1
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Tao R, Grimm M. Simulation of Uterus Active Contraction and Fetus Delivery in ls-dyna. J Biomech Eng 2024; 146:101002. [PMID: 38635234 DOI: 10.1115/1.4065341] [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: 11/16/2023] [Accepted: 04/05/2024] [Indexed: 04/19/2024]
Abstract
Vaginal childbirth is the final phase of pregnancy when one or more fetuses pass through the birth canal from the uterus, and it is a biomechanical process. The uterine active contraction, causing the pushing force on the fetus, plays a vital role in regulating the fetus delivery process. In this project, the active contraction behaviors of muscle tissue were first modeled and investigated. After that, a finite element method (FEM) model to simulate the uterine cyclic active contraction and delivery of a fetus was developed in ls-dyna. The active contraction was driven through contractile fibers modeled as one-dimensional truss elements, with the Hill material model governing their response. Fibers were assembled in the longitudinal, circumferential, and normal (transverse) directions to correspond to tissue microstructure, and they were divided into seven regions to represent the strong anisotropy of the fiber distribution and activity within the uterus. The passive portion of the uterine tissue was modeled with a Neo Hookean hyperelastic material model. Three active contraction cycles were modeled. The cyclic uterine active contraction behaviors were analyzed. Finally, the fetus delivery through the uterus was simulated. The model of the uterine active contraction presented in this paper modeled the contractile fibers in three-dimensions, considered the anisotropy of the fiber distribution, provided the uterine cyclic active contraction and propagation of the contraction waves, performed a large deformation, and caused the pushing effect on the fetus. This model will be combined with a model of pelvic structures so that a complete system simulating the second stage of the delivery process of a fetus can be established.
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Affiliation(s)
- Ru Tao
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI 48824
| | - Michele Grimm
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI 48824; Department of Biomedical Engineering, Michigan State University, East Lansing, MI 48823; College of Engineering and Applied Sciences, University at Albany, Albany, NY 12222
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2
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Fang S, Shi L, Vink JSY, Feltovich H, Hall TJ, Myers KM. Equilibrium Mechanical Properties of the Nonhuman Primate Cervix. J Biomech Eng 2024; 146:081001. [PMID: 38270929 PMCID: PMC10983698 DOI: 10.1115/1.4064558] [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: 11/30/2022] [Revised: 10/19/2023] [Accepted: 10/23/2023] [Indexed: 01/26/2024]
Abstract
Cervical remodeling is critical for a healthy pregnancy. Premature tissue changes can lead to preterm birth (PTB), and the absence of remodeling can lead to post-term birth, causing significant morbidity. Comprehensive characterization of cervical material properties is necessary to uncover the mechanisms behind abnormal cervical softening. Quantifying cervical material properties during gestation is challenging in humans. Thus, a nonhuman primate (NHP) model is employed for this study. In this study, cervical tissue samples were collected from Rhesus macaques before pregnancy and at three gestational time points. Indentation and tension mechanical tests were conducted, coupled with digital image correlation (DIC), constitutive material modeling, and inverse finite element analysis (IFEA) to characterize the equilibrium material response of the macaque cervix during pregnancy. Results show, as gestation progresses: (1) the cervical fiber network becomes more extensible (nonpregnant versus pregnant locking stretch: 2.03 ± 1.09 versus 2.99 ± 1.39) and less stiff (nonpregnant versus pregnant initial stiffness: 272 ± 252 kPa versus 43 ± 43 kPa); (2) the ground substance compressibility does not change much (nonpregnant versus pregnant bulk modulus: 1.37 ± 0.82 kPa versus 2.81 ± 2.81 kPa); (3) fiber network dispersion increases, moving from aligned to randomly oriented (nonpregnant versus pregnant concentration coefficient: 1.03 ± 0.46 versus 0.50 ± 0.20); and (4) the largest change in fiber stiffness and dispersion happen during the second trimester. These results, for the first time, reveal the remodeling process of a nonhuman primate cervix and its distinct regimes throughout the entire pregnancy.
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Affiliation(s)
- Shuyang Fang
- Department of Mechanical Engineering, Columbia University, New York, NY 10027
| | - Lei Shi
- Department of Mechanical Engineering, Columbia University, New York, NY 10027
| | - Joy-Sarah Y. Vink
- Department of Obstetrics and Gynecology, Columbia University, New York, NY 10027
| | - Helen Feltovich
- Department of Maternal Fetal Medicine, Intermountain Healthcare, Park City, UT 84060
| | - Timothy J. Hall
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53706
| | - Kristin M. Myers
- Department of Mechanical Engineering, Columbia University, New York, NY 10027
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3
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Böl M, Leichsenring K, Kohn S, Ehret AE. The anisotropic and region-dependent mechanical response of wrap-around tendons under tensile, compressive and combined multiaxial loads. Acta Biomater 2024:S1742-7061(24)00301-5. [PMID: 38838908 DOI: 10.1016/j.actbio.2024.05.053] [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: 12/01/2023] [Revised: 05/20/2024] [Accepted: 05/30/2024] [Indexed: 06/07/2024]
Abstract
The present work reports on the multiaxial region and orientation-dependent mechanical properties of two porcine wrap-around tendons under tensile, compressive and combined loads based on an extensive study with n=175 samples. The results provide a detailed dataset of the anisotropic tensile and compressive longitudinal properties and document a pronounced tension-compression asymmetry. Motivated by the physiological loading conditions of these tendons, which include transversal compression at bony abutments in addition to longitudinal tension, we systematically investigated the change in axial tension when the tendon is compressed transversally along one or both perpendicular directions. The results reveal that the transversal compression can increase axial tension (proximal-distal direction) in both cases to orders of 30%, yet by a larger amount in the first case (transversal compression in anterior-posterior direction), which seems to be more relevant for wrap-around tendons in-vivo. These quantitative measurements are in line with earlier findings on auxetic properties of tendon tissue, but show for the first time the influence of this property on the stress response of the tendon, and may thus reveal an important functional principle within these essential elements of force transmission in the body. STATEMENT OF SIGNIFICANCE: The work reports for the first time on multiaxial region and orientation-dependent mechanical properties of wrap-around tendons under various loads. The results indicate that differences in the mechanical properties exist between zones that are predominantly in a uniaxial tensile state and those that experience complex load states. The observed counterintuitive increase of the axial tension upon lateral compression points at auxetic properties of the tendon tissue which may be pivotal for the function of the tendon as an element of the musculoskeletal system. It suggests that the tendon's performance in transmitting forces is not diminished but enhanced when the action line is deflected by a bony pulley around which the tendon wraps, representing an important functional principle of tendon tissue.
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Affiliation(s)
- Markus Böl
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, Braunschweig D-38106, Germany.
| | - Kay Leichsenring
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, Braunschweig D-38106, Germany
| | - Stephan Kohn
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, Braunschweig D-38106, Germany
| | - Alexander E Ehret
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland; Institute for Mechanical Systems, ETH Zurich, Zürich, CH-8092, Switzerland
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4
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Ojha AK, Rajasekaran R, Hansda AK, Choudhury P, Biswas A, Sharma S, Chaudhuri PP, Dogra N, Goswami R, Chaudhury K, Dhara S. Biochemical and immunomodulatory insights of extracellular matrix from decellularized human whole cervix: recellularization and in vivoECM remodeling interplay. Biofabrication 2024; 16:035014. [PMID: 38663394 DOI: 10.1088/1758-5090/ad4393] [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: 07/15/2023] [Accepted: 04/25/2024] [Indexed: 05/08/2024]
Abstract
Extracellular matrix (ECM) rich whole organ bio-scaffolds, preserving structural integrity and essential growth factors, has potential towards regeneration and reconstruction. Women with cervical anomalies or trauma can benefit from clinical cervicovaginal repair using constructs rich in site specific ECM. In this study, complete human cervix decellularization was achieved using a modified perfusion-based stir bench top decellularization method. This was followed by physico-chemical processes including perfusion of ionic agents, enzymatic treatment and washing using detergent solutions for a duration of 10-12 d. Histopathological analysis, as well as DNA quantification confirmed the efficacy of the decellularization process. Tissue ultrastructure integrity was preserved and the same was validated via scanning electron microscopy and transmission electron microscopy studies. Biochemical analysis and structural characterizations like Fourier transform infrared, Raman spectroscopy of decellularized tissues demonstrated preservation of important proteins, crucial growth factors, collagen, and glycosaminoglycans.In vitrostudies, using THP-1 and human umbilical vein endothelial cell (HUVEC) cells, demonstrated macrophage polarization from M1 to M2 and vascular functional genes enhancement, respectively, when treated with decellularized human cervical matrix (DHCp). Crosslinked DHC scaffolds were recellularized with site specific human cervical epithelial cells and HUVEC, showing non-cytotoxic cell viability and enhanced proliferation. Furthermore, DHC scaffolds showed immunomodulatory effectsin vivoon small rodent model via upregulation of M2 macrophage genes as compared to decellularized rat cervix matrix scaffolds (DRC). DHC scaffolds underwent neo-vascularization followed by ECM remodeling with enhanced tissue integration.
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Affiliation(s)
- Atul Kumar Ojha
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Ragavi Rajasekaran
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Arman Kunwar Hansda
- School of Bioscience, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Priyanka Choudhury
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Asmita Biswas
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Sunita Sharma
- Institute of Reproductive Medicine, Salt Lake, Kolkata, India
| | - Prithwis Pal Chaudhuri
- Department of Obstetrics and Gynecology, Zenith Super specialty hospital, Kolkata, India
| | - Nantu Dogra
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Ritobrata Goswami
- School of Bioscience, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Koel Chaudhury
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Santanu Dhara
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur, India
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5
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Kurt I, Kulhan M, AlAshqar A, Borahay MA. Uterine Collagen Cross-Linking: Biology, Role in Disorders, and Therapeutic Implications. Reprod Sci 2024; 31:645-660. [PMID: 37907804 DOI: 10.1007/s43032-023-01386-7] [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: 06/22/2023] [Accepted: 10/13/2023] [Indexed: 11/02/2023]
Abstract
Collagen is an essential constituent of the uterine extracellular matrix that provides biomechanical strength, resilience, structural integrity, and the tensile properties necessary for the normal functioning of the uterus. Cross-linking is a fundamental step in collagen biosynthesis and is critical for its normal biophysical properties. This step occurs enzymatically via lysyl oxidase (LOX) or non-enzymatically with the production of advanced glycation end-products (AGEs). Cross-links found in uterine tissue include the reducible dehydro-dihydroxylysinonorleucine (deH-DHLNL), dehydro-hydroxylysinonorleucine (deH-HLNL), and histidinohydroxymerodesmosine (HHMD); and the non-reducible pyridinoline (PYD), deoxy-pyridinoline (DPD); and a trace of pentosidine (PEN). Collagen cross-links are instrumental for uterine tissue integrity and the continuation of a healthy pregnancy. Decreased cervical cross-link density is observed in preterm birth, whereas increased tissue stiffness caused by increased cross-link density is a pathogenic feature of uterine fibroids. AGEs disrupt embryo development, decidualization, implantation, and trophoblast invasion. Uterine collagen cross-linking regulators include steroid hormones, such as progesterone and estrogen, prostaglandins, proteoglycans, metalloproteinases, lysyl oxidases, nitric oxide, nicotine, and vitamin D. Thus, uterine collagen cross-linking presents an opportunity to design therapeutic targets and warrants further investigation in common uterine disorders, such as uterine fibroids, cervical insufficiency, preterm birth, dystocia, endometriosis, and adenomyosis.
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Affiliation(s)
- Irem Kurt
- Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Selcuk University Faculty of Medicine, 42000, Konya, Turkey
| | - Mehmet Kulhan
- Department of Gynecology and Obstetrics, Selcuk University Faculty of Medicine, 42000, Konya, Turkey
| | - Abdelrahman AlAshqar
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, 06510, USA
| | - Mostafa A Borahay
- Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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6
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Mohammadkhah M, Klinge S. Review paper: The importance of consideration of collagen cross-links in computational models of collagen-based tissues. J Mech Behav Biomed Mater 2023; 148:106203. [PMID: 37879165 DOI: 10.1016/j.jmbbm.2023.106203] [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: 06/23/2023] [Revised: 09/25/2023] [Accepted: 10/17/2023] [Indexed: 10/27/2023]
Abstract
Collagen as the main protein in Extra Cellular Matrix (ECM) is the main load-bearing component of fibrous tissues. Nanostructure and architecture of collagen fibrils play an important role in mechanical behavior of these tissues. Extensive experimental and theoretical studies have so far been performed to capture these properties, but none of the current models realistically represent the complexity of network mechanics because still less is known about the collagen's inner structure and its effect on the mechanical properties of tissues. The goal of this review article is to emphasize the significance of cross-links in computational modeling of different collagen-based tissues, and to reveal the need for continuum models to consider cross-links properties to better reflect the mechanical behavior observed in experiments. In addition, this study outlines the limitations of current investigations and provides potential suggestions for the future work.
