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

Meta-analysis of the efficacy of laparoscopic uterosacral ligament suspension in patients with pelvic organ prolapse

OBJECTIVE

This study aimed to evaluate the efficacy of laparoscopic uterosacral ligament suspension (LUSLS) for pelvic organ prolapse (POP) using a meta-analysis method.

METHODS

All articles about LUSLS published in English from Jan. 2010 to Jan. 2020 were retrieved using a computer from search engines, including PubMed, EMbase, Cochrane Library, CNKI, Wanfang, VIP, and Chinese Medical Journals. Meta-analysis was performed by two evaluators using RevMan 5.3 software according to the inclusion criteria.

RESULTS

A total of five studies were finally included, with 361 LUSLS cases and 361 control cases. LUSLS group showed a shorter operation duration (SMD-1.96; 95% CI = -3.90- -0.03; P = 0.05), more POP-quantification system (Q) (I) (SMD1.64; 95% CI = 1.05-2.56; P = 0.03), than the control group, with significant differences. There was no difference in the complication incidence, hospital stay, POP-Q>=II between the 2 groups (P > 0.05).

CONCLUSION

LUSLS was a safe and effective treatment for POP. Patients had higher postoperative satisfaction, shorter operation duration and satisfactory outcome. More high-quality randomized controlled trials are required in the future to make the results of the meta-analysis more accurate.

Depth-Resolved Attenuation Mapping of the Vaginal Wall under Prolapse and after Laser Treatment Using Cross-Polarization Optical Coherence Tomography: A Pilot Study

Vaginal wall prolapse is the most common type of pelvic organ prolapse and is mainly associated with collagen bundle changes in the lamina propria. Neodymium (Nd:YAG) laser treatment was used as an innovative, minimally invasive and non-ablative procedure for the treatment of early-stage vaginal wall prolapse. The purpose of this pilot study was to assess connective tissue changes in the vaginal wall under prolapse without treatment and after Nd:YAG laser treatment using cross-polarization optical coherence tomography (CP OCT) with depth-resolved attenuation mapping. A total of 26 freshly excised samples of vaginal wall from 26 patients with age norm (n = 8), stage I-II prolapses without treatment (n = 8) and stage I-II prolapse 1-2 months after Nd:YAG laser treatment (n = 10) were assessed. As a result, for the first time, depth-resolved attenuation maps of the vaginal wall in the B-scan projection in the co- and cross-polarization channels were constructed. Two parameters within the lamina propria were target calculated: the median value and the percentages of high (≥4 mm-1) and low (<4 mm-1) attenuation coefficient values. A significant (p < 0.0001) decrease in the parameters in the case of vaginal wall prolapse compared to the age norm was identified. After laser treatment, a significant (p < 0.0001) increase in the parameters compared to the normal level was also observed. Notably, in the cross-channel, both parameters showed a greater difference between the groups than in the co-channel. Therefore, using the cross-channel achieved more reliable differentiation between the groups. To conclude, attenuation coefficient maps allow visualization and quantification of changes in the condition of the connective tissue of the vaginal wall. In the future, CP OCT could be used for in vivo detection of early-stage vaginal wall prolapse and for monitoring the effectiveness of treatment.

Injectable polyisocyanide hydrogel as healing supplement for connective tissue regeneration in an abdominal wound model

In pelvic organ prolapse (POP) patients, the uterus, bladder and/or rectum descends into vagina due to weakened support tissues. High recurrence rates after POP surgery suggest an urgent need for improved surgical outcomes. Our aim is to promote connective tissue healing that results in stimulated tissue support functions by surgically applying a hydrogel functionalized with biological cues. We used known vaginal wound healing promoting factors (basic fibroblast growth factor, β-estradiol, adipose-derived stem cells) in the biomimetic and injectable polyisocyanide (PIC) hydrogel, which in itself induces regenerative vaginal fibroblast behavior. The regenerative capacity of injected PIC hydrogel, and the additional pro-regenerative effects of these bioactive factors was evaluated in abdominal wounds in rabbits. Assessment of connective tissue healing (tensile testing, histology, immunohistochemistry) revealed that injection with all PIC formulations resulted in a statistically significant stiffness and collagen increase over time, in contrast to sham. Histological evaluation indicated new tissue growth with moderate to mild immune activity at the hydrogel - tissue interface. The results suggest that PIC injection in an abdominal wound improves healing towards regaining load-bearing capacity, which encourages us to investigate application of the hydrogel in a more translational vaginal model for POP surgery in sheep.

