Combination of histochemical analyses and micro-MRI reveals regional changes of the murine cervix in preparation for labor

Early Magnetic Resonance Imaging Measurements and Prediction of Second Trimester Pregnancy Loss: a Nomogram Model Analysis

Objective

To investigate the magnetic resonance imaging (MRI) features of women with prior second-trimester pregnancy loss, and to establish a nomogram prediction model for subsequent miscarriage.

Methods

A retrospective cohort study of women with prior second-trimester pregnancy loss from January 2018 to December 2021 in Second Affiliated Hospital of Soochow University was performed. A total of 245 patients were included. Data from January 2018 to December 2019 were used to construct the model, and data from January 2020 to December 2021 were used to evaluate the model. Data on maternal demographic characteristics, MRI cervical measurements were extracted. The prediction model was constructed with independent variables determined by multivariate logistic regression analyses. Through receiver-operating characteristic (ROC) curve analysis, the predictive ability of the model for subsequent second trimester pregnancy loss in women was evaluated, and internal validation was performed through validation data.

Results

Thin cervix was observed in 77 (31.42%) women with prior second-trimester pregnancy loss, the mean longitudinal diameter of cervical canal on MRI was 11.76±2.75mm. The model reached a sensitivity of 80%, specificity of 75.90%, positive predictive value (PPV) of 55.80% and negative predictive value of 90.90%; ROC characteristics proved that the model was superior to any single parameter with an AUC of 0.826.

Conclusion

Our observations showed that thin cervix and longitudinal diameter of cervical canal reliably predicted second trimester pregnancy loss. We developed and validated a nomogram model to predict the individual probability of second trimester pregnancy loss in the next pregnancy and hopefully improve the prediction and indication of interventions.

Precise lymph node biopsy for endometrial cancer confined to the uterus: Analysis of 43 clinical cases

OBJECTIVE

To explore a precise association between tumor location and lymph node (LN) biopsy algorithm in uterine confined endometrial cancer (EC).

MATERIALS AND METHODS

Patients with EC treated in the Department of Obstetrics and Gynecology, South Branch of Fujian Provincial Hospital were included in this observational retrospective study. Based on the procedure of treatment, patients were separated to stage I (2015.07-2019.09) and stage II (2019.09-2021.9). In each stage, patients were separated to high and low-risk group by the predicted results. Patients in the high-risk group received systematic lymphadenectomy in stage I and sentinel lymph node (SLN) dissection in stage II. The efficiency of lymph node metastasis (LNM) detection rates was compared between stage I and stage II cases. Precise lymph node biopsy algorithm was also constructed based on the outcomes of stage II.

RESULTS

Overall, 43 patients, 28 in stage I and 15 in stage II, were included in the study. No recurrence or death cases had been found within follow-up terms. Based on the difference in the detection efficiency of LNM (p > 0.05), there was no difference between two stages. Thus, systematic lymphadenectomy and SLN biopsy provided similar success rates. The location of tumor site was also important for deciding whether pelvic or para-aortic SLN should be sampled for LNM.

CONCLUSIONS

Precise SLN biopsy for EC confined to the uterus showed comparable LNM detection rate as systematic lymphadenectomy. EC location may be used to determine whether pelvic or para-aortic SLN sampling should be conducted for treatment.

Pregnancy-induced remodeling of the murine reproductive tract: a longitudinal in vivo magnetic resonance imaging study

Mammalian pregnancy requires gradual yet extreme remodeling of the reproductive organs to support the growth of the embryos and their birth. After delivery, the reproductive organs return to their non-pregnant state. As pregnancy has traditionally been understudied, there are many unknowns pertaining to the mechanisms behind this remarkable remodeling and repair process which, when not successful, can lead to pregnancy-related complications such as maternal trauma, pre-term birth, and pelvic floor disorders. This study presents the first longitudinal imaging data that focuses on revealing anatomical alterations of the vagina, cervix, and uterine horns during pregnancy and postpartum using the mouse model. By utilizing advanced magnetic resonance imaging (MRI) technology, T1-weighted and T2-weighted images of the reproductive organs of three mice in their in vivo environment were collected at five time points: non-pregnant, mid-pregnant (gestation day: 9-10), late pregnant (gestation day: 16-17), postpartum (24-72 h after delivery) and three weeks postpartum. Measurements of the vagina, cervix, and uterine horns were taken by analyzing MRI segmentations of these organs. The cross-sectional diameter, length, and volume of the vagina increased in late pregnancy and then returned to non-pregnant values three weeks after delivery. The cross-sectional diameter of the cervix decreased at mid-pregnancy before increasing in late pregnancy. The volume of the cervix peaked at late pregnancy before shortening by 24-72 h postpartum. As expected, the uterus increased in cross-sectional diameter, length, and volume during pregnancy. The uterine horns decreased in size postpartum, ultimately returning to their average non-pregnant size three weeks postpartum. The newly developed methods for acquiring longitudinal in vivo MRI scans of the murine reproductive system can be extended to future studies that evaluate functional and morphological alterations of this system due to pathologies, interventions, and treatments.