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Affiliation(s)
- Melika Mohammadkhah
- Technische Universität Berlin, Institute of Mechanics, Chair of Structural Mechanics and Analysis, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany.
| | - Sandra Klinge
- Technische Universität Berlin, Institute of Mechanics, Chair of Structural Mechanics and Analysis, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
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7
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Yoshida K. Bioengineering and the cervix: The past, current, and future for addressing preterm birth. Curr Res Physiol 2023; 6:100107. [PMID: 38107784 PMCID: PMC10724223 DOI: 10.1016/j.crphys.2023.100107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/23/2023] [Accepted: 09/20/2023] [Indexed: 12/19/2023] Open
Abstract
The uterine cervix plays two important but opposing roles during pregnancy - as a mechanical barrier that maintains the fetus for nine months and as a compliant structure that dilates to allow for the delivery of a baby. In some pregnancies, however, the cervix softens and dilates prematurely, leading to preterm birth. Bioengineers have addressed and continue to address the lack of reduction in preterm birth rates by developing novel technologies to diagnose, prevent, and understand premature cervical remodeling. This article highlights these existing and emerging technologies and concludes with open areas of research related to the cervix and preterm birth that bioengineers are currently well-positioned to address.
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Affiliation(s)
- Kyoko Yoshida
- Department of Biomedical Engineering, University of Minnesota, 7-105 Nils Hasselmo Hall, 312 Church Street SE, Minneapolis, MN, 55455, USA
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8
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Ojha AK, Rajasekaran R, Hansda AK, Singh A, Dutta A, Seesala VS, Das S, Dogra N, Sharma S, Goswami R, Chaudhury K, Dhara S. Biodegradable Multi-layered Silk Fibroin-PCL Stent for the Management of Cervical Atresia: In Vitro Cytocompatibility and Extracellular Matrix Remodeling In Vivo. ACS APPLIED MATERIALS & INTERFACES 2023; 15:39099-39116. [PMID: 37579196 DOI: 10.1021/acsami.3c06585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
Cervical atresia is a rare congenital Müllerian duct anomaly that manifests as the absence or deformed nonfunctional presence of the cervix. Herein, a multi-layered biodegradable stent is fabricated using a homogeneous blend of silk fibroin with polycaprolactone using hexafluoroisopropanol as a common solution. Briefly, a concentric cylinder of 3D honeycomb layer is sandwiched within electrospun sheets for fixing at the cervico-uterine junction to pave the way of cervical reconstruction. An average length of 40 mm with 3 mm diameter is fabricated for the hybrid stent design. SEM evidences an evenly distributed pore architecture of the electrospun layer, and mechanical characterization of stent reveals a tensile strength of 1.7 ± 0.2 MPa, with a Young's modulus of 5.9 ± 0.1 MPa. Physico-chemical characterization confirms the presence of silk fibroin and poly caprolactone within the engineered stent. Following 14 days of pepsin enzymatic degradation, 18% degradation and a contact angle measurement of 97° are observed. In vitro cytocompatibility studies are performed using site-specific primary human cervical squamous, columnar epithelial cells, and human endometrial stromal cells. The study demonstrates non-cytotoxic cells' viability (no significant toxicity), improved cell anchoring, adherence among the stent layers, and proliferation in the 3D microenvironment. Furthermore, in vivo subcutaneous studies in the rodent model indicate that the implanted stent undergoes constructive remodeling, neo-tissue creation, neo-vasculature formation, and re-epithelialization while maintaining patency for 2 months.
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Affiliation(s)
- Atul Kumar Ojha
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Ragavi Rajasekaran
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Armaan Kunwar Hansda
- School of Bioscience, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Apoorva Singh
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Abir Dutta
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Venkata Sundeep Seesala
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Samir Das
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Nantu Dogra
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Sunita Sharma
- Institute of Reproductive Medicine, Salt Lake 700106, Kolkata, India
| | - Ritobrata Goswami
- School of Bioscience, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Koel Chaudhury
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Santanu Dhara
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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9
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Shi L, Myers K. A finite porous-viscoelastic model capturing mechanical behavior of human cervix under multi-step spherical indentation. J Mech Behav Biomed Mater 2023; 143:105875. [PMID: 37187153 PMCID: PMC10330483 DOI: 10.1016/j.jmbbm.2023.105875] [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: 02/01/2023] [Revised: 04/12/2023] [Accepted: 04/26/2023] [Indexed: 05/17/2023]
Abstract
The cervix is a soft tissue exhibiting time-dependent behavior under mechanical loads. The cervix is a vital mechanical barrier to protect the growing fetus. The remodeling of the cervical tissue, characterized by an increase in time-dependent material properties, is necessary for a safe parturition. The failure of its mechanical function and accelerated tissue remodeling is hypothesized to lead to preterm birth, which is birth before 37 weeks of gestation. To understand the mechanism of the time-dependent behavior of the cervix under compressive states, we employ a porous-viscoelastic material model to describe a set of spherical indentation tests performed on nonpregnant and term pregnant tissue. A genetic algorithm-based inverse finite element analysis is used to fit the force-relaxation data by optimizing the material parameters, and the statistical analysis of the optimized material parameters is conducted on different sample groups. The force response is captured well using the porous-viscoelastic model. The indentation force-relaxation of the cervix is explained by the porous effects and the intrinsic viscoelastic properties of the extracellular matrix (ECM) microstructure. The hydraulic permeability obtained from the inverse finite element analysis agrees with the trend of the value directly measured previously by our group. The nonpregnant samples are found significantly more permeable than the pregnant samples. Within nonpregnant samples, the posterior internal os is found significantly less permeable than the anterior and posterior external os. The proposed model exhibits the superior capability to capture the force-relaxation response of the cervix under indentation, as compared to the conventional quasi-linear viscoelastic framework (range of r2 of the porous-viscoelastic model 0.88-0.98 vs. quasi-linear model: 0.67-0.89). As a constitutive model with a relatively simple form, the porous-viscoelastic framework has the potential to be used to understand disease mechanisms of premature cervical remodeling, model contact of the cervix with biomedical devices, and interpret force readings from novel in-vivo measurement tools such as an aspiration device.
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Affiliation(s)
- Lei Shi
- Department of Mechanical Engineering, Columbia University, 500 W 120th St, MC 4703, New York, 10027, NY, USA
| | - Kristin Myers
- Department of Mechanical Engineering, Columbia University, 500 W 120th St, MC 4703, New York, 10027, NY, USA.
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10
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Hunter PJ, Awoyemi T, Ayede AI, Chico RM, David AL, Dewey KG, Duggan CP, Gravett M, Prendergast AJ, Ramakrishnan U, Ashorn P, Klein N. Biological and pathological mechanisms leading to the birth of a small vulnerable newborn. Lancet 2023; 401:1720-1732. [PMID: 37167990 DOI: 10.1016/s0140-6736(23)00573-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 03/08/2023] [Accepted: 03/14/2023] [Indexed: 05/13/2023]
Abstract
The pathway to a thriving newborn begins before conception and continues in utero with a healthy placenta and the right balance of nutrients and growth factors that are timed and sequenced alongside hormonal suppression of labour until a mature infant is ready for birth. Optimal nutrition that includes adequate quantities of quality protein, energy, essential fats, and an extensive range of vitamins and minerals not only supports fetal growth but could also prevent preterm birth by supporting the immune system and alleviating oxidative stress. Infection, illness, undernourishment, and harmful environmental exposures can alter this trajectory leading to an infant who is too small due to either poor growth during pregnancy or preterm birth. Systemic inflammation suppresses fetal growth by interfering with growth hormone and its regulation of insulin-like growth factors. Evidence supports the prevention and treatment of several maternal infections during pregnancy to improve newborn health. However, microbes, such as Ureaplasma species, which are able to ascend the cervix and cause membrane rupture and chorioamnionitis, require new strategies for detection and treatment. The surge in fetal cortisol late in pregnancy is essential to parturition at the right time, but acute or chronically high maternal cortisol levels caused by psychological or physical stress could also trigger labour onset prematurely. In every pathway to the small vulnerable newborn, there is a possibility to modify the course of pregnancy by supporting improved nutrition, protection against infection, holistic maternal wellness, and healthy environments.
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Affiliation(s)
- Patricia J Hunter
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK.
| | | | - Adejumoke I Ayede
- Department of Paediatrics, College of Medicine, University of Ibadan and University College Hospital, Ibadan, Nigeria
| | - R Matthew Chico
- Department of Disease Control, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Anna L David
- UCL Elizabeth Garrett Anderson Institute for Women's Health, University College London, London, UK
| | - Kathryn G Dewey
- Department of Nutrition, University of California at Davis, Davis, CA, USA
| | - Christopher P Duggan
- Department of Nutrition and Department of Global Health and Population, Harvard TH Chan School of Public Health, Boston, MA, USA; Center for Nutrition, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Michael Gravett
- Department of Obstetrics & Gynecology, University of Washington, Seattle, WA, USA
| | - Andrew J Prendergast
- Blizard Institute, Queen Mary University of London, London, UK; Zvitambo Institute for Maternal & Child Health Research, Harare, Zimbabwe
| | | | - Per Ashorn
- Center for Child, Adolescent, and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University and Tampere University Hospital, Tampere, Finland
| | - Nigel Klein
- UCL Great Ormond Street Institute of Child Health, University College London, London, UK
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11
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Shi L, Hu L, Lee N, Fang S, Myers K. Three-Dimensional Anisotropic Hyperelastic Constitutive Model Describing the Mechanical Response of Human and Mouse Cervix. Acta Biomater 2022; 150:277-294. [PMID: 35931278 DOI: 10.1016/j.actbio.2022.07.062] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 07/25/2022] [Accepted: 07/28/2022] [Indexed: 11/18/2022]
Abstract
The mechanical function of the uterine cervix is critical for a healthy pregnancy. During pregnancy, the cervix undergoes significant softening to allow for a successful delivery. Abnormal cervical remodeling is suspected to contribute to preterm birth. Material constitutive models describing known biological shifts in pregnancy are essential to predict the mechanical integrity of the cervix. In this work, the material response of human cervical tissue under spherical indentation and uniaxial tensile tests loaded along different anatomical directions is experimentally measured. A deep-learning segmentation tool is applied to capture the tissue deformation during the uniaxial tensile tests. A 3-dimensional, equilibrium anisotropic continuous fiber constitutive model is formulated, considering collagen fiber directionality, fiber bundle dispersion, and the entropic nature of wavy cross-linked collagen molecules. Additionally, the universality of the material model is demonstrated by characterizing previously published mouse cervix mechanical data. Overall, the proposed material model captures the tension-compression asymmetric material responses and the remodeling characteristics of both human and mouse cervical tissue. The pregnant (PG) human cervix (mean locking stretch ζ=2.4, mean initial stiffness ξ=12 kPa, mean bulk modulus κ=0.26 kPa, mean dispersion b=1.0) is more compliant compared with the nonpregnant (NP) cervix (mean ζ=1.3, mean ξ=32 kPa, mean κ=1.4 kPa, mean b=1.4). Creating a validated material model, which describes the role of collagen fiber directionality, dispersion, and crosslinking, enables tissue-level biomechanical simulations to determine which material and anatomical factors drive the cervix to open prematurely. STATEMENT OF SIGNIFICANCE: In this study, we report a 3D anisotropic hyperelastic constitutive model based on Langevin statistic mechanics and successfully describe the material behavior of both human and mouse cervical tissue using this model. This model bridges the connection between the extracellular matrix (ECM) microstructure remodeling and the macro mechanical properties change of the cervix during pregnancy via microstructure-associated material parameters. This is the first model, to our knowledge, to connect the the entropic nature of wavy cross-linked collagen molecules with the mechanical behavior of the cervix. Inspired by microstructure, this model provides a foundation to understand further the relationship between abnormal cervical ECM remodeling and preterm birth. Furthermore, with a relatively simple form, the proposed model can be applied to other fibrous tissues in the future.
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Affiliation(s)
- Lei Shi
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Lingfeng Hu
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Nicole Lee
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Shuyang Fang
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Kristin Myers
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA.
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12
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Böl M, Kohn S, Leichsenring K, Morales-Orcajo E, Ehret AE. On multiscale tension-compression asymmetry in skeletal muscle. Acta Biomater 2022; 144:210-220. [PMID: 35339701 DOI: 10.1016/j.actbio.2022.03.034] [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: 10/11/2021] [Revised: 03/11/2022] [Accepted: 03/17/2022] [Indexed: 11/17/2022]
Abstract
Skeletal muscle tissue shows a clear asymmetry with regard to the passive stresses under tensile and compressive deformation, referred to as tension-compression asymmetry (TCA). The present study is the first one reporting on TCA at different length scales, associated with muscle tissue and muscle fibres, respectively. This allows for the first time the comparison of TCA between the tissue and one of its individual components, and thus to identify the length scale at which this phenomenon originates. Not only the passive stress-stretch characteristics were recorded, but also the volume changes during the axial tension and compression experiments. The study reveals clear differences in the characteristics of TCA between fibres and tissue. At tissue level TCA increases non-linearly with increasing deformation and the ratio of tensile to compressive stresses at the same magnitude of strain reaches a value of approximately 130 at 13.5% deformation. At fibre level instead it initially drops to a value of 6 and then rises again to a TCA of 14. At a deformation of 13.5%, the tensile stress is about 6 times higher. Thus, TCA is about 22 times more expressed at tissue than fibre scale. Moreover, the analysis of volume changes revealed little compressibility at tissue scale whereas at fibre level, especially under compressive stress, the volume decreases significantly. The data collected in this study suggests that the extracellular matrix has a distinct role in amplifying the TCA, and leads to more incompressible tissue behaviour. STATEMENT OF SIGNIFICANCE: This article analyses and compares for the first time the tension-compression asymmetry (TCA) displayed by skeletal muscle at tissue and fibre scale. In addition, the volume changes of tissue and fibre specimens with application of passive tensile and compressive loads are studied. The study identifies a key role of the extracellular matrix in establishing the mechanical response of skeletal muscle tissue: It contributes significantly to the passive stress, it is responsible for the major part of tissue-scale TCA and, most probably, prevents/balances the volume changes of muscle fibres during deformation. These new results thus shed light on the origin of TCA and provide new information to be used in microstructure-based approaches to model and simulate skeletal muscle tissue.