An experimental study of the vascular embolism caused by recombinant type III collagen implants and hyaluronic acid

BACKGROUND

There are significant differences in the reported incidence of vascular complications that result from the injection of different soft tissue fillers. This study aimed to compare the risk of vascular embolism after recombinant type III collagen implants and hyaluronic acid (HA) injection into arteries.

METHODS

Different concentrations of recombinant type III collagen and Restylane were injected into the central ear artery of rabbits, to construct an immediate embolization model. We screened for vascular recanalization and tissue necrosis at 30 min, 1 day, and 7 days after injection, and histopathology examination was processed on Day 7.

RESULTS

At 30 min after injection, complete recanalization of the central ear artery was observed in 17 rabbits in the C1 group while none in the HA group. On Day 1 after injection, complete recanalization of the CEA main trunk was observed in all rabbits in the collagen group while 50% in the HA group. There was a significant difference between the C1 group and the HA group in terms of vascular recanalization and skin necrosis.

CONCLUSION

Under the present experimental conditions, the risk of causing vascular embolism was much lower with collagen than with Restylane. Different doses of collagen at different injection rates have the same safety profile.

Age-related changes in the ratio of Type I/III collagen and fibril diameter in mouse skin

The content of type I collagen (COL-I) and type III collagen (COL-III) and the ratio between them not only affect the skin elasticity and mechanical strength, but also determine the fibril diameter. In this research, we investigated the age-related changes in COL-I/COL-III ratio with their formed fibril diameter. The experimental result was obtained from high performance liquid chromatography-mass spectrometer, hydroxyproline determination, picrosirius red staining and transmission electron microscopes (TEM), respectively. The result indicated that the COL-I/COL-III ratio in mouse skin increased with aging. From the 0th to 9th week, the COL-I/COLIII ratio increased from 1.3:1 to 4.5:1. From the 9th to the 18th week, it remained between 4.5:1 and 4.9:1. The total content of COL-I and COL-III firstly increased and then decreased with aging. The TEM result showed that the fibril diameter increased with aging. From the 0th to 9th week, the average fibril diameter increased from 40 to 112 nm; From the 9th to 18th weeks, it increased from 112 to 140 nm. After the 9th week. The fibril diameter showed obvious uneven distribution. Thus, the COL-I/COLIII ratio was proportional to the fibril diameter, but inversely proportional to the uniformity of fibril diameter.

Electrospun Silk Fibroin-CNT Composite Fibers: Characterization and Application in Mediating Fibroblast Stimulation

Electrospinning is a simple, low-cost, and highly efficient technique to generate desirable nano/microfibers from polymer solutions. Silk fibroin (SF), a biopolymer found in Bombyx mori cocoons, has attracted attention for various biomedical applications. In this study, functionalized CNT was incorporated in SF to generate biocomposite fibers by electrospinning. The electrospun (E-spun) fibers were well aligned with morphology mimicking the locally oriented ECM proteins in connective tissues. While as-spun fibers dissolved in water in just two minutes, ethanol vapor post-treatment promoted β-sheet formation leading to improved fiber stability in an aqueous environment (>14 days). The addition of a minute amount of CNT effectively improved the E-spun fiber alignment and mechanical strength while retained high biocompatibility and biodegradability. The fibers’ electrical conductivity increased by 13.7 folds and 21.8 folds, respectively, in the presence of 0.1 w% and 0.2 w% CNT in SF fibers. With aligned SF-CNT 0.1 % fibers as a cell culture matrix, we found electrical stimulation effectively activated fibroblasts from patients of pelvic organ prolapse (POP), a connective tissue disorder. The stimulation boosted the fibroblasts’ productivity of collagen III (COLIII) and collagen I (COLI) by 74 folds and 58 folds, respectively, and reduced the COLI to COLIII ratio favorable for tissue repair. The developed material and method offer a simple, direct, and effective way to remedy the dysfunctional fibroblasts of patients for personalized cell therapeutic treatment of diseases and health conditions associated with collagen disorder.

