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Jiang H, Bo Z. Application value of ultrasound elastography for screening of early pregnancy cervical insufficiency: a retrospective case-control study. J Matern Fetal Neonatal Med 2024; 37:2299111. [PMID: 38199820 DOI: 10.1080/14767058.2023.2299111] [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: 10/13/2023] [Accepted: 12/20/2023] [Indexed: 01/12/2024]
Abstract
OBJECTIVE This study aimed to investigate changes in the cervical strain rate (SR), cervical length (CL), and uterine artery blood flow parameters during early pregnancy in women with cervical insufficiency and evaluate the clinical efficacy of these markers for screening of cervical insufficiency in early pregnancy. METHODS This retrospective study in 60 pregnant women with cervical insufficiency and 100 normal pregnant women was conducted between September 2021 and January 2023 and measured ultrasound parameters of the cervix during early pregnancy. The cervical SR, CL, and uterine artery resistance index (RI) were measured in both groups at 11-14 weeks of gestation. Strain elastography represented by the SR was used to assess the hardness of the internal and external cervical openings. RESULTS During early pregnancy, the SR at the internal and external cervical openings were significantly higher in the cervical insufficiency group than those in the normal pregnancy group (SR I: 0.19 ± 0.018% vs. 0.16 ± 0.014%; SR E: 0.26 ± 0.028% vs. 0.24 ± 0.025%; p < .001). The CL was significantly shorter in the cervical insufficiency group than that measured in the normal pregnancy group (34.3 ± 2.9 mm vs. 35.2 ± 1.99 mm; p = .036), while cervical blood perfusion was also poorer in the cervical insufficiency group than that in the normal pregnancy group (uterine artery RI: 0.76 ± 0.07 vs. 0.74 ± 0.05; p = .048). Receiver operating characteristic (ROC) curve analysis showed that the optimal critical values for diagnosing cervical insufficiency were 0.17% for SR I, 0.25% for SR E, 33.8 mm for CL, and 0.78 for uterine artery RI. Of these parameters, the ROC curve for SR I had the largest area under the curve [AUC = 0.89 (p < .001)], with the highest sensitivity (78%) and specificity (82%). Multivariate logistic regression analysis demonstrated that the SR at the internal cervical opening (OR 17.47, 95% confidence interval (CI) 5.08-60.08; p < .001) and CL (OR 5.05, 95% CI 1.66-15.32; p = .004) still showed significant differences between the two groups. CONCLUSION Cervical elastography is an effective tool for screening early pregnancy cervical insufficiency. The SR at the internal cervical opening is a valuable indicator for screening cervical insufficiency and has superior clinical efficacy for screening for this condition compared to that of CL and the uterine artery blood flow index.
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Affiliation(s)
- Hua Jiang
- Department of Ultrasound in Medicine, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Zhang Bo
- Department of Ultrasound in Medicine, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China
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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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Shukla R, Arshee MR, Laws MJ, Flaws JA, Bagchi MK, Wagoner Johnson AJ, Bagchi IC. Chronic exposure of mice to phthalates enhances TGF beta signaling and promotes uterine fibrosis. Reprod Toxicol 2023; 122:108491. [PMID: 37863342 DOI: 10.1016/j.reprotox.2023.108491] [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: 07/24/2023] [Revised: 10/04/2023] [Accepted: 10/17/2023] [Indexed: 10/22/2023]
Abstract
Phthalates are synthetic chemicals widely used as plasticizers and stabilizers in various consumer products. Because of the extensive production and use of phthalates, humans are exposed to these chemicals daily. While most studies focus on a single phthalate, humans are exposed to a mixture of phthalates on a regular basis. The impact of continuous exposure to phthalate mixture on uterus is largely unknown. Thus, we conducted studies in which adult female mice were exposed for 6 months to 0.15 ppm and 1.5 ppm of a mixture of phthalates via chow ad libitum. Our studies revealed that consumption of phthalate mixture at 0.15 ppm and 1.5 ppm for 6 months led to a significant increase in the thickness of the myometrial layer compared to control. Further investigation employing RNA-sequencing revealed an elevated transforming growth factor beta (TGF-β) signaling in the uteri of mice fed with phthalate mixture. TGF-β signaling is associated with the development of fibrosis, a consequence of excessive accumulation of extracellular matrix components, such as collagen fibers in a tissue. Consistent with this observation, we found a higher incidence of collagen deposition in uteri of mice exposed to phthalate mixture compared to unexposed controls. Second Harmonic Generation (SHG) imaging showed disorganized collagen fibers and nanoindentation indicated a local increase in uterine stiffness upon exposure to phthalate mixture. Collectively, our results demonstrate that chronic exposure to phthalate mixture can have adverse effects on uterine homeostasis.