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Affiliation(s)
- Markus Böl
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
| | - Stephan Kohn
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, D-38106 Braunschweig, Germany
| | - Kay Leichsenring
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, D-38106 Braunschweig, Germany
| | - Enrique Morales-Orcajo
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, D-38106 Braunschweig, Germany
| | - Alexander E Ehret
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland; Institute for Mechanical Systems, ETH Zurich, CH-8092, Zürich, Switzerland
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13
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Jayyosi C, Lee N, Madhukaran SP, Nallasamy S, Mahendroo M, Myers K. The swelling behavior of the mouse cervix: Changing kinetics with osmolarity and the role of hyaluronan in pregnancy. Acta Biomater 2021; 135:414-424. [PMID: 34411755 DOI: 10.1016/j.actbio.2021.08.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 08/11/2021] [Accepted: 08/12/2021] [Indexed: 11/29/2022]
Abstract
The cervical remodeling process during pregnancy is characterized by progressive compositional and structural changes in the tissues extra-cellular matrix (ECM). Appropriately timed remodeling is critical for healthy gestation and prevention of premature cervical softening leading to preterm birth (PTB). Modification of the ECM glycosaminoglycans (GAGs) content with advancing pregnancy, especially the non-sulfated GAG hyaluronan (HA), is a fundamental change associated with cervical remodeling. While GAGs have numerous physiological roles, the mechanical consequence of evolving GAG content on cervical structure-function behavior remains an open question. Additionally, an understanding of cervical swelling properties, postulated to be regulated in part by GAGs, is required for the appropriate definition of a reference configuration for mechanical tests and to enhance biological understanding. To investigate cervical swelling, osmotic loading tests are conducted on isolated wild type mouse cervices throughout pregnancy. These tests are performed in various osmolarity solutions to assess the influence of the media on swelling kinetics. A genetically altered strain of mice with depletion of cervical HA is also tested to elucidate the contribution of HA to tissue swelling. Results show ex vivo cervical swelling is significant with volume changes ranging from 20 to 100% after 3h of free swelling. The swelling kinetics depend highly on osmolarity of the media and is altered with advancing pregnancy. The contribution of HA to swelling is only significant in hypo-osmotic solution when HA cervical content is high at the end of pregnancy. In summary, it is critical to account for swelling deformation mechanisms after excision in mechanical experiments. STATEMENT OF SIGNIFICANCE: The cervical extracellular matrix (ECM) undergoes drastic changes to fulfill the functional change of the cervix during pregnancy. Inappropriate timing for this transformation can result in preterm birth, a severe clinical challenge. One of the fundamental changes of the cervical ECM is the significant modification of the glycosaminoglycan content, especially hyaluronan (HA), which is thought to contribute significantly to the swelling and mechanical properties of the cervix. This study aims to measure the swelling kinetics of cervical tissue during pregnancy and to investigate the role of HA in these swelling tendencies. Results show the significant swelling of cervical tissue, which evolves as pregnancy progresses, highlighting a key material property feature of the remodeled cervix. Using a mouse strain with a cervical HA depletion, this work shows HA contributes to the swelling trends of late-term cervical tissue, in a hypo-osmotic solution.
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Affiliation(s)
- C Jayyosi
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - N Lee
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - S P Madhukaran
- Department of Obstetrics and Gynecology and Cecil H. and Ida Green Center for Reproductive Biological Science, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - S Nallasamy
- Department of Obstetrics and Gynecology and Cecil H. and Ida Green Center for Reproductive Biological Science, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - M Mahendroo
- Department of Obstetrics and Gynecology and Cecil H. and Ida Green Center for Reproductive Biological Science, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - K Myers
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA.
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14
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O’Hara S, Zelesco M, Sun Z. Use of shear wave elastography on the maternal cervix to recognise cervical insufficiency using a transabdominal ultrasound approach. Australas J Ultrasound Med 2021; 24:89-98. [PMID: 34765416 PMCID: PMC8412007 DOI: 10.1002/ajum.12236] [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: 07/20/2020] [Revised: 10/04/2020] [Accepted: 10/26/2020] [Indexed: 11/06/2022] Open
Abstract
INTRODUCTION The ramifications of preterm birth on society and the role of cervical length in identifying cervical insufficiency are well known. The main goal of this work was to apply shear wave elastography to the maternal cervix to assess the stiffness of the cervix and identify cervical insufficiency, using a transabdominal ultrasound approach. METHODS Measurements of shear wave speed were obtained using a transabdominal ultrasound approach, at the anterior and posterior portions of the internal and external cervical os on 504 participants. A total of 455 participants were contacted following the expected date of birth of the fetus and birth details were obtained. RESULTS The anterior and posterior portions of the internal os showed a significant correlation between shear wave speed and time until delivery of the fetus for women who gave birth spontaneously, with R 2 Linear being 0.024 (P = 0.012) and 0.017 (P = 0.05) respectively, and these correlations increased for the group of participants that were scanned between the 18th and end of the 20th week of pregnancy to R 2 Linear = 0.043 (P = 0.001) and 0.021 (P = 0.040) respectively. A ratio of internal os/external os anteriorly also showed a correlation of R 2 Linear = 0.030 (P = 0.009). CONCLUSION A transabdominal ultrasound technique has identified a reduction in shear wave speeds at the internal os in the mid-trimester, in women who had a subsequent preterm birth.
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Affiliation(s)
- Sandra O’Hara
- SKG RadiologyPerthWestern AustraliaAustralia
- Discipline of Medical Radiation SciencesSchool of Molecular and Life SciencesCurtin UniversityPerthWestern AustraliaAustralia
| | - Marilyn Zelesco
- Department of Medical ImagingFiona Stanley HospitalMurdochWestern AustraliaAustralia
| | - Zhonghua Sun
- Discipline of Medical Radiation SciencesSchool of Molecular and Life SciencesCurtin UniversityPerthWestern AustraliaAustralia
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15
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Conway CK, Varghese A, Mahendroo M, Miller KS. The Role of Biaxial Loading on Smooth Muscle Contractility in the Nulliparous Murine Cervix. Ann Biomed Eng 2021; 49:1874-1887. [PMID: 33880630 DOI: 10.1007/s10439-021-02778-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/06/2021] [Indexed: 12/17/2022]
Abstract
Throughout the estrus cycle, the extracellular matrix (ECM) and cervical smooth muscle cells (cSMC) coordinate to accomplish normal physiologic function in the non-pregnant cervix. While previous uniaxial experiments provide fundamental knowledge about cervical contractility and biomechanics, the specimen preparation is disruptive to native organ geometry and does not permit simultaneous assessment of circumferential and axial properties. Thus, a need remains to investigate cervical contractility and passive biomechanics within physiologic multiaxial loading. Biaxial inflation-extension experiments overcome these limitations by preserving geometry, ECM-cell interactions, and multiaxially loading the cervix. Utilizing in vivo pressure measurements and inflation-extension testing, this study presented methodology and examined maximum biaxial contractility and biomechanics in the nulliparous murine cervix. The study showed that increased pressure resulted in decreased contractile potential in the circumferential direction, however, axial contractility remained unaffected. Additionally, total change in axial stress ([Formula: see text]) increased significantly (p < 0.05) compared to circumferential stress ([Formula: see text]) with maximum contraction. However, passive stiffness was significantly greater (p < 0.01) in the circumferential direction. Overall, axial cSMC may have a critical function in maintaining cervical homeostasis during normal function. Potentially, a loss of axial contractility in the cervix during pregnancy may result in maladaptive remodeling such as cervical insufficiency.
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Affiliation(s)
- Cassandra K Conway
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Ave, New Orleans, LA, 70118, USA
| | - Asha Varghese
- Obstetrics and Gynecology and Green Center for Reproductive Sciences, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Mala Mahendroo
- Obstetrics and Gynecology and Green Center for Reproductive Sciences, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Kristin S Miller
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Ave, New Orleans, LA, 70118, USA.
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16
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Fang S, McLean J, Shi L, Vink JSY, Hendon CP, Myers KM. Anisotropic Mechanical Properties of the Human Uterus Measured by Spherical Indentation. Ann Biomed Eng 2021; 49:1923-1942. [PMID: 33880632 DOI: 10.1007/s10439-021-02769-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 03/26/2021] [Indexed: 12/11/2022]
Abstract
The mechanical function of the uterus is critical for a successful pregnancy. During gestation, uterine tissue grows and stretches to many times its size to accommodate the growing fetus, and it is hypothesized the magnitude of uterine tissue stretch triggers the onset of contractions. To establish rigorous mechanical testing protocols for the human uterus in hopes of predicting tissue stretch during pregnancy, this study measures the anisotropic mechanical properties of the human uterus using optical coherence tomography (OCT), instrumented spherical indentation, and video extensometry. In this work, we perform spherical indentation and digital image correlation to obtain the tissue's force and deformation response to a ramp-hold loading regimen. We translate previously reported fiber architecture, measured via optical coherence tomography, into a constitutive fiber composite material model to describe the equilibrium material behavior during indentation. We use an inverse finite element method integrated with a genetic algorithm (GA) to fit the material model to our experimental data. We report the mechanical properties of human uterine specimens taken across different anatomical locations and layers from one non-pregnant (NP) and one pregnant (PG) patient; both patients had pathological uterine tissue. Compared to NP uterine tissue, PG tissue has a more dispersed fiber distribution and equivalent stiffness material parameters. In both PG and NP uterine tissue, the mechanical properties differ significantly between anatomical locations.
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Affiliation(s)
- Shuyang Fang
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - James McLean
- Department of Electrical Engineering, Columbia University, New York, NY, 10027, USA
| | - Lei Shi
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Joy-Sarah Y Vink
- Department of Obstetrics and Gynecology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Christine P Hendon
- Department of Electrical Engineering, Columbia University, New York, NY, 10027, USA
| | - Kristin M Myers
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA.
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17
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Roa C, Du Le VN, Mahendroo M, Saytashev I, Ramella-Roman JC. Auto-detection of cervical collagen and elastin in Mueller matrix polarimetry microscopic images using K-NN and semantic segmentation classification. BIOMEDICAL OPTICS EXPRESS 2021; 12:2236-2249. [PMID: 33996226 PMCID: PMC8086465 DOI: 10.1364/boe.420079] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/10/2021] [Accepted: 03/17/2021] [Indexed: 05/25/2023]
Abstract
We propose an approach for discriminating fibrillar collagen fibers from elastic fibers in the mouse cervix in Mueller matrix microscopy using convolutional neural networks (CNN) and K-nearest neighbor (K-NN) for classification. Second harmonic generation (SHG), two-photon excitation fluorescence (TPEF), and Mueller matrix polarimetry images of the mice cervix were collected with a self-validating Mueller matrix micro-mesoscope (SAMMM) system. The components and decompositions of each Mueller matrix were arranged as individual channels of information, forming one 3-D voxel per cervical slice. The classification algorithms analyzed each voxel and determined the amount of collagen and elastin, pixel by pixel, on each slice. SHG and TPEF were used as ground truths. To assess the accuracy of the results, mean-square error (MSE), peak signal-to-noise ratio (PSNR), and structural similarity (SSIM) were used. Although the training and testing is limited to 11 and 5 cervical slices, respectively, MSE accuracy was above 85%, SNR was greater than 40 dB, and SSIM was larger than 90%.
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Affiliation(s)
- Camilo Roa
- Department of Biological Sciences, College of Arts, Sciences and Education, Florida International University, 11200 SW 8th Street, Miami, FL 33199, USA
- These authors contributed equally
| | - V N Du Le
- Department of Biomedical Engineering, College of Engineering and Computing, Florida International University, 10555 West Flagler Street, Miami, FL 33174, USA
- These authors contributed equally
| | - Mala Mahendroo
- Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Ilyas Saytashev
- Department of Ophthalmology, Herbert Wertheim College of Medicine, Florida International University, 11200 SW 8 Street, Miami, FL 33199, USA
| | - Jessica C Ramella-Roman
- Department of Biomedical Engineering, College of Engineering and Computing, Florida International University, 10555 West Flagler Street, Miami, FL 33174, USA
- Department of Ophthalmology, Herbert Wertheim College of Medicine, Florida International University, 11200 SW 8 Street, Miami, FL 33199, USA
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18
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Wendel JRH, Wang X, Smith LJ, Hawkins SM. Three-Dimensional Biofabrication Models of Endometriosis and the Endometriotic Microenvironment. Biomedicines 2020; 8:biomedicines8110525. [PMID: 33233463 PMCID: PMC7700676 DOI: 10.3390/biomedicines8110525] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/06/2020] [Accepted: 11/19/2020] [Indexed: 12/22/2022] Open
Abstract
Endometriosis occurs when endometrial-like tissue grows outside the uterine cavity, leading to pelvic pain, infertility, and increased risk of ovarian cancer. The present study describes the optimization and characterization of cellular spheroids as building blocks for Kenzan scaffold-free method biofabrication and proof-of-concept models of endometriosis and the endometriotic microenvironment. The spheroid building blocks must be of a specific diameter (~500 μm), compact, round, and smooth to withstand Kenzan biofabrication. Under optimized spheroid conditions for biofabrication, the endometriotic epithelial-like cell line, 12Z, expressed high levels of estrogen-related genes and secreted high amounts of endometriotic inflammatory factors that were independent of TNFα stimulation. Heterotypic spheroids, composed of 12Z and T-HESC, an immortalized endometrial stromal cell line, self-assembled into a biologically relevant pattern, consisting of epithelial cells on the outside of the spheroids and stromal cells in the core. 12Z spheroids were biofabricated into large three-dimensional constructs alone, with HEYA8 spheroids, or as heterotypic spheroids with T-HESC. These three-dimensional biofabricated constructs containing multiple monotypic or heterotypic spheroids represent the first scaffold-free biofabricated in vitro models of endometriosis and the endometriotic microenvironment. These efficient and innovative models will allow us to study the complex interactions of multiple cell types within a biologically relevant microenvironment.