Lysyl oxidase-like 1 deficiency alters ultrastructural and biomechanical properties of the peripapillary sclera in mice

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Lysyl oxidate-like 1 knockout (Loxl1^-/-) mice have decreased vision without elevated intraocular pressure.

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Loxl1^-/- mice exhibit biometric changes of the anterior segment of the eye.

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Loxl1^-/- mice have altered elastin and collagen structure in peripapillary sclera.

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Structural alternations of peripapillary sclera correlate with its increased stiffness in Loxl1^-/- mice.

Lysyl oxidase-like 1 encoded by the LOXL1 gene is a member of the lysyl oxidase family of enzymes that are important in the maintenance of extracellular matrix (ECM)-rich tissue. LOXL1 is important for proper elastic fiber formation and mice lacking LOXL1 (Loxl1^−/−) exhibit systemic elastic fiber disorders, such as pelvic organ prolapse, a phenotype associated with exfoliation syndrome (XFS) in humans. Patients with XFS have a significant risk of developing exfoliation glaucoma (XFG), a severe form of glaucoma, which is a neurodegenerative condition leading to irreversible blindness if not detected and treated in a timely fashion. Although Loxl1^−/− mice have been used extensively to investigate mechanisms of pelvic organ prolapse, studies of eyes in those mice are limited and some showed inconsistent ocular phenotypes. In this study we demonstrate that Loxl1^−/− mice have significant anterior segment biometric abnormalities which recapitulate some human XFS features. We then focused on the peripapillary sclera (PPS), a critical structure for maintaining optic nerve health. We discovered quantitative and qualitive changes in ultrastructure of PPS, such as reduced elastic fibers, enlarged collagen fibrils, and transformed collagen lamella organization detected by transmission electron microscopy (TEM). Importantly, these changes corelate with altered tissue biomechanics detected by Atomic Force Microscopy (AFM) of PPS in mice. Together, our results support a crucial role for LOXL1 in ocular tissue structure and biomechanics, and Loxl1^−/− mice could be a valuable resource for understanding the role of scleral tissue biomechanics in ocular disease.

Distinctive structure, composition and biomechanics of collagen fibrils in vaginal wall connective tissues associated with pelvic organ prolapse

Collagen is the predominant structural protein within connective tissues. Pelvic organ prolapse (POP) is characterized by weakening of the pelvic floor connective tissues and loss of support for pelvic organs. In this study, we examined the multiscale structure, molecular composition and biomechanics of native collagen fibrils in connective tissues of the posterior vaginal fornix collected from healthy women and POP patients, and established the correlation of these properties with clinical POP quantification (POP-Q) scores. The collagen characteristics, including collagen amount, ratio of Collagen I and Collagen III, collagen fibril d-period, alignment and stiffness, were found to change progressively with the increase of the clinical measurement of Point C, a measure of uterine descent and apical prolapse. The results imply that a severe prolapse is associated with stiffer collagen fibrils, reduced collagen d-period, increased fibril alignment and imbalanced collagen synthesis, degradation and deposition. Additionally, prolapse progression appears to be synchronized with deterioration of the collagen matrix, suggesting that a POP-Q score obtained via a non-invasive clinical test can be potentially used to quantitatively assess collagen abnormality of a patient's local tissue. STATEMENT OF SIGNIFICANCE: Abnormal collagen metabolism and deposition are known to associate with connective tissue disorders, such as pelvic organ prolapse. Quantitative correlation of the biochemical and biophysical characteristics of collagen in a prolapse patient's tissue with the clinical diagnostic measurements is unexplored and unestablished. This study fills the knowledge gap between clinical prolapse quantification and the individual's cellular and molecular disorders leading to connective tissue failure, thus, provides the basis for clinicians to employ personalized treatment that can best manage the patient's condition and to alert pre-symptomatic patients for early management to avoid unwanted surgery.

Late Changes in the Extracellular Matrix of the Bladder after Radiation Therapy for Pelvic Tumors

Radiation therapy is one of the cardinal approaches in the treatment of malignant tumors of the pelvis. It leads to the development of radiation-induced complications in the normal tissues. Thus, the evaluation of radiation-induced changes in the extracellular matrix of the normal tissue is deemed urgent, since connective tissue stroma degradation plays a crucial role in the development of Grade 3-4 adverse effects (hemorrhage, necrosis, and fistula). Such adverse effects not only drastically reduce the patients' quality of life but can also become life-threatening. The aim of this study is to quantitatively analyze the bladder collagen state in patients who underwent radiation therapy for cervical and endometrial cancer and in patients with chronic bacterial cystitis and compare them to the normal bladder extracellular matrix.