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Affiliation(s)
- Ritwik Shukla
- Departments of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Mahmuda R Arshee
- Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Mary J Laws
- Departments of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jodi A Flaws
- Departments of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Carle R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Milan K Bagchi
- Molecular & Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Carle R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Amy J Wagoner Johnson
- Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Carle R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Indrani C Bagchi
- Departments of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Carle R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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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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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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Pittokopitou S, Mavrogianni D, Pergialiotis V, Pappa KI, Antsaklis P, Theodora M, Sindos M, Papapanagiotou A, Domali A, Stavros S, Drakakis P, Daskalakis G. Expression of Stemness Markers in the Cervical Smear of Patients with Cervical Insufficiency. Cells 2023; 12:cells12081183. [PMID: 37190092 DOI: 10.3390/cells12081183] [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: 02/03/2023] [Revised: 04/04/2023] [Accepted: 04/07/2023] [Indexed: 05/17/2023] Open
Abstract
The presence of stem cells has been previously described in human precancerous and malignant cervical cultures. Previous studies have shown a direct interplay of the stem cell niche, which is present in practically every tissue with the extracellular matrix. In the present study, we sought to determine the expression of stemness markers in cytological specimens collected from the ectocervix among women with cervical insufficiency during the second trimester of pregnancy and women with normal cervical length. A prospective cohort of 59 women was enrolled of whom 41 were diagnosed with cervical insufficiency. The expression of OCT-4 and NANOG was higher in the cervical insufficiency group compared to the control group (-5.03 (-6.27, -3.72) vs. -5.81 (-7.67, -5.02) p = 0.040 for OCT4) and (-7.47 (-8.78, -6.27) vs. -8.5 (-10.75, -7.14), p = 0.035 for NANOG. Differences in the DAZL gene were not significantly different (5.94 (4.82, 7.14) vs. 6.98 (5.87, 7.43) p = 0.097). Pearson correlation analysis indicated the existence of a moderate correlation of OCT-4 and Nanog with cervical length. Considering this information, the enhanced activity of stemness biomarkers among pregnant women diagnosed with cervical insufficiency may be predisposed to cervical insufficiency, and its predictive accuracy remains to be noted in larger population sizes.