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Affiliation(s)
- Jillian R. H. Wendel
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (J.R.H.W.); (X.W.)
| | - Xiyin Wang
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (J.R.H.W.); (X.W.)
| | - Lester J. Smith
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
- 3D Bioprinting Core, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Shannon M. Hawkins
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (J.R.H.W.); (X.W.)
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Correspondence: ; Tel.: +1-317-274-8225
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19
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Callejas A, Melchor J, Faris IH, Rus G. Hyperelastic Ex Vivo Cervical Tissue Mechanical Characterization. SENSORS (BASEL, SWITZERLAND) 2020; 20:E4362. [PMID: 32764345 PMCID: PMC7472274 DOI: 10.3390/s20164362] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 07/19/2020] [Accepted: 08/03/2020] [Indexed: 12/18/2022]
Abstract
This paper presents the results of the comparison between a proposed Fourth Order Elastic Constants (FOECs) nonlinear model defined in the sense of Landau's theory, and the two most contrasted hyperelastic models in the literature, Mooney-Rivlin, and Ogden models. A mechanical testing protocol is developed to investigate the large-strain response of ex vivo cervical tissue samples in uniaxial tension in its two principal anatomical locations, the epithelial and connective layers. The final aim of this work is to compare the reconstructed shear modulus of the epithelial and connective layers of cervical tissue. According to the obtained results, the nonlinear parameter A from the proposed FOEC model could be an important biomarker in cervical tissue diagnosis. In addition, the calculated shear modulus depended on the anatomical location of the cervical tissue (μepithelial = 1.29 ± 0.15 MPa, and μconnective = 3.60 ± 0.63 MPa).
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Affiliation(s)
- Antonio Callejas
- Department of Structural Mechanics, University of Granada, 18010 Granada, Spain; (I.H.F.); (G.R.)
- Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
| | - Juan Melchor
- Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
- Excellence Research Unit, “Modelling Nature” (MNat), University of Granada, 18010 Granada, Spain
- Department of Statistics and Operations Research, University of Granada, 18010 Granada, Spain
| | - Inas H. Faris
- Department of Structural Mechanics, University of Granada, 18010 Granada, Spain; (I.H.F.); (G.R.)
- Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
| | - Guillermo Rus
- Department of Structural Mechanics, University of Granada, 18010 Granada, Spain; (I.H.F.); (G.R.)
- Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
- Excellence Research Unit, “Modelling Nature” (MNat), University of Granada, 18010 Granada, Spain
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20
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Shi L, Yao W, Gan Y, Zhao LY, Eugene McKee W, Vink J, Wapner RJ, Hendon CP, Myers K. Anisotropic Material Characterization of Human Cervix Tissue Based on Indentation and Inverse Finite Element Analysis. J Biomech Eng 2020; 141:2736280. [PMID: 31374123 DOI: 10.1115/1.4043977] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Indexed: 11/08/2022]
Abstract
The cervix is essential to a healthy pregnancy as it must bear the increasing load caused by the growing fetus. Preterm birth is suspected to be caused by the premature softening and mechanical failure of the cervix. The objective of this paper is to measure the anisotropic mechanical properties of human cervical tissue using indentation and video extensometry. The human cervix is a layered structure, where its thick stromal core contains preferentially aligned collagen fibers embedded in a soft ground substance. The fiber composite nature of the tissue provides resistance to the complex three-dimensional loading environment of pregnancy. In this work, we detail an indentation mechanical test to obtain the force and deformation response during loading which closely matches in vivo conditions. We postulate a constitutive material model to describe the equilibrium material behavior to ramp-hold indentation, and we use an inverse finite element method based on genetic algorithm (GA) optimization to determine best-fit material parameters. We report the material properties of human cervical slices taken at different anatomical locations from women of different obstetric backgrounds. In this cohort of patients, the anterior internal os (the area where the cervix meets the uterus) of the cervix is stiffer than the anterior external os (the area closest to the vagina). The anatomic anterior and posterior quadrants of cervical tissue are more anisotropic than the left and right quadrants. There is no significant difference in material properties between samples of different parities (number of pregnancies reaching viable gestation age).
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Affiliation(s)
- Lei Shi
- Department of Mechanical Engineering, Columbia University, New York, NY 10027 e-mail:
| | - Wang Yao
- Department of Mechanical Engineering, Columbia University, New York, NY 10027 e-mail:
| | - Yu Gan
- Department of Electrical Engineering, Columbia University, New York, NY 10027 e-mail:
| | - Lily Y Zhao
- Department of Mechanical Engineering, Columbia University, New York, NY 10027 e-mail:
| | - W Eugene McKee
- Department of Mechanical Engineering, Columbia University, New York, NY 10027 e-mail:
| | - Joy Vink
- Department of Obstetrics and Gynecology, Columbia University, New York, NY 10032 e-mail:
| | - Ronald J Wapner
- Department of Obstetrics and Gynecology, Columbia University, New York, NY 10032 e-mail:
| | - Christine P Hendon
- Department of Electrical Engineering, Columbia University, New York, NY 10027 e-mail:
| | - Kristin Myers
- Department of Mechanical Engineering, Columbia University, New York, NY 10027 e-mail:
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21
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Rus G, Faris IH, Torres J, Callejas A, Melchor J. Why Are Viscosity and Nonlinearity Bound to Make an Impact in Clinical Elastographic Diagnosis? SENSORS (BASEL, SWITZERLAND) 2020; 20:E2379. [PMID: 32331295 PMCID: PMC7219338 DOI: 10.3390/s20082379] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 12/24/2022]
Abstract
The adoption of multiscale approaches by the biomechanical community has caused a major improvement in quality in the mechanical characterization of soft tissues. The recent developments in elastography techniques are enabling in vivo and non-invasive quantification of tissues' mechanical properties. Elastic changes in a tissue are associated with a broad spectrum of pathologies, which stems from the tissue microstructure, histology and biochemistry. This knowledge is combined with research evidence to provide a powerful diagnostic range of highly prevalent pathologies, from birth and labor disorders (prematurity, induction failures, etc.), to solid tumors (e.g., prostate, cervix, breast, melanoma) and liver fibrosis, just to name a few. This review aims to elucidate the potential of viscous and nonlinear elastic parameters as conceivable diagnostic mechanical biomarkers. First, by providing an insight into the classic role of soft tissue microstructure in linear elasticity; secondly, by understanding how viscosity and nonlinearity could enhance the current diagnosis in elastography; and finally, by compounding preliminary investigations of those elastography parameters within different technologies. In conclusion, evidence of the diagnostic capability of elastic parameters beyond linear stiffness is gaining momentum as a result of the technological and imaging developments in the field of biomechanics.
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Affiliation(s)
- Guillermo Rus
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
- Excellence Research Unit “ModelingNature” MNat UCE.PP2017.03, University of Granada, 18071 Granada, Spain
| | - Inas H. Faris
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
| | - Jorge Torres
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
| | - Antonio Callejas
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
| | - Juan Melchor
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
- Excellence Research Unit “ModelingNature” MNat UCE.PP2017.03, University of Granada, 18071 Granada, Spain
- Department of Statistics and Operations Research, University of Granada, 18071 Granada, Spain
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22
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Gou K, Topol H, Demirkoparan H, Pence TJ. Stress-Swelling Finite Element Modeling of Cervical Response With Homeostatic Collagen Fiber Distributions. J Biomech Eng 2020; 142:1072289. [PMID: 31891375 DOI: 10.1115/1.4045810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Indexed: 01/01/2023]
Abstract
During pregnancy, the cervix experiences significant mechanical property change due to tissue swelling, and to ongoing changes in the collagen content. In this paper, we model how these two effects contribute to cervical deformation as the pressure load on top of the cervix increases. The cervix and its surrounding supporting ligaments are taken into consideration in the resulting mechanical analysis. The cervix itself is treated as a multilayered tube-like structure, with layer-specific collagen orientation. The cervical tissue in each layer is treated in terms of a collagen constituent that remodels with time within a ground substance matrix that experiences swelling. The load and swelling are taken to change sufficiently slowly so that the collagen properties at any instant can be regarded as being in a state of homeostasis. Among other things, the simulations show how the luminal cross-sectional area varies along its length as a function of pressure and swelling. In general, an increase in pressure causes an overall shortening of the lumen while an increase in swelling has the opposite effect.
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Affiliation(s)
- Kun Gou
- Department of Science and Mathematics, Texas A&M University-San Antonio, San Antonio, TX 78224
| | - Heiko Topol
- Carnegie Mellon University in Qatar, Education City, P.O. Box 24866, Doha, Qatar
| | - Hasan Demirkoparan
- Carnegie Mellon University in Qatar, Education City, P.O. Box 24866, Doha, Qatar
| | - Thomas J Pence
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI 48824
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23
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Abstract
The cervix is the essential gatekeeper for birth. Incomplete cervix remodeling contributes to problems with delivery at or post-term while preterm birth is a major factor in perinatal morbidity and mortality in newborns. Lack of cervix biopsies from women during the period preceding term or preterm birth have led to use of rodent models to advanced understanding of the mechanism for prepartum cervix remodeling. The critical transition from a soft cervix to a compliant prepartum lower uterine segment has only recently been recognized to occur in various mammalian species when progesterone in circulation is at or near the peak of pregnancy in preparation for birth. In rodents, characterization of ripening resembles an inflammatory process with a temporal coincidence of decreased density of cell nuclei, decline in cross-linked extracellular collagen, and increased presence of macrophages in the cervix. Although a role for inflammation in parturition and cervix remodeling is not a new concept, a comprehensive examination of literature in this review reveals that many conclusions are drawn from comparisons before and after ripening has occurred, not during the process. The present review focuses on essential phenotypes and functions of resident myeloid and possibly other immune cells to bridge the gap with evidence that specific biomarkers may assess the progress of ripening both at term and with preterm birth. Moreover, use of endpoints to determine the effectiveness of various therapeutic approaches to forestall remodeling and reduce risks for preterm birth, or facilitate ripening to promote parturition will improve the postpartum well-being of mothers and newborns.
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Affiliation(s)
- Steven M Yellon
- Department of Basic Sciences, Longo Center for Perinatal Biology, School of Medicine, Loma Linda University, Loma Linda, CA, United States
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24
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Yoshida K, Jayyosi C, Lee N, Mahendroo M, Myers KM. Mechanics of cervical remodelling: insights from rodent models of pregnancy. Interface Focus 2019; 9:20190026. [PMID: 31485313 PMCID: PMC6710664 DOI: 10.1098/rsfs.2019.0026] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2019] [Indexed: 01/01/2023] Open
Abstract
The uterine cervix undergoes a complex remodelling process during pregnancy, characterized by dramatic changes in both extracellular matrix (ECM) structure and mechanical properties. Understanding the cervical remodelling process in a term or preterm birth will aid efforts for the prevention of preterm births (PTBs), which currently affect 14.8 million babies annually worldwide. Animal models of pregnancy, particularly rodents, continue to provide valuable insights into the cervical remodelling process, through the study of changes in ECM structure and mechanical properties at defined gestation time points. Currently, there is a lack of a collective, quantitative framework to relate the complex, nonlinear mechanical behaviour of the rodent cervix to changes in ECM structure. This review aims to fill this gap in knowledge by outlining the current understanding of cervical remodelling during pregnancy in rodent models in the context of solid biomechanics. Here we highlight the collective contribution of multiple mechanical studies which give evidence that cervical softening coincides with known ECM changes throughout pregnancy. Taken together, mechanical tests on tissue from pregnant rodents reveal the cervix's remarkable ability to soften dramatically during gestation to allow for a compliant tissue that can withstand damage and can dissipate mechanical loads.
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Affiliation(s)
- Kyoko Yoshida
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Charles Jayyosi
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Nicole Lee
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Mala Mahendroo
- Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kristin M. Myers
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
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25
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Conway CK, Qureshi HJ, Morris VL, Danso EK, Desrosiers L, Knoepp LR, Goergen CJ, Miller KS. Biaxial biomechanical properties of the nonpregnant murine cervix and uterus. J Biomech 2019; 94:39-48. [PMID: 31353018 DOI: 10.1016/j.jbiomech.2019.07.011] [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: 02/01/2019] [Revised: 06/12/2019] [Accepted: 07/09/2019] [Indexed: 12/18/2022]
Abstract
From a biomechanical perspective, female reproductive health is an understudied area of research. There is an incomplete understanding of the complex function and interaction between the cervix and uterus. This, in part, is due to the limited research into multiaxial biomechanical functions and geometry of these organs. Knowledge of the biomechanical function and interaction between these organs may elucidate etiologies of conditions such as preterm birth. Therefore, the objective of this study was to quantify the multiaxial biomechanical properties of the murine cervix and uterus using a biaxial testing set-up. To accomplish this, an inflation-extension testing protocol (n = 15) was leveraged to quantify biaxial biomechanical properties while preserving native matrix interactions and geometry. Ultrasound imaging and histology (n = 10) were performed to evaluate regional geometry and microstructure, respectively. Histological analysis identified a statistically significant greater collagen content and significantly smaller smooth muscle content in the cervix as compared to the uterus. No statistically significant differences in elastic fibers were identified. Analysis of bilinear fits revealed a significantly stiffer response from the circumferentially orientated ECM fibers compared to axially orientated fibers in both organs. Bilinear fits and a two-fiber family constitutive model showed that the cervix was significantly less distensible than the uterus. We submit that the regional biaxial information reported in this study aids in establishing an appropriate reference configuration for mathematical models of the uterine-cervical complex. Thus, may aid future work to elucidate the biomechanical mechanisms leading to cervical or uterine conditions.