MATERIALS AND METHODS

One hundred and five patients with Grade 2-4 of radiation cystitis, 67 patients with bacterial chronic cystitis, and 20 volunteers without bladder pathology were enrolled. Collagen changes were evaluated depending on its hierarchical level: fibrils and fibers level by atomic force microscopy; fibers and bundles level by two-photon microscopy in the second harmonic generation (SHG) mode; general collagen architectonics by cross-polarization optical coherence tomography (CP OCT).

RESULTS

The main sign of the radiation-induced damage of collagen fibrils and fibers was the loss of the ordered "basket-weave" packing and a significant increase in the total area of ruptures deeper than 1 µm compared to the intact sample. The numerical analysis of SHG images detected that a decrease in the SHG signal intensity of collagen is correlated with the increase in the grade of radiation cystitis. The OCT signal brightness in cross-polarization images demonstrated a gradual decrease compared to the intact bladder depending on the grade of the adverse event.

CONCLUSIONS

The observed correspondence between the extracellular matrix changes at the microscopic level and at the level of the general organ architectonics allows for the consideration of CP OCT as a method of "optical biopsy" in the grading of radiation-induced collagen damage.

Effects of the decrease of β-catenin expression on human vaginal fibroblasts of women with pelvic organ prolapse

BACKGROUND

Pelvic organ prolapse (POP) lowers the quality of life in elderly women, and there have been no studies on its role in the pathogenesis of POP. The purpose of this study is to investigate the effect of β-catenin on proliferation and collagen anabolism in human vaginal fibroblasts (HVFs).

MATERIALS AND METHODS

The adherence and differential adherence methods were used to culture and purify HVFs. RNA interference was applied to knockdown β-catenin and lithium chloride was used to activate Wnt/β-catenin signaling pathway. β-catenin nuclear translocation was tested by immunofluorescence, and HVF proliferation was detected by performing MTT assays.

RESULTS

The expression of β-catenin, phosphorylated-β-catenin, phosphorylated-glycogen synthase kinase 3β (p-GSK3β), collagen I, matrix metalloproteinase 2 (MMP2), and tissue-derived inhibitors of metalloproteinases 2 (TIMP2) was assessed by western blot analysis. The expression of β-catenin and collagen I was lower in HVFs of POP group than that of control group. The proliferation rate of HVFs in POP group was lower than that in control group. Knockdown of β-catenin decreased the cell proliferation rate and the expression of collagen I. Lithium chloride can activate the Wnt/β-catenin signaling pathway.

CONCLUSION

β-catenin participates in the proliferation and collagen I synthesis of HVFs. The decrease of β-catenin expression may be closely related to the occurrence, and development of POP. LiCl can activate the Wnt/β-catenin signaling pathway in HVFs and thus increase HVFs proliferation and collagen synthesis.

Aligned Collagen-CNT Nanofibrils and the Modulation Effect on Ovarian Cancer Cells

Fibrillar collagen is a one-dimensional biopolymer and is the most abundant structural protein in the extracellular matrix (ECM) of connective tissues. Due to the unique properties of carbon nanotubes (CNTs), considerable attention has been given to the application of CNTs in developing biocomposite materials for tissue engineering and drug delivery. When introduced to tissues, CNTs inevitably interact and integrate with collagen and impose a discernible effect on cells in the vicinity. The positive effect of the collagen-CNT (COL-CNT) matrix in tissue regeneration and the cytotoxicity of free CNTs have been investigated extensively. In this study, we aimed to examine the effect of COL-CNT on mediating the interaction between the matrix and SKOV3 ovarian cancer cells. We generated unidirectionally aligned collagen and COL-CNT nanofibrils, mimicking the structure and dimension of collagen fibrils in native tissues. AFM analysis revealed that the one-dimensional structure, high stiffness, and low adhesion of COL-CNT greatly facilitated the polarization of SKOV3 cells by regulating the β−1 integrin-mediated cell–matrix interaction, cytoskeleton rearrangement, and cell migration. Protein and gene level analyses implied that both collagen and COL-CNT matrices induced the epithelial–mesenchymal transition (EMT), and the COL-CNT matrix prompted a higher level of cell transformation. However, the induced cells expressed CD44 at a reduced level and MMP2 at an increased level, and they were responsive to the chemotherapy drug gemcitabine. The results suggested that the COL-CNT matrix induced the transdifferentiation of the epithelial cancer cells to mature, less aggressive, and less potent cells, which are inapt for tumor metastasis and chemoresistance. Thus, the presence of CNT in a collagen matrix is unlikely to cause an adverse effect on cancer patients if a controlled dose of CNT is used for drug delivery or tissue regeneration.

