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Gimenez C, Alperin M, De Vita R. The Effect of Menopause on Vaginal Tissue Mechanics: A Brief Review. J Biomech Eng 2024; 146:060903. [PMID: 37542707 DOI: 10.1115/1.4063101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 08/01/2023] [Indexed: 08/07/2023]
Abstract
Often called "the change of life," menopause affects every part of a woman's body. As the sex hormones decrease, the reproductive organs experience the most remarkable changes, with the vagina becoming thinner, drier, and less elastic. Despite the important implications of these changes in genitourinary conditions, there are only a few experimental studies that focus on quantifying the effect of menopause on the mechanical properties of the vagina. These studies are mostly conducted using uniaxial tests on strips of vaginal tissues isolated from rats, rabbits, and sheep and, in only a few cases, from humans. The purpose of this article is to present a systematic review of experimental protocols, methods, and results that are currently published on how menopause alters the mechanical behavior of the vagina. This review will enable new investigators in the biomechanics field to identify important gaps and frame research questions that inform the design of new treatment options for menopausal symptoms.
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Affiliation(s)
- Clara Gimenez
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061
- Virginia Tech
| | - Marianna Alperin
- Division of Urogynecology and Pelvic Reconstructive Surgery, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Diego, Sanford Consortium for Regenerative Medicine, La Jolla, CA 92097
| | - Raffaella De Vita
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061
- Virginia Tech Services
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2
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Mahapatra C, Kumar R. Biophysical Mechanisms of Vaginal Smooth Muscle Contraction: The Role of the Membrane Potential and Ion Channels. PATHOPHYSIOLOGY 2024; 31:225-243. [PMID: 38804298 PMCID: PMC11130850 DOI: 10.3390/pathophysiology31020018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/10/2024] [Accepted: 05/14/2024] [Indexed: 05/29/2024] Open
Abstract
The vagina is an essential component of the female reproductive system and is responsible for providing female sexual satisfaction. Vaginal smooth muscle contraction plays a crucial role in various physiological processes, including sexual arousal, childbirth, and urinary continence. In pathophysiological conditions, such as pelvic floor disorders, aberrations in vaginal smooth muscle function can lead to urinary incontinence and pelvic organ prolapse. A set of cellular and sub-cellular physiological mechanisms regulates the contractile properties of the vaginal smooth muscle cells. Calcium influx is a crucial determinant of smooth muscle contraction, facilitated through voltage-dependent calcium channels and calcium release from intracellular stores. Comprehensive reviews on smooth muscle biophysics are relatively scarce within the scientific literature, likely due to the complexity and specialized nature of the topic. The objective of this review is to provide a comprehensive description of alterations in the cellular physiology of vaginal smooth muscle contraction. The benefit associated with this particular approach is that conducting a comprehensive examination of the cellular mechanisms underlying contractile activation will enable the creation of more targeted therapeutic agents to control vaginal contraction disorders.
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Affiliation(s)
- Chitaranjan Mahapatra
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158, USA
- Paris Saclay Institute of Neuroscience, 91440 Saclay, France
| | - Ravinder Kumar
- Department of Pathology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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3
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White SE, Karbasion N, Snider JC, Florian-Rodriguez M, Bersi MR, Miller KS. Remodeling of murine vaginal smooth muscle function with reproductive age and elastic fiber disruption. Acta Biomater 2024; 175:186-198. [PMID: 38151068 DOI: 10.1016/j.actbio.2023.12.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 12/19/2023] [Accepted: 12/21/2023] [Indexed: 12/29/2023]
Abstract
Advanced maternal age during pregnancy is associated with increased risk of vaginal tearing during delivery and maladaptive postpartum healing. Although the underlying mechanisms of age-related vaginal injuries are not fully elucidated, changes in vaginal microstructure may contribute. Smooth muscle cells promote the contractile nature of the vagina and contribute to pelvic floor stability. While menopause is associated with decreased vaginal smooth muscle content, whether contractile changes occur before the onset of menopause remains unknown. Therefore, the first objective of this study was to quantify the active mechanical behavior of the murine vagina with age. Further, aging is associated with decreased vaginal elastin content. As such, the second objective was to determine if elastic fiber disruption alters vaginal contractility. Vaginal samples from mice aged 2-14 months were used in maximum contractility experiments and biaxial extension-inflation protocols. To evaluate the role of elastic fibers with age, half of the vaginal samples were randomly allocated to enzymatic elastic fiber disruption. Contractile potential decreased and vaginal material stiffness increased with age. These age-related changes in smooth muscle function may be due, in part, to changes in microstructural composition or contractile gene expression. Furthermore, elastic fiber disruption had a diminished effect on smooth muscle contractility in older mice. This suggests a decreased functional role of elastic fibers with age. Quantifying the age-dependent mechanical contribution of smooth muscle cells and elastic fibers to vaginal properties provides a first step towards better understanding how age-related changes in vaginal structure may contribute to tissue integrity and healing. STATEMENT OF SIGNIFICANCE: Advanced maternal age at the time of pregnancy is linked to increased risks of vaginal tearing during delivery, postpartum hemorrhaging, and the development of pelvic floor disorders. While the underlying causes of increased vaginal injuries with age and associated pathologies remain unclear, changes in vaginal microstructure, such as elastic fibers and smooth muscle cells, may contribute. Menopause is associated with fragmented elastic fibers and decreased smooth muscle content; however, how reproductive aging affects changes in the vaginal composition and the mechanical properties remains unknown. Quantifying the mechanical contribution of smooth muscle cells and elastic fibers to vaginal properties with age will advance understanding of the potential structural causes of age-related changes to tissue integrity and healing.