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Affiliation(s)
- Cassandra K Conway
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Ave, New Orleans, LA 70118, USA.
| | - Hamna J Qureshi
- Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Drive, West Lafayette, IN 47907, USA.
| | - Victoria L Morris
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Ave, New Orleans, LA 70118, USA.
| | - Elvis K Danso
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Ave, New Orleans, LA 70118, USA.
| | - Laurephile Desrosiers
- Department of Female Pelvic Medicine & Reconstructive Surgery, Ochsner Clinical School, 1514 Jefferson Highway, New Orleans, LA 70121, USA.
| | - Leise R Knoepp
- Department of Female Pelvic Medicine & Reconstructive Surgery, Ochsner Clinical School, 1514 Jefferson Highway, New Orleans, LA 70121, USA.
| | - Craig J Goergen
- Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Drive, West Lafayette, IN 47907, USA.
| | - Kristin S Miller
- Department of Biomedical Engineering, Tulane University, 6823 St. Charles Ave, New Orleans, LA 70118, USA.
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26
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Böl M, Iyer R, Dittmann J, Garcés-Schröder M, Dietzel A. Investigating the passive mechanical behaviour of skeletal muscle fibres: Micromechanical experiments and Bayesian hierarchical modelling. Acta Biomater 2019; 92:277-289. [PMID: 31077887 DOI: 10.1016/j.actbio.2019.05.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 04/24/2019] [Accepted: 05/06/2019] [Indexed: 02/06/2023]
Abstract
Characterisation of the skeletal muscle's passive properties is a challenging task since its structure is dominated by a highly complex and hierarchical arrangement of fibrous components at different scales. The present work focuses on the micromechanical characterisation of skeletal muscle fibres, which consist of myofibrils, by realising three different deformation states, namely, axial tension, axial compression, and transversal compression. To the best of the authors' knowledge, the present study provides a novel comprehensive data set representing of different deformation states. These data allow for a better understanding of muscle fibre load transfer mechanisms and can be used for meaningful modelling approaches. As the present study shows, axial tension and compression experiments reveal a strong tension-compression asymmetry at fibre level. In comparison to the tissue level, this asymmetric behaviour is more pronounced at the fibre scale, elucidating the load transfer mechanism in muscle tissue and aiding in the development of future modelling strategies. Further, a Bayesian hierarchical modelling approach was used to consider the experimental fluctuations in a parameter identification scheme, leading to more comprehensive parameter distributions that reflect the entire observed experimental uncertainty. STATEMENT OF SIGNIFICANCE: This article examines for the first time the mechanical properties of skeletal muscle fibres under axial tension, axial compression, and transversal compression, leading to a highly comprehensive data set. Moreover, a Bayesian hierarchical modelling concept is presented to identify model parameters in a broad way. The results of the deformation states allow a new and comprehensive understanding of muscle fibres' load transfer mechanisms; one example is the effect of tension-compression asymmetry. On the one hand, the results of this study contribute to the understanding of muscle mechanics and thus to the muscle's functional understanding during daily activity. On the other hand, they are relevant in the fields of skeletal muscle multiscale, constitutive modelling.
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Affiliation(s)
- Markus Böl
- Institute of Solid Mechanics, Technische Universität Braunschweig, Braunschweig D-38106, Germany.
| | - Rahul Iyer
- Institute of Solid Mechanics, Technische Universität Braunschweig, Braunschweig D-38106, Germany
| | - Johannes Dittmann
- Institute of Solid Mechanics, Technische Universität Braunschweig, Braunschweig D-38106, Germany
| | - Mayra Garcés-Schröder
- Institute of Micro Technology, Technische Universität Braunschweig, Braunschweig D-38124, Germany
| | - Andreas Dietzel
- Institute of Micro Technology, Technische Universität Braunschweig, Braunschweig D-38124, Germany
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27
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Horinouchi T, Yoshizato T, Muto M, Fujii M, Kozuma Y, Shinagawa T, Morokuma S, Kakuma T, Ushijima K. Gestational age-related changes in shear wave speed of the uterine cervix in normal pregnancy at 12-35 weeks' gestation. J Perinat Med 2019; 47:393-401. [PMID: 30817303 DOI: 10.1515/jpm-2018-0250] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 01/21/2019] [Indexed: 02/06/2023]
Abstract
Background This study aimed to analyze age-related changes in shear wave speed (SWS) of the normal uterine cervix. Methods We studied 362 women with a normal singleton pregnancy at 12-35 weeks' gestation. The SWS of the cervix was measured using transvaginal ultrasonography at the internal os region of the anterior cervix (IOA), posterior cervix (IOP) and cervical canal (IOC), and at the external os region of the anterior cervix (EOA), posterior cervix (EOP) and cervical canal (EOC). The following parameters were analyzed: (1) time trend of SWS of the individual sampling points, (2) comparison of SWS in the internal cervical region and SWS in the external cervical region, and (3) comparison of SWS between the internal and external cervical regions. Statistical analyses were performed using mixed-effects models. Results The SWS of IOP decreased in bilinear regression, with a critical change in the rate at 22 weeks, whereas the SWS of the remaining points decreased linearly. The estimated values of SWS of IOP at 84, 154 and 251 days were higher than those of IOA and IOC (P<0.001). The estimated values of SWS of IOP at 84 and 154 days were higher than those of EOP (P<0.001). Significant differences between IOP and EOP were shown until 244 days (P<0.05). The estimated value of SWS of IOC at 84 days was higher than that of EOC (P<0.001). Significant differences between IOC and EOC were shown until 210 days (P<0.05). Conclusion The SWS of the uterine cervix in pregnancy decreases with advancing gestation. The SWS of IOP had the highest value among the sampling points with unique characteristics.
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Affiliation(s)
- Takashi Horinouchi
- Department of Obstetrics and Gynecology, School of Medicine, Kurume University, Kurume, Japan
| | - Toshiyuki Yoshizato
- Department of Obstetrics and Gynecology, School of Medicine, Kurume University, Kurume, Japan
| | - Megumi Muto
- Department of Obstetrics and Gynecology, School of Medicine, Kurume University, Kurume, Japan
| | - Masahiro Fujii
- Department of Biostatistics, School of Medicine, Kurume University, Kurume, Japan
| | - Yutaka Kozuma
- Department of Obstetrics and Gynecology, School of Medicine, Kurume University, Kurume, Japan
| | - Takaaki Shinagawa
- Department of Obstetrics and Gynecology, School of Medicine, Kurume University, Kurume, Japan
| | - Seiichi Morokuma
- Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Tatsuyuki Kakuma
- Department of Biostatistics, School of Medicine, Kurume University, Kurume, Japan
| | - Kimio Ushijima
- Department of Obstetrics and Gynecology, School of Medicine, Kurume University, Kurume, Japan
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28
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Mechanobiology of mice cervix: expression profile of mechano-related molecules during pregnancy. Cell Tissue Res 2019; 376:443-456. [PMID: 30671632 DOI: 10.1007/s00441-018-02983-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 12/11/2018] [Indexed: 01/10/2023]
Abstract
There is a known reciprocation between the chronic exertion of force on tissue and both increased tissue density (e.g., bone) and hypertrophy (e.g., heart). This can also be seen in cervical tissue where the excessive gravitational forces associated with multiple fetal pregnancies promote preterm births. While there is a well-known regulation of cervical remodeling (CR) by sex steroid hormones and growth factors, the role of mechanical force is less appreciated. Using proteome-wide technology, we previously provided evidence for the presence of and alteration in mechano-related signaling molecules in the mouse cervix during pregnancy. Here, we profile the expression of select cytoskeletal factors (filamin-A, gelsolin, vimentin, actinin-1, caveolin-1, transgelin, keratin-8, profilin-1) and their associated signaling molecules [focal adhesion kinase (FAK) and the Rho GTPases CDC42, RHOA, and RHOB] in cervices of pregnant mice by real-time PCR and confocal immunofluorescence microscopy. Messenger RNA and protein levels increased for each of these 12 factors, except for 3 (keratin-8, profilin-1, RHOA) that decreased during the course of pregnancy and this corresponded with an increase in gravitational force exerted by the fetus on the cervix. We therefore conclude that size or weight of the growing fetus likely plays a key role in CR through mechanotransduction processes.
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29
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Evaluating residual strain throughout the murine female reproductive system. J Biomech 2018; 82:299-306. [PMID: 30458959 DOI: 10.1016/j.jbiomech.2018.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 10/31/2018] [Accepted: 11/01/2018] [Indexed: 01/10/2023]
Abstract
Mounting evidence suggests that cells within soft tissues seek to maintain a preferred biomechanical state. Residual stress is defined as the stress that remains in a tissue when all external loads are removed and contributes to tissue mechanohomeostasis by decreasing the transmural gradient of wall stress. Current computational models of pelvic floor mechanics, however, often do not consider residual stress. Residual strain, a result of residual stress can be quantitatively measured through opening angle experiments. Therefore, the objective of this study is to quantify the regional variations in opening angles along the murine female reproductive system at estrus and diestrus, to quantify residual strain in the maintenance state of sexually mature females. Further, evidence suggests that hydrophilic glycosaminoglycan/proteoglycans are integral to cervical remodeling. Thus, variations in opening angles following hypo-osmotic loading are evaluated. Opening angle experiments were performed along the murine reproductive system in estrus (n = 8) and diestrus (n = 8) and placed in hypo-osmotic solution. Measurements of thickness and volume were also obtained for each group. Differences (p < 0.05) in opening angle were observed with respect to region and loading, however, differences with respect to estrous stage were not significant. Thickness values were significant (p < 0.05) with respect to region only. The effects of both estrous cycle and region resulted in significant differences (p < 0.05) in observed volume. The observed regional differences indicate variation in the stress-free state among the reproductive system which may have implications for future computational models to advance women's reproductive health.
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30
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Chue-Sang J, Holness N, Gonzalez M, Greaves J, Saytashev I, Stoff S, Gandjbakhche A, Chernomordik VV, Burkett G, Ramella-Roman JC. Use of Mueller matrix colposcopy in the characterization of cervical collagen anisotropy. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-9. [PMID: 30088376 PMCID: PMC8357193 DOI: 10.1117/1.jbo.23.12.121605] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 07/23/2018] [Indexed: 05/18/2023]
Abstract
Annually, about 15 million preterm infants are born in the world. Of these, due to complications resulting from their premature birth, about 1 million would die before the age of five. Since the high incidence of preterm birth (PTB) is partially due to the lack of effective diagnostic modalities, methodologies are needed to determine risk of PTB. We propose a noninvasive tool based on polarized light imaging aimed at measuring the organization of collagen in the cervix. Cervical collagen has been shown to remodel with the approach of parturition. We used a full-field Mueller matrix polarimetric colposcope to assess and compare cervical collagen content and structure in nonpregnant and pregnant women in vivo. Local collagen directional azimuth was used and a total of eight cervices were imaged.
