Screening of gestational diabetes mellitus in early pregnancy by oral glucose tolerance test and glycosylated fibronectin: study protocol for an international, prospective, multicentre cohort trial.

INTRODUCTION: As the accurate diagnosis and treatment of gestational diabetes mellitus (GDM) is of increasing importance; new diagnostic approaches for the assessment of GDM in early pregnancy were recently suggested. We evaluate the diagnostic power of an 'early' oral glucose tolerance test (OGTT) 75 g and glycosylated fibronectin (glyFn) for GDM screening in a normal cohort. METHODS AND ANALYSIS: In a prospective cohort study, 748 singleton pregnancies are recruited in 6 centres in Switzerland, Austria and Germany. Women are screened for pre-existing diabetes mellitus and GDM by an 'early' OGTT 75 g and/or the new biomarker, glyFn, at 12-15 weeks of gestation. Different screening strategies are compared to evaluate the impact on detection of GDM by an OGTT 75 g at 24-28 weeks of gestation as recommended by the International Association of Diabetes and Pregnancy Study Groups (IADPSG). A new screening algorithm is created by using multivariable risk estimation based on 'early' OGTT 75 g and/or glyFn results, incorporating maternal risk factors. Recruitment began in May 2014. ETHICS AND DISSEMINATION: This study received ethical approval from the ethics committees in Basel, Zurich, Vienna, Salzburg and Freiburg. It was registered under http://www.ClinicalTrials.gov (NCT02035059) on 12 January 2014. Data will be presented at international conferences and published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT02035059.

Engineered cell instructive matrices for fetal membrane healing.

Iatrogenic preterm prelabour rupture of fetal membranes (iPPROM) occurs in 6-45% of the cases after fetoscopic procedures, posing a significant threat to fetal survival and well-being. The number of diagnostic and therapeutic prenatal interventions available is increasing, thus developing treatment options for iPPROM is becoming more important than ever before. Fetal membranes exhibit very restricted regeneration and little is known about factors which might modulate their healing potential, rendering various materials and strategies to seal or heal fetal membranes pursued over the past decades relatively fruitless. Additionally, biocompatible materials with tunable in vivo stability and mechanical and biological properties have not been available. Using poly(ethylene glycol)-based biomimetic matrices, we provide evidence that, upon presentation of appropriate biological cues in three dimensions, mesenchymal progenitor cells from the amnion can be mobilized, induced to proliferate and supported in maintaining their native extracellular matrix production, thus creating a suitable environment for healing to take place. These data suggest that engineering materials with defined mechanical and biochemical properties and the ability to present migration- and proliferation-inducing factors, such as platelet-derived growth factor, basic fibroblast growth factor or epidermal growth factor, could be key in resolving the clinical problem of iPPROM and allowing the field of fetal surgery to move forward.

Mussel mimetic tissue adhesive for fetal membrane repair: initial in vivo investigation in rabbits.

OBJECTIVE: Iatrogenic preterm prelabour rupture of fetal membranes (iPPROM) remains the main complication after invasive interventions into the intrauterine cavity. The aim of this study was to evaluate the sealing capability and tissue interaction of mussel-mimetic tissue adhesive (mussel glue) in comparison to fibrin glue on punctured fetal membranes in vivo. STUDY DESIGN: A mid-gestational rabbit model was used for testing the materials. The fetal sacs of pregnant rabbits at day 23 were randomly assigned into experimental groups: unoperated (negative control), unclosed puncture (positive control), commercially available fibrin glue (FG) with decellularized amnion scaffold (DAM), mussel glue (MG) with DAM, or mussel glue alone. Evaluation was done at term (30 days' gestation) assessing fetal survival, fetal membrane integrity and histology of the membranes. RESULTS: Fetal survival was not significantly lower in any of the treatment groups compared to the negative control. All plugging materials could be found at the end of the pregnancy and no adverse effects on the fetus or the pregnant does could be observed. Sac integrity was higher in all treatment groups compared to the positive control group but significant only in the FG+DAM group. Cellular infiltration could be seen in fibrin glue and DAM in contrast to mussel glue which was only tightly adhering to the surrounding tissue. These cells were mostly of mesenchymal phenotype staining positive for vimentin. CD68 positive macrophages were found clustered around all the plugging materials, but their numbers were only significantly increased for the mussel glue alone group compared to negative controls. CONCLUSIONS: Mussel glues performance in sealing fetal membranes in the rabbit model was comparable to that of fibrin glue. Taking into account its other favorable properties, it is a noteworthy candidate for a clinically applicable fetal membrane sealant.

Second harmonic generation microscopy of fetal membranes under deformation: normal and altered morphology.