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Affiliation(s)
- Shelby E White
- Department of Biomedical Engineering, Tulane University, New Orleans, LA, USA
| | - Niyousha Karbasion
- Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA
| | - J Caleb Snider
- Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Maria Florian-Rodriguez
- Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Matthew R Bersi
- Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Kristin S Miller
- Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Mechanical Engineering, University of Texas at Dallas, Richardson, TX, USA; Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA.
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Suarez AC, Gimenez CJ, Russell SR, Wang M, Munson JM, Myers KM, Miller KS, Abramowitch SD, De Vita R. Pregnancy-induced remodeling of the murine reproductive tract: a longitudinal in vivo magnetic resonance imaging study. Sci Rep 2024; 14:586. [PMID: 38182631 PMCID: PMC10770079 DOI: 10.1038/s41598-023-50437-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 12/20/2023] [Indexed: 01/07/2024] Open
Abstract
Mammalian pregnancy requires gradual yet extreme remodeling of the reproductive organs to support the growth of the embryos and their birth. After delivery, the reproductive organs return to their non-pregnant state. As pregnancy has traditionally been understudied, there are many unknowns pertaining to the mechanisms behind this remarkable remodeling and repair process which, when not successful, can lead to pregnancy-related complications such as maternal trauma, pre-term birth, and pelvic floor disorders. This study presents the first longitudinal imaging data that focuses on revealing anatomical alterations of the vagina, cervix, and uterine horns during pregnancy and postpartum using the mouse model. By utilizing advanced magnetic resonance imaging (MRI) technology, T1-weighted and T2-weighted images of the reproductive organs of three mice in their in vivo environment were collected at five time points: non-pregnant, mid-pregnant (gestation day: 9-10), late pregnant (gestation day: 16-17), postpartum (24-72 h after delivery) and three weeks postpartum. Measurements of the vagina, cervix, and uterine horns were taken by analyzing MRI segmentations of these organs. The cross-sectional diameter, length, and volume of the vagina increased in late pregnancy and then returned to non-pregnant values three weeks after delivery. The cross-sectional diameter of the cervix decreased at mid-pregnancy before increasing in late pregnancy. The volume of the cervix peaked at late pregnancy before shortening by 24-72 h postpartum. As expected, the uterus increased in cross-sectional diameter, length, and volume during pregnancy. The uterine horns decreased in size postpartum, ultimately returning to their average non-pregnant size three weeks postpartum. The newly developed methods for acquiring longitudinal in vivo MRI scans of the murine reproductive system can be extended to future studies that evaluate functional and morphological alterations of this system due to pathologies, interventions, and treatments.
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Affiliation(s)
- Aileen C Suarez
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, 325 Stanger Street, Blacksburg, VA, 24061, USA
| | - Clara J Gimenez
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, 325 Stanger Street, Blacksburg, VA, 24061, USA
| | - Serena R Russell
- Department of Mechanical Engineering, Columbia University, 234 S W. Mudd, New York, NY, 10027, USA
| | - Maosen Wang
- Fralin Biomedical Research Institute, Virginia Tech, 4 Riverside Circle,, Roanoke, VA, 24016, USA
| | - Jennifer M Munson
- Fralin Biomedical Research Institute, Virginia Tech, 4 Riverside Circle,, Roanoke, VA, 24016, USA
| | - Kristin M Myers
- Department of Mechanical Engineering, Columbia University, 234 S W. Mudd, New York, NY, 10027, USA
| | - Kristin S Miller
- Department of Mechanical Engineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Steven D Abramowitch
- Department of Bioengineering, University of Pittsburgh, 3700 O'Hara Street, Pittsburgh, PA, 15261, USA
| | - Raffaella De Vita
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, 325 Stanger Street, Blacksburg, VA, 24061, USA.
