ≥1/month, and pelvic organ prolapse as a positive response to "Do you have a bulge or something falling out that you can see or feel in your vaginal area?" Bone quality and quantity were assessed using the trabecular bone score (TBS) and bone mineral density respectively: bone strength was defined by combined quality/quantity index, low strength being equivalent to moderate to severe fracture risk; low quality as TBS ≤ 1.31; low quantity by T-score <-1 or on osteoporosis medication.

RESULTS

Of 681 subjects, 262 had low bone strength whereas 419 were normal using the combined quality/quantity bone assessment. Characteristics were similar except for age (low bone strength: 69.0 ± 8.2 vs normal: 65.0 ± 7.1, p < 0.01) and smoking (8.8% vs 3.3%, p < 0.01). Low bone strength was associated with any UI (adjusted odds ratio [aOR]: 1.48, 1.05-2.10), stress (aOR: 1.53, 1.06-2.21), and mixed (aOR :1.45, 1.02-2.05). Women with low bone quality had increased odds of UI (any, urgency, mixed), whereas none of the pelvic floor disorder symptoms was associated with low bone quantity.

CONCLUSIONS

Low bone strength defined by a combined quantity/quality index, as well as low bone quality alone, were associated with increased risk of UI.

Low expression of collagen type-1 in sacrouterine ligament as risk factor of stage III-IV uterine prolapse

BACKGROUND

Despite being non-life threatening, uterine prolapse is a reproductive health problem that interferes psychosocial life, economical and sexual function. Uterine prolapse can be caused by direct trauma resulting in damaged and weakened levator ani muscle which in turn causing sacrouterine ligament to stretch in order to maintain uterus normal position. The main component of sacrouterine ligament is collagen. Types of collagen that was involved in the occurrence of uterine prolapse are which plays a role of risk of occurrence uterine prolapse is collagen type-1 and type-3. Collagen type-1 has a good resistance and flexible to strain. If there is a disruption in the expression of collagen in sacrouterine ligament, it will result in cause uterine prolapse.

OBJECTIVE

The aim of this study is to prove low expression of collagen type-1 in sacrouterine ligament is a risk factor for the occurrence of stage III-IV uterine prolapse.

STUDY DESIGN

This study was an observational study using case-control approach. A total of 22 cases of stage III-IV uterine prolapse and 22 cases of non-uterine prolapse as control group were selected by consecutive sampling. This study was carried out in Sanglah General Hospital and Pathobiology Laboratory of Veterinary Faculty of Udayana. Samples were taken from sacrouterine ligament of individual with stage III-IV uterine prolapse compared to non-prolapse uterine who had undergone total hysterectomy.

RESULTS

Chi-square analysis with 95 % confidence interval indicated that low expression of collagen type-1 was 6 times more likely to be the risk factor of stage III-IV uterine prolapse (OR = 5.95; 95 %CI = 1.59-22.33; p = 0.006).

CONCLUSION

Low collagen type-1 in sacrouterine ligament is a risk factor of stage III-IV uterine prolapse.

Expression of Heparanase in uterosacral ligaments of women with or without uterine prolapse

OBJECTIVE

Pelvic organ prolapse (POP) is a global health problem for which the pathophysiological mechanism remains unclear. The loss of extracellular matrix proteins is considered an important molecular basis for this pathology. Heparanase is a heparin sulfate degrading endoglycosidase that has an important role in various biological processes and is a key component of extracellular matrix. The aim of this study was to compare expression of Heparanase in connective tissue of uterosacral ligaments in women with or without uterine prolapse.

STUDY DESIGN

Thirty-nine women who underwent hysterectomy for benign reasons were enrolled in the study. Twenty-three women with uterine prolapse (stage ≥3) who underwent vaginal hysterectomy (VH) - POP group, were compared to sixteen women without uterine prolapse who underwent abdominal hysterectomy (stage <2) - control group. Uterosacral ligaments (USL) biopsies were obtained from all uterine specimens near their origin. All tissue samples were analyzed by immunohistochemistry and tested for the presence of Heparanase using antiheparanse antibody 733.

RESULTS

Heparanse positive staining was more common in the connective tissue of uterosacral ligaments in women with uterine prolapse. Positive staining was seen in 17/23 (73.9 %) women with uterine prolapse compared to 4/16 (25 %) without uterine prolapse (p = 0.003). On multivariate logistic regression analysis, positive staining displayed a trend for an independent association with POP, after controlling for menopausal status and parity (OR 13.57, 95 %CI 0.82-224.4, p = 0.06).

CONCLUSION

Heparanase expression is more common in the connective tissue of uterosacral ligaments in women with uterine prolapse compared to women with no prolapse.

Anti-inflammatory effect of adipose-derived stem cells in the treatment of pelvic organ prolapse

Objective

This study investigated the effect of recombinant human connective tissue growth factor (hCTGF) on rat adipose-derived stem cells (ADSCs) and explored the feasibility of using ADSCs to treat pelvic organ prolapse.

Methods

ADSCs were isolated from rat inguinal adipose tissue and characterized by flow cytometry and for osteogenic and adipogenic differentiation. ADSCs were treated with recombinant hCTGF and qRT-PCR was performed to detect collagen I and III expression on post-treatment days 7, 14, and 28. Osteogenic and adipogenic differentiation of ADSCs was performed to evaluate the effect of hCTGF. ADSCs were seeded in biological grafting materials, acellular porcine pericardium (APP) and acellular bovine pericardium (ABP), then implanted in the rat vagina. Histology was performed to observe inflammation among different groups.

Results

Collagen I and III expression in ADSCs was significantly increased, and the ability to differentiate into osteogenic and adipogenic lineages was diminished after hCTGF treatment. APP and ABP seeded with ADSCs significantly decreased inflammation and protected from degradation in vivo compared with APP and ABP only; ABP seeded with ADSCs had the lowest inflammation.

Conclusion

hCTGF regulates collagen I and III expression and induces ADSC differentiation in vitro. ADSCs decrease inflammation associated with APP and ABP in vivo.

The in vivo biocompatibility of titanized polypropylene lightweight mesh is superior to that of conventional polypropylene mesh

OBJECTIVE

To evaluate the histological response to and changes in the biomechanical properties of titanized polypropylene lightweight mesh and conventional polypropylene mesh at 1 and 12 weeks following implantation in the sheep vagina.

METHODS

We compared a titanized polypropylene lightweight mesh (TiLOOP Mesh) to a conventional polypropylene mesh (Gynemesh PS) in a sheep vagina model. Explants were harvested after 1 and 12 weeks (n = 6/mesh type/time point) for histological observation. After 12 weeks, mesh-tissue complex specimens were biomechanically assessed by a uniaxial tension system.

RESULTS

One week after implantation, there was no significant difference in the inflammatory response between the two groups. Twelve weeks after implantation, the TiLOOP light mesh elicited a lower inflammatory response than was observed for the Gynemesh PS (1.44 ± 0.61 vs 2.05 ± 0.80, P = .015). Twelve weeks after implantation, the collagen I/III ratio was lower in the TiLOOP light mesh group than in the Gynemesh PS group (9.41 ± 5.06 vs 15.21 ± 8.21, P = .019). The messenger RNA expression levels of the inflammatory factors interleukin 10 and tumor necrosis factor α were lower in the TiLOOP Mesh group than in the Gynemesh PS group at both 1 and 12 weeks (P < .05). There were no significant differences in any of the evaluated biomechanical characteristics between the two meshes (P > .05).