Distinctive roles of fibrillar collagen I and collagen III in mediating fibroblast-matrix interaction: A nanoscopic study

One major goal in tissue engineering is to create functional materials, mimicking scaffolds in native tissues, to modulate cell function for tissue repair. Collagen is the most abundant structural protein in human body. Though collagen I (COLI) and collagen III (COLIII) are the predominant collagen types in connective tissues and they form stable hybrid fibrils at varied ratios, cell responses to the hybrid matrices are underinvestigated. In this work, we aim to explicate the distinctive roles of COLI and COLIII in fibroblast activation. Unidirectionally aligned COLI, COLIII and COLI-COLIII hybrid nanofibrils were generated via epitaxial growth of collagen on mica. AFM analyses revealed that, with the increase of COLI/COLIII ratio, the fibril width and stiffness increased and the binding affinity of cells to the matrix decreased. A hybrid matrix was found to activate fibroblasts the most effectively, characterized by extensive cell polarization with rigid stress fiber bundles and high α-SMA expression, and by the highest-level of collagen synthesis. It is ascribed to the fine balance between biochemical and biophysical cues achieved on the hybrid matrix. Thus, matrices of aligned COLI-COLIII hybrid fibrils and their derived multifunctional composites can be good candidates of implantation scaffolds for tissue regeneration.

Evaluation of extracellular matrix protein expression and apoptosis in the uterosacral ligaments of patients with or without pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

This study aimed to compare the expression levels of extracellular matrix (ECM) and apoptosis proteins in the uterosacral ligament (USL) of patients with and without pelvic organ prolapse (POP).

METHODS

The USL were obtained from patients with POP-Q ≥ III (n = 35) and without POP (n = 20). Immunohistochemistry (IHC) staining and RT-qPCR were conducted to assess the protein and mRNA levels, respectively. The levels of type I collagen (COLI), type III collagen (COLIII), matrix metalloproteinase (MMP)1, MMP2, MMP9, tissue inhibitor of metalloproteinase (TIMP)1, TIMP2, estrogen receptor (ER)α, ERβ and apoptosis-related gene B cell lymphoma 2 (Bcl-2)-associated agonist of cell death (Bad) and Bcl-2-associated X (Bax) in the USL were analyzed.

RESULTS

The protein expression and mRNA levels of MMP2 and MMP9, mRNA levels of BAD and BAX, and protein expression of active cleaved-Caspase3 were significantly higher in the POP group. There were no evident differences in COLIII, MMP1 or ERβ expression at either the mRNA or protein level or in TIMP1, TIMP2 or Caspase3 by IHC between the two groups. However, obvious decreases in COLI and ERα were evident at both the mRNA and protein levels in the POP group, and the mRNA levels of TIMP1 and TIMP2 were also decreased compared to those of the control group.

CONCLUSION

ECM in the USL tissues of POP patients is remodeled compared with non-POP patients and is characterized by decreased synthesis and increased degradation of collagen; moreover, the levels of the main proteins involved in apoptosis are increased in POP tissue.

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.

Electrospun Nanofiber Meshes With Endometrial MSCs Modulate Foreign Body Response by Increased Angiogenesis, Matrix Synthesis, and Anti-Inflammatory Gene Expression in Mice: Implication in Pelvic Floor

Purpose

Transvaginal meshes for the treatment of Pelvic Organ Prolapse (POP) have been associated with severe adverse events and have been banned for clinical use in many countries. We recently reported the design of degradable poly L-lactic acid-co-poly ε-caprolactone nanofibrous mesh (P nanomesh) bioengineered with endometrial mesenchymal stem/stromal cells (eMSC) for POP repair. We showed that such bioengineered meshes had high tissue integration as well as immunomodulatory effects in vivo. This study aimed to determine the key molecular players enabling eMSC-based foreign body response modulation.

