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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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Buchanan LM, Domingo MJ, White SE, Vanoven TN, Karbasion N, Bersi MR, Pence IJ, Florian-Rodriguez M, Miller KS. Advances in vaginal bioengineering: Applications, techniques, and needs. Curr Res Physiol 2023; 6:100111. [PMID: 38107786 PMCID: PMC10724214 DOI: 10.1016/j.crphys.2023.100111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 10/05/2023] [Accepted: 10/13/2023] [Indexed: 12/19/2023] Open
Affiliation(s)
- Lily M. Buchanan
- University of Texas at Dallas, Department of Bioengineering, 800 W. Campbell Rd, Richardson, TX, 75080, USA
| | - Mari J.E. Domingo
- Tulane University, Department of Biomedical Engineering, 6823 St. Charles Ave, New Orleans, LA, 70118, USA
| | - Shelby E. White
- Tulane University, Department of Biomedical Engineering, 6823 St. Charles Ave, New Orleans, LA, 70118, USA
| | - Triniti N. Vanoven
- University of Texas at Dallas, Department of Bioengineering, 800 W. Campbell Rd, Richardson, TX, 75080, USA
- University of Texas Southwestern Medical Center, Department of Biomedical Engineering, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Niyousha Karbasion
- Washington University at St. Louis, Department of Mechanical Engineering and Materials Science, 1 Brookings Dr, St. Louis, MO, 63130, USA
| | - Matthew R. Bersi
- Washington University at St. Louis, Department of Mechanical Engineering and Materials Science, 1 Brookings Dr, St. Louis, MO, 63130, USA
| | - Isaac J. Pence
- University of Texas at Dallas, Department of Bioengineering, 800 W. Campbell Rd, Richardson, TX, 75080, USA
- University of Texas Southwestern Medical Center, Department of Biomedical Engineering, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- University of Texas Southwestern Medical Center, Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- University of Texas Southwestern Medical Center, Department of Internal Medicine, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Maria Florian-Rodriguez
- University of Texas Southwestern Medical Center, Department of Obstetrics and Gynecology, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- University of Texas Southwestern Medical Center, Cecil H. and Ida Green Center for Reproductive Biology Sciences, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Kristin S. Miller
- University of Texas at Dallas, Department of Bioengineering, 800 W. Campbell Rd, Richardson, TX, 75080, USA
- University of Texas Southwestern Medical Center, Department of Biomedical Engineering, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- University of Texas Southwestern Medical Center, Department of Obstetrics and Gynecology, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- University of Texas at Dallas, Department of Mechanical Engineering, 800 W. Campbell Rd, Richardson, TX, 75080, USA
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Viegas Madrid V, Casado Varela J, Enciso S, Gómez de Vicente JM, Sánchez Margallo FM, López-Fando L. Comparative anatomy of the ovine and human pelvis for laparoscopic sacrocolpopexy: evaluating the effectiveness of the ovine model. Int Urogynecol J 2023; 34:2301-2306. [PMID: 37154898 DOI: 10.1007/s00192-023-05549-7] [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: 02/15/2023] [Accepted: 04/08/2023] [Indexed: 05/10/2023]
Abstract
INTRODUCTION AND HYPOTHESIS Laparoscopic sacrocolpopexy (LSC) is a functional reconstructive surgery used to treat pelvic organ prolapse (POP) in middle-aged women. Although LSC is widely used, its implementation is hindered by perceived technical difficulties and surgical learning curves. Surgeons require adequate experience with LSC prior to performing the procedure on patients to improve their quality of life. This study is aimed at demonstrating the effectiveness of the ovine model (OM) for training and research in LSC, while also comparing anatomical differences between ovine and human models during the procedure. METHODS The animal model and training were provided by the Jesús Usón Minimally Invasive Surgery Centre. Urologists and gynecologists with experience in LSC participated in a course and their findings were recorded and documented. RESULTS Differences in patient positioning, trocar placement, and reperitonealization were identified between the ovine and human models. Hysterectomy is always performed in the ovine model, whereas it is not mandatory in humans. There are also differences in the dissection of the levator ani muscle and attachment point of the posterior mesh to the uterus between the two models. Despite differences in some areas, the ovine pelvic structure and vagina are similar in size to those of humans. CONCLUSIONS The ovine model is a valuable tool for surgeons in their learning curve for LSC, allowing for safe and effective practice prior to performing the procedure on patients. The use of the OM can help to improve the quality of life for women affected by pelvic organ prolapse.
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Affiliation(s)
| | | | - Silvia Enciso
- Minimally Invasive Surgery Centre Jesús Usón, Urology, Cáceres, Spain
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Vodegel EV, Guler Z, Ras L, Mackova K, Groeneveld ACHM, Bezuidenhout D, Deprest J, Jeffery ST, Roovers JPWR. Vaginal changes after ovariectomy in ewes: A large animal model for genitourinary syndrome of menopause. Int J Gynaecol Obstet 2023; 162:1042-1049. [PMID: 37151087 DOI: 10.1002/ijgo.14816] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 03/29/2023] [Accepted: 04/12/2023] [Indexed: 05/09/2023]
Abstract
OBJECTIVE To evaluate the effect of iatrogenic menopause on the physiology of the vagina of the ewe and to evaluate if vaginal changes in ewes can be translated to women with genitourinary syndrome of menopause (GSM). METHODS Preclinical research with Dohne Merino ewes. Iatrogenic menopause was induced by bilateral ovariectomy (OVX). Animals were randomized for surgery, blinded for allocation and outcome assessment. Differences between groups were determined by linear regression analyses at 5 months after OVX. Outcome measures were vaginal epithelial thickness, pH, vaginal maturation value, vaginal maturation index, epithelial glycogen accumulation, content of elastin fibers, collagen, and vascularity. RESULTS OVX ewes (n = 20) showed epithelial thinning of the vaginal wall from 146 μm to 47 μm (mean, P < 0.001). Furthermore, epithelial glycogen accumulation and vascularity of the vaginal wall significantly decreased (43% and 23%, respectively) as compared with the control group (no intervention; n = 5). No significant differences were found for other outcome measures. CONCLUSION This study established the ewe as a suitable large animal model for GSM. Furthermore, the similar relevant outcomes in humans and ewes hold great value for future translational research for the evaluation and optimization of different treatment modalities for GSM.