CONCLUSION

Although the titanized polypropylene lightweight mesh induces slightly less tissue reactivity and has better in vivo biocompatibility, further studies should be conducted including the complications and the success rate of pelvic organ prolapse in patients before recommending it in pelvic floor reconstruction.

Tissue Composition and Biomechanical Property Changes in the Vaginal Wall of Ovariectomized Young Rats

Ideal animal models are needed to reflect the changes in the biochemical and biomechanical properties of the vagina that occur in pelvic organ prolapse (POP). In this study, we aimed to demonstrate the short and long-term effect of menopause on the biochemical and biomechanical properties of rat anterior vaginas. Here, Sprague-Dawley rats were bilaterally ovariectomized to induce menopause. Rats without ovariectomy served as the normal control group (n=12). The histology changes and the expression of collagen I, III, and a-SMA were assessed to indicate the biochemical changes in the vagina 2 weeks, 4 weeks, and 16 weeks after ovariectomy (n=6 for 2 and 4 weeks, n=12 for 16 weeks). Uniaxial biomechanical testing was conducted in the control group and ovariectomized rats 16 weeks after ovariectomy. Compared with the control group, the ovariectomy group showed a significant increase in the expression of collagen I 2 weeks after ovariectomy, while collagen III showed a declining trend. Two weeks after ovariectomy, the smooth muscle bundles began to become disorganized, and the fraction of smooth muscle in the nonvascular muscularis of the proximal vagina was significantly decreased (P<0.001). However, there was no difference in the expression of a-SMA in the distal vagina. Compared with the control group, the ovariectomy group had stiffer vaginas with a declining trend in the ultimate load 16 weeks after ovariectomy. In conclusion, surgically induced menopause had a significant short- and long-term impact on tissue composition and biomechanical properties of the rat vagina, which may lead to increased susceptibility to POP development.

Molecular aspects of collagenolysis associated with stress urinary incontinence in women with urethral hypermobility vs intrinsic sphincter deficiency

AIMS

We aimed to assess the alterations in specific molecular mechanisms associated with collagenolysis and their correlation in cases of stress urinary incontinence (SUI) by urethral hypermobility (UH) and by intrinsic sphincter deficiency (ISD).

METHODS

We evaluated the messenger RNA (mRNA) expression of matrix metalloproteinases (MMP1, MMP2, and MMP9), specific tissue inhibitors of metalloproteinases (TIMPs), and associated proteins (TIMP1, TIMP2, and α-2-macroglobulin [A2McG]) in the suburethral tissue of women with SUI (half with SUI by UH and half with SUI by ISD) by reverse-transcriptase quantitative polymerase chain reaction and determined the correlations of the expression of these proteins on each pathological condition.

RESULTS

In the suburethral tissue, we found significantly altered MMP2 mRNA levels, being higher in women with ISD than in those with UH. Still, MMP1 and MMP9 exhibited a tendency to a higher expression in women with ISD. Concerning the TIMPs expression, no significant statistical differences were found between women with UH and ISD. When evaluating the MMP/TIMP ratios, we found significant statistical differences between MMP9/TIMP1 and MMP9/A2McG. In fact, the correlations of the expression MMP9 with TIMP1 and A2McG were lost for women with UH. The ratios between MMP1/TIMP1 and MMP1/A2McG were similar, although there was a tendency of higher ratio in ISD for MMP2/TIMP2 and MMP2/A2McG.

CONCLUSION

Our results point toward higher collagenolysis in the suburethral tissue of women with SUI by ISD.

Correlation Between Autophagy and Collagen Deposition in Patients With Pelvic Organ Prolapse

OBJECTIVES

The aim of this study was to explore the link between autophagy and collagen metabolism in patients with pelvic organ prolapse (POP) by detecting the expressions of autophagy factors, collagen, desmin, cytokeratin, and vimentin.

METHODS

Histology of anterior vaginal wall and uterosacral ligament was assessed by hematoxylin-eosin staining in POP and non-POP control patients (n = 50 per group). Expressions of collagen types I and III, LC3II, beclin 1, and p62 were examined by Western blot analysis. Expressions of LC3, vimentin, desmin, and cytokeratin were detected by immunohistochemical staining. A linkage between the mean of LC3 integrated option density summation (IOD SUM) and POP clinicopathologic parameters including Pelvic Organ Prolapse Quantification (POP-Q) staging, age, body mass index, gravidity, and parity was analyzed by χ test, respectively.

RESULTS

Compared with the control group, the following differences were found both in the vaginal wall and in the uterosacral ligament of the POP group: hematoxylin-eosin staining showed that collagen was more fragmented and disorganized. Expressions of collagen types I and III, LC3II, and beclin 1 were diminished, whereas the p62 level was elevated in Western blotting. Immunohistochemical staining showed that expression of LC3 was down-regulated, whereas vimentin level was increased. There were no significant differences in the expressions of desmin and cytokeratin in the 2 groups (P > 0.05). Mean of LC3 IOD SUM was highly linked to the POP-Q stage in the POP group (P < 0.05), whereas there was no significant correlation between the mean of LC3 IOD SUM and POP groups in age, body mass index, gravidity, and parity, respectively(P > 0.05).

CONCLUSIONS

Autophagic activity is impaired in the POP group, which may relate to collagen deposition.

Collagen changes in pelvic support tissues in women with pelvic organ prolapse

Pelvic organ prolapse is a group of diseases caused by weakened pelvic supportive tissue, but the pathophysiology is not completely understood. Collagen is one of the most important components of the extracellular matrix in connective tissue, as it maintains the supportive functions of the pelvic floor. Collagen I and III are two major subtypes in pelvic tissues. With conflicting results of different studies, changes of their content and ratio are still disputed. The structure of collagen fibrils of pelvic organ prolapse patients become loose, disorderly and discontinuous and become stiffer than control group. Strong mechanical stress and imbalance matrix metalloproteinases /tissue-derived inhibitors of metalloproteinases can lead to collagen anabolism abnormalities causing changes of collagen content and structure. These changes are inter-influenced and are involved by multiple signaling pathways, including TGF-β/Smad, AGE/RAGE, MAPK, PI3K/AKT, and NF-κB. Collagen changes, including content, morphologic and biomechanical changes and catabolism abnormalities, can destroy the supportive function of the pelvic floor and are closely related to the development of pelvic organ prolapse. Epidemiological data also show a genetic predisposition to collagen changes. Research about collagen changes in the pelvic floor supportive tissues is limited and controversial. Small sample sizes and different recruitment criteria, biopsy sites, and research methods make comparisons between various studies difficult. More research concerning collagen changes is needed to better understand the pathogenesis of pelvic organ prolapse.

The increased of MMP-9 and MMP-2 with the decreased of TIMP-1 on the uterosacral ligament after childbirth

Introduction

Pelvic floor dysfunction is one of the causes of morbidity that have very active role in the degradation of collagen and elastin through an intermediary changes in matrix metalloproteinases (MMP) and its regulation. This research to evaluate level of MMP-9, MMP-2 and TIMP-1 expression on uterosacral ligament in women after vaginal delivery.

Methods

This research was conducted by collecting samples in consecutive sampling of biopsy uterosacral ligament from primigravida who underwent cesarean section because of obstructive labor at stage 1 and 2. As control, biopsy samples were taken from uterosacral ligament of primigravida a term who have not entered the labor phase and undergoing elective caesarean section surgery. The method in this study was cross sectional. The examination of MMP-9, MMP-2, and TIMP-1 expression by immunohistochemistry based on comparison of the sample and the control differences.

Results

There are differences in the levels of Matrix Metalloproteinase-9, Matrix Metalloproteinase-2, and TIMP-1 in the uterosacral ligament of primigravida women in labor compared with women who are never in labor.