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Sueters J, Xiao F, Roovers JP, Bouman MB, Groenman F, Maas H, Huirne J, Smit T. Creation of a decellularized vaginal matrix from healthy human vaginal tissue for potential vagina reconstruction: experimental studies. Int J Surg 2023; 109:3905-3918. [PMID: 37755377 PMCID: PMC10720790 DOI: 10.1097/js9.0000000000000727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 08/21/2023] [Indexed: 09/28/2023]
Abstract
BACKGROUND When a disorder causes the absence of a healthy, full-size vagina, various neovaginal creation methods are available. Sometimes dilation or stretching of the vaginal cavity is sufficient, but intestinal or dermal flap tissue is generally required. However, different inherent tissue properties cause complications. Therefore, a lost body part should be replaced with a similar material. The use of organ-specific acellular vaginal tissue carries great potential, as its similar architecture and matrix composition make it suitable for vaginal regeneration. METHODS The authors developed an optimized protocol for decellularization of healthy human vaginal tissue. Resected colpectomy tissue from 12 healthy transgender patients was used. Successful decellularization was confirmed by applying acellular criteria from in-vivo remodeling reports. Suitability as a tissue-mimicking scaffold for vaginal reconstruction was determined by visible structural features, biocompatibility during stretching, and the presence of visible collagen, elastin, laminin, and fibronectin. RESULTS Histological examination confirmed the preservation of structural features, and minimal cellular residue was seen during fluorescence microscopy, DNA and RNA quantification, and fragment length examination. Biomechanical testing showed decreased peak load (55%, P <0.05), strain at rupture (23%, P <0.01), and ultimate tensile stress (55%, P <0.05) after decellularization, while the elastic modulus (68%) did not decrease significantly. Fluorescence microscopy revealed preserved Fibronectin-I/II/III and Laminin-I/II, while Collagen-I and Ficolin-2B were decreased but mostly retained. CONCLUSIONS The absence of cellular residue, moderately altered biomechanical extracellular matrix properties, and mostly preserved structural proteins appear to make our decellularized human vaginal matrix a suitable tissue-mimicking scaffold for vagina transplantation when tissue survival through vascularization and innervation are accomplished in the future.
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Affiliation(s)
- Jayson Sueters
- Department of Gynaecology, Amsterdam Reproduction and Development
| | - Fangxin Xiao
- Department of Human Movement Sciences, Faculty of Behavioral and Movement Sciences, Vrije Universiteit Amsterdam
- AMS – Musculoskeletal Health, Amsterdam Movement Sciences, VU Research Institutes
- School of Exercise and Health, Shanghai University of Sport, Shanghai, China
| | - Jan-Paul Roovers
- Department of Obstetrics and Gynecology, Amsterdam Reproduction and Development
| | - Mark-Bram Bouman
- Department of Plastic, Reconstructive and Hand Surgery, Amsterdam UMC – location VUmc
| | - Freek Groenman
- Department of Obstetrics and Gynecology, Amsterdam Reproduction and Development
| | - Huub Maas
- Department of Plastic, Reconstructive and Hand Surgery, Amsterdam UMC – location VUmc
- Department of Human Movement Sciences, Faculty of Behavioral and Movement Sciences, Vrije Universiteit Amsterdam
| | - Judith Huirne
- Department of Gynaecology, Amsterdam Reproduction and Development
| | - Theo Smit
- Department of Gynaecology, Amsterdam Reproduction and Development
- Department of Medical Biology, Amsterdam UMC – location AMC, Amsterdam, The Netherlands
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Clark-Patterson GL, Buchanan LM, Ogola BO, Florian-Rodriguez M, Lindsey SH, De Vita R, Miller KS. Smooth muscle contribution to vaginal viscoelastic response. J Mech Behav Biomed Mater 2023; 140:105702. [PMID: 36764168 DOI: 10.1016/j.jmbbm.2023.105702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/22/2023] [Accepted: 02/01/2023] [Indexed: 02/05/2023]
Abstract