Methods

SUSD2⁺ eMSC were purified from single cell suspensions obtained from endometrial biopsies from cycling women by magnetic bead sorting. Electrospun P nanomeshes with and without eMSC were implanted in a NSG mouse skin wound repair model for 1 and 6 weeks. Quantitative PCR was used to assess the expression of extracellular matrix (ECM), cell adhesion, angiogenesis and inflammation genes as log₂ fold changes compared to sham controls. Histology and immunostaining were used to visualize the ECM, blood vessels, and multinucleated foreign body giant cells around implants.

Results

Bioengineered P nanomesh/eMSC constructs explanted after 6 weeks showed significant increase in 35 genes associated with ECM, ECM regulation, cell adhesion angiogenesis, and immune response in comparison to P nanomesh alone. In the absence of eMSC, acute inflammatory genes were significantly elevated at 1 week. However, in the presence of eMSC, there was an increased expression of anti-inflammatory genes including Mrc1 and Arg1 by 6 weeks. There was formation of multinucleated foreign body giant cells around both implants at 6 weeks that expressed CD206, a M2 macrophage marker.

Conclusion

This study reveals that eMSC modulate the foreign body response to degradable P nanomeshes in vivo by altering the expression profile of mouse genes. eMSC reduce acute inflammatory and increase ECM synthesis, angiogenesis and anti-inflammatory gene expression at 6 weeks while forming newly synthesized collagen within the nanomeshes and neo-vasculature in close proximity. From a tissue engineering perspective, this is a hallmark of a highly successful implant, suggesting significant potential as alternative surgical constructs for the treatment of POP.

Comparison of the Structural Characteristics of Native Collagen Fibrils Derived from Bovine Tendons using Two Different Methods: Modified Acid-Solubilized and Pepsin-Aided Extraction

Native collagen fibrils (CF) were successfully extracted from bovine tendons using two different methods: modified acid-solubilized extraction for A-CF and pepsin-aided method for P-CF. The yields of A-CF and P-CF were up to 64.91% (±1.07% SD) and 56.78% (±1.22% SD) (dry weight basis), respectively. The analyses of both amino acid composition and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) confirmed that A-CF and P-CF were type I collagen fibrils. Both A-CF and P-CF retained the intact crystallinity and integrity of type I collagen’s natural structure by FTIR spectra, circular dichroism spectroscopy (CD) and X-ray diffraction detection. The aggregation structures of A-CF and P-CF were displayed by UV–Vis. However, A-CF showed more intact aggregation structure than P-CF. Microstructure and D-periodicities of A-CF and P-CF were observed (SEM and TEM). The diameters of A-CF and P-CF are about 386 and 282 nm, respectively. Although both A-CF and P-CF were theoretically concordant with the Schmitt hypothesis, A-CF was of evener thickness and higher integrity in terms of aggregation structure than P-CF. Modified acid-solubilized method provides a potential non-enzyme alternative to extract native collagen fibrils with uniform thickness and integral aggregation structure.

Changes in β-Catenin Expression in the Anterior Vaginal Wall Tissues of Women With Pelvic Organ Prolapse: A Potential Pathophysiological Mechanism

OBJECTIVES

The purpose of this study was to investigate the expression of β-catenin in the lamina propria of the anterior vaginal wall of women with pelvic organ prolapse (POP) compared with the expression in the controls.

METHODS

Anterior vaginal wall tissues were obtained from women undergoing POP surgery for stage 3 or greater POP (POP group, n = 30; age, 58 ± 7.839 years), with a menopause rate of 70%, and from women without POP undergoing hysterectomy for benign indications (control group, n = 30; age, 54.7 ± 7.173 years), with a menopause rate of 50%. Hematoxylin and eosin staining and Masson trichrome staining were performed on anterior vaginal wall sections. β-Catenin, p-β-catenin, glycogen synthase kinase 3β (GSK3β), p-GSK3β, collagen I, collagen III, MMP2, MMP9, TIMP2, caspase 3, proliferating cell nuclear antigen, and cyclin D1 were evaluated using immunohistochemical analysis. Lamina propria tissues were obtained for Western blot analyses.