Conclusion

There are increased levels of Matrix Metalloproteinase-9 and Matrix Metalloproteinase-2 with the decreased of TIMP-1 in the uterosacral ligament of primigravida women who underwent cesarean section because of obstructive labor at stage 1 and 2.

Expressions of homeobox, collagen and estrogen genes in women with uterine prolapse

OBJECTIVE

Genetic contribution is thought to be involved in the pathophysiology of pelvic organ prolapse (POP). We aimed to study the gene expression profiles of the genes HomeoboxA11 (HOXA11), HomeoboxA13 (HOXA13), Collagen Type I (COL1A), Collagen Type III (COL3A), estrogen receptor genes (ESR1 and ESR2) of round (RL) and uterosacral ligaments (USL) in postmenopausal women with uterine prolapse.

STUDY DESIGN

Gene expressions of 32 postmenopausal women with prolapse were analysed according to gene expressions of 8 postmenopausal women without prolapse. Quantitative real-time PCR (qRT-PCR) method was used for the detection of expression levels of the genes. Student's t-Test and Mann-Whitney U test were used for statistical analysis.

RESULTS

In the USL specimens of all women with uterine prolapse HOXA13 and ESR1 gene expressions were decreased compared to controls (0.5 fold, p = 0.04 and 0.82 fold, p = 0.04, respectively). In the RL specimens, ESR2 gene expression was decreased 0.7 fold in women with prolapse when compared to controls (p = 0.04). In the USL specimens of women with advanced stages of prolapse (stage ≥3), HOXA13 and COL3A gene expressions were decreased compared to controls (0.44 fold, p = 0.043 and 0.39 fold, p = 0.045, respectively). In the RL specimens, ESR2 gene expression was decreased 0.65 fold in women with prolapse when compared to controls (p = 0.052).

CONCLUSION

The significant decrease in the expression of the genes HOXA13, COL3A in the USL and ESR2 in the RL especially in advanced stages of prolapse, implicate that these gene expressions may play a role in the development of uterine prolapse.

Effects of elastase digestion on the murine vaginal wall biaxial mechanical response

Although the underlying mechanisms of pelvic organ prolapse (POP) remain unknown, disruption of elastic fiber metabolism within the vaginal wall extracellular matrix has been highly implicated. It has been hypothesized that elastic fiber fragmentation correlates to decreased structural integrity and increased risk of prolapse; however, the mechanisms by which elastic fiber damage may contribute to prolapse are poorly understood. Further, the role of elastic fibers in normal vaginal wall mechanics has not been fully ascertained. Therefore, the objective of this study is to investigate the contribution of elastic fibers to murine vaginal wall mechanics. Vaginal tissue from C57BL/6 female mice were mechanically tested using biaxial extension-inflation protocols before and after intraluminal exposure to elastase. Elastase digestion induced marked changes in the vaginal geometry, and biaxial mechanical properties, suggesting that elastic fibers may play an important role in vaginal wall mechanical function. Additionally, a constitutive model that considered two diagonal families of collagen fibers with a slight preference towards the circumferential direction described the data reasonably well before and after digestion. The present findings may be important to determine the underlying structural and mechanical mechanisms of POP, and aid in the development of growth and remodeling models for improved assessment and prediction of changes in structure-function relationships with prolapse development. Keywords: vaginal wall, women's health, mechanical testing, pelvic floor disorders, elastic fibers Disclosures: none.

New insight into glycation levels and pelvic organ prolapse - A combination of clinical and biochemical studies

OBJECTIVES

Pelvic Organ Prolapse (POP) is a multifactorial disease with ageing as a most notable risk factor. Advanced Glycation End products (AGEs), biochemical markers of ageing are increased in prolapsed tissues. It is however unclear if AGEs are a cause or outcome of prolapse. By combining analysis of clinically relevant parameters in women with prolapse and POP tissues biochemically, this study aims to bridge the gap between existing clinical and biochemical research on the cause of POP.

METHODS

Following national and local ethical approval, a case study of 49 POP and 16 control tissues was carried out. The AGEs' marker, pentosidine, was quantified via High Performance Liquid Chromatography. Oestrogen (ER-α) and glyoxalase I (GLO-I) expression of the tissues were studied. Age, obstetric factors and co-morbidities (hypertension, smoking, diabetes mellitus) were recorded and compared with biochemical findings.

RESULTS

Lower expressions of ER-α and GLO-I were observed in POP tissues in the comparison to the control, which also had significantly higher pentosidine content. Prolapsed tissue population had more notable age-dependent increase in pentosidine with significant differences between the 6^th and 7^th decade. Hypertension and smoking, which were more prevalent amongst women with POP, were associated with higher amounts of pentosidine in the vaginal tissues.

CONCLUSION

In the light of recent research regarding the relationship between POP and glycation, the present study shows that age-related oestrogen decline is a key player in glycation accumulation in prolapsed vaginal tissues and that glycation is a cause rather than an effect of prolapse. Hypertension is a significant POP association which is linked to high glycation level.

Biaxial Mechanical Assessment of the Murine Vaginal Wall Using Extension-Inflation Testing

Progress toward understanding the underlying mechanisms of pelvic organ prolapse (POP) is limited, in part, due to a lack of information on the biomechanical properties and microstructural composition of the vaginal wall. Compromised vaginal wall integrity is thought to contribute to pelvic floor disorders; however, normal structure-function relationships within the vaginal wall are not fully understood. In addition to the information produced from uniaxial testing, biaxial extension-inflation tests performed over a range of physiological values could provide additional insights into vaginal wall mechanical behavior (i.e., axial coupling and anisotropy), while preserving in vivo tissue geometry. Thus, we present experimental methods of assessing murine vaginal wall biaxial mechanical properties using extension-inflation protocols. Geometrically intact vaginal samples taken from 16 female C57BL/6 mice underwent pressure-diameter and force-length preconditioning and testing within a pressure-myograph device. A bilinear curve fit was applied to the local stress-stretch data to quantify the transition stress and stretch as well as the toe- and linear-region moduli. The murine vaginal wall demonstrated a nonlinear response resembling that of other soft tissues, and evaluation of bilinear curve fits suggests that the vagina exhibits pseudoelasticity, axial coupling, and anisotropy. The protocols developed herein permit quantification of biaxial tissue properties. These methods can be utilized in future studies in order to assess evolving structure-function relationships with respect to aging, the onset of prolapse, and response to potential clinical interventions.

Differential gene expression of extracellular-matrix-related proteins in the vaginal apical compartment of women with pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Pelvic organ prolapse (POP) is a multifactorial disorder that impairs the quality of life (QoL) of older women in particular. The purpose of this study was to elucidate the pathogenesis of POP by focusing on the extracellular matrix (ECM).

METHODS

Patients were classified into two groups-with or without cervical elongation-using the POP quantification system. Specimens were obtained from 29 women with POP during hysterectomy. The expression of fibulin-5, elastin, integrin β1 (ITGβ1), lysyl oxidase-like protein-1 (LOXL1) and collagen in the vagina, uterosacral ligament, and uterine cervix was investigated by quantitative real-time polymerase chain reaction (RT-PCR) and correlation between gene levels and severity of POP examined. The location of proteins was analyzed using immunohistochemical staining and expression of fibulin-5 protein analyzed by Western blotting.

RESULTS

Fibulin-5 and elastin were mainly expressed in lamina propria and fibromuscular layers of the vagina and uterosacral ligament. Gene levels of fibulin-5 and ITGβ1 in uterosacral ligaments increased with severity of POP in women with cervical elongation, while no correlation was observed in women with a normal cervix. In women with uterine cervical elongation, each ECM-related gene significantly increased with POP staging. Furthermore, fibulin-5 protein also increased in the uterosacral ligament and uterine cervix.