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Affiliation(s)
- Joseph Chue-Sang
- Florida International University, Department of Biomedical Engineering, Miami, Florida, United States
| | - Nola Holness
- Florida International University, Nicole Wertheim College of Nursing and Health Sciences, Miami, Florida, United States
| | - Mariacarla Gonzalez
- Florida International University, Department of Biomedical Engineering, Miami, Florida, United States
| | - Joan Greaves
- Jackson Memorial Hospital, Holtz Children’s Hospital, Miami, Florida, United States
| | - Ilyas Saytashev
- Florida International University, Herbert Wertheim College of Medicine, Miami, Florida, United States
| | - Susan Stoff
- Florida International University, Department of Biomedical Engineering, Miami, Florida, United States
| | - Amir Gandjbakhche
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland, United States
| | - Viktor V. Chernomordik
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland, United States
| | - Gene Burkett
- University of Miami, Leonard Miller School of Medicine, Department of Obstetrics and Gynecology, Miami, Florida, United States
| | - Jessica C. Ramella-Roman
- Florida International University, Department of Biomedical Engineering, Miami, Florida, United States
- Florida International University, Herbert Wertheim College of Medicine, Miami, Florida, United States
- Address all correspondence to: Jessica C. Ramella-Roman, E-mail:
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31
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O’Brien CM, Vargis E, Rudin A, Slaughter JC, Thomas G, Newton JM, Reese J, Bennett KA, Mahadevan-Jansen A. In vivo Raman spectroscopy for biochemical monitoring of the human cervix throughout pregnancy. Am J Obstet Gynecol 2018; 218:528.e1-528.e18. [PMID: 29410109 DOI: 10.1016/j.ajog.2018.01.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 01/11/2018] [Accepted: 01/23/2018] [Indexed: 12/22/2022]
Abstract
BACKGROUND The cervix must undergo significant biochemical remodeling to allow for successful parturition. This process is not fully understood, especially in instances of spontaneous preterm birth. In vivo Raman spectroscopy is an optical technique that can be used to investigate the biochemical composition of tissue longitudinally and noninvasively in human beings, and has been utilized to measure physiology and disease states in a variety of medical applications. OBJECTIVE The purpose of this study is to measure in vivo Raman spectra of the cervix throughout pregnancy in women, and to identify biochemical markers that change with the preparation for delivery and postpartum repair. STUDY DESIGN In all, 68 healthy pregnant women were recruited. Raman spectra were measured from the cervix of each patient monthly in the first and second trimesters, weekly in the third trimester, and at the 6-week postpartum visit. Raman spectra were measured using an in vivo Raman system with an optical fiber probe to excite the tissue with 785 nm light. A spectral model was developed to highlight spectral regions that undergo the most changes throughout pregnancy, which were subsequently used for identifying Raman peaks for further analysis. These peaks were analyzed longitudinally to determine if they underwent significant changes over the course of pregnancy (P < .05). Finally, 6 individual components that comprise key biochemical constituents of the human cervix were measured to extract their contributions in spectral changes throughout pregnancy using a linear combination method. Patient factors including body mass index and parity were included as variables in these analyses. RESULTS Raman peaks indicative of extracellular matrix proteins (1248 and 1254 cm-1) significantly decreased (P < .05), while peaks corresponding to blood (1233 and 1563 cm-1) significantly increased (P < .0005) in a linear manner throughout pregnancy. In the postpartum cervix, significant increases in peaks corresponding to actin (1003, 1339, and 1657 cm-1) and cholesterol (1447 cm-1) were observed when compared to late gestation, while signatures from blood significantly decreased. Postpartum actin signals were significantly higher than early pregnancy, whereas extracellular matrix proteins and water signals were significantly lower than early weeks of gestation. Parity had a significant effect on blood and extracellular matrix protein signals, with nulliparous patients having significant increases in blood signals throughout pregnancy, and higher extracellular matrix protein signals in early pregnancy compared to patients with prior pregnancies. Body mass index significantly affected actin signal contribution, with low body mass index patients showing decreasing actin contribution throughout pregnancy and high body mass index patients demonstrating increasing actin signals. CONCLUSION Raman spectroscopy was successfully used to biochemically monitor cervical remodeling in pregnant women during prenatal visits. This foundational study has demonstrated sensitivity to known biochemical dynamics that occur during cervical remodeling, and identified patient variables that have significant effects on Raman spectra throughout pregnancy. Raman spectroscopy has the potential to improve our understanding of cervical maturation, and be used as a noninvasive preterm birth risk assessment tool to reduce the incidence, morbidity, and mortality caused by preterm birth.
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Hao J, Yao W, Harris WBR, Vink JY, Myers KM, Donnelly E. Characterization of the collagen microstructural organization of human cervical tissue. Reproduction 2018; 156:71-79. [PMID: 29712877 DOI: 10.1530/rep-17-0763] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 04/30/2018] [Indexed: 11/08/2022]
Abstract
The cervix shortens and softens as its collagen microstructure remodels in preparation for birth. Altered cervical tissue collagen microstructure can contribute to a mechanically weak cervix and premature cervical dilation and delivery. To investigate the local microstructural changes associated with anatomic location and pregnancy, we used second-harmonic generation microscopy to quantify the orientation and spatial distribution of collagen throughout cervical tissue from 4 pregnant and 14 non-pregnant women. Across patients, the alignment and concentration of collagen within the cervix was more variable near the internal os and less variable near the external os. Across anatomic locations, the spatial distribution of collagen within a radial zone adjacent to the inner canal of the cervix was more homogeneous than that of a region comprising the middle and outer radial zones. Two regions with different collagen distribution characteristics were found. The anterior and posterior sections in the outer radial zone were characterized by greater spatial heterogeneity of collagen than that of the rest of the sections. Our findings suggest that the microstructural alignment and distribution of collagen varies with anatomic location within the human cervix. These observed differences in collagen microstructural alignment may reflect local anatomic differences in cervical mechanical loading and function. Our study deepens the understanding of specific microstructural cervical changes in pregnancy and informs investigations of potential mechanisms for normal and premature cervical remodeling.
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Affiliation(s)
- Jia Hao
- Department of Materials Science and EngineeringCornell University, Ithaca, New York, USA
| | - Wang Yao
- Department of Mechanical EngineeringColumbia University, New York, New York, USA
| | - W B Ryan Harris
- Department of Materials Science and EngineeringCornell University, Ithaca, New York, USA
| | - Joy Y Vink
- Department of Obstetrics and GynecologyColumbia University Medical Center, New York, New York, USA
| | - Kristin M Myers
- Department of Mechanical EngineeringColumbia University, New York, New York, USA
| | - Eve Donnelly
- Department of Materials Science and EngineeringCornell University, Ithaca, New York, USA .,Research DivisionHospital for Special Surgery, New York, New York, USA
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Barnum CE, Fey JL, Weiss SN, Barila G, Brown AG, Connizzo BK, Shetye SS, Elovitz MA, Soslowsky LJ. Tensile Mechanical Properties and Dynamic Collagen Fiber Re-Alignment of the Murine Cervix are Dramatically Altered Throughout Pregnancy. J Biomech Eng 2017; 139:2621587. [PMID: 28418563 DOI: 10.1115/1.4036473] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Indexed: 12/26/2022]
Abstract
The cervix is a unique organ able to dramatically change its shape and function by serving as a physical barrier for the growing fetus and then undergoing dramatic dilation allowing for delivery of a term infant. As a result, the cervix endures changing mechanical forces from the growing fetus. There is an emerging concept that the cervix may change or remodel "early" in many cases of spontaneous preterm birth (sPTB). However, the mechanical role of the cervix in both normal and preterm birth remains unclear. Therefore, the primary objective of this study was to determine the mechanical and structural responses of murine cervical tissue throughout a normal gestational time course. In this study, both tissue structural and material properties were determined via a quasi-static tensile load-to-failure test, while simultaneously obtaining dynamic collagen fiber re-alignment via cross-polarization imaging. This study demonstrated that the majority of the mechanical properties evaluated decreased at midgestation and not just at term, while collagen fiber re-alignment occurred earlier in the loading curve for cervices at term. This suggests that although structural changes in the cervix occur throughout gestation, the differences in material properties function in combination with collagen fiber re-alignment as mechanical precursors to regulate term gestation. This work lays a foundation for investigating cervical biomechanics and the role of the cervix in preterm birth.
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Affiliation(s)
- Carrie E Barnum
- McKay Orthopedic Research Laboratory, University of Pennsylvania, Philadelphia, PA 19104
| | - Jennifer L Fey
- McKay Orthopedic Research Laboratory, University of Pennsylvania, Philadelphia, PA 19104
| | - Stephanie N Weiss
- McKay Orthopedic Research Laboratory, University of Pennsylvania, Philadelphia, PA 19104
| | - Guillermo Barila
- Maternal and Child Health Research Program, Department of Obstetrics and Gynecology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Amy G Brown
- Maternal and Child Health Research Program, Department of Obstetrics and Gynecology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Brianne K Connizzo
- McKay Orthopedic Research Laboratory, University of Pennsylvania, Philadelphia, PA 19104;Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Snehal S Shetye
- McKay Orthopedic Research Laboratory, University of Pennsylvania, Philadelphia, PA 19104
| | - Michal A Elovitz
- Maternal and Child Health Research Program, Department of Obstetrics and Gynecology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Louis J Soslowsky
- McKay Orthopedic Research Laboratory, University of Pennsylvania, Philadelphia, PA 19104 e-mail:
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Westervelt AR, Fernandez M, House M, Vink J, Nhan-Chang CL, Wapner R, Myers KM. A Parameterized Ultrasound-Based Finite Element Analysis of the Mechanical Environment of Pregnancy. J Biomech Eng 2017; 139:2612939. [PMID: 28303276 DOI: 10.1115/1.4036259] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Indexed: 11/08/2022]
Abstract
Preterm birth is the leading cause of childhood mortality and can lead to health risks in survivors. The mechanical functions of the uterus, fetal membranes, and cervix have dynamic roles to protect the fetus during gestation. To understand their mechanical function and relation to preterm birth, we built a three-dimensional parameterized finite element model of pregnancy. This model is generated by an automated procedure that is informed by maternal ultrasound measurements. A baseline model at 25 weeks of gestation was characterized, and to visualize the impact of cervical structural parameters on tissue stretch, we evaluated the model sensitivity to (1) anterior uterocervical angle, (2) cervical length, (3) posterior cervical offset, and (4) cervical stiffness. We found that cervical tissue stretching is minimal when the cervical canal is aligned with the longitudinal uterine axis, and a softer cervix is more sensitive to changes in the geometric variables tested.
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Affiliation(s)
- Andrea R Westervelt
- Department of Mechanical Engineering, Columbia University, New York, NY 10027 e-mail:
| | - Michael Fernandez
- Department of Mechanical Engineering, Columbia University, New York, NY 10027 e-mail:
| | - Michael House
- Department of Obstetrics and Gynecology, Tufts Medical Center, Boston, MA 02111 e-mail:
| | - Joy Vink
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY 10032 e-mail:
| | - Chia-Ling Nhan-Chang
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY 10032 e-mail:
| | - Ronald Wapner
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY 10032 e-mail:
| | - Kristin M Myers
- Mem. ASME Department of Mechanical Engineering, Columbia University, New York, NY 10027 e-mail:
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Chue-Sang J, Bai Y, Stoff S, Gonzalez M, Holness N, Gomes J, Jung R, Gandjbakhche A, Chernomordik VV, Ramella-Roman JC. Use of Mueller matrix polarimetry and optical coherence tomography in the characterization of cervical collagen anisotropy. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-9. [PMID: 28853246 PMCID: PMC5997002 DOI: 10.1117/1.jbo.22.8.086010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 07/24/2017] [Indexed: 05/20/2023]
Abstract
Preterm birth (PTB) presents a serious medical health concern throughout the world. There is a high incidence of PTB in both developed and developing countries ranging from 11% to 15%, respectively. Recent research has shown that cervical collagen orientation and distribution changes during pregnancy may be useful in predicting PTB. Polarization imaging is an effective means to measure optical anisotropy in birefringent materials, such as the cervix's extracellular matrix. Noninvasive, full-field Mueller matrix polarimetry (MMP) imaging methodologies, and optical coherence tomography (OCT) imaging were used to assess cervical collagen content and structure in nonpregnant porcine cervices. We demonstrate that the highly ordered structure of the nonpregnant porcine cervix can be observed with MMP. Furthermore, when utilized ex vivo, OCT and MMP yield very similar results with a mean error of 3.46% between the two modalities.
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Affiliation(s)
- Joseph Chue-Sang
- Florida International University, Department of Biomedical Engineering, Miami, Florida, United States
| | - Yuqiang Bai
- Florida International University, Department of Biomedical Engineering, Miami, Florida, United States
| | - Susan Stoff
- Florida International University, Department of Biomedical Engineering, Miami, Florida, United States
| | - Mariacarla Gonzalez
- Florida International University, Department of Biomedical Engineering, Miami, Florida, United States
| | - Nola Holness
- Florida International University, Nicole Wertheim College of Nursing and Health Sciences, Miami, Florida, United States
| | - Jefferson Gomes
- Florida International University, Department of Biomedical Engineering, Miami, Florida, United States
| | - Ranu Jung
- Florida International University, Department of Biomedical Engineering, Miami, Florida, United States
| | - Amir Gandjbakhche
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland, United States
| | - Viktor V. Chernomordik
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Rockville, Maryland, United States
| | - Jessica C. Ramella-Roman
- Florida International University, Department of Biomedical Engineering, Miami, Florida, United States
- Florida International University, Herbert Wertheim College of Medicine, Miami, Florida, United States
- Address all correspondence to: Jessica C. Ramella-Roman, E-mail:
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O'Brien CM, Herington JL, Brown N, Pence IJ, Paria BC, Slaughter JC, Reese J, Mahadevan-Jansen A. In vivo Raman spectral analysis of impaired cervical remodeling in a mouse model of delayed parturition. Sci Rep 2017; 7:6835. [PMID: 28754971 PMCID: PMC5533720 DOI: 10.1038/s41598-017-07047-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 06/21/2017] [Indexed: 12/01/2022] Open
Abstract
Monitoring cervical structure and composition during pregnancy has high potential for prediction of preterm birth (PTB), a problem affecting 15 million newborns annually. We use in vivo Raman spectroscopy, a label-free, light-based method that provides a molecular fingerprint to non-invasively investigate normal and impaired cervical remodeling. Prostaglandins stimulate uterine contractions and are clinically used for cervical ripening during pregnancy. Deletion of cyclooxygenase-1 (Cox-1), an enzyme involved in production of these prostaglandins, results in delayed parturition in mice. Contrary to expectation, Cox-1 null mice displayed normal uterine contractility; therefore, this study sought to determine whether cervical changes could explain the parturition differences in Cox-1 null mice and gestation-matched wild type (WT) controls. Raman spectral changes related to extracellular matrix proteins, lipids, and nucleic acids were tracked over pregnancy and found to be significantly delayed in Cox-1 null mice at term. A cervical basis for the parturition delay was confirmed by other ex vivo tests including decreased tissue distensibility, hydration, and elevated progesterone levels in the Cox-1 null mice at term. In conclusion, in vivo Raman spectroscopy non-invasively detected abnormal remodeling in the Cox-1 null mouse, and clearly demonstrated that the cervix plays a key role in their delayed parturition.