Smooth muscle cells contribute to the mechanical function of various soft tissues, however, their contribution to the viscoelastic response when subjected to multiaxial loading remains unknown. The vagina is a fibromuscular viscoelastic organ that is exposed to prolonged and increased pressures with daily activities and physiologic processes such as vaginal birth. The vagina changes in geometry over time under prolonged pressure, known as creep. Vaginal smooth muscle cells may contribute to creep. This may be critical for the function of vaginal and other soft tissues that experience fluctuations in their biomechanical environment. Therefore, the objective of this study was to develop methods to evaluate the contribution of smooth muscle to vaginal creep under multiaxial loading using extension - inflation tests. The vaginas from wildtype mice (C57BL/6 × 129SvEv; 3-6 months; n = 10) were stimulated with various concentrations of potassium chloride then subjected to the measured in vivo pressure (7 mmHg) for 100 s. In a different cohort of mice (n = 5), the vagina was stimulated with a single concentration of potassium chloride then subjected to 5 and 15 mmHg. A laser micrometer measured vaginal outer diameter in real-time. Immunofluorescence evaluated the expression of alpha-smooth muscle actin and myosin heavy chain in the vaginal muscularis (n = 6). When smooth muscle contraction was activated, vaginal creep behavior increased compared to the relaxed state. However, increased pressure decreased the active creep response. This study demonstrated that extension - inflation protocols can be used to evaluate smooth muscle contribution to the viscoelastic response of tubular soft tissues.
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Affiliation(s)
| | - Lily M Buchanan
- University of Texas at Dallas, Department of Bioengineering, 800 W. Campbell Road, Richardson, TX, 75080, USA.
| | - Benard O Ogola
- Augusta University, Vascular Biology Center, Medical College of Georgia at Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912, USA.
| | - Maria Florian-Rodriguez
- University of Texas Southwestern Medical Center, Department of Obstetrics and Gynecology, Division of Female Pelvic Medicine and Reconstructive Surgery and Cecil H and Ida Green Center for Reproductive Biological Sciences, 5323 Harry Hines Boulevard, Dallas, TX, 75390-9032, USA.
| | - Sarah H Lindsey
- Tulane University School of Medicine, Department of Pharmacology, 1430 Tulane Ave, New Orleans, LA, 70112, USA.
| | - Raffaella De Vita
- Virginia Tech,Department of Biomedical Engineering and Mechanics, 330 A Kelly Hall, 325 Stanger St, Blacksburg, VA, 24061, USA.
| | - Kristin S Miller
- Tulane University, Department of Biomedical Engineering, 6823 St Charles Ave, New Orleans, LA, 70118, USA; University of Texas at Dallas, Department of Bioengineering, 800 W. Campbell Road, Richardson, TX, 75080, USA.
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7
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Snyder W, McGuire JA, Mou C, Dillard DA, Iliescu T, De Vita R. Data-driven variational multiscale reduced order modeling of vaginal tissue inflation. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023; 39:e3660. [PMID: 36333869 DOI: 10.1002/cnm.3660] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 09/04/2022] [Accepted: 10/30/2022] [Indexed: 06/16/2023]
Abstract
The vagina undergoes large finite deformations and has complex geometry and microstructure, resulting in material and geometric nonlinearities, complicated boundary conditions, and nonhomogeneities within finite element (FE) simulations. These nonlinearities pose a significant challenge for numerical solvers, increasing the computational time by several orders of magnitude. Simplifying assumptions can reduce the computational time significantly, but this usually comes at the expense of simulation accuracy. This study proposed the use of reduced order modeling (ROM) techniques to capture experimentally measured displacement fields of rat vaginal tissue during inflation testing in order to attain both the accuracy of higher-fidelity models and the speed of simpler simulations. The proper orthogonal decomposition (POD) method was used to extract the significant information from FE simulations generated by varying the luminal pressure and the parameters that introduce the anisotropy in the selected constitutive model. A new data-driven (DD) variational multiscale (VMS) ROM framework was extended to obtain the displacement fields of rat vaginal tissue under pressure. For comparison purposes, we also investigated the classical Galerkin ROM (G-ROM). In our numerical study, both the G-ROM and the DD-VMS-ROM decreased the FE computational cost by orders of magnitude without a significant decrease in numerical accuracy. Furthermore, the DD-VMS-ROM improved the G-ROM accuracy at a modest computational overhead. Our numerical investigation showed that ROM has the potential to provide efficient and accurate computational tools to describe vaginal deformations, with the ultimate goal of improving maternal health.