CONCLUSIONS

The severity of POP and gene expression of ECM-related proteins were inversely correlated in vaginal tissue in a normal and elongated cervix. These results suggested that the differing progression of the two types of POP have a relationship with ECM-related protein.

Immunohistochemical expression of hypoxia-inducible factor-1α in stromal cells of vaginal tissue in post-menopausal women with pelvic organ prolapse

Background & objectives:

Pelvic organ prolapse (POP) is a common medical condition that affects adult women of different ages. The support of a normal pelvic floor is the result of complex interactions between ligaments, muscles, connective tissue and vaginal walls. Hypoxia and oxidative stress can reduce protein synthesis in the pelvic muscles that may contribute to muscular atrophy. Hypoxia-inducible factor-1α (HIF-1α) is a transcriptional activator which, expressed in response to hypoxia, activates a number of genes involved in cellular response to hypoxia. However, a potential role of hypoxia and oxidative stress in pathogenesis of POP is not known. This study was aimed to compare the level of HIF-1α immunohistochemical expression in the vaginal stromal cells of postmenopausal women with and without POP.

Methods:

Samples of the vaginal tissue from 120 menopausal women were obtained during surgery, and immunohistochemical expression of HIF-1α was assessed. There were 60 women with POP while 60 women in the control group were without prolapse but with benign gynaecological diseases.

Results:

In post-menopausal women with prolapse, significant differences were observed in the number of HIF-1α-positive stromal cells in the vaginal tissue compared to the control group. There was a significant increase in the number of HIF-1α in the stromal cells of the vaginal tissue in women with prolapse.

Interpretation & conclusions:

Difference in expression of HIF-1α in stromal cells of the vaginal tissue in the post-menopausal women with and without POP suggests that prolonged hypoxia probably has an important role in the aetiopathogenesis of POP.

Collagen XVIII and LOXL-4 polymorphisms in women with and without advanced pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

We verified the presence of single nucleotide polymorphisms (SNP) rs2236479 of the collagen 18 (COL18A1) and rs2862296 of the lysyl oxidase-like 4 (LOXL-4) genes and the association with pelvic organ prolapse (POP) in Brazilian women and determined risk factors for POP development.

METHODS

We assessed 532 postmenopausal women divided into POP (stages III and IV) and control (stages 0 and I) groups by examination and peripheral blood sample collection. DNA sequences of interest were analyzed by real-time reverse-transcriptase polymerase chain reaction (RT-PCR). We used logistic regression models for the analyses, with p < 0.005 for significance.

RESULTS

The frequency of homozygous polymorphic alleles (AA) in COL18A1 and (GG) in LOXL-4 were similar in both groups (17.5% and 15.4% for COL18A1 and 18.9% and 20.6% for LOXL-4, respectively). There were no associations between those polymorphisms or other genotypes and POP. Multiple logistic regression analysis identified age [odds ratio (OR) = 1.10, confidence interval (CI) 95% = 1.07; 1.14), number of vaginal births (OR = 1.66, CI 95% = 1.36; 2.03), and family history (OR = 2.55 CI 95% = 1.43; 4.55) as independent risk factors for POP.

CONCLUSION

Our study suggests lack of association between DNA polymorphisms rs2236479 of COL18A1 and rs2862296 of LOXL-4 with advanced POP in this population.

Transcriptional Regulation of Connective Tissue Metabolism Genes in Women With Pelvic Organ Prolapse

OBJECTIVE

The aim of this study was to compare differences in expressions and relationships between key genes involved in extracellular matrix metabolism and tissue cellularity in women with and without pelvic organ prolapse (POP).

METHODS

A total of 80 biopsies (anterior cuff, posterior cuff, and/or leading edge) were obtained from 30 women: n = 10 premenopausal without POP (controls), n = 10 premenopausal with POP, and n = 10 postmenopausal with POP. Quantitative reverse-transcriptase polymerase chain reaction was used to assess gene expression of bone morphogenetic protein 1 (BMP1), collagen types I (COL1) and III (COL3), relaxin family peptide receptor 1 (RXFP1), matrix metallopeptidase 2, and TIMP metallopeptidase inhibitors 2 and 3. Hematoxylin and eosin staining was used to assess cellularity of the connective tissue layer. Kruskal-Wallis test, Mann-Whitney U test, Pearson correlation, or linear regression analyses were used, as appropriate.

RESULTS

Bone morphogenetic protein 1 expression was significantly up-regulated in patients with POP compared with controls. Bone morphogenetic protein 1 expression was correlated with COL1 expression in all groups but only correlated with TIMP metallopeptidase inhibitor 3 expression in controls. Similarly, COL3 expression was correlated with RXFP1 expression in women with POP but not in controls. The degree of dependence (slope of the regression line) between COL1 and COL3 expressions was significantly elevated in premenopausal women with POP compared with the other 2 groups. The slopes between COL1-COL3, COL3-matrix metallopeptidase 2, COL1-RXFP1, and COL3-RXFP1 expressions were significantly lower in postmenopausal women compared with premenopausal women with POP. No differences were found in overall tissue cellularity.

CONCLUSIONS

Bone morphogenetic protein 1 expression may play a significant role in the pathophysiology of POP. The finding that BMP1 expression was correlated with COL1 expression in all groups suggests a conserved association between BMP1 and collagen synthesis in the vaginal wall. The elevated slope between COL1 and COL3 expressions may be associated with early (premenopausal) development of POP. The expression of RXFP1 in postmenopausal women and its altered intergene regulation suggests a role for RXFP1 in connective tissue metabolism outside pregnancy.

Measuring tissue displacement of the anterior vaginal wall using the novel aspiration technique in vivo

Little is known about the mechanical properties of pelvic floor structures and their role in the course and treatment of pelvic organ prolapse (POP). We hypothesize that in vivo mechanical properties of the vaginal wall are related to the appearance of POP and pre-and post-operative states. We used a suction device for intravaginal application, the aspiration device, to evaluate two in vivo mechanical parameters of the anterior vaginal wall, the load dependent tissue displacement and the initial displacement, by image analysis in pre- and post-menopausal women with (POP) and without (control) cystocele (POP: pre-menopausal: N = 6, post-menopausal: N = 19, control: pre-menopausal: N = 17, post-menopausal: N = 6). Mechanical parameters in women with and without cystocele and pre- and post-operative parameters were compared. Statistically significant differences were observed between the two mechanical parameters in pre- and post-operative states (P = 0.04, P = 0.03), but not between the parameters for women with and without cystocele (P = 0.92, P = 0.75). The mechanical behavior of pelvic floor structures is influenced by factors such as POP, age or estrogenization that are apparent at different length scales, which cannot be separated by the aspiration based biomechanical measurements. When comparing pre- and post-operative states of the same patient, a firmer tissue response was observed after intervention.