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Affiliation(s)
- Eva V Vodegel
- Department of Obstetrics and Gynaecology, Amsterdam UMC Location University of Amsterdam, Amsterdam, Netherlands
- Amsterdam Reproduction and Development Research Institute, Amsterdam, Netherlands
| | - Zeliha Guler
- Department of Obstetrics and Gynaecology, Amsterdam UMC Location University of Amsterdam, Amsterdam, Netherlands
- Amsterdam Reproduction and Development Research Institute, Amsterdam, Netherlands
| | - Lamees Ras
- Department of Obstetrics and Gynaecology, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
| | - Katerina Mackova
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium
- Institute for the Care of Mother and Child, Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Anne C H M Groeneveld
- Department of Obstetrics and Gynaecology, Amsterdam UMC Location University of Amsterdam, Amsterdam, Netherlands
- Amsterdam Reproduction and Development Research Institute, Amsterdam, Netherlands
| | - Deon Bezuidenhout
- Cardiovascular Research Unit, Cape Hearth Center, University of Cape Town, Cape Town, South Africa
| | - Jan Deprest
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium
- Pelvic Floor Unit, University Hospitals KU Leuven, Leuven, Belgium
| | - Stephen T Jeffery
- Department of Obstetrics and Gynaecology, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
| | - Jan-Paul W R Roovers
- Department of Obstetrics and Gynaecology, Amsterdam UMC Location University of Amsterdam, Amsterdam, Netherlands
- Amsterdam Reproduction and Development Research Institute, Amsterdam, Netherlands
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Fang F, Zhao Z, Xiao J, Wen J, Wu J, Miao Y. Current practice in animal models for pelvic floor dysfunction. Int Urogynecol J 2023; 34:797-808. [PMID: 36287229 DOI: 10.1007/s00192-022-05387-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 08/31/2022] [Indexed: 11/29/2022]
Abstract
INTRODUCTION AND HYPOTHESIS The objective was to explore the current practice of using animal models for female pelvic floor dysfunction (PFD). METHODS By applying PFD and animal models as the keywords, we made a computerized search using PubMed, Ovid-Medline and Ovid-Embase from 2000 to 2022. The publications on the construction and application of animal models for PFD were included, and the results are presented in narrative text. RESULTS Studies on PFD primarily use rodents, large quadrupeds, and nonhuman primates (NHPs). NHPs are closest to humans in anatomy and biomechanics of the pelvic floor, followed by large quadrupeds and rodents. Rodents are more suitable for studying molecular mechanism, histopathology of PFD, and mesh immune rejection. Large quadrupeds are adaptable to the study of pelvic floor biomechanics and the development of new surgical instruments for PFD. NHPs are suitable for studying the occurrence and pathogenesis of pelvic organ prolapse. Among modeling methods, violent destruction of pelvic floor muscles, regulation of hormone levels, and denervation were used to simulate the occurrence of PFD. Gene knockout can be used to study both the pathogenesis of PFD and the efficacy of treatments. Other methods such as abdominal wall defect, vaginal defect, and in vitro organ bath system are more frequently used to observe wound healing after surgery and to verify the efficacy of treatments. CONCLUSIONS The rat is currently the most applicable animal type for numerous modeling methods. Vaginal dilation is the most widely used modeling method for research on the pathogenesis, pathological changes, and treatment of PFD.
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Affiliation(s)
- Fei Fang
- Department of Obstetrics and Gynecology, Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, West China Second University Hospital, Sichuan University, West China Campus, Chengdu, 610041, Sichuan Province, China
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, 610041, Sichuan Province, China
| | - Zhiwei Zhao
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, 610041, Sichuan Province, China
| | - Jingyue Xiao
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, 610041, Sichuan Province, China
| | - Jirui Wen
- Deep Underground Space Medical Center, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, China
| | - Jiang Wu
- Deep Underground Space Medical Center, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, China
| | - Yali Miao
- Department of Obstetrics and Gynecology, Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, West China Second University Hospital, Sichuan University, West China Campus, Chengdu, 610041, Sichuan Province, China.
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Douglass A, Dattilo M, Feola AJ. Evidence for Menopause as a Sex-Specific Risk Factor for Glaucoma. Cell Mol Neurobiol 2023; 43:79-97. [PMID: 34981287 PMCID: PMC9250947 DOI: 10.1007/s10571-021-01179-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 12/03/2021] [Indexed: 01/07/2023]
Abstract
Glaucoma is a leading cause of irreversible blindness worldwide and is characterized by progressive loss of visual function and retinal ganglion cells (RGC). Current epidemiological, clinical, and basic science evidence suggest that estrogen plays a role in the aging of the optic nerve. Menopause, a major biological life event affecting all women, coincides with a decrease in circulating sex hormones, such as estrogen. While 59% of the glaucomatous population are females, sex is not considered a risk factor for developing glaucoma. In this review, we explore whether menopause is a sex-specific risk factor for glaucoma. First, we investigate how menopause is defined as a sex-specific risk factor for other pathologies, including cardiovascular disease, osteoarthritis, and bone health. Next, we discuss clinical evidence that highlights the potential role of menopause in glaucoma. We also highlight preclinical studies that demonstrate larger vision and RGC loss following surgical menopause and how estrogen is protective in models of RGC injury. Lastly, we explore how surgical menopause and estrogen signaling are related to risk factors associated with developing glaucoma (e.g., intraocular pressure, aqueous outflow resistance, and ocular biomechanics). We hypothesize that menopause potentially sets the stage to develop glaucoma and therefore is a sex-specific risk factor for this disease.