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Affiliation(s)
- William Snyder
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia, USA
| | - Jeffrey A McGuire
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia, USA
| | - Changhong Mou
- Department of Mathematics, Virginia Tech, Blacksburg, Virginia, USA
| | - David A Dillard
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia, USA
| | - Traian Iliescu
- Department of Mathematics, Virginia Tech, Blacksburg, Virginia, USA
| | - Raffaella De Vita
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia, USA
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Dubik J, Tartaglione A, Miller KS, Dillard DA, De Vita R. History-Dependent Deformations of Rat Vaginas under Inflation. Integr Comp Biol 2022; 62:icac110. [PMID: 35781491 DOI: 10.1093/icb/icac110] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The vagina is a highly inhomogeneous, anisotropic, and viscoelastic organ that undergoes significant deformations in vivo. The mechanical attributes of this organ facilitate important physiological functions during menstruation, intercourse, and birthing. Despite the crucial mechanical role that the vagina plays within the female reproductive system, the deformations that the organ can sustain over time under constant pressure, in both the longitudinal direction (LD) and circumferential direction (CD), have not been fully characterized. This experimental study focuses on quantifying the creep properties of the vagina via ex vivo inflation testing using the rat as animal model. Toward this end, rat vaginas were subjected to three consecutively increasing constant luminal pressures (28 kPa, 55 kPa, and 83 kPa) using a custom-built experimental setup and the resulting inhomogeneous deformations were measured using the digital image correlation (DIC) method. The vagina was found to deform significantly more in the CD than the LD at any constant pressure, suggesting that the organ primarily adapts to constant pressures by significantly changing the diameter rather that the length. The change in deformation over time (i.e., creep) was significantly higher during the 1st inflation test at a constant pressure of 28 kPa than over the 2nd and 3rd inflation tests at constant pressures of 55 kPa and 83 kPa, respectively. The findings of this study on the mechanical behavior of the vagina could serve to advance our limited knowledge about the physiology and pathophysiology of this important reproductive organ.
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Affiliation(s)
- Justin Dubik
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, 330A Kelly Hall, 325 Stanger Street, Blacksburg, 24061, VA, USA
| | - Alfonsina Tartaglione
- Department of Mathematics and Physics, Università degli Studi della Campania "Luigi Vanvitelli", Viale Abramo Lincoln 5, Caserta, 81100, CE, Italy
| | - Kristin S Miller
- Department of Biomedical Engineering, Tulane University, 531 Lindy Boggs, New Orleans, 70118, LA, USA
| | - David A Dillard
- Department of Biomedical Engineering and Mechanics, Virginia Tech, 219A Norris Hall, 495 Old Turner Street, Blacksburg, 24061, VA, USA
| | - Raffaella De Vita
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, 330A Kelly Hall, 325 Stanger Street, Blacksburg, 24061, VA, USA
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9
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Donaldson K, Thomas J, Zhu Y, Clark-Deener S, Alperin M, De Vita R. In-plane and out-of-plane deformations of gilt utero-sacral ligaments. J Mech Behav Biomed Mater 2022; 131:105249. [PMID: 35526346 DOI: 10.1016/j.jmbbm.2022.105249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 04/07/2022] [Accepted: 04/17/2022] [Indexed: 11/27/2022]
Abstract
The uterosacral ligaments (USLs) are supportive structures of the uterus and apical vagina. The mechanical function of these ligaments within the pelvic floor is crucial not only in normal physiological conditions but also in reconstructive surgeries for pelvic organ prolapse. Discrepancies in their anatomical and histological description exist in the literature, but such discrepancies are likely due to large variations of these structures. This makes mechanical testing very challenging, requiring the development of advanced methods for characterizing their mechanical properties. This study proposes the use of planar biaxial testing, digital image correlation (DIC), and optical coherence tomography (OCT) to quantify the deformations of the USLs, both in-plane and out-of-plane. Using the gilts as an animal model, the USLs were found to deform significantly less in their main direction (MD) of in vivo loading than in the direction perpendicular to it (PD) at increasing equibiaxial stresses. Under constant equibiaxial loading, the USLs deform over time equally, at comparable rates in both the MD and PD. The thickness of the USLs decreases as the equibiaxial loading increases but, under constant equibiaxial loading, the thickness increases in some specimens and decreases in others. These findings could contribute to the design of new mesh materials that augment the support function of USLs as well as noninvasive diagnostic tools for evaluating the integrity of the USLs.