Skin advanced glycation content reflects vaginal tissue glycation level in relation to pregnancy

A few studies have revealed that the advanced glycation content of the vaginal wall in pelvic organ prolapse tissues is elevated. This elevation makes advanced glycation a significant association with the disease. Early detection of vaginal wall glycation could therefore be relevant in the prevention and management of pelvic organ prolapse. A vaginal wall biopsy to detect this would be ideal, but is invasive. Therefore the use of a more accessible organ to access, such as skin, would be beneficial. Our previous independent study suggests that conditions such as pregnancy, can induce a change in the vaginal tissues' glycation content. The aim of this study was to assess whether the skin glycation undergoes similar changes as observed in vaginal tissue glycation in the same subjects in order to prove the hypothesis that skin advanced glycation content can predict vaginal tissue glycation. A rat model was used. The vaginal tissues from non-pregnant and E15-E18 pregnant rats and skin tissues from the same rats were taken for the measurement of advanced glycation content. The glycation marker, pentosidine, was quantified by a high performance liquid chromatography. Our results demonstrated that glycation content in vaginal wall tissues from pregnant rats was lower than the tissues from non-pregnant ones, and a strong positive association between skin and vaginal wall pentosidine level was observed. We conclude that skin pentosidine is reflective of vaginal wall pentosidine. Skin glycation may therefore be a potential tool in the prediction and management of pelvic organ prolapse.

THE INFLUENCE OF PELVIC ORGAN PROLAPSE ON THE PASSIVE BIOMECHANICAL PROPERTIES OF PELVIC FLOOR MUSCLES

The biomechanical properties of the female pelvic floor tissues, such as muscles, fascia or ligaments are relevant when explaining pelvic disorders, since these may result from changes in the properties of those tissues. The aim of this study is to understand the influence of pelvic organ prolapse (POP) on the passive biomechanical properties of the pelvic floor muscles. For this purpose, magnetic resonance images at Valsalva maneuver were used, and an inverse finite element analysis technique was applied. The numerical models of the pubovisceralis muscle and pelvic bones were built from axial magnetic resonance images acquired at rest. The numerical simulation was based on the finite element method (FEM), by which the material constants were determined for three different constitutive models (Neo-Hookean, Mooney–Rivlin and Yeoh). The ratio between the values of the material constants for women with and without prolapse was approximately 43% for the parameter [Formula: see text] in the Neo-Hookean constitutive model, 57% and 24% for [Formula: see text] and [Formula: see text] in the Mooney–Rivlin constitutive model, and 35%, 21% and 14% for [Formula: see text], [Formula: see text] and [Formula: see text] in the Yeoh constitutive model. For the three constitutive models, the mean values of the material properties related with stiffness were higher for the muscles of women with POP. These increases in stiffness are in line with other experimental works involving vaginal tissue, which showing that the elasticity module is significantly higher in the prolapsed tissue when compared with normal tissue.

The present work presents a noninvasive methodology based on the application of the FEM, which allows the establishment of a relationship between the stiffness of the pelvic floor muscles of women with POP and without this pathology.

Biomimetic implants for pelvic floor repair

BACKGROUND

Polypropylene implants are used for the reconstructive surgery of urogynaecological disorders like pelvic organ prolapse, but severe complications associated with their use have been reported. There is evidence that surface properties and a difference in mechanical stiffness between the implant and the host tissue contribute to these adverse events. Electrospinning is an innovative engineering alternative that provides a biomimetic microstructure for implants, resulting in a different mechano-biological performance.

AIM

The main objective of this review is to inform about the potential of electrospun matrices as an alternative modality for pelvic floor repair.

METHODS

Publications with the following studies of electrospun matrices were reviewed: (i) the technique; (ii) in vitro use for soft tissue engineering; (iii) in vivo use for reconstruction of soft tissues in animals; and (iv) clinical use in humans.

RESULTS

Electrospun matrices provide a synthetic mimic of natural extracellular matrix (ECM), favoring cellular attachment, proliferation and matrix deposition, through which a proper, low-inflammatory tissue-implant interaction can be established. Electrospun sheets can also be created with sufficient mechanical strength and stiffness for usage in prolapse surgery.

CONCLUSION

Electrospun matrices mimic the structural topography of the extracellular matrix and can be functionalized for better biological performance. As such, they have great potential for the next generation of urogynecological implants. However, their long-term safety and efficacy must still be established in vivo.

The role of GPX1 in the pathogenesis of female pelvic organ prolapse

Gestation and delivery can increase intra-abdominal pressure, which are well-known risk factors for Pelvic Organ Prolapse (POP). But the pathogenesis mechanism of POP remains unclear. Our previous research showed that the expression of glutathione peroxidase type 1 (GPX1) decreased in pelvic floor ligaments from POP patients, implying that oxidative stress (OS) may be related to POP. The aim of this study was to figure out the role of GPx1 regulation in the pathogenesis of POP. Women (>45 years) who received hysterectomy surgery were enrolled in this research, identified by screening. We applied mechanical strain of 0μ, 5333 μ to GPX1-overexpressing human uterosacral ligament fibroblasts (hUSLFs) isolated from menopausal women without POP respectively for 4 hours, in order to investigate the changes of cell apoptosis, oxidative status and ECM metabolism when cytomechanics model loaded on GPX1-overexpressing hUSLFs. Comparing with the non-transfection and mock-vehicle groups, we found that GPX1 not only protects hUSLFs from cell apoptosis, oxidative damage, but also improves the remodeling of ECM induced by mechanical stimulation. These results suggested that mechanical strain caused abnormalities of ECM metabolism via OS pathway in hUSLFs, which was involved in the pathogenesis of POP, and that GPx1 played a significant role in regulating mechanical strain induced POP.

Structural Failure Sites in Anterior Vaginal Wall Prolapse: Identification of a Collinear Triad

OBJECTIVE

To test the null hypothesis that six factors representing potential fascial and muscular failure sites contribute equally to the presence and size of a cystocele: two vaginal attachment factors (apical support and paravaginal defects), two vaginal wall factors (vaginal length and width), and two levator ani factors (hiatus size and levator ani defects).

METHODS

Thirty women with anterior-predominant prolapse (women in a case group) and 30 women in a control group underwent three-dimensional stress magnetic resonance imaging. The location of the anterior vaginal wall at maximal Valsalva was identified with the modified Pelvic Inclination Coordinate System and the six factors measured. Analysis included repeated-measure analysis of variance, logistic regression, and stepwise linear regression.

RESULTS

We identified a collinear triad consisting of apical location, paravaginal location, and hiatus size that were not only the strongest predictors of cystocele size, but were also highly correlated with one another (r=0.84-0.89, P<.001) for the presence and size of the prolapse. Together they explain up to 83% of the variation in cystocele size. Among the less significant vaginal factors, vaginal length explained 19% of the variation in cystocele size, but no significant difference in vaginal width existed. Women in the case group were more likely to have abnormalities in collinear triad factors (up to 80%) than vaginal wall factors (up to 23.3%). Combining the strongest collinear triad with the vaginal factors, the model explained 92.5% of the variation in cystocele size.

CONCLUSION

Apical location, paravaginal location, and hiatus size are highly correlated and are strong predictors of cystocele presence and size.

Recent Advances in Understanding Pelvic-Floor Tissue of Women With and Without Pelvic Organ Prolapse: Considerations for Physical Therapists

Pelvic organ prolapse is a fairly common condition that imposes significant symptoms, diminished quality of life, social burden, financial expense, and surgical risk on women. As evidence supporting the benefit of pelvic-floor muscle training in nonsurgical management of pelvic organ prolapse grows, physical therapists are becoming a provider of choice interacting with women affected by pelvic organ prolapse. This perspective article will review recent research on tissue characteristics of 3 key components of pelvic organ support: skeletal muscle, ligament, and vaginal wall. This information will be summarized as implications for physical therapists. An improved understanding of pelvic-floor tissue in women with and without pelvic organ prolapse will provide a more comprehensive appreciation of the interaction of multiple systems in the disorder.