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Affiliation(s)
- Amber Douglass
- grid.484294.7Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Decatur, GA USA
| | - Michael Dattilo
- grid.189967.80000 0001 0941 6502Department of Ophthalmology, Emory Eye Center, Emory University School of Medicine, B2503, Clinic B Building, 1365B Clifton Road NE, Atlanta, GA 30322 USA ,grid.414026.50000 0004 0419 4084Department of Ophthalmology, Atlanta Veterans Affairs Medical Center, Atlanta, GA USA ,grid.213917.f0000 0001 2097 4943Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA USA
| | - Andrew J. Feola
- grid.484294.7Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Decatur, GA USA ,grid.189967.80000 0001 0941 6502Department of Ophthalmology, Emory Eye Center, Emory University School of Medicine, B2503, Clinic B Building, 1365B Clifton Road NE, Atlanta, GA 30322 USA ,grid.213917.f0000 0001 2097 4943Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA USA
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Gardella B, Scatigno AL, Belli G, Gritti A, Visoná SD, Dominoni M. Aging of Pelvic Floor in Animal Models: A Sistematic Review of Literature on the Role of the Extracellular Matrix in the Development of Pelvic Floor Prolapse. Front Med (Lausanne) 2022; 9:863945. [PMID: 35492348 PMCID: PMC9051040 DOI: 10.3389/fmed.2022.863945] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/28/2022] [Indexed: 11/13/2022] Open
Abstract
Pelvic organ prolapse (POP) affects many women and contributes significantly to a decrease in their quality of life causing urinary and/or fecal incontinence, sexual dysfunction and dyspareunia. To better understand POP pathophysiology, prevention and treatment, many researchers resorted to evaluating animal models. Regarding this example and because POP affects principally older women, our aim was to provide an overview of literature on the possible biomechanical changes that occur in the vaginas of animal models and their supportive structures as a consequence of aging. Papers published online from 2000 until May 2021 were considered and particular attention was given to articles reporting the effects of aging on the microscopic structure of the vagina and pelvic ligaments in animal models. Most research has been conducted on rodents because their vagina structure is well characterized and similar to those of humans; furthermore, they are cost effective. The main findings concern protein structures of the connective tissue, known as elastin and collagen. We have noticed a significant discordance regarding the quantitative changes in elastin and collagen related to aging, especially because it is difficult to detect them in animal specimens. However, it seems to be clear that aging affects the qualitative properties of elastin and collagen leading to aberrant forms which may affect the elasticity and the resilience of tissues leading to pelvic floor disease. The analysis of histological changes of pelvic floor tissues related to aging underlines how these topics appear to be not fully understood so far and that more research is necessary.
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Affiliation(s)
- Barbara Gardella
- Department of Obstetrics and Gynecology, Fondazione IRCCS Policlinico San Matteo, University of Pavia, Pavia, Italy
| | - Annachiara Licia Scatigno
- Department of Obstetrics and Gynecology, Fondazione IRCCS Policlinico San Matteo, University of Pavia, Pavia, Italy
| | - Giacomo Belli
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy
| | - Andrea Gritti
- Department of Obstetrics and Gynecology, Fondazione IRCCS Policlinico San Matteo, University of Pavia, Pavia, Italy
| | - Silvia Damiana Visoná
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy
| | - Mattia Dominoni
- Department of Obstetrics and Gynecology, Fondazione IRCCS Policlinico San Matteo, University of Pavia, Pavia, Italy
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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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Clark-Patterson GL, Roy S, Desrosiers L, Knoepp LR, Sen A, Miller KS. Role of fibulin-5 insufficiency and prolapse progression on murine vaginal biomechanical function. Sci Rep 2021; 11:20956. [PMID: 34697337 PMCID: PMC8546087 DOI: 10.1038/s41598-021-00351-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 08/31/2021] [Indexed: 02/04/2023] Open
Abstract
The vagina plays a critical role in supporting the pelvic organs and loss of support leads to pelvic organ prolapse. It is unknown what microstructural changes influence prolapse progression nor how decreased elastic fibers contributes to vaginal remodeling and smooth muscle contractility. The objective for this study was to evaluate the effect of fibulin-5 haploinsufficiency, and deficiency with progressive prolapse on the biaxial contractile and biomechanical function of the murine vagina. Vaginas from wildtype (n = 13), haploinsufficient (n = 13), and deficient mice with grade 1 (n = 9) and grade 2 or 3 (n = 9) prolapse were explanted for biaxial contractile and biomechanical testing. Multiaxial histology (n = 3/group) evaluated elastic and collagen fiber microstructure. Western blotting quantified protein expression (n = 6/group). A one-way ANOVA or Kruskal-Wallis test evaluated statistical significance. Pearson's or Spearman's test determined correlations with prolapse grade. Axial contractility decreased with fibulin-5 deficiency and POP (p < 0.001), negatively correlated with prolapse grade (ρ = - 0.80; p < 0.001), and positively correlated with muscularis elastin area fraction (ρ = - 0.78; p = 0.004). Circumferential (ρ = 0.71; p < 0.001) and axial (ρ = 0.69; p < 0.001) vaginal wall stresses positively correlated with prolapse grade. These findings demonstrated that fibulin-5 deficiency and prolapse progression decreased vaginal contractility and increased vaginal wall stress. Future work is needed to better understand the processes that contribute to prolapse progression in order to guide diagnostic, preventative, and treatment strategies.