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Affiliation(s)
- Savvia Pittokopitou
- 1st Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Alexandra Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - Despina Mavrogianni
- 1st Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Alexandra Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - Vasilios Pergialiotis
- 1st Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Alexandra Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - Kalliopi I Pappa
- 1st Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Alexandra Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - Panagiotis Antsaklis
- 1st Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Alexandra Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - Marianna Theodora
- 1st Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Alexandra Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - Michail Sindos
- 1st Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Alexandra Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - Angeliki Papapanagiotou
- Department of Biological Chemistry, Medical School, National and Kapodistrial University of Athens, 11528 Athens, Greece
| | - Aikaterini Domali
- 1st Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Alexandra Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - Sofoklis Stavros
- 1st Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Alexandra Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - Peter Drakakis
- 1st Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Alexandra Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - George Daskalakis
- 1st Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Alexandra Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
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7
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Ostadi Moghaddam A, Arshee MR, Lin Z, Sivaguru M, Phillips H, McFarlin BL, Toussaint KC, Wagoner Johnson AJ. An indentation-based framework for probing the glycosaminoglycan-mediated interactions of collagen fibrils. J Mech Behav Biomed Mater 2023; 140:105726. [PMID: 36827935 PMCID: PMC10061372 DOI: 10.1016/j.jmbbm.2023.105726] [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: 11/15/2022] [Revised: 02/01/2023] [Accepted: 02/11/2023] [Indexed: 02/17/2023]
Abstract
Microscale deformation processes, such as reorientation, buckling, and sliding of collagen fibrils, determine the mechanical behavior and function of collagenous tissue. While changes in the structure and composition of tendon have been extensively studied, the deformation mechanisms that modulate the interaction of extracellular matrix (ECM) constituents are not well understood, partly due to the lack of appropriate techniques to probe the behavior. In particular, the role of glycosaminoglycans (GAGs) in modulating collagen fibril interactions has remained controversial. Some studies suggest that GAGs act as crosslinkers between the collagen fibrils, while others have not found such evidence and postulate that GAGs have other functions. Here, we introduce a new framework, relying on orientation-dependent indentation behavior of tissue and computational modeling, to evaluate the shear-mediated function of GAGs in modulating the collagen fibril interactions at a length scale more relevant to fibrils compared to bulk tests. Specifically, we use chondroitinase ABC to enzymatically deplete the GAGs in tendon; measure the orientation-dependent indentation response in transverse and longitudinal orientations; and infer the microscale deformation mechanisms and function of GAGs from a microstructural computational model and a modified shear-lag model. We validate the modeling approach experimentally and show that GAGs facilitate collagen fibril sliding with minimal crosslinking function. We suggest that the molecular reconfiguration of GAGs is a potential mechanism for their microscale, strain-dependent viscoelastic behavior. This study reveals the mechanisms that control the orientation-dependent indentation response by affecting the shear deformation and provides new insights into the mechanical function of GAGs and collagen crosslinkers in collagenous tissue.
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Affiliation(s)
- A Ostadi Moghaddam
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - M R Arshee
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Z Lin
- School of Engineering, Brown University, Providence, RI, 02912, USA
| | - M Sivaguru
- Flow Cytometry and Microscopy to Omics, Roy J. Carver Biotechnology Center, University of Illinois at Urbana-Champaign, Champaign, IL, 61820, USA
| | - H Phillips
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - B L McFarlin
- Department of Women, Children and Family Health Science, University of Illinois College of Nursing, Chicago, IL, 60612, USA
| | - K C Toussaint
- School of Engineering, Brown University, Providence, RI, 02912, USA
| | - A J Wagoner Johnson
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Champaign, IL, 61820, USA; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
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8
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Ostadi Moghaddam A, Arshee MR, Lin Z, Sivaguru M, Phillips H, McFarlin BL, Toussaint KC, Wagoner Johnson AJ. Orientation-dependent indentation reveals the crosslink-mediated deformation mechanisms of collagen fibrils. Acta Biomater 2023; 158:347-357. [PMID: 36638936 PMCID: PMC10039649 DOI: 10.1016/j.actbio.2023.01.005] [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: 09/20/2022] [Revised: 12/18/2022] [Accepted: 01/03/2023] [Indexed: 01/12/2023]
Abstract
The spatial arrangement and interactions of the extracellular matrix (ECM) components control the mechanical behavior of tissue at multiple length scales. Changes in microscale deformation mechanisms affect tissue function and are often hallmarks of remodeling and disease. Despite their importance, the deformation mechanisms that modulate the mechanical behavior of collagenous tissue, particularly in indentation and compression modes of deformation, remain poorly understood. Here, we develop an integrated computational and experimental approach to investigate the deformation mechanisms of collagenous tissue at the microscale. While the complex deformation arising from indentation with a spherical probe is often considered a pitfall rather than an opportunity, we leverage this orientation-dependent deformation to examine the shear-regulated interactions of collagen fibrils and the role of crosslinks in modulating these interactions. We specifically examine tendon and cervix, two tissues rich in collagen with quite different microstructures and mechanical functions. We find that interacting, crosslinked collagen fibrils resist microscale longitudinal compressive forces, while widely used constitutive models fail to capture this behavior. The reorientation of collagen fibrils tunes the compressive stiffness of complex tissues like cervix. This study offers new insights into the mechanical behavior of collagen fibrils during indentation, and more generally, under longitudinal compressive forces, and illustrates the mechanisms that contribute to the experimentally observed orientation-dependent mechanical behavior. STATEMENT OF SIGNIFICANCE: Remodeling and disease can affect the deformation and interaction of tissue constituents, and thus mechanical function of tissue. Yet, the microscale deformation mechanisms are not well characterized in many tissues. Here, we develop a combined experimental-computational approach to infer the microscale deformation mechanisms of collagenous tissues with very different functions: tendon and cervix. Results show that collagen fibrils resist microscale forces along their length, though widely-used constitutive models do not account for this mechanism. This deformation process partially modulates the compressive stiffness of complex tissues such as cervix. Computational modeling shows that crosslink-mediated shear deformations are central to this unexpected behavior. This study offers new insights into the deformation mechanisms of collagenous tissue and the function of collagen crosslinkers.