Extracellular matrix metabolism disorder induced by mechanical strain on human parametrial ligament fibroblasts

Pelvic organ prolapse (POP) is a global health problem that may seriously impact the quality of life of the sufferer. The present study aimed to investigate the potential mechanisms underlying alterations in extracellular matrix (ECM) metabolism in the pathogenesis of POP, by investigating the expression of ECM components in human parametrial ligament fibroblasts (hPLFs) subject to various mechanical strain loads. Fibroblasts derived from parametrial ligaments were cultured from patients with POP and without malignant tumors, who underwent vaginal hysterectomy surgery. Fibroblasts at generations 3‑6 of exponential phase cells were selected, and a four‑point bending device was used for 0, 1,333 or 5,333 µ mechanical loading of cells at 0.5 Hz for 4 h. mRNA and protein expression levels of collagen type I α 1 chain (COL1A1), collagen type III α 1 chain (COL3A1), elastin, matrix metalloproteinase (MMP) ‑2 and ‑9, and transforming growth factor (TGF)‑β1 were detected by reverse transcription‑quantitative polymerase chain reaction and western blotting, respectively. Under increased mechanical strain (5,333 µ), mRNA and protein expression levels of COL1A1, COL3A1 elastin and TGF‑β1 decreased, particularly COL1A1; however, mRNA and protein expression levels of MMP‑2 and ‑9 were significantly increased, compared with the control group (0 µ strain). Following 1,333 µ mechanical strain, mRNA and protein expression levels of COL1A1, COL3A1 elastin and MMP‑2 increased, and MMP‑9 decreased, whereas no significant differences were observed in TGF‑β1 mRNA and protein expression levels. In conclusion, ECM alterations may be involved in pathogenesis of POP, with decreased synthesis and increased degradation of collagen and elastin. Furthermore, the TGF‑β1 signaling pathway may serve an important role in this process and thus may supply a new target and strategy for understanding the etiology and therapy of POP.

Optical techniques for cervical neoplasia detection

This paper provides an overview of the current research in the field of optical techniques for cervical neoplasia detection and covers a wide range of the existing and emerging technologies. Using colposcopy, a visual inspection of the uterine cervix with a colposcope (a binocular microscope with 3- to 15-fold magnification), has proven to be an efficient approach for the detection of invasive cancer. Nevertheless, the development of a reliable and cost-effective technique for the identification of precancerous lesions, confined to the epithelium (cervical intraepithelial neoplasia) still remains a challenging problem. It is known that even at early stages the neoplastic transformations of cervical tissue induce complex changes and modify both structural and biochemical properties of tissues. The different methods, including spectroscopic (diffuse reflectance spectroscopy, induced fluorescence and autofluorescence spectroscopy, Raman spectroscopy) and imaging techniques (confocal microscopy, optical coherence tomography, Mueller matrix imaging polarimetry, photoacoustic imaging), probe different tissue properties that may serve as optical biomarkers for diagnosis. Both the advantages and drawbacks of these techniques for the diagnosis of cervical precancerous lesions are discussed and compared.

Does the vaginal wall become thinner as prolapse grade increases?

INTRODUCTION AND HYPOTHESIS

The pathophysiology of prolapse is not well understood. However, two main theories predominate: either the fibromuscular layer of the vagina develops a defect/tears away from its supports, or its tissues are stretched and attenuated. The aim of this study was to assess how vaginal wall thickness (VWT) is related to vaginal prolapse.

METHODS

The study group comprised 243 women with symptomatic prolapse recruited from the Outpatient Department of a tertiary referral centre for urogynaecology. A history was taken and women were examined to determine their POP-Q score. Using a previously validated technique, ultrasonography was used to measure the mean VWT at three anatomical sites on the anterior and posterior walls. Scores were then compared using t tests, the Kruskal-Wallis test and the Friedman test.

RESULTS

The mean age of the patients was 59.7 years (SD 12.0 years range 38 - 84 years). For each measurement VWT reduced as prolapse grade increased until the prolapse extended beyond the hymen. Women with grade 3 prolapse had a significantly higher mean VWT than women with grade 1 or 2 contained prolapse. Menopause status did not have a significant effect on the VWT.

CONCLUSIONS

VWT is lower in women with vaginal prolapse until the prolapse extends beyond the hymen and then VWT is thicker and comparable with women without prolapse. This may be explained by changes in the vaginal tissue including reduction of collagen, elastin and smooth muscle, as well as fibrosis in exposed tissues, rather than by defects in the vagina.

Vaginal Fibroblastic Cells from Women with Pelvic Organ Prolapse Produce Matrices with Increased Stiffness and Collagen Content

Pelvic organ prolapse (POP) is characterised by the weakening of the pelvic floor support tissues, and often by subsequent prolapse of the bladder outside the body, i.e. cystocele. The bladder is kept in place by the anterior vaginal wall which consists of a dense extracellular matrix rich in collagen content that is maintained and remodelled by fibroblastic cells, i.e. fibroblasts and myofibroblasts. Since altered matrix production influences tissue quality, and myofibroblasts are involved in normal and pathological soft tissue repair processes, we evaluated matrix production of cells derived from pre- and post-menopausal POP and non-POP control anterior vaginal wall tissues. Results showed that cells from postmenopausal POP women deposited matrices with high percentage of collagen fibres with less anisotropic orientation and increased stiffness than those produced by controls. There was a transient increase in myofibroblastic phenotype that was lost after the peak of tissue remodelling. In conclusion, affected fibroblasts from postmenopausal prolapsed tissues produced altered matrices in vitro compared to controls. Such aberrant altered matrix production does not appear to be a consequence of abnormal phenotypical changes towards the myofibroblastic lineage.

Elastin density: Link between histological and biomechanical properties of vaginal tissue in women with pelvic organ prolapse?

INTRODUCTION AND HYPOTHESIS

The aim of the study was to correlate histological and biomechanical characteristics of the vaginal wall in women with pelvic organ prolapse (POP).

METHODS

Tissue samples were collected from the anterior [point Ba; POP Questionnaire (POP-Q)] and/or posterior (point Bp; POP-Q) vaginal wall of 15 women who underwent vaginal surgery for POP. Both histological and biomechanical assessments were performed from the same tissue samples in 14 of 15 patients. For histological assessment, the density of collagen and elastin fibers was determined by combining high-resolution virtual imaging and computer-assisted digital image analysis. For biomechanical testing, uniaxial tension tests were performed to evaluate vaginal tissue stiffness at low (C0) and high (C1) deformation rates.

RESULTS

Biomechanical testing highlights the hyperelastic behavior of the vaginal wall. At low strains (C0), vaginal tissue appeared stiffer when elastin density was low. We found a statistically significant inverse relationship between C0 and the elastin/collagen ratio (p = 0.048) in the lamina propria. However, at large strain levels (C1), no clear relationship was observed between elastin density or elastin/collagen ratio and stiffness, likely reflecting the large dispersion of the mechanical behavior of the tissue samples.

CONCLUSION

Histological and biomechanical properties of the vaginal wall vary from patient to patient. This study suggests that elastin density deserves consideration as a relevant factor of vaginal stiffness in women with POP.

Is There a Relationship Between Pelvic Organ Prolapse and Tissue Fibrillin-1 Levels?

Purpose:

Pelvic organ prolapse is a multifactorial disorder in which extracellular matrix defects are implicated. Fibrillin-1 level is reduced in stress urinary incontinence. In Marfan syndrome, which is associated with mutations in Fibrillin-1, pelvic floor disorders are commonly observed. We hypothesize that Fibrillin-1 gene expression is altered in pelvic organ prolapse.