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Affiliation(s)
| | - Sambit Roy
- Department of Animal Sciences, Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, 48824, USA
| | - Laurephile Desrosiers
- Department of Female Pelvic Medicine and Reconstructive Surgery, University of Queensland Ochsner Clinical School, New Orleans, 70121, USA
| | - Leise R Knoepp
- Department of Female Pelvic Medicine and Reconstructive Surgery, University of Queensland Ochsner Clinical School, New Orleans, 70121, USA
| | - Aritro Sen
- Department of Animal Sciences, Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, 48824, USA
| | - Kristin S Miller
- Department of Biomedical Engineering, Tulane University, New Orleans, 70118, USA.
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Huntington A, Abramowitch SD, Moalli PA, De Vita R. Strains induced in the vagina by smooth muscle contractions. Acta Biomater 2021; 129:178-187. [PMID: 34033971 DOI: 10.1016/j.actbio.2021.05.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/12/2021] [Accepted: 05/13/2021] [Indexed: 12/26/2022]
Abstract
The ability of the vagina to contract gives rise to a set of active mechanical properties that contribute to the complex function of this organ in-vivo. Regional differences in the morphology of the vagina have been long recognized, but the large heterogeneous deformations that the vagina experiences during contractions have never been quantified. Furthermore, there is no consensus regarding differences in contractility along the two primary anatomical directions of the vagina: the longitudinal direction (LD) and the circumferential direction (CD). In this study, square vaginal specimens from healthy virgin rats (n=15) were subjected to isometric planar biaxial tests at four equi-biaxial stretches of 1.0, 1.1, 1.2, and 1.3. Contractions were induced at each stretch by a high concentration potassium solution. The digital image correlation method was used to perform full-field strain measurements during contractions. The vagina was found to undergo significantly higher compressive strains, tensile strains, and contractile forces along the LD than along the CD during contractions. Specifically, when computed over all the applied equi-biaxial stretches, mean (± std. dev.) absolute maximum compressive strains were -(13.43 ± 1.56)% along the LD and -(3.19 ± 0.25)% along the CD, mean absolute maximum tensile strains were (10.92 ± 1.73)% along the LD and (3.62 ± 0.57)% along the CD, and mean maximum contractile forces were 6.24 ± 0.55 mN along the LD and 3.35 ± 0.56 mN along the CD. Moreover, the vaginal tissue appeared to undergo compression in the proximal region and tension in the distal region while kept at constant equi-biaxial stretches. The active mechanical properties of the healthy vagina need to be fully investigated so that detrimental alterations in vaginal contractility, such as those caused by pelvic floor disorders and current treatment strategies, can be prevented. STATEMENT OF SIGNIFICANCE: Contractile forces of the vagina have been measured by several investigators using uniaxial tensile testing methods. Unlike previous studies, in this study planar-biaxial tests of vaginal specimens were performed while the full-field strains of the vagina, as induced by smooth muscle contraction, were measured. The vagina was found to generate significantly larger contractile strains and forces in the longitudinal direction than in the circumferential direction. Knowledge of the contractile mechanics of the healthy vagina is essential to understand the detrimental effects that pelvic organ prolapse and the use of surgical meshes have on the functionality of smooth muscle in the vagina.
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Affiliation(s)
- Alyssa Huntington
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Steven D Abramowitch
- Translational Biomechanics Lab, Department of Bioengineering, University of Pittsburgh, Benedum Hall, 3700 O'Hara Street, Pittsburgh, PA, 15213, USA
| | - Pamela A Moalli
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Magee-Womens Research Institute, 204 Craft Ave, Pittsburgh, PA, 15213, USA
| | - Raffaella De Vita
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, 24061, USA.
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11
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Mori da Cunha MGMC, Mackova K, Hympanova LH, Bortolini MAT, Deprest J. Animal models for pelvic organ prolapse: systematic review. Int Urogynecol J 2021; 32:1331-1344. [PMID: 33484287 PMCID: PMC8203535 DOI: 10.1007/s00192-020-04638-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 12/02/2020] [Indexed: 12/27/2022]
Abstract
INTRODUCTION AND HYPOTHESIS We aimed to summarize the knowledge on the pathogenesis of pelvic organ prolapse (POP) generated in animal models. METHODS We searched MEDLINE, Embase, Cochrane and the Web of Science to establish what animal models are used in the study of suggested risk factors for the development of POP, including pregnancy, labor, delivery, parity, aging and menopause. Lack of methodologic uniformity precluded meta-analysis; hence, results are presented as a narrative review. RESULTS A total of 7426 studies were identified, of which 51 were included in the analysis. Pregnancy has a measurable and consistent effect across species. In rats, simulated vaginal delivery induces structural changes in the pelvic floor, without complete recovery of the vaginal muscular layer and its microvasculature, though it does not induce POP. In sheep, first vaginal delivery has a measurable effect on vaginal compliance; measured effects of additional deliveries are inconsistent. Squirrel monkeys can develop POP. Denervation of their levator ani muscle facilitates this process in animals that delivered vaginally. The models used do not develop spontaneous menopause, so it is induced by ovariectomy. Effects of menopause depend on the age at ovariectomy and the interval to measurement. In several species menopause is associated with an increase in collagen content in the longer term. In rodents there were no measurable effects of age apart of elastin changes. We found no usable data for other species. CONCLUSION In several species there are measurable effects of pregnancy, delivery and iatrogenic menopause. Squirrel monkeys can develop spontaneous prolapse.