Mechanical Response of Mouse Cervices Lacking Decorin and Biglycan During Pregnancy

Cervical remodeling is critical for a healthy pregnancy. The proper regulation of extracellular matrix (ECM) turnover leads to remodeling throughout gestation, transforming the tissue from a stiff material to a compliant, extensible, viscoelastic tissue prepared for delivery. Small leucine rich proteoglycans (SLRPs) are known to regulate structural fiber assembly in the cervical ECM and overall tissue material properties. To quantify the SLRPs' mechanical role in the cervix, whole cervix specimens from non-pregnant and late pregnant knockout mice of SLRPs, decorin and biglycan, were subjected to cyclic load-unload, ramp-hold, and load-to-failure mechanical tests. Further, a fiber composite material model, accounting for collagen fiber bundle waviness, was developed to describe the three-dimensional large deformation equilibrium behavior of the cervix. In nonpregnant tissue, SLRP KO cervices have the same equilibrium material properties as wild-type tissue. In contrast, the load-to-failure and ramp-hold tests reveal SLRPs impact rupture and time-dependent relaxation behavior. Loss of decorin in NP cervices results in inferior rupture properties. While remodeling recovers cervical strength, the SLRP-deficient tissue has diminished ability to dissipate stress during a ramp-hold. In mice with a combined loss of decorin and biglycan, the pregnant cervix loses its extensibility, compliance, and viscoelasticity. Taken together, these results suggest decorin and biglycan are necessary for key compliance and viscoelastic material property features of a healthy remodeled pregnant cervix.

The swelling behavior of the mouse cervix: Changing kinetics with osmolarity and the role of hyaluronan in pregnancy

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.

Transcriptome changes in maternal peripheral blood during term parturition mimic perturbations preceding spontaneous Preterm birth†

The complex physiologic process of parturition includes the onset of labor, which requires the orchestrated stimulation of a common pathway involving uterine contractility, cervical ripening, and chorioamniotic membrane activation. However, the labor-specific processes taking place in these tissues have limited use as predictive biomarkers unless they can be probed in non-invasive samples, such as the peripheral blood. Herein, we utilized a transcriptomic dataset to assess labor-specific changes in the peripheral blood of women who delivered at term. We identified a set of genes that were differentially expressed with labor and enriched for immunological processes, and these gene expression changes were strongly correlated with results from prior studies, providing in silico validation of our findings. We then identified significant correlations between labor-specific transcriptomic changes in the maternal circulation and those reported in the chorioamniotic membranes, myometrium, and cervix of women at term, demonstrating that tissue-specific labor signatures are partly mirrored in the peripheral blood. Last, we demonstrated a significant overlap between the peripheral blood transcriptomic changes in term parturition and those observed in asymptomatic women prior to the diagnosis of preterm prelabor rupture of membranes who delivered preterm. Collectively, we provide evidence that the normal process of labor at term is characterized by a unique immunological expression signature, which may serve as a useful tool for assessing labor status and potentially identifying women at risk for preterm birth.

Transcriptome and proteome dynamics of cervical remodeling in the mouse during pregnancy

During gestation, the female reproductive tract must maintain pregnancy while concurrently preparing for parturition. Here, we explore the transitions in gene expression and protein turnover (fractional synthesis rates [FSR]) by which the cervix implements a transition from rigid to compliant. Shifts in gene transcription to achieve immune tolerance and alter epithelial cell programs begin in early pregnancy. Subsequently, in mid-to-late pregnancy transcriptional programs emerge that promote structural reorganization of the extracellular matrix (ECM). Stable isotope labeling revealed a striking slowdown of overall FSRs across the proteome on gestation day 6 that reverses in mid-to-late pregnancy. An exception was soluble fibrillar collagens and proteins of collagen assembly, which exhibit high turnover in non-pregnant cervix compared to other tissues and FSRs that continue throughout pregnancy. This finding provides a mechanism to explain how cross-linked collagen is replaced by newly synthesized, less-cross-linked collagens, which allows increased tissue compliance during parturition. The rapid transition requires a reservoir of newly synthesized, less cross-linked collagens, which is assured by the high FSR of soluble collagens in the cervix. These findings suggest a previously unrecognized form of "metabolic flexibility" for ECM in the cervix that underlies rapid transformation in compliance to allow parturition.