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Affiliation(s)
- Christine M O'Brien
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37232, USA.,Biophotonics Center, Vanderbilt University, Nashville, TN, 37232, USA
| | - Jennifer L Herington
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Naoko Brown
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Isaac J Pence
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37232, USA.,Biophotonics Center, Vanderbilt University, Nashville, TN, 37232, USA
| | - Bibhash C Paria
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - James C Slaughter
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Jeff Reese
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37232, USA.,Biophotonics Center, Vanderbilt University, Nashville, TN, 37232, USA.,Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.,Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Anita Mahadevan-Jansen
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37232, USA. .,Biophotonics Center, Vanderbilt University, Nashville, TN, 37232, USA.
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Myers KM, Elad D. Biomechanics of the human uterus. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2017; 9. [PMID: 28498625 DOI: 10.1002/wsbm.1388] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 02/23/2017] [Accepted: 03/01/2017] [Indexed: 12/15/2022]
Abstract
The appropriate biomechanical function of the uterus is required for the execution of human reproduction. These functions range from aiding the transport of the embryo to the implantation site, to remodeling its tissue walls to host the placenta, to protecting the fetus during gestation, to contracting forcefully for a safe parturition and postpartum, to remodeling back to its nonpregnant condition to renew the cycle of menstruation. To serve these remarkably diverse functions, the uterus is optimally geared with evolving and contractile muscle and tissue layers that are cued by chemical, hormonal, electrical, and mechanical signals. The relationship between these highly active biological signaling mechanisms and uterine biomechanical function is not completely understood for normal reproductive processes and pathological conditions such as adenomyosis, endometriosis, infertility and preterm labor. Animal studies have illuminated the rich structural function of the uterus, particularly in pregnancy. In humans, medical imaging techniques in ultrasound and magnetic resonance have been combined with computational engineering techniques to characterize the uterus in vivo, and advanced experimental techniques have explored uterine function using ex vivo tissue samples. The collective evidence presented in this review gives an overall perspective on uterine biomechanics related to both its nonpregnant and pregnant function, highlighting open research topics in the field. Additionally, uterine disease and infertility are discussed in the context of tissue injury and repair processes and the role of computational modeling in uncovering etiologies of disease. WIREs Syst Biol Med 2017, 9:e1388. doi: 10.1002/wsbm.1388 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Kristin M Myers
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - David Elad
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel.,Department of Biomedical Engineering, Columbia University, New York, NY, USA
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Modifying the strength and strain concentration profile within collagen scaffolds using customizable arrays of poly-lactic acid fibers. J Mech Behav Biomed Mater 2016; 66:28-36. [PMID: 27829193 DOI: 10.1016/j.jmbbm.2016.10.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/18/2016] [Accepted: 10/26/2016] [Indexed: 02/03/2023]
Abstract
The tendon-to-bone junction is a highly specialized tissue which dissipates stress concentrations between mechanically dissimilar tendon and bone. Upon injury, the local heterogeneities across this insertion are not regenerated, leading to poor functional outcomes such as formation of scar tissue at the insertion and re-failure rates exceeding 90%. Although current tissue engineering methods are moving towards the development of spatially-graded biomaterials to begin to address these injuries, significant opportunities remain to engineer the often complex local mechanical behavior of such biomaterials to enhance their bioactivity. Here, we describe the use of three-dimensional printing techniques to create customizable arrays of poly-lactic acid (PLA) fibers that can be incorporated into a collagen scaffold under development for tendon bone junction repair. Notably, we use additive manufacturing concepts to generate arrays of spatially-graded fibers from biodegradable PLA that are incorporated into collagen scaffolds to create a collagen-PLA composite. We demonstrate the ability to tune the mechanical performance of the fiber-scaffold composite at the bulk scale. We also demonstrate the incorporation of spatially-heterogeneous fiber designs to establish non-uniform local mechanical performance of the composite biomaterial under tensile load, a critical element in the design of multi-compartment biomaterials for tendon-to-bone regeneration applications. Together, this work highlights the capacity to use multi-scale composite biomaterials to control local and bulk mechanical properties, and provides key insights into design elements under consideration for mechanically competent, multi-tissue regeneration platforms.
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Yilmaz Dogru H, Albayrak E, Delibas IB, Isguder CK, Ozsoy AZ, Cakmak B, Ozmen Z, Aktas F. Can myometrial elasticity, as determined by elastography at 18-22 weeks of gestation, predict preterm delivery? J Obstet Gynaecol Res 2016; 42:1686-1693. [PMID: 27558070 DOI: 10.1111/jog.13110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 05/11/2016] [Accepted: 06/18/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Hatice Yilmaz Dogru
- Department of Obstetrics and Gynecology, Medical Faculty, Gaziosmanpasa University, Tokat, Turkey
| | - Eda Albayrak
- Department of Radiology, Medical Faculty, Gaziosmanpasa University, Tokat, Turkey
| | - Ilhan Bahri Delibas
- Department of Obstetrics and Gynecology, Medical Faculty, Gaziosmanpasa University, Tokat, Turkey
| | - Cigdem Kunt Isguder
- Department of Obstetrics and Gynecology, Medical Faculty, Gaziosmanpasa University, Tokat, Turkey
| | - Asker Zeki Ozsoy
- Department of Obstetrics and Gynecology, Medical Faculty, Gaziosmanpasa University, Tokat, Turkey
| | - Bulent Cakmak
- Department of Obstetrics and Gynecology, Medical Faculty, Gaziosmanpasa University, Tokat, Turkey
| | - Zafer Ozmen
- Department of Radiology, Medical Faculty, Gaziosmanpasa University, Tokat, Turkey
| | - Fatma Aktas
- Department of Radiology, Medical Faculty, Gaziosmanpasa University, Tokat, Turkey
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Yoshida K, Mahendroo M, Vink J, Wapner R, Myers K. Material properties of mouse cervical tissue in normal gestation. Acta Biomater 2016; 36:195-209. [PMID: 26961804 DOI: 10.1016/j.actbio.2016.03.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 02/09/2016] [Accepted: 03/01/2016] [Indexed: 01/04/2023]
Abstract
UNLABELLED An appropriately timed cervical remodeling process is critical for a healthy delivery, yet little is known about the material property changes of the cervix in pregnancy because obtaining human tissue samples is difficult. Rodent models offer advantages including accurately timed pregnant tissues and genetically altered models. Determining the material properties of the mouse cervix, however, is challenging because of its small size and complex geometry. The aim of this study is to quantify cervical material property changes in a normal mouse pregnancy using a microstructurally-inspired porous fiber composite model. We mechanically test intact, whole, gestation-timed mouse cervix by pulling apart tensioned sutures through its inner canal. To interpret our mechanical testing results, we conduct an inverse finite element analysis, taking into account the combined loading state of the thick-walled cylindrical tissue. We fit the material model to previous osmotic swelling data and load-deformation data from this study using a nonlinear optimization scheme, and validate the model by predicting a separate set of deformation data. Overall, the proposed porous fiber composite model captures the mechanical behavior of the mouse cervix in large deformation. The evolution of cervical material parameters indicates that in a normal mouse pregnancy, the cervix begins to soften between day 6 and day 12 of a 19-day gestation period. The material parameter associated with the collagen fiber stiffness decreases from 3.4MPa at gestation day 6 to 9.7e-4MPa at gestation day 18, while the ground substance stiffness decreases from 2.6e-1MPa to 7.0e-4MPa. STATEMENT OF SIGNIFICANCE Accelerated cervical remodeling can lead to extremely premature births. Little is known, however, about the material property changes of the cervix in pregnancy because pregnant human tissue samples are limited. Rodent models overcome this limitation and provide access to gestation-timed samples. Measuring the material property changes of the mouse cervix in pregnancy is challenging due to its small size and complex geometry. Here, we establish a combined experimental and modeling framework. We use this framework to determine the cervical material property changes throughout a normal mouse pregnancy. We present our experimental methods for mechanically testing whole, intact cervical tissue samples. We fit a porous fiber composite material model to the mechanical data and show that the mouse cervix begins to soften between day 6 and day 12 of a 19-day gestation period.
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Abstract
The problem of preterm birth continues to pose one of the most significant research challenges that we face due to its immense scope and complexity. With evidence that 95% of cases of spontaneous preterm birth are intractable to current interventions, our best hope in resolving this problem may lie in new, innovative ideas. Novel approaches to researching preterm birth are currently underway, building upon our prior discoveries and probing into the unknown on multiple fronts. Here we discuss some of the major focuses of future investigation that provide a promising outlook for discovery, including advanced techniques to evaluate the cervix, new strategies to identify the role of the microbiome, and advances in molecular and epigenetic-based research.
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Affiliation(s)
- Joses Jain
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Cynthia Gyamfi-Bannerman
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
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Brown JE, Partlow BP, Berman AM, House MD, Kaplan DL. Injectable silk-based biomaterials for cervical tissue augmentation: an in vitro study. Am J Obstet Gynecol 2016; 214:118.e1-9. [PMID: 26314518 PMCID: PMC4698015 DOI: 10.1016/j.ajog.2015.08.046] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 07/23/2015] [Accepted: 08/19/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cerclage therapy is an important treatment option for preterm birth prevention. Several patient populations benefit from cerclage therapy including patients with a classic history of cervical insufficiency; patients who present with advanced cervical dilation prior to viability; and patients with a history of preterm birth and cervical shortening. Although cerclage is an effective treatment option in some patients, it can be associated with limited efficacy and procedure complications. Development of an alternative to cerclage therapy would be an important clinical development. Here we report on an injectable, silk protein-based biomaterial for cervical tissue augmentation. The rationale for the development of an injectable biomaterial is to restore the native properties of cervical tissue. While cerclage provides support to the tissue, it does not address excessive tissue softening, which is a central feature of the pathogenesis of cervical insufficiency. Silk protein-based hydrogels, which are biocompatible and naturally degrade in vivo, are suggested as a platform for restoring the native properties of cervical tissue and improving cervical function. OBJECTIVE We sought to study the properties of an injectable, silk-based biomaterial for potential use as an alternative treatment for cervical insufficiency. These biomaterials were evaluated for mechanical tunability, biocompatibility, facile injection, and in vitro degradation. STUDY DESIGN Silk protein solutions were cross-linked by an enzyme catalyzed reaction to form elastic biomaterials. Biomaterials were formulated to match the native physical properties of cervical tissue during pregnancy. The cell compatibility of the materials was assessed in vitro using cervical fibroblasts, and biodegradation was evaluated using concentrated protease solution. Tissue augmentation or bulking was demonstrated using human cervical tissue from nonpregnant hysterectomy specimens. Mechanical compression tests measured the tissue stiffness as a function of the volume of injected biomaterial. RESULTS Silk protein concentration, molecular weight, and concentration of cross-linking agent were varied to generate biomaterials that functioned from hard gels to viscous fluids. Biomaterials that matched the mechanical features of cervical tissues were chosen for further study. Cervical fibroblasts cultured on these biomaterials were proliferative and metabolically active over 6 days. Biomaterials were degraded in protease solution, with rate of mass loss dependent on silk protein molecular weight. Injection of cervical tissue samples with 100 μL of the biomaterial resulted in a significant volume increase (22.6% ± 8.8%, P < .001) with no significant change in tissue stiffness. CONCLUSION Cytocompatible, enzyme cross-linked silk protein biomaterials show promise as a tissue bulking agent. The biomaterials were formulated to match the native mechanical properties of human cervical tissue. These biomaterials should be explored further as a possible alternative to cerclage for providing support to the cervix during pregnancy.
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Affiliation(s)
- Joseph E Brown
- Department of Biomedical Engineering, Tufts University, Medford, MA
| | | | - Alison M Berman
- Department of Biomedical Engineering, Tufts University, Medford, MA
| | - Michael D House
- Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Tufts Medical Center, Boston, MA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, MA.
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Gan Y, Yao W, Myers KM, Hendon CP. An automated 3D registration method for optical coherence tomography volumes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:3873-6. [PMID: 25570837 DOI: 10.1109/embc.2014.6944469] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Optical coherence tomography (OCT) is able to provide high resolution volumetric data for biological tissues. However, the field of view (FOV) of OCT is sometimes smaller than the field of interest, which limits the clinical application of OCT. One way to overcome the drawback is to stitch multiple 3D volumes. In this paper, we propose a novel method to register multiple overlapped volumetric OCT data into a single volume. The relative positions of overlapped volumes were estimated on en face plane and at depth. On en face plane, scale invariant feature transform (SIFT) was implemented to extract the keypoints in each volume. Based on the invariant features, volumes were paired through keypoint matching. Then, we formulated the relationship between paired offsets and absolute positions as a linear model and estimated the centroid of each volume using least square method. Moreover, we calibrated the depth displacement in each paired volume and aligned the z coordinates of volumes globally. The algorithm was validated through stitching multiple volumetric OCT datasets of human cervix tissue and of swine heart. The experimental results demonstrated that our method is capable of visualizing biological samples over a wider FOV, which enhances the investigation of tissue structure such as fiber orientation.