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Affiliation(s)
- Marina Gabriela M C Mori da Cunha
- Centre for Surgical Technologies, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
- Department of Development and Regeneration, Woman and Child, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
| | - Katerina Mackova
- Centre for Surgical Technologies, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
- Department of Development and Regeneration, Woman and Child, Group Biomedical Sciences, KU Leuven, Leuven, Belgium
- Institute for the Care of Mother and Child, Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Lucie Hajkova Hympanova
- Institute for the Care of Mother and Child, Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Maria Augusta T Bortolini
- Department of Gynecology, Sector of Urogynecology, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Jan Deprest
- Centre for Surgical Technologies, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.
- Department of Development and Regeneration, Woman and Child, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.
- Pelvic Floor Unit, University Hospitals, KU Leuven, Leuven, Belgium.
- Department of Development and Regeneration, Center of Surgical Technologies UZ Herestraat, Herestraat49, B3000, Leuven, Belgium.
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Mackova K, Deprest J. Authors' reply re: Vaginal Er:YAG laser application in the menopausal ewe model: a randomised estrogen and sham-controlled trial. BJOG 2021; 128:1100-1101. [PMID: 33629524 DOI: 10.1111/1471-0528.16653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/27/2021] [Indexed: 11/28/2022]
Affiliation(s)
- K Mackova
- Department of Development and Regeneration, Cluster Urogenital, Abdominal and Plastic Surgery, KU Leuven, Leuven, Belgium
- Institute for the Care of Mother and Child, Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - J Deprest
- Department of Development and Regeneration, Cluster Urogenital, Abdominal and Plastic Surgery, KU Leuven, Leuven, Belgium
- Pelvic Floor Unit, University Hospitals KU Leuven, Leuven, Belgium
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The ewe as an animal model of vaginal atrophy and vaginal Er:YAG laser application. ACTA ACUST UNITED AC 2020; 28:198-206. [PMID: 33235032 DOI: 10.1097/gme.0000000000001679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE In sheep of reproductive age, we aimed to document decrease in epithelial thickness, glycogen amount, and other vaginal changes after castration and the effect of Er:YAG laser as used clinically. METHODS On day 0, 16 sheep underwent ovariectomy. They were randomized to sham or three vaginal Er:YAG laser applications at monthly intervals. Primary outcome was vaginal epithelial thickness (d60, d71, d73, d77, and d160). Secondary outcomes included indicators of atrophy (vaginal health index = VHI), pH, cytology, morphology at the above time points, microcirculation focal depth (FD; d70 and d160), and at sacrifice (d160) vaginal dimensions and active and passive biomechanical testing. RESULTS Menopausal changes between 60 and 160 days after ovariectomy included a progressive decrease in epithelial thickness, in VHI, FD, glycogen, elastin content and vasculature, and an increase in pH and collagen content. In lasered animals, the first day a few white macroscopic foci were visible and an increase in pH was measured. Both disappeared within 3 days. Seven days after laser the epithelial thickness increased. At sacrifice (d160), there were no differences between sham and laser group in vaginal dimensions, morphometry, mitotic and apoptotic activity, active contractility, vaginal compliance, except for a lower blood vessel density in the lamina propria of the midvagina in the laser group. CONCLUSIONS In reproductive sheep, ovariectomy induces vaginal atrophy evidenced in different outcome measurements. Vaginal Er:YAG laser induced visual impact, a short-term increase in epithelial thickness yet no long-term changes compared to sham therapy in menopausal controls.
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Mackova K, Mazzer AM, Mori Da Cunha M, Hajkova Hympanova L, Urbankova I, Kastelein AW, Vodegel E, Vander Linden K, Fehervary H, Guler Z, Roovers JP, Krofta L, Verhaeghe J, Deprest J. Vaginal Er:YAG laser application in the menopausal ewe model: a randomised estrogen and sham-controlled trial. BJOG 2020; 128:1087-1096. [PMID: 33017509 DOI: 10.1111/1471-0528.16558] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2020] [Indexed: 01/12/2023]
Abstract
OBJECTIVE To describe effects of non-ablative erbium-doped:yttrium-aluminium-garnet (Er:YAG) laser on vaginal atrophy induced by iatrogenic menopause in the ewe. DESIGN Animal experimental, randomised, sham and estrogen-treatment controlled study with blinding for primary outcome. SETTING KU Leuven, Belgium. SAMPLE Twenty-four ewes. METHODS Menopause was surgically induced, after which the ewes were randomised to three groups receiving vaginal Er:YAG laser application three times, with a 1-month interval; three sham manipulations with a 1-month interval; or estrogen replacement and sham manipulations. At given intervals, ewes were clinically examined and vaginal wall biopsies were taken. Vaginal compliance was determined by passive biomechanical testing from explants taken at autopsy. MAIN OUTCOME MEASURES Vaginal epithelial thickness (primary), composition of the lamina propria (collagen, elastin, glycogen and vessel content), vaginal compliance, clinical signs. RESULTS Animals exposed to Er:YAG laser application and sham manipulation, but not to estrogens, displayed a significant and comparable increase in vaginal epithelial thickness between baseline and 7 days after the third application (69% and 67%, respectively, both P < 0.0008). In laser-treated ewes, temporary vaginal discharge and limited thermal injury were observed. Estrogen-substituted ewes displayed a more prominent increase in epithelial thickness (202%; P < 0.0001) and higher vaginal compliance (P < 0.05). None of the interventions induced changes in the lamina propria. CONCLUSIONS Vaginal Er:YAG laser has comparable effect to sham manipulation in menopausal ewes. TWEETABLE ABSTRACT Vaginal Er:YAG laser has comparable effect to sham manipulation in menopausal ewes #LASER #GSM #RCT.