RESULTS

Hematoxylin and eosin staining and Masson trichrome staining showed that the collagen fibers were more disorganized and fragmented in the POP group than in the control group. In the POP samples, β-catenin (mean density, POP vs control, 0.43 ± 0.13 vs 0.58 ± 0.16), p-GSK3β, collagen I, collagen III, proliferating cell nuclear antigen, and cyclin D1 were downregulated in the lamina propria, whereas in the control group, p-β-catenin, TIMP2, and caspase 3 were downregulated (P < 0.05 for all). GSK3β was not different between the 2 groups (P > 0.05).

CONCLUSION

We demonstrated that decreased β-catenin may play an important role in the onset of POP by affecting collagen anabolism.

Mitofusin2 regulates the proliferation and function of fibroblasts: The possible mechanisms underlying pelvic organ prolapse development

The present study aimed to investigate the effects of Mitofusin2 (Mfn2) on the proliferation of human uterosacral ligament fibroblasts and on the expression of procollagen. We also aimed to identify the possible signal transduction pathway involved in the development of pelvic organ prolapse (POP). For this purpose, uterosacral ligaments were harvested from POP and non‑pelvic organ prolapse (NPOP) patients for fibroblast culture. Cellular proliferation and the cell cycle were assessed following transduction with lentiviral vectors for the overexpression and suppression of Mfn2. The expression levels of the proteins Mfn2, procollagens, phosphoprotein 21 wild‑type p53 activating fragment (p21Waf1), cyclin‑dependent kinase 2 (CDK2), extracellular signal‑regulated kinase1/2 (ERK1/2) and rapidly accelerated fibrosarcoma‑1 (Raf‑1) were examined. Overexpression of Mfn2 resulted in the decreased proliferation of cells and the induction of G0/G1 phase arrest. Concomitantly, the relative expression levels of procollagen proteins, CDK2 and the phosphorylation levels of ERK1/2 and Raf‑1 proteins were notably decreased, while the levels of the p21waf1 protein were increased in the Mfn2 overexpressing group. Opposing results were reported cells following Mfn2 silencing via RNA interference. The results of the present study indicated that the cell cycle of the fibroblasts, their cellular proliferation and the levels of the procollagen proteins could be inhibited via the Ras‑Raf‑ERK axis as a result of the increased levels of Mfn2 during the development of POP.

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.

Electrospun protein-CNT composite fibers and the application in fibroblast stimulation

Functional biopolymer scaffolds are in high demand for tissue regeneration. In this study, we incorporated functionalized CNT in collagen or silk protein solution to generate biocomposite fibers by electrospinning. The addition of CNT reinforced the strength of the scaffolds and rendered the fibers electrical conductivity to not only facilitate the E-spun fiber formation but also grant the fibers an additional functionality that can be utilized for cell stimulation. Considering fiber dimension, alignment, mechanical strength, electrical conductivity and biocompatibility, silk-CNT fibers containing a minute amount of CNT (0.05%) outperformed other fiber types. The modulation effect of these fibers was examined by their application in inducing polarization and activation of fibroblasts with cellular deficit. While the fibroblasts on both collagen-CNT and silk-CNT fibers synthesized a substantially higher level of collagen type III (COLIII) than cells on pure protein fibers to reduce the abnormally high COLI/COLIII ratio, electrical stimulation boosted the collagen productivity by 20 folds in cells on silk-CNT than on collagen-CNT due to silk-CNT's high electrical conductivity. The developed approach can be potentially utilized to remedy the dysfunctional fibroblasts for therapeutic treatment of diseases and health conditions associated with collagen disorder.

Technique development and measurement of cross-sectional area of the pubovisceral muscle on MRI scans of living women

INTRODUCTION AND HYPOTHESIS

Measurements of the anatomic cross-sectional area (CSA) of the pubovisceral muscle (PVM) in women are confounded by the difficulty of separating the muscle from the adjacent puborectal (PRM) and iliococcygeal (ICM) muscles when visualized in a plane orthogonal to the fiber direction. We tested the hypothesis that it might be possible to measure the PVM CSA within a defined region of interest based on magnetic resonance images (MRI).

METHODS

MRI scans of 11 women with unilateral PVM tears and seven primiparous women with intact muscles following elective C-section were used to identify the PVM injury zone defined by the mean location of its boundaries with the adjacent intact PRM and ICM from existing anatomic reference points using 3D Slicer and ImageJ software. Then, from the 15 or more 2-mm transverse slices available, the slice with the maximum anatomic CSA of the left and right PVM was found in 24 primiparous women with bilaterally intact muscles who had delivered via C-section.

