Material properties of mouse cervical tissue in normal gestation

Kyoko Yoshida, Mala Mahendroo, Joy Vink, Ronald Wapner, Kristin Myers

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

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 3.4. MPa at gestation day 6 to 9.7e-4. MPa at gestation day 18, while the ground substance stiffness decreases from 2.6e-1. MPa to 7.0e-4. MPa. 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.

Original languageEnglish (US)
JournalActa Biomaterialia
DOIs
StateAccepted/In press - Aug 14 2015

Fingerprint

Materials properties
Tissue
Cervix Uteri
Pregnancy
Fibers
Composite materials
Stiffness
Geometry
Mechanical testing
Rodentia
Canals
Collagen
Swelling
Finite Element Analysis
Premature Birth
Finite element method
Sutures
Testing

Keywords

  • Biomechanics
  • Cervix
  • Constitutive modeling
  • Pregnancy

ASJC Scopus subject areas

  • Biomaterials
  • Biomedical Engineering
  • Biotechnology
  • Biochemistry
  • Molecular Biology

Cite this

Material properties of mouse cervical tissue in normal gestation. / Yoshida, Kyoko; Mahendroo, Mala; Vink, Joy; Wapner, Ronald; Myers, Kristin.

In: Acta Biomaterialia, 14.08.2015.

Research output: Contribution to journalArticle

Yoshida, Kyoko ; Mahendroo, Mala ; Vink, Joy ; Wapner, Ronald ; Myers, Kristin. / Material properties of mouse cervical tissue in normal gestation. In: Acta Biomaterialia. 2015.
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