Methods:

Thirty women undergoing colporrhaphy or hysterectomy because of cystocele, rectocele, cystorectocele, or uterine prolapse were assigned to a pelvic prolapse study group, and thirty women undergone hysterectomy for nonpelvic prolapse conditions were assigned to a control group. Real-time polymerase chain reaction was conducted on vaginal tissue samples to measure the expression of Fibrillin-1. Expression levels were compared between study and control groups by Mann-Whitney U test with Bonferroni revision.

Results:

Fibrillin-1 gene expression was not significantly lower in the study group than in the control group. Similarly, no significant correlation between Fibrillin-1 levels and grade of pelvic prolapse was found. Age over 40 years (P=0.018) and menopause (P=0.027) were both associated with reduced Fibrillin-1 levels in the pelvic prolapse group, whereas the delivery of babies weighing over 3,500 g at birth was associated with increased Fibrillin-1 expression (P=0.006).

Conclusions:

The results did not indicate a significant reduction in Fibrillin-1 gene expression in pelvic prolapse disorders; however, reduced Fibrillin-1 may contribute to increased pelvic organ prolapse risk with age and menopause. Increased Fibrillin-1 gene expression may be a compensatory mechanism in cases of delivery of babies with high birth weight. Further studies are needed for a better understanding of these observations.

Identifying distinct nanoscopic features of native collagen fibrils towards early diagnosis of pelvic organ prolapse

Pelvic organ prolapse (POP) is characterized by weakening of the connective tissues and loss of support for the pelvic organs. Collagen is the predominant, load-bearing protein within pelvic floor connective tissues. In this study, we examined the nanoscopic structures and biomechanics of native collagen fibrils in surgical, vaginal wall connective tissues from healthy women and POP patients. Compared to controls, collagen fibrils in POP samples were bulkier, more uneven in width and stiffer with aberrant D-period. Additionally, the ratio of collagen I (COLI) and collagen III (COLIII) is doubled in POP with a concomitant reduction of the amount of total collagen. Thus, POP is characterized by abnormal biochemical composition and biophysical characteristics of collagen fibrils that form a loose and fragile fiber network accountable for the weak load-bearing capability. The study identifies nanoscale alterations in collagen as diagnostic markers that could enable pre-symptomatic or early diagnosis of POP.

FROM THE CLINICAL EDITOR

Pelvic organ prolapse (POP) occurs due to abnormalities of the supporting connective tissues. The underlying alterations of collagen fibers in the connective tissues have not been studied extensively. In this article, the authors showed that collagen fibrils in POP patients were much different from normal controls. The findings may provide a framework for the diagnosis of other connective diseases.

Age at hysterectomy as a predictor for subsequent pelvic organ prolapse repair

INTRODUCTION AND HYPOTHESIS

The aim of this study was to investigate the association between patient age at the time of hysterectomy and subsequent pelvic organ prolapse (POP) surgery.

METHODS

We gathered data on all benign hysterectomies and POP surgeries performed in Denmark on Danish women from 1977 to 2009 from the Danish National Patient Registry. The cohort consisted of 154,882 hysterectomized women, who were followed up for up to 32 years. Survival analysis for each age group at hysterectomy was performed using Kaplan-Meier product limit methods.

RESULTS

For all hysterectomized women, we found that low age at hysterectomy yielded a lower risk of subsequent POP surgery than did hysterectomy at an older age. This difference diminished after stratification by indication; all non-POP hysterectomies had a low cumulative incidence at 8-11 % at the end of the follow-up period. For all women hysterectomized, the predominant compartment for POP surgery was the posterior. Women hysterectomized when aged over 66 years had a higher proportion of POP surgery in the apical compartment than in the other age groups (p = 0.000).

CONCLUSION

Our findings indicate that age at hysterectomy only marginally influences the risk of subsequent POP surgery for women hysterectomized for indications other than POP. If POP is the indication for hysterectomy, the risk of undergoing subsequent POP surgery increases substantially.

Pelvic reconstruction improves pelvic floor strength in pelvic organ prolapse patients

OBJECTIVE

To evaluate pelvic floor muscle strength after the modified pelvic reconstruction procedure for pelvic organ prolapse (POP).

MATERIALS AND METHODS

Patients were assigned to two groups consisting of 37 patients diagnosed with POP and undergoing modified pelvic reconstruction (reconstruction group), and 30 patients admitted to our hospital during the same period for other surgical indications (control group). Vaginal palpation of pelvic floor muscle strength was performed according to the modified Oxford grading system before operating on the two groups and again in the 3(rd) month following surgery for the reconstruction group. A comparative study was performed to evaluate the differences between the two groups and the improvement of pelvic floor muscle strength in the reconstruction group.

RESULTS

The pelvic floor muscle strength was significantly improved postoperatively when compared with preoperative results in the reconstruction group (t = -17.478, p < 0.001). However, pre- and postoperative muscle strength in the reconstruction group was significantly lower relative to the control group, respectively (χ(2) = 63.293, p < 0.001; χ(2) = 31.550, p < 0.001).

CONCLUSION

The modified pelvic reconstruction procedure could improve pelvic floor muscle strength in POP patients, which remains lower when compared with the normal population. Pelvic floor muscle strength should be included in the assessment of surgical outcomes in POP.

A nonlinear-elastic constitutive model for soft connective tissue based on a histologic description: Application to female pelvic soft tissue

To understand the mechanical behavior of soft tissues, two fields of science are essential: biomechanics and histology. Nonetheless, those two fields have not yet been studied together often enough to be unified by a comprehensive model. This study attempts to produce such model. Biomechanical uniaxial tension tests were performed on vaginal tissues from 7 patients undergoing surgery. In parallel, vaginal tissue from the same patients was histologically assessed to determine the elastic fiber ratio. These observations demonstrated a relationship between the stiffness of tissue and its elastin content. To extend this study, a mechanical model, based on an histologic description, was developed to quantitatively correlate the mechanical behavior of vaginal tissue to its elastic fiber content. A satisfactory single-parameter model was developed assuming that the mechanical behavior of collagen and elastin was the same for all patients and that tissues are only composed of collagen and elastin. This single-parameter model showed good correlation with experimental results. The single-parameter mechanical model described here, based on histological description, could be very useful in helping to understand and better describe soft tissues with a view to their characterization. The mechanical behavior of a tissue can thus be determined thanks to its elastin content without introducing too many unidentified parameters.

Association of matrix metalloproteinase-10 polymorphisms with susceptibility to pelvic organ prolapse

AIM

The aim of this study was to explore the correlation between genetic mutations in matrix metalloproteinase-10 (MMP-10) and susceptibility to pelvic organ prolapse (POP).

MATERIAL AND METHODS

From September 2011 to December 2013, 263 subjects were recruited, including 91 patients with POP (case group) and 172 non-POP patients (control group). Total MMP-10 concentrations in serum were measured by enzyme-linked immunosorbent assay. The genotyping of MMP-10 was achieved by quantitative real-time polymerase chain reaction. All data were analyzed with SPSS 18.0.

RESULTS

We found that parity, menopause, history of total hysterectomy, and family history of POP were all significantly higher in the POP group than in the control group (P = 0.017, P = 0.046, P = 0.0029 and P < 0.001, respectively). Serum MMP-10 levels were obviously higher in the POP group than in the control group (P < 0.05). In addition, there was a statistically significant difference between the two groups in the distribution frequency of the MMP-10 (rs17435959G/C) genotype (P < 0.05). However, the distribution frequency of the MMP-10 (rs17293607C/T) genotype between the two groups showed no significant differences (P > 0.05). Furthermore, the patients with parity > 2 and postmenopausal women had elevated serum MMP-10 levels, and the patients with parity > 2 and postmenopausal women who carried the G/C + C/C genotype in the MMP-10 gene had an increased risk of POP.