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Affiliation(s)
- K Mackova
- Department of Development and Regeneration, Cluster Urogenital, Abdominal and Plastic Surgery, KU Leuven, Leuven, Belgium.,Third Faculty of Medicine, Institute for the Care of Mother and Child, Charles University, Prague, Czech Republic
| | - A M Mazzer
- Department of Obstetrics and Gynaecology, San Raffaele University, Milan, Italy
| | - Mgmc Mori Da Cunha
- Department of Development and Regeneration, Cluster Urogenital, Abdominal and Plastic Surgery, KU Leuven, Leuven, Belgium
| | - L Hajkova Hympanova
- Department of Development and Regeneration, Cluster Urogenital, Abdominal and Plastic Surgery, KU Leuven, Leuven, Belgium.,Third Faculty of Medicine, Institute for the Care of Mother and Child, Charles University, Prague, Czech Republic
| | - I Urbankova
- Third Faculty of Medicine, Institute for the Care of Mother and Child, Charles University, Prague, Czech Republic
| | - A W Kastelein
- Department of Obstetrics and Gynaecology, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - E Vodegel
- Department of Obstetrics and Gynaecology, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - K Vander Linden
- Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - H Fehervary
- Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Z Guler
- Department of Obstetrics and Gynaecology, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - J P Roovers
- Department of Obstetrics and Gynaecology, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - L Krofta
- Third Faculty of Medicine, Institute for the Care of Mother and Child, Charles University, Prague, Czech Republic
| | - J Verhaeghe
- Department of Development and Regeneration, Cluster Urogenital, Abdominal and Plastic Surgery, KU Leuven, Leuven, Belgium.,Pelvic Floor Unit, University Hospitals KU Leuven, Leuven, Belgium
| | - J Deprest
- Department of Development and Regeneration, Cluster Urogenital, Abdominal and Plastic Surgery, KU Leuven, Leuven, Belgium.,Pelvic Floor Unit, University Hospitals KU Leuven, Leuven, Belgium
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Allen RS, Douglass A, Vo H, Feola AJ. Ovariectomy worsens visual function after mild optic nerve crush in rodents. Exp Eye Res 2020; 202:108333. [PMID: 33129829 DOI: 10.1016/j.exer.2020.108333] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/16/2020] [Accepted: 10/22/2020] [Indexed: 11/30/2022]
Abstract
Glaucoma is the leading cause of irreversible blindness worldwide, and women represent roughly 60% of the affected population. Early menopause and estrogen signaling defects are risk factors for glaucoma. Recently, we found that surgical menopause exacerbated visual dysfunction in an ocular hypertension model of glaucoma. Here, we investigated if surgical menopause exacerbated visual dysfunction in a model of direct retinal ganglion cell (RGC) damage via optic nerve crush (ONC). Female Long Evans rats (n = 12) underwent ovariectomy (OVX) to induce surgical menopause or Sham surgery. Eight weeks post-surgery, baseline visual function was assessed via optomotor response. Afterwards, rats underwent monocular ONC. Visual function was assessed at 4, 8, and 12 weeks post-ONC. At 12 weeks, retinal function via electroretinography and retinal nerve fiber layer (RNFL) thickness via optical coherence tomography were measured. Visual acuity was reduced after ONC (p < 0.001), with surgical menopausal animals having 31.7% lower visual acuity than Sham animals at 12 weeks (p = 0.01). RNFL thinning (p < 0.0001) and decreased RGC function (p = 0.0016) occurred at 12 weeks in ONC groups. Surgical menopause worsens visual acuity after direct RGC damage using an ONC model. This demonstrates that surgical menopause plays a role in visual function after injury.
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Affiliation(s)
- Rachael S Allen
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, GA, USA; Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Amber Douglass
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, GA, USA
| | - Harrison Vo
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, GA, USA
| | - Andrew J Feola
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, GA, USA; Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.
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Huntington A, Donaldson K, De Vita R. Contractile Properties of Vaginal Tissue. J Biomech Eng 2020; 142:080801. [PMID: 32203570 PMCID: PMC10854261 DOI: 10.1115/1.4046712] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 02/26/2020] [Indexed: 01/11/2024]
Abstract
The vagina is an important organ of the female reproductive system that has been largely understudied in the field of biomechanics. In recent years, some research has been conducted to evaluate the mechanical properties of the vagina, but much has focused on characterizing the passive mechanical properties. Because vaginal contractions play a central role in sexual function, childbirth, and development and treatment of pelvic floor disorders, the active mechanical properties of the vagina must be also quantified. This review surveys and summarizes published experimental studies on the active properties of the vagina including the differences in such properties determined by anatomic regions and orientations, neural pathways, life events such as pregnancy and menopause, pelvic floor disorders such as prolapse, and surgical mesh treatment. Conflicting experimental findings are presented, illustrating the need for further research on the active properties of the vagina. However, consensus currently exists regarding the negative impact of surgical mesh on vaginal contractility. This review also identifies knowledge gaps and future research opportunities, thus proving a firm foundation for novice and experienced researchers in this emerging area of biomechanics and encouraging more activity on women's sexual and reproductive health research.