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Myers KM, Feltovich H, Mazza E, Vink J, Bajka M, Wapner RJ, Hall TJ, House M. The mechanical role of the cervix in pregnancy. J Biomech 2015; 48:1511-23. [PMID: 25841293 PMCID: PMC4459908 DOI: 10.1016/j.jbiomech.2015.02.065] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 02/28/2015] [Indexed: 01/10/2023]
Abstract
Appropriate mechanical function of the uterine cervix is critical for maintaining a pregnancy to term so that the fetus can develop fully. At the end of pregnancy, however, the cervix must allow delivery, which requires it to markedly soften, shorten and dilate. There are multiple pathways to spontaneous preterm birth, the leading global cause of death in children less than 5 years old, but all culminate in premature cervical change, because that is the last step in the final common pathway to delivery. The mechanisms underlying premature cervical change in pregnancy are poorly understood, and therefore current clinical protocols to assess preterm birth risk are limited to surrogate markers of mechanical function, such as sonographically measured cervical length. This is what motivates us to study the cervix, for which we propose investigating clinical cervical function in parallel with a quantitative engineering evaluation of its structural function. We aspire to develop a common translational language, as well as generate a rigorous integrated clinical-engineering framework for assessing cervical mechanical function at the cellular to organ level. In this review, we embark on that challenge by describing the current landscape of clinical, biochemical, and engineering concepts associated with the mechanical function of the cervix during pregnancy. Our goal is to use this common platform to inspire novel approaches to delineate normal and abnormal cervical function in pregnancy.
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Affiliation(s)
- Kristin M Myers
- Department of Mechanical Engineering, Columbia University, New York, NY, USA.
| | - Helen Feltovich
- Department of Obstetrics and Gynecology, Intermountain Healthcare, Provo, UT, USA; Department of Medical Physics, University of Wisconsin, Madison, WI, USA
| | - Edoardo Mazza
- Department of Mechanical and Process Engineering, ETH Zurich, & EMPA Dübendorf, Switzerland
| | - Joy Vink
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY USA
| | - Michael Bajka
- Department of Obstetrics and Gynecology, University Hospital of Zurich, Switzerland
| | - Ronald J Wapner
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY USA
| | - Timothy J Hall
- Department of Medical Physics, University of Wisconsin, Madison, WI, USA
| | - Michael House
- Department of Obstetrics and Gynecology, Tufts Medical Center, Boston, MA, USA
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Fernandez M, House M, Jambawalikar S, Zork N, Vink J, Wapner R, Myers K. Investigating the mechanical function of the cervix during pregnancy using finite element models derived from high-resolution 3D MRI. Comput Methods Biomech Biomed Engin 2015; 19:404-17. [PMID: 25970655 PMCID: PMC4644115 DOI: 10.1080/10255842.2015.1033163] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Preterm birth is a strong contributor to perinatal mortality, and preterm infants that survive are at risk for long-term morbidities. During most of pregnancy, appropriate mechanical function of the cervix is required to maintain the developing fetus in utero. Premature cervical softening and subsequent cervical shortening are hypothesized to cause preterm birth. Presently, there is a lack of understanding of the structural and material factors that influence the mechanical function of the cervix during pregnancy. In this study we build finite element models of the pregnant uterus, cervix, and fetal membrane based on magnetic resonance imagining data in order to examine the mechanical function of the cervix under the physiologic loading conditions of pregnancy. We calculate the mechanical loading state of the cervix for two pregnant patients: 22 weeks gestational age with a normal cervical length and 28 weeks with a short cervix. We investigate the influence of (1) anatomical geometry, (2) cervical material properties, and (3) fetal membrane material properties, including its adhesion properties, on the mechanical loading state of the cervix under physiologically relevant intrauterine pressures. Our study demonstrates that membrane-uterus interaction, cervical material modeling, and membrane mechanical properties are factors that must be deliberately and carefully handled in order to construct a high quality mechanical simulation of pregnancy.
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Affiliation(s)
- M. Fernandez
- Columbia University, Department of Mechanical Engineering, 500 W 120 Street, New York, NY, USA
| | - M. House
- Tufts Medical Center, Department of Obstetrics and Gynecology, 800 Washington Street #360, Boston, MA, USA
| | - S. Jambawalikar
- Columbia University Medical Center, Department of Radiology, 622 West 168 Street, PB-1-301, New York, NY, USA
| | - N. Zork
- Columbia University Medical Center, Department of Radiology, 622 West 168 Street, PB-1-301, New York, NY, USA
| | - J. Vink
- Columbia University Medical Center, Department of Radiology, 622 West 168 Street, PB-1-301, New York, NY, USA
| | - R. Wapner
- Columbia University Medical Center, Department of Radiology, 622 West 168 Street, PB-1-301, New York, NY, USA
| | - K. Myers
- Columbia University, Department of Mechanical Engineering, 500 W 120 Street, New York, NY, USA
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Gan Y, Yao W, Myers KM, Vink JY, Wapner RJ, Hendon CP. Analyzing three-dimensional ultrastructure of human cervical tissue using optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2015; 6:1090-108. [PMID: 25908997 PMCID: PMC4399652 DOI: 10.1364/boe.6.001090] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 02/26/2015] [Accepted: 02/27/2015] [Indexed: 05/20/2023]
Abstract
During pregnancy, the uterine cervix is the mechanical barrier that prevents delivery of a fetus. The underlying cervical collagen ultrastructure, which influences the overall mechanical properties of the cervix, plays a role in maintaining a successful pregnancy until term. Yet, not much is known about this collagen ultrastructure in pregnant and nonpregnant human tissue. We used optical coherence tomography to investigate the directionality and dispersion of collagen fiber bundles in the human cervix. An image analysis tool has been developed, combining a stitching method with a fiber orientation measurement, to study axially sliced cervix samples. This tool was used to analyze the ultrastructure of ex-vivo pregnant and non-pregnant hysterectomy tissue samples taken at the internal os, which is the region of the cervix adjacent to the uterus. With this tool, directionality maps of collagen fiber bundles and dispersion of collagen fiber orientation were analyzed. It was found that that the overall preferred directionality of the collagen fibers for both the nonpregnant and pregnant samples were circling around the inner cervical canal. Pregnant samples showed greater dispersion than non-pregnant samples. Lastly, we observed regional differences in collagen fiber dispersion. Fibers closer to the inner canal showed more dispersion than the fibers on the radial edges.
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Affiliation(s)
- Yu Gan
- Department of Electrical Engineering, Columbia University, New York, New York,
USA
| | - Wang Yao
- Department of Mechanical Engineering, Columbia University, New York, New York,
USA
| | - Kristin. M Myers
- Department of Mechanical Engineering, Columbia University, New York, New York,
USA
| | - Joy Y. Vink
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, New York,
USA
| | - Ronald. J. Wapner
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, New York,
USA
| | - Christine P. Hendon
- Department of Electrical Engineering, Columbia University, New York, New York,
USA
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Myers KM, Hendon CP, Gan Y, Yao W, Yoshida K, Fernandez M, Vink J, Wapner RJ. A continuous fiber distribution material model for human cervical tissue. J Biomech 2015; 48:1533-40. [PMID: 25817474 DOI: 10.1016/j.jbiomech.2015.02.060] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 02/28/2015] [Indexed: 10/23/2022]
Abstract
The uterine cervix during pregnancy is the vital mechanical barrier which resists compressive and tensile loads generated from a growing fetus. Premature cervical remodeling and softening is hypothesized to result in the shortening of the cervix, which is known to increase a woman׳s risk of preterm birth. To understand the role of cervical material properties in preventing preterm birth, we derive a cervical material model based on previous mechanical, biochemical and histological experiments conducted on nonpregnant and pregnant human hysterectomy cervical tissue samples. In this study we present a three-dimensional fiber composite model that captures the equilibrium material behavior of the tissue in tension and compression. Cervical tissue is modeled as a fibrous composite material, where a single family of preferentially aligned and continuously distributed collagen fibers are embedded in a compressible neo-Hookean ground substance. The total stress in the collagen solid network is calculated by integrating the fiber stresses. The shape of the fiber distribution is described by an ellipsoid where semi-principal axis lengths are fit to optical coherence tomography measurements. The composite material model is fit to averaged mechanical testing data from uni-axial compression and tension experiments, and averaged material parameters are reported for nonpregnant and term pregnant human cervical tissue. The model is then evaluated by investigating the stress and strain state of a uniform thick-walled cylinder under a compressive stress with collagen fibers preferentially aligned in the circumferential direction. This material modeling framework for the equilibrium behavior of human cervical tissue serves as a basis to determine the role of preferentially-aligned cervical collagen fibers in preventing cervical deformation during pregnancy.
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Affiliation(s)
- Kristin M Myers
- Department of Mechanical Engineering, Columbia University School of Engineering and Applied Science, 500 W. 120th Street, Mudd 220, New York, NY 10027, USA.
| | - Christine P Hendon
- Department of Electrical Engineering, Columbia University School of Engineering and Applied Science, New York, NY, USA
| | - Yu Gan
- Department of Electrical Engineering, Columbia University School of Engineering and Applied Science, New York, NY, USA
| | - Wang Yao
- Department of Mechanical Engineering, Columbia University School of Engineering and Applied Science, 500 W. 120th Street, Mudd 220, New York, NY 10027, USA
| | - Kyoko Yoshida
- Department of Mechanical Engineering, Columbia University School of Engineering and Applied Science, 500 W. 120th Street, Mudd 220, New York, NY 10027, USA
| | - Michael Fernandez
- Department of Mechanical Engineering, Columbia University School of Engineering and Applied Science, 500 W. 120th Street, Mudd 220, New York, NY 10027, USA
| | - Joy Vink
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY, USA
| | - Ronald J Wapner
- Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY, USA
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Maurer MM, Badir S, Pensalfini M, Bajka M, Abitabile P, Zimmermann R, Mazza E. Challenging the in-vivo assessment of biomechanical properties of the uterine cervix: A critical analysis of ultrasound based quasi-static procedures. J Biomech 2015; 48:1541-8. [PMID: 25791058 DOI: 10.1016/j.jbiomech.2015.02.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 02/17/2015] [Indexed: 01/14/2023]
Abstract
Measuring the stiffness of the uterine cervix might be useful in the prediction of preterm delivery, a still unsolved health issue of global dimensions. Recently, a number of clinical studies have addressed this topic, proposing quantitative methods for the assessment of the mechanical properties of the cervix. Quasi-static elastography, maximum compressibility using ultrasound and aspiration tests have been applied for this purpose. The results obtained with the different methods seem to provide contradictory information about the physiologic development of cervical stiffness during pregnancy. Simulations and experiments were performed in order to rationalize the findings obtained with ultrasound based, quasi-static procedures. The experimental and computational results clearly illustrate that standardization of quasi-static elastography leads to repeatable strain values, but for different loading forces. Since force cannot be controlled, this current approach does not allow the distinction between a globally soft and stiff cervix. It is further shown that introducing a reference elastomer into the elastography measurement might overcome the problem of force standardization, but a careful mechanical analysis is required to obtain reliable stiffness values for cervical tissue. In contrast, the maximum compressibility procedure leads to a repeatable, semi-quantitative assessment of cervical consistency, due to the nonlinear nature of the mechanical behavior of cervical tissue. The evolution of cervical stiffness in pregnancy obtained with this procedure is in line with data from aspiration tests.
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Affiliation(s)
- M M Maurer
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland.
| | - S Badir
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - M Pensalfini
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - M Bajka
- Department of Obstetrics and Gynecology, University Hospital Zurich, 8091 Zurich, Switzerland
| | - P Abitabile
- Hospital Laufenburg, 5080 Laufenburg, Switzerland
| | - R Zimmermann
- Department of Obstetrics and Gynecology, University Hospital Zurich, 8091 Zurich, Switzerland
| | - E Mazza
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland; EMPA, Swiss Federal Laboratories for Materials Testing and Research, 8600 Dubendorf, Switzerland
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Hee L. Overview of the methods available for biomechanical testing of the uterine cervix in vivo. Acta Obstet Gynecol Scand 2014; 93:1219-37. [PMID: 25174701 DOI: 10.1111/aogs.12483] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 08/16/2014] [Indexed: 01/01/2023]
Abstract
OBJECTIVE To give an overview of the methods available for biomechanical testing of the non-pregnant and pregnant uterine cervix in vivo. METHODS The following databases were searched. PubMed, Embase, and Cochrane Library. Additional studies were identified from reference lists. Only studies on in vivo biomechanical testing on both pregnant and non-pregnant women were included. MAIN OUTCOME MEASURES Estimation of distensibility, compressibility, and biochemical composition of the uterine cervix. RESULTS The distensibility methods evaluated a physiologic variable and might serve as a gold standard; however, they may never be clinically useful as they involve instrumentation of the cervical canal. The compression methods evaluated an unphysiological variable but despite that, they seemed to evaluate biologically relevant figures and were non-invasive. Of the methods evaluating the biomechanical properties indirectly, those based on ultrasound may be clinically useful. Other indirect methods only measured variables within the most superficial layer of the distal uterine cervix, so further studies are needed to evaluate whether these measurements reflect the entire organ. Both compression methods and indirect methods were similar or superior to the Bishop score and to cervical length measurements regarding prediction of spontaneous preterm delivery and successful induction of labor in small studies. CONCLUSION The methods may have the potential to detect the biomechanical changes in the uterine cervix before the cervical length has shortened. The most promising methods need large-scale clinical testing regarding induction of labor and preterm delivery before they can be used in the clinic.
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Affiliation(s)
- Lene Hee
- Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark
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Öcal FD, Çekmez Y, Erdoğdu E, Gezer M, Fanuscu İ, Özkan H, Kara OF, Küçüközkan T. The utility of cervical elastosonography in prediction of cervical insufficiency: cervical elastosonography and cervical insufficiency. J Matern Fetal Neonatal Med 2014; 28:812-8. [DOI: 10.3109/14767058.2014.933801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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