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Affiliation(s)
- A Ostadi Moghaddam
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - M R Arshee
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Z Lin
- School of Engineering, Brown University, Providence, RI 02912, USA
| | - M Sivaguru
- Flow Cytometry and Microscopy to Omics, Roy J. Carver Biotechnology Center, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA
| | - H Phillips
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - B L McFarlin
- Department of Women, Children and Family Health Science, University of Illinois College of Nursing, Chicago, IL 60612, USA
| | - K C Toussaint
- School of Engineering, Brown University, Providence, RI 02912, USA
| | - A J Wagoner Johnson
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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9
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Measurement of cervical softness before cerclage placement with an aspiration-based device. Am J Obstet Gynecol MFM 2023; 5:100881. [PMID: 36724813 DOI: 10.1016/j.ajogmf.2023.100881] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/23/2023] [Accepted: 01/24/2023] [Indexed: 01/30/2023]
Abstract
BACKGROUND An abnormally soft cervix could contribute to the pathophysiology of cervical shortening and cervical insufficiency. Multiple techniques to measure cervical softness have been developed but none are used routinely in clinical practice. A clinically acceptable technique to measure cervical softness could improve identification of patients at risk for cervix-related preterm birth. OBJECTIVE This study aimed to measure cervical softness in patients with cervical insufficiency and in normal controls using a novel, aspiration-based device. We hypothesized that the cervix is softer in patients with cervical insufficiency. STUDY DESIGN This was a cross-sectional study of patients presenting for cerclage at a single academic medical center. Cervical softness was measured using a noninvasive, aspiration-based device placed on the anterior lip of the cervix during a speculum examination. The device measured the aspiration pressure required to displace cervical tissue to a predefined deformation level. Stiff tissue required increased aspiration pressure, whereas soft tissue required lower pressure values. Cerclage patients were subdivided into 3 groups, namely history-indicated, ultrasound-indicated, and examination-indicated cerclage. Controls were healthy volunteers between 12+0 weeks and 23+6 weeks of gestation without a history of cervical insufficiency and were matched by gestational age to the patients in the cerclage groups. Women with a cerclage in place, multiple gestations, active genital infection, or previous cervical excision procedures were excluded. Delivery information was subsequently recorded as well. RESULTS Data from 133 women were analyzed; of those, 54 patients were in the cerclage group (23 history-indicated, 12 ultrasound-indicated, and 19 examination-indicated participants) and 79 were controls (40 in the first trimester and 39 in the second trimester groups). Patients who presented for ultrasound-indicated cerclage had significantly softer cervices (median; interquartile range) than second trimester controls (62 mbar; 50.5-114 vs 81 mbar; 75-101; P=.042). The difference in cervical softness was not significantly different between the history-indicated and examination-indicated cerclage groups and their respective control groups. CONCLUSION Patients presenting for ultrasound-indicated cerclage had significantly softer cervices than normal controls as measured by an aspiration-based device. Quantitative measurement of cervical softness with the aspiration-based device is a promising technique for objective measurement of cervical softness during pregnancy.
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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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