CONCLUSION

We support the view that the rs17435959 polymorphism of the MMP-10 gene may be associated with an increased risk of POP.

Local Oestrogen for Pelvic Floor Disorders: A Systematic Review

OBJECTIVE

The decline in available oestrogen after menopause is a possible etiological factor in pelvic floor disorders like vaginal atrophy (VA), urinary incontinence (UI), overactive bladder (OAB) and pelvic organ prolapse (POP). This systematic review will examine the evidence for local oestrogen therapy in the treatment of these pelvic floor disorders.

EVIDENCE ACQUISITION

We performed a systematic search in MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and the non-MEDLINE subset of PubMed from inception to May 2014. We searched for local oestrogens and VA (I), UI/OAB (II) and POP (III). Part I was combined with broad methodological filters for randomized controlled trials (RCTs) and secondary evidence. For part I and II two reviewers independently selected RCTs evaluating the effect of topical oestrogens on symptoms and signs of VA and UI/OAB. In part III all studies of topical oestrogen therapy in the treatment of POP were selected. Data extraction and the assessment of risk of bias using the Cochrane Risk of Bias Tool was undertaken independently by two reviewers.

EVIDENCE SYNTHESIS

The included studies varied in ways of topical application, types of oestrogen, dosage and treatment durations. Objective and subjective outcomes were assessed by a variety of measures. Overall, subjective and urodynamic outcomes, vaginal maturation and vaginal pH changed in favor of vaginal oestrogens compared to placebo. No obvious differences between different application methods were revealed. Low doses already seemed to have a beneficial effect. Studies evaluating the effect of topical oestrogen in women with POP are scarce and mainly assessed symptoms and signs associated with VA instead of POP symptoms.

CONCLUSION

Topical oestrogen administration is effective for the treatment of VA and seems to decrease complaints of OAB and UI. The potential for local oestrogens in the prevention as well as treatment of POP needs further research.

Histological and mechanical differences in the skin of patients with rectal prolapse

INTRODUCTION

It is still an enigma that some patients develop rectal prolapse whilst others with similar risk factors do not. Biomechanical assessment of the skin may provide further insight into the aetiology of this complex condition. Elastin fibres are an abundant and integral part of many extracellular matrices and are especially critical for providing the property of elastic recoil to tissues. The significance of elastin fibres is clearly reflected by the numerous human conditions in which a skin phenotype occurs as a result of elastin fibre abnormalities.

METHOD

Between January and June 2013, skin specimens were obtained prospectively during surgery on 20 patients with rectal prolapse and 21 patients without prolapse undergoing surgery for other indications. Expression levels of elastin in the skin were measured by Orcein staining, and Image J. Tensile tests were performed using the Zwick Roell device, with custom ceramic clamps. For statistical analysis, Student's t test was used.

RESULTS

Histological analysis of prolapse vs control showed percentage dermal elastin fibres of 9 vs 5.8 % (p = 0.001) in males and 6.5 vs 5.3 % (p = 0.05) in females. Patients with more severe prolapse (external) had a significantly (p = 0.05) higher percentage dermal elastin fibres 6.9 vs 6.1 % than internal prolapse. Young's modulus of patients with prolapse was lower in males (3.3 vs 2.8, p = 0.05) and females (3.1 vs 2.7, p = 0.05).

CONCLUSION

Patients with prolapse have a higher concentration of elastin fibres in the skin, and these differences are quantitatively demonstrated through mechanical testing. This suggests that the aetiology may be a result of a dysfunction of elastin fibre assembly.

Optimization of Picrosirius red staining protocol to determine collagen fiber orientations in vaginal and uterine cervical tissues by Mueller polarized microscopy

Polarized microscopy provides unique information on anisotropic samples. In its most complete implementation, namely Mueller microscopy, this technique is well suited for the visualization of fibrillar proteins orientations, with collagen in the first place. However, the intrinsic optical anisotropy of unstained tissues has to be enhanced by Picrosirius Red (PR) staining to enable Mueller measurements. In this work, we compared the orientation mapping provided by Mueller and second harmonic generation (SHG) microscopies on PR stained samples of vaginal and uterine cervix tissues. SHG is a multiphoton technique that is highly specific to fibrillar collagen, and was taken as the "gold standard" for its visualization. We showed that Mueller microscopy can be safely used to determine collagen orientation in PR stained cervical tissue. In contrast, in vaginal samples, Mueller microscopy revealed orientations not only of collagen but also of other anisotropic structures. Thus PR is not fully specific to collagen, which necessitates comparison to SHG microscopy in every type of tissue. In addition to this study of PR specificity, we determined the optimal values of the staining parameters. We found that staining times of 5 min, and sample thicknesses of 5 µm were sufficient in cervical and vaginal tissues.

The association between vaginal parity and hiatal dimensions: a retrospective observational study in a tertiary urogynaecological centre

OBJECTIVE

Vaginal childbirth has a substantial effect on pelvic organ supports, which may be mediated by levator ani (LA) avulsion or hiatal overdistension. Although the impact of a first vaginal delivery on the hiatus has been investigated, little is known about the effect of subsequent births. This study was designed to evaluate the association between vaginal parity and hiatal dimension.

DESIGN

Retrospective observational study.

SETTING

A tertiary urogynaecological unit in Australia.

POPULATION

A total of 780 archived data sets of women seen for symptoms of lower urinary tract and pelvic floor dysfunction.

METHODS

Standardised in-house interview and assessment using the International Continence Society (ICS) pelvic organ prolapse quantification (POP-Q), and four-dimensional translabial ultrasound. Offline analysis for hiatal dimensions was undertaken blinded to history and clinical examination.

MAIN OUTCOME MEASURES

Hiatal area on maximum Valsalva.

RESULTS

Of 780 women, 64 were excluded because of missing ultrasound volumes, leaving 716 for analysis: 96% (n = 686) were parous, with a median parity of three (interquartile range, IQR 2-3), and 91.2% (n = 653) were vaginally parous. Levator avulsion was found in 21% (n = 148). The mean hiatal area on Valsalva was 29 cm(2) (SD 9.4 cm(2) ). On one-way anova, vaginal parity was significantly associated with hiatal area (P < 0.001). Most of the effect seems to occur with the first delivery. Subsequent deliveries do not seem to have any significant effect on hiatal dimensions. This remained true after controlling for potential confounding factors using multivariate regression analysis (P = 0.0123).

CONCLUSIONS

Vaginal parity was strongly associated with hiatal area on Valsalva. Most of this effect seems to be associated with the first vaginal delivery.

Collagen structure deterioration in the skin of patients with pelvic organ prolapse determined by atomic force microscopy

We used atomic force microscopy (AFM) to diagnose pathological changes in the extracellular matrix (ECM) of skin connective tissue in patients with pelvic organ prolapse (POP). POP is a common condition affecting women that considerably decreases the patients' quality of life. Deviations from normal morphology of the skin ECM from patients with POP occur including packing and arrangement of individual collagen fibers and arrangement of collagen fibrils. The nanoindentation study revealed significant deterioration of the mechanical properties of collagen fibril bundles in the skin of POP patients as compared with the skin of healthy subjects. Changes in the skin ECM appeared to correlate well with changes in the ECM of the pelvic ligament tissue associated with POP. AFM data on the ECM structure of normal and pathologically altered connective tissue were in agreement with results of the standard histological study on the same clinical specimens. Thus, AFM and related techniques may serve as independent or complementary diagnostic tools for tracking POP-related pathological changes of connective tissue.