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Affiliation(s)
- Kandace Donaldson
- Department of Biomedical Engineering and Mechanics, Virginia Tech, 330A Kelly Hall, 325 Stanger Street, Blacksburg, VA, 24061, USA
| | - Joseph Thomas
- Department of Electrical and Computer Engineering, Virginia Tech, 460 Turner Street, Suite 303, Blacksburg, VA, 24061, USA
| | - Yizheng Zhu
- Department of Electrical and Computer Engineering, Virginia Tech, 460 Turner Street, Suite 303, Blacksburg, VA, 24061, USA
| | - Sherrie Clark-Deener
- Department of Large Animal Clinical Sciences, Virginia Tech, 215 Duckpond Drive, Blacksburg, VA, 24061, USA
| | - Marianna Alperin
- Department of Obstetrics, Gynecology & Reproductive Sciences, Division of Female Medicine and Reconstructive Surgery, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Raffaella De Vita
- Department of Biomedical Engineering and Mechanics, Virginia Tech, 330A Kelly Hall, 325 Stanger Street, Blacksburg, VA, 24061, USA.
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10
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Editorial overview: Biomedical Engineering and Women’s Health - Breaking new ground in gender and sex-specific research. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2022. [DOI: 10.1016/j.cobme.2022.100392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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11
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Clark-Patterson G, Domingo M, Miller KS. Biomechanics of Pregnancy and Vaginal Delivery. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2022. [DOI: 10.1016/j.cobme.2022.100386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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12
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Huntington AJ, Udayasuryan B, Du P, Verbridge SS, Abramowitch SD, Vita RD. Smooth Muscle Organization and Nerves in the Rat Vagina: A First Look Using Tissue Clearing and Immunolabeling. Ann Biomed Eng 2022; 50:440-451. [PMID: 35182248 DOI: 10.1007/s10439-022-02928-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 02/06/2022] [Indexed: 12/28/2022]
Abstract
Smooth muscle fibers within the vagina, as well as the nerve fibers that contribute to their control mechanisms, are important for the maintenance and alteration of vaginal length and tone. Vaginal smooth muscle (VaSM) is typically described as being arranged into two distinct concentric layers: an inner circular muscular layer and an outer longitudinal muscular layer. However, the distribution of VaSM oriented in the longitudinal direction (LD) and circumferential direction (CD) has never been quantified. In this study, tissue clearing and immunohistochemistry were performed so that the VaSM, and surrounding nerves, within whole rat vaginas ([Formula: see text]) could be imaged without tissue sectioning, preserving the three-dimensional architecture of the organs. Using these methods, the vagina was viewed through the full thickness of the muscularis layer, from the distal to the proximal regions. The VaSM orientation in the proximal and distal regions and the VaSM content along the LD and CD were quantified. Additionally, a qualitative assessment of vaginal nerves was performed. When compared using a permuted version of the Watson [Formula: see text] test, the orientation of VaSM in the proximal and distal regions were found to be significantly different in 4 of the 6 imaged rat vaginas ([Formula: see text]). While the distal vagina contained a similar amount of VaSM oriented within [Formula: see text] of the LD and within [Formula: see text] of the CD, the proximal vagina contained significantly more VaSM oriented towards the LD than towards the CD. Nerve fibers were found to be wavy, running both parallel and perpendicular to vascular and non-vascular smooth muscle within the vagina. Micro-structural analyses, like the one conducted here, are necessary to understand the physiological function and pathological changes of the vagina.
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Affiliation(s)
- Alyssa J Huntington
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, 330A Kelly Hall, 325 Stanger Street, Blacksburg, 24061, VA, USA
| | - Barath Udayasuryan
- Department of Biomedical Engineering and Mechanics, Virginia Tech, 330 Kelly Hall, 325 Stanger Street, Blacksburg, 24061, VA, USA
| | - Pang Du
- Department of Statistics, Virginia Tech, 417A Hutcheson Hall, 250 Drillfield Drive, Blacksburg, 24061, VA, USA
| | - Scott S Verbridge
- Department of Biomedical Engineering and Mechanics, Virginia Tech, 330 Kelly Hall, 325 Stanger Street, Blacksburg, 24061, VA, USA
| | - Steven D Abramowitch
- Translational Biomechanics Lab, Department of Bioengineering, University of Pittsburgh, Benedum Hall, 3700 O'Hara Street, Pittsburgh, 15213, PA, USA
| | - Raffaella De Vita
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, 330A Kelly Hall, 325 Stanger Street, Blacksburg, 24061, VA, USA.
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