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Affiliation(s)
- Alyssa Huntington
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061
| | - Kandace Donaldson
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061
| | - Raffaella De Vita
- STRETCH Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061
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Danso EK, Schuster JD, Johnson I, Harville EW, Buckner LR, Desrosiers L, Knoepp LR, Miller KS. Comparison of Biaxial Biomechanical Properties of Post-menopausal Human Prolapsed and Non-prolapsed Uterosacral Ligament. Sci Rep 2020; 10:7386. [PMID: 32355180 PMCID: PMC7193612 DOI: 10.1038/s41598-020-64192-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 03/28/2020] [Indexed: 11/10/2022] Open
Abstract
Uterosacral ligaments (USLs) provide structural support to the female pelvic floor, and a loss of USL structural integrity or biomechanical function may induce pelvic organ prolapse (POP). Alterations in extracellular matrix composition and organization dictate USL mechanical function. Changes in USL microstructure and corresponding mechanical properties, however, are not fully understood, nor is it understood how microstructure and mechanics change with onset and progression of POP. This is due, in part, as USL properties are primarily characterized along a single direction (uniaxial test), whereas the USL is loaded in multiple directions simultaneously within the body. Biaxial testing permits the acquisition of biomechanical data from two axes simultaneously, and thus simulates a more physiologic assessment compared to the traditional uniaxial testing. Therefore, the objective of this study was to quantify the biaxial biomechanical properties and histological composition of the USL in post-menopausal women with and without POP at various stages. Potential correlations between tissue microstructural composition and mechanical function were also examined. Tangential modulus was lower and peak stretch higher in POP III/IV compared to non-POP and POP I/II in the main in vivo loading direction; however, no significant differences in mechanical properties were observed in the perpendicular loading direction. Collagen content positively correlated to tangential modulus in the main in vivo loading direction (r = 0.5, p = 0.02) and negatively correlated with the peak stretch in both the main in vivo (r = -0.5, p = 0.02) and perpendicular loading directions (r = -0.3, p = 0.05). However, no statistically significant differences in USL composition were observed, which may be due to the small sample size and high variability of small sections of human tissues. These results provide first step towards understanding what microstructural and mechanical changes may occur in the USL with POP onset and progression. Such information may provide important future insights into the development of new surgical reconstruction techniques and graft materials for POP treatment.
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Affiliation(s)
- Elvis K Danso
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Ave, New Orleans, LA, 70118, USA
| | - Jason D Schuster
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Ave, New Orleans, LA, 70118, USA
| | - Isabella Johnson
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Ave, New Orleans, LA, 70118, USA
- Department of Epidemiology, Tulane University, 1440 Canal Street, Suite 2000, New Orleans, LA, 70112, USA
| | - Emily W Harville
- Department of Epidemiology, Tulane University, 1440 Canal Street, Suite 2000, New Orleans, LA, 70112, USA
| | - Lyndsey R Buckner
- Department of Research, Biorepository Unit, Ochsner Health System, 1514 Jefferson Highway, New Orleans, LA, 70121, USA
| | - Laurephile Desrosiers
- Department of Female Pelvic Medicine & Reconstruction Surgery, Ochsner Clinical School, 1514 Jefferson Highway, New Orleans, LA, 70121, USA
| | - Leise R Knoepp
- Department of Female Pelvic Medicine & Reconstruction Surgery, Ochsner Clinical School, 1514 Jefferson Highway, New Orleans, LA, 70121, USA
| | - Kristin S Miller
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Ave, New Orleans, LA, 70118, USA.
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The importance of developing relevant animal models to assess existing and new materials. Curr Opin Urol 2020; 29:400-406. [PMID: 31008781 DOI: 10.1097/mou.0000000000000625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW We summarize the recent literature on the use of different animal models for testing existing and new materials for treatment of pelvic organ prolapse. RECENT FINDINGS A wide spectrum of animal models is being used in urogynecology, both for the study of physiologic and pathophysiologic processes, training in surgical procedures, yet mainly to study the host response to implant materials. The quality of studies is variable, and procedures, read-outs, and reporting are not standardized. This makes comparison very difficult. The research community is experimenting with different knitting patterns, novel polymers, bioactivation, as well as resorbable rather than durable implants. Outcomes of the experiments are dependent on the location of implantation. Lighter polypropylene constructs seem to induce a less vigorous host response than elder heavier products. Modification of the surface yields contradictory findings. Resorbable acellular collagen matrices may be reintroduced as prophylactically inserted support structures. SUMMARY Although animal experimentation with novel candidate implants is advocated, there is a lack of standardization in reporting. The concept of resorbable construct is being revived, as durable materials have caused clinical graft-related complications. Large animal experiments seem to provide interesting and more comprehensive information, yet their use may be contested.
