Relationships of maternal serum levels of vascular endothelial growth factor and tensile strength properties of the cervix in a rat model of chronic hypoxia

Expression of mRNA vascular endothelial growth factor in hypospadias patients

Background

Hypospadias is a relatively common genital anomaly in humans, usually followed by inelastic dartos that causes penile chordee. Vascular endothelial growth factor (VEGF) is strongly linked to the viscoelasticity of tissues and their elastic phase. This study aimed to evaluate VEGF expressions in (1) fascia dartos between hypospadias and controls and (2) chordee severity.

Methods

This prospective cohort study involved 65 specimens from patients with hypospadias and ten specimens from controls. The samples were analyzed by quantitative real-time polymerase chain reaction (qPCR) for VEGF expression.

Results

The expressions of VEGF were not different between proximal and distal hypospadias patients and controls (fold change: distal − 0.25; fold change: proximal − 0.2; p = 0.664). The scaled expressions related to chordee severity were mild − 0.1; moderate 0.1; severe − 0.25 (p = 0.660).

Conclusions

VEGF expressions might not affect the severity of hypospadias and chordee, implying the pathogenesis is complex involving many growth factors. Further study with a larger sample size is necessary to clarify and confirm our findings.

Vascular endothelial growth factor induces mRNA expression of pro-inflammatory factors in the uterine cervix of mice

Inflammation is believed to play a role in uterine cervical remodeling and infection-induced preterm labor. One of the distinct features of remodeling uterine cervix is presence of prominent vascular events, such as angiogenesis, vasodilation, and vascular permeability. Although the functional significance of these features is not yet clear, we know that in most tissue types, vascular remodeling is intricately intertwined with inflammation. Since vascular endothelial growth factor (VEGF) is the major architect of vascular remodeling, we sought to examine and elucidate the potential relationship between VEGF and inflammation in the uterine cervix of non-pregnant mice. The animals used were divided into 4 treatment groups: A) negative control (vehicle only), B) positive control (lipopolysaccharide, LPS), C) recombinant VEGF-164 protein, and D) LPS + VEGF blocker (n = 3). After the appropriate treatments, the uterine cervices were harvested and analyzed using real-time PCR and confocal fluorescence microscopy. Results showed that exogenous VEGF upregulates expression of interleukin (IL)-6 and tumor necrosis factor (TNF)-α mRNAs, whereas VEGF blocker partially diminishes the LPS-induced expression of pro-inflammatory factors compared to the positive control group. We conclude that a positive feed-forward relationship likely exists between VEGF and inflammation in the uterine cervix, thus implicating VEGF in inflammation-induced preterm labor.

Hyaluronidase modifies the biomechanical properties of the rat cervix and shortens the duration of labor independent of myometrial contractility

OBJECTIVE

To investigate the effect of intracervical hyaluronidase on the biomechanical properties of the cervix and on uterine contractility.

STUDY DESIGN

Sprague-Dawley rats (n = 33, term day 22) were injected with hyaluronidase (100 IU) or saline solution on day 18 of gestation (n = 8-9/group). On day 21, labor was induced with mifepristone (8 mg/rat). Injection-to-delivery times were recorded. Biomechanical properties of the cervix were assessed using stretch-tension analysis. Myometrial contractility was investigated in response to hyaluronidase (0.2-200 IU/mL), oxytocin (10(-10)M to 10(-5)M), and potassium chloride (60 mM).

RESULTS

Delivery times were shorter in the hyaluronidase group (P = .03). Cervices of the treated animals showed higher measures of elasticity and plasticity (P = .02 for both). Myometrial sensitivity to hyaluronidase, oxytocin, or potassium chloride was not affected by the cervical application of hyaluronidase (P > .05 for all).

CONCLUSION

Cervical hyaluronidase treatment shortens labor and alters the biomechanical properties of the cervix, independent of the myometrium.

Genetic background affects the biomechanical behavior of the postpartum mouse cervix

OBJECTIVE

We hypothesized that the genetic makeup has an impact on the functional behavior of the uterine cervix. Therefore, we compared the biomechanical properties of uterine cervix in postpartum in 2 strains of mice that differ in their underlying regenerative collagen remodeling characteristics: MRL/MpJ+/+ (MRL: high regenerative repair) and C57BL/6 (C57: low regenerative high fibrotic repair).

STUDY DESIGN

Cervical tensile proprieties were assessed on day 3, 15, and 60 postpartum in MRL (n = 14) and C57 (n = 13) mice (4-5 animals at each time point). Stress-strain curves were generated using Shimadzu EZ-test instrumentation. Cervical tissue was stretched by 0.42 mm/min until rupture. Parameters of viscoelasticity including slope (a measure of stiffness), yield point (YP; moment when tissue changes its proprieties from elastic to plastic), and break point (BP; measure of tissue strength) were recorded and analyzed blindly between strains. Data were normalized to the weight of the tissue and analyzed by 2-way analysis of variance. Histological and collagen birefringence evaluation of the uterine cervix (MRL: n = 4; C57: n = 4) was performed 5 days after delivery.

RESULTS

At 3 and 15 days postpartum, cervices of MRL mice were significantly more compliant than those of C57 (P < .001). MRL mice displayed a significant increase in stiffness from day 3 to day 60 (slope, median +/- SEM: day 3: 3.1 +/- 0.5 vs day 15: 20.3 +/- 4.9 vs day 60: 33.1 +/- 3.5 N/mm per gram; P < .001). In contrast, the stiffness of C57 cervices reached maximum on day 15 (slope day 3: 14.1 +/- 4.3 vs day 15: 40.0 +/- 6.5 N/mm per gram; P = .02) and rested at a similar level on day 60 (day 60: 26.1 +/- 7.0 N/mm per gram; day 60 vs day 15: P = .937). More force was required to reach YP in C57 on day 3 (C57: 72.5 +/- 14.7 vs MRL: 19.9 +/- 1.6 N/g; P < .001) but not on either day 15 (C57: 156.1 +/- 27.5 vs MRL: 109.2 +/- 26.0 N/g; P = .120) or on day 60 (C57: 143.4 +/- 26.5 vs MRL: 164.5 +/- 18.7 N/g; P = .412). There was a significant decrease in BP in both strains on both day 15 and day 60 compared with day 3 postpartum (P = .856 for strain, P = .008 for day). MRL mice displayed significantly less cervical collagen birefringence compared with C57 control (P < .001) but increased proteoglycan staining and increased water content.

CONCLUSION

We provide evidence that genetic makeup may have an impact on cervical tissue remodeling and function. There are significant differences in postpartum cervical stiffness and compliance that vary with the regenerative collagen remodeling phenotype.