RESULTS

Mean [± standard deviation (SD)] of the maximum left or right PVM cross-section areas for the 24 women, measured by two different raters, was 1.25 ± 0.29 cm² (range 0.75-1.86). The 5th, 50th, and 95th percentile values were 0.77, 1.23, and 1.80 cm², respectively. Inter- and intrarater measurement repeatability intraclass correlation coefficients exceeded 0.89 and 0.90, respectively.

CONCLUSIONS

It is possible to use MRI to identify the volume of interest with the maximum anatomic cross section of the PVM belly while minimizing the inadvertent inclusion of adjacent PRM or ICM in that measurement.

Early Effects of Ionizing Radiation on the Collagen Hierarchical Structure of Bladder and Rectum Visualized by Atomic Force Microscopy

Radiation therapy, widely used in the treatment of a variety of malignancies in the pelvic area, is associated with inevitable damage to the surrounding healthy tissues. We have applied atomic force microscopy (AFM) to track the early damaging effects of ionizing radiation on the collagen structures in the experimental animals' bladder and rectum. The first signs of the low-dose radiation (2 Gy) effect were detected by AFM as early as 1 week postirradiation. The observed changes were consistent with initial radiation destruction of the protein matrix. The alterations in the collagen fibers' packing 1 month postirradiation were indicative of the onset of fibrotic processes. The destructive effect of higher radiation doses was probed 1 day posttreatment. The severity of the radiation damage was proportional to the dose, from relatively minor changes in the collagen packing at 8 Gy to the growing collagen matrix destruction at higher doses and complete three-dimensional collagen network restructuring towards fibrotic-type architecture at the dose of 22 Gy. The AFM study appeared superior to the optical microscopy-based studies in its sensitivity to early radiation damage of tissues, providing valuable additional information on the onset and development of the collagen matrix destruction and remodeling.

Correlations between Mitofusin 2 Expression in Fibroblasts and Pelvic Organ Prolapse: An In vitro Study

BACKGROUND

Both Mitofusin 2 (Mfn2) and pelvic organ prolapse (POP) are related to aging. The aim of the present study was to investigate the variations of Mfn2 expression in the uterosacral ligaments of patients with and/or without POP and their correlations with the expression of procollagen.

METHODS

Fibroblasts were cultured using tissue specimens that were harvested from the uterosacral ligaments of POP and non-POP (NPOP) patients (n = 10 for each group) from September 2016 to December 2016. The Cell Counting Kit-8 (CCK-8) assay was used to compare the differences in cell proliferation between the two groups. Relative quantitative reverse transcription-polymerase chain reaction and Western blotting assays were employed to assess the differences in the mRNA and protein expression levels of Mfn2 and procollagen 1A1/1A2/3A1 between the two groups. The changes in procollagen expression were assessed following the downregulation of Mfn2 in the POP group using RNAi. The data were assessed with independent sample t- test or general linear model univariate analysis using the SPSS 13.0 software.

RESULTS

The results from CCK-8 assay indicated that cell viability in the POP group was significantly lower compared with that of the NPOP group (td5, 7, 9, 11= -5.925, -6.851, -9.129, and -9.661, respectively, all P < 0.001, from D5 to D11). The mRNA and protein expression levels of Mfn2 in the cultured fibroblasts of the POP group were significantly higher compared with those of the NPOP group (mRNA: t = 2.425, P = 0.032; protein: t = 2.392, P = 0.037, respectively), whereas only the expression levels of procollagen 1A1/1A2/3A1 were significantly higher in the NPOP group (mRNA: t = -2.165, P1A1 = 0.041; t = -2.741, P1A2 = 0.026; t = -2.147, P3A1 = 0.045, respectively; protein: t = -2.418, P1A1 = 0.029; t = -2.405, P1A2 = 0.033; t = -2.470, P3A1 = 0.012, respectively). The expression levels of procollagen in the POP group increased following the downregulation of Mfn2.

CONCLUSIONS

The proliferation rate and cell viability of the fibroblasts in the POP group were significantly lower compared with those in the NPOP group. In the POP fibroblasts, Mfn2 expression was increased, while procollagen expression was decreased.