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Feola AJ, Fu J, Allen R, Yang V, Campbell IC, Ottensmeyer A, Ethier CR, Pardue M. Menopause exacerbates visual dysfunction in experimental glaucoma. Exp Eye Res 2019; 186:107706. [PMID: 31226338 DOI: 10.1016/j.exer.2019.107706] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 06/03/2019] [Accepted: 06/17/2019] [Indexed: 10/26/2022]
Abstract
Glaucoma is the leading cause of irreversible blindness worldwide. Recently, estrogen deficiencies caused by early menopause, alterations in estrogen signaling via mutations in estrogen receptors, and polymorphisms along estrogen metabolic pathways have all been linked to an increased risk of developing glaucoma. Here, we examined how menopause and age impact visual function and retinal structure in an experimental model of glaucoma. Young (3-4 months) and aged (9-10 months) female Brown Norway rats were divided into pre- and post-menopausal cohorts by surgically inducing menopause via ovariectomy (OVX). After six weeks, ocular hypertension (OHT) was induced unilaterally for a period of eight weeks. Four cohorts were successfully followed to eight weeks: young sham (n = 8), young OVX (n = 9), aged sham (n = 10), and aged OVX (n = 11) animals. Intraocular pressure (IOP) was monitored weekly in all groups. Prior to inducing OHT (baseline) and at four and eight weeks after inducing OHT, we assessed visual acuity via the optomotor response (OMR) and retinal structure using optical coherence tomography (OCT). OHT decreased the OMR in all cohorts. We found that spatial frequency thresholds decreased by 54% in OVX animals after OHT compared to sham animals after OHT, regardless of age (p < 0.001). We also found thinning of the retinal nerve fiber layer (RNFL) and loss of total retinal thickness after induction of OHT. Aged animals had more thinning of the RNFL and loss of total retinal thickness compared to young animals (p < 0.001). Overall, OHT caused significant changes in visual function and retinal structure. Observing that OVX in young and aged animals further decreased spatial frequency thresholds after OHT suggests that an estrogen deficiency may intensify visual impairment after OHT.
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Affiliation(s)
- Andrew J Feola
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, GA, United States; Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States.
| | - Jieming Fu
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, GA, United States
| | - Rachael Allen
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, GA, United States; Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States
| | - Victoria Yang
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, GA, United States
| | - Ian C Campbell
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, GA, United States; Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States
| | | | - C Ross Ethier
- Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States
| | - Machelle Pardue
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, GA, United States; Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States
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Rynkevic R, Ferreira J, Martins P, Parente M, Fernandes AA. Linking hyperelastic theoretical models and experimental data of vaginal tissue through histological data. J Biomech 2019; 82:271-279. [PMID: 30466952 DOI: 10.1016/j.jbiomech.2018.10.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 10/29/2018] [Accepted: 10/31/2018] [Indexed: 10/27/2022]
Abstract
Mechanical characterization of living tissues and computer-based simulations related to medical issues, has become increasingly important to improve diagnostic processes and treatments evaluation. This work proposes a link between the mechanical testing and the material model predictions through histological data of vaginal tissue. Histological data was used to link tensile testing experiments with material-dependent parameters; the approach was adequate to capture the nonlinear response of ovine vaginal tissue over a large strain range. The experimental data obtained on a previous study, has two main components: tensile testing and histological analysis of the ovine vaginal tissue. Uniaxial tensile test data and histological data were collected from three sheep groups: virgins, pregnant and parous. The distal part of vaginal wall was selected since it is prone to tears induced by vaginal delivery. The HGO (Holzapfel-Gasser-Ogden) model parameters were fitted using a stochastic approach, namely the Simple Genetic Algorithm (SGA). The SGA was able to fit the experimental data successfully (R2 > 0.986). The dimensionless coefficient ξ, was highly correlated with histological data. The ratio was seen to increase linearly with increasing collagen content. Coefficient ξ brings a new way of interpreting and understanding experimental data; it connects the nonlinear mechanical behaviour (tensile test) with tissue's morphology (histology). It can be used as an 'inverse' (approximate) method to estimate the mechanical properties without direct experimental measurements, through basic histology. In this context, the proposed methodology appears very promising in estimating the response of the tissue via histological information.
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Affiliation(s)
- Rita Rynkevic
- University of Porto, Faculty of Engineering, Portugal; INEGI, University of Porto, Faculty of Engineering, Portugal; KU Leuven, Department Development and Regeneration, Biomedical Sciences, Leuven, Belgium; Centre for Surgical Technologies, Group Biomedical Sciences, Belgium.
| | - João Ferreira
- University of Porto, Faculty of Engineering, Portugal; INEGI, University of Porto, Faculty of Engineering, Portugal.
| | - Pedro Martins
- University of Porto, Faculty of Engineering, Portugal; INEGI, University of Porto, Faculty of Engineering, Portugal.
| | - Marco Parente
- University of Porto, Faculty of Engineering, Portugal; INEGI, University of Porto, Faculty of Engineering, Portugal.
| | - Antonio A Fernandes
- University of Porto, Faculty of Engineering, Portugal; INEGI, University of Porto, Faculty of Engineering, Portugal.
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Anisotropy of the Passive and Active Rat Vagina Under Biaxial Loading. Ann Biomed Eng 2018; 47:272-281. [PMID: 30136151 DOI: 10.1007/s10439-018-02117-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 08/16/2018] [Indexed: 12/19/2022]
Abstract
Pelvic organ prolapse, the descent of the pelvic organs from their normal anatomical position, is a common condition among women that is associated with mechanical alterations of the vaginal wall. In order to characterize the complex mechanical behavior of the vagina, we performed planar biaxial tests of vaginal specimens in both the passive (relaxed) and active (contracted) states. Specimens were isolated from virgin, female Long-Evans rats (n = 16) and simultaneously stretched along the longitudinal direction (LD) and circumferential direction (CD) of the vagina. Tissue contraction was induced by electric field stimulation (EFS) at incrementally increasing values of stretch and, subsequently, by KCl. On average, the vagina was stiffer in the CD than in the LD (p < 0.001). The mean maximum EFS-induced active stress was significantly higher in the CD than in the LD (p < 0.01). On the contrary, the mean KCl-induced active stress was lower in the CD than in the LD (p < 0.01). When comparing the mean maximum EFS-induced active stress to the mean KCl-induced active stress, no differences were found in the CD (p = 0.366) but, in the LD, the mean active stress was much higher in response to the KCl stimulation (p < 0.001). Collectively, these results suggest that the anisotropic behavior of the vaginal tissue is determined not only by collagen and smooth muscle fiber organization but also by the innervation.
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