INTRODUCTION: Insight into the microstructure of fetal membrane and its response to deformation is important for understanding causes of preterm premature rupture of the membrane. However, the microstructure of fetal membranes under deformation has not been visualized yet. Second harmonic generation microscopy, combined with an in-situ stretching device, can provide this valuable information. METHODS: Eight fetal membranes were marked over the cervix with methylene blue during elective caesarean section. One sample per membrane of reflected tissue, between the placenta and the cervical region, was cyclically stretched with a custom built inflation device. Samples were mounted on an in-situ stretching device and imaged with a multiphoton microscope at different deformation levels. Microstructural parameters such as thickness and collagen orientation were determined. Image entropy was evaluated for the spongy layer. RESULTS: The spongy layer consistently shows an altered collagen structure in the cervical and cycled tissue compared with the reflected membrane, corresponding to a significantly higher image entropy. An increased thickness of collagenous layers was found in cervical and stretched samples in comparison to the reflected tissue. Significant collagen fibre alignment was found to occur already at moderate deformation in all samples. CONCLUSIONS: For the first time, second harmonic generation microscopy has been used to visualize the microstructure of fetal membranes. Repeated mechanical loading was shown to affect the integrity of the amnion-chorion interface which might indicate an increased risk of premature rupture of fetal membrane. Moreover, mechanical loading might contribute to morphological alterations of the fetal membrane over the cervical region.

Multiaxial mechanical behavior of human fetal membranes and its relationship to microstructure.

This study was directed to the measurement of the mechanical response of fetal membranes to physiologically relevant loading conditions. Characteristic mechanical parameters were determined and their relation to the microstructural constituents collagen and elastin as well as to the pyridinium cross-link concentrations analyzed. 51 samples from twelve fetal membranes were tested on a custom-built inflation device, which allows mechanical characterization within a multiaxial state of stress. Methods of nonlinear continuum mechanics were used to extract representative mechanical parameters. Established biochemical assays were applied for the determination of the collagen and elastin content. Collagen cross-link concentrations were determined by high-performance liquid chromatography measurements. The results indicate a distinct correlation between the mechanical parameters of high stretch stiffness and membrane tension at rupture and the biochemical data of collagen content and pyridinoline as well as deoxypyridinoline concentrations. No correlation was observed between the mechanical parameters and the elastin content. Moreover, the low stretch stiffness is, with a value of 105 ± 31 × 10(-3) N/ mm much higher for a biaxial state of stress compared to a uniaxial stress configuration. Determination of constitutive model equations leads to better predictive capabilities for a reduced polynomial hyperelastic model with only terms related to the second invariant, I 2, of the right Cauchy-Green deformation tensor. Relevant insights were obtained on the mechanical behavior of fetal membranes. Collagen and its cross-linking were shown to determine membrane's stiffness and strength for multiaxial stress states. Their nonlinear deformation behavior characterizes the fetal membranes as I 2 material.

Mussel-mimetic tissue adhesive for fetal membrane repair: an ex vivo evaluation.

Iatrogenic preterm prelabor rupture of membranes (iPPROM) remains the main complication after invasive interventions into the intrauterine cavity. Here, the proteolytic stability of mussel-mimetic tissue adhesive (mussel glue) and its sealing behavior on punctured fetal membranes are evaluated. The proteolytic degradation of mussel glue and fibrin glue were compared in vitro. Critical pressures of punctured and sealed fetal membranes were determined under close to physiological conditions using a custom-made inflation device. An inverse finite element procedure was applied to estimate mechanical parameters of mussel glue. Mussel glue was insensitive whereas fibrin glue was sensitive towards proteolytic degradation. Mussel glue sealed 3.7mm fetal membrane defect up to 60mbar (45mmHg) when applied under wet conditions, whereas fibrin glue needed dry membrane surfaces for reliable sealing. The mussel glue can be represented by a neo-Hookean material model with elastic coefficient C(1)=9.63kPa. Ex-vivo-tested mussel glue sealed fetal membranes and resisted pressures achieved during uterine contractions. Together with good stability in proteolytic environments, this makes mussel glue a promising sealing material for future applications.

Mussel-mimetic tissue adhesive for fetal membrane repair: a standardized ex vivo evaluation using elastomeric membranes.

OBJECTIVE: Iatrogenic preterm premature rupture of membranes (iPPROM), the main complication of invasive interventions in the prenatal period, seriously limits the benefit of diagnostic or surgical prenatal procedures. This study aimed to evaluate preventive plugging of punctured fetal membranes in an ex vivo situation using a new mussel-mimetic tissue adhesive (mussel glue) to inhibit leakage. METHODS: A novel biomechanical test device that tests the closure of injured membranes under near-physiological conditions was used. Mussel glue, a poly(ethylene glycol)-based hydrogel, was used to seal membrane defects of up to 3 mm in mechanically well-defined elastomeric membranes with three different degrees of stiffness. RESULTS: Elastomeric test membranes were successfully employed for testing mussel glue under well-defined conditions. Mussel glue plugs were distended by up to 94%, which translated to an improved sealing efficiency on elastomeric membranes with high stiffness. For the stiffest membrane tested, a critical burst pressure of 48 mbar (36 mmHg) was accomplished in this ex vivo setting. CONCLUSIONS: Mussel glue appears to efficiently seal membrane defects under well-standardized ex vivo conditions. As repaired membranes resist pressures measured in amniotic cavities, mussel glue might represent a novel sealing method for iatrogenic membrane defects.