Connexin 43 is overexpressed in human fetal membrane defects after fetoscopic surgery

Comparison of Amnio-Exchange With a Novel Synthetic Amniotic Fluid Versus Commercially Used Fluids for Fetal Therapy: An In Vivo Rodent Model

OBJECTIVE

Normal Saline (NS) and Lactated Ringer's (LR) damage human amniotic epithelium in vitro when compared with a synthetic amniotic fluid (Amnio-well, AW). We sought to evaluate the effect of amnio-exchange with NS, LR, and AW in vivo.

METHODS

On day E17.5, pregnant rats underwent amnio-exchange with NS, LR, or AW. Fetuses in each pregnant rat that did not undergo amnio-exchange acted as controls. Amnions were harvested at E20.5 and ultrastructure evaluated via electron microscopy. Protein levels of cleaved matrix metalloproteinase 9 (MMP9) and collagen 1 (Col1a) were evaluated via Western Blot. Connexin-43 expression was evaluated via immunofluorescence (IF).

RESULTS

There was an increase in amnion microfractures and epithelial cellular shrinkage with NS and LR compared with control and AW. The cleaved MMP9/Col1 ratio was increased 3.9-fold in NS (p < 0.001) and 4.5-fold LR (p = 0.0201) relative to control, whereas AW expression was similar to control (p = 0.636). Connexin-43 was also increased on IF in NS and LR relative to AW (mean gray intensity 26.5 ± 4.5, 26.5 ± 6.7, 19.2 ± 3.4, p < 0.001).

CONCLUSION

Amnio-exchange with NS and LR led to increased amniotic microfractures and collagen degradation compared with synthetic amniotic fluid. Larger models are warranted to validate or refute these findings.

Miniaturized bioengineered models for preterm fetal membrane healing

INTRODUCTION

The reason for the absence of fetal membrane (FM) healing after a fetoscopic intervention is not known. We hypothesize that the lack of robust miniaturized models to study preterm FM functions is currently hampering the development of new treatments for FM healing. Specifically, miniaturized models to study preterm FM healing with minimal amounts of tissue are currently lacking.

METHODS

In this study, we collected FMs from planned cesarean deliveries and developed different ex vivo models with an engineered biomaterial to study FM healing. Then, the effect of PDGF-BB on the migration of cells from preterm and term FMs was evaluated.

RESULTS

FMs could be viably cultured ex vivo for 14 days. In a model of punctured FMs, migration of cells into FM defects was less pronounced than migration out of the tissue into the biomaterial. In a miniaturized model of preterm cell migration, PDGF-BB promoted migration of preterm amnion cells into the biomaterial.

DISCUSSION AND CONCLUSION

By using a novel miniaturized model of preterm tissue, we here successfully demonstrate that PDGF-BB can promote preterm FM cell migration of microtissues encapsulated in a three-dimensional environment.

Biomaterial-based treatments for the prevention of preterm birth after iatrogenic rupture of the fetal membranes

Minimally invasive interventions to ameliorate or correct fetal abnormalities are becoming a clinical reality. However, the iatrogenic premature preterm rupture of the fetal membranes (FMs) (iPPROM), which may result in...

Perinatal Outcomes after Fetal Endoscopic Tracheal Occlusion for Isolated Congenital Diaphragmatic Hernia: Rapid Review

OBJECTIVE

 To compare the perinatal outcomes of fetuses with isolated congenital diaphragmatic hernia after fetal endoscopic tracheal occlusion (FETO) and antenatal expectant management.

DATA SOURCES

 In this rapid review, searches were conducted in the MEDLINE, PMC, EMBASE and CENTRAL databases between August 10th and September 4th, 2020. Randomized controlled trials (RCTs), quasi-RCTs or cluster-RCTs published in English in the past ten years were included.

STUDY SELECTION

 We retrieved 203 publications; 180 studies were screened by abstract. Full-text selection was performed for eight studies, and 1 single center RCT met the inclusion criteria (41 randomized women; 20 in the FETO group, and 21 in the control group).

DATA COLLECTION

 Data collection was performed independently, by both authors, in two steps (title and abstract and full-text reading).

DATA SYNTHESIS

 There were no cases of maternal mortality. The mean gestational age at delivery was of 35.6 ±  2.4 weeks in the intervention group, and of 37.4 ±  1.9 weeks among the controls (p < 0.01). Survival until 6 months of age was reported in 50% of the intervention group, and in 5.8% of the controls (p < 0.01; relative risk: 10.5; 95% confidence interval [95%CI]: 1.5-74.7). Severe postnatal pulmonary hypertension was found in 50% of the infants in the intervention group, and in 85.7% of controls (p = 0.02; relative risk: 0.6; 95%CI: 0.4-0.9). An analysis of the study indicated some concerns of risk of bias. The quality of evidence was considered moderate to low.

CONCLUSION

 Current evidence is limited but suggests that FETO may be an effective intervention to improve perinatal outcomes.

Comprehensive quantitative characterization of the human term amnion proteome

•

We report an unprecedented quantitative high coverage of the human amnion proteome.

•

We identified novel proteins that hold great promise for understanding fetal membrane biology.

•

Together, this comprehensive proteome provides a basis for the evaluation of pre-term or diseased fetal membranes.

The loss of fetal membrane (FM) integrity and function at an early time point during pregnancy can have devastating consequences for the fetus and the newborn. However, biomaterials for preventive sealing and healing of FMs are currently non-existing, which can be partly attributed to the current fragmentary knowledge of FM biology. Despite recent advances in proteomics analysis, a robust and comprehensive description of the amnion proteome is currently lacking. Here, by an optimized protein sample preparation and offline fractionation before liquid chromatography coupled to mass spectrometry (LC-MS) analysis, we present a characterization of the healthy human term amnion proteome, which covers more than 40% of the previously reported transcripts in similar RNA sequencing datasets and, with more than 5000 identifications, greatly outnumbers previous reports. Together, beyond providing a basis for the study of compromised and preterm ruptured FMs, this comprehensive human amnion proteome is a stepping-stone for the development of novel healing-inducing biomaterials. The proteomic dataset has been deposited in the ProteomeXchange Consortium with the identifier PXD019410.

Histological response and expression of collagen, metalloproteinases MMP-1 and MMP-9 and tissue inhibitors of metalloproteinases TIMP-1 and TIMP-2 in fetal membranes following open intrauterine surgery: an experimental study

Objective: To characterize aspects of the repair process by evaluating the tissue collagen density, metalloproteinases and tissue inhibitor of matrix metalloproteinases in the fetal membranes following open fetal surgery for myelomeningocele (MMC).Design: Experimental.Setting: Two Brazilian hospitals in 2013-2014.Population: 30 fetal membranes collected after elective cesarean deliveries, in patients who underwent open fetal surgery for MMC intrauterine repair.Methods: Regions within and surrounding the scar area and regions distant from the surgical site were evaluated for collagen concentration and expression of MMP-1, MMP-9, TIMP-1 and TIMP-2.Results: Collagen was increased in regions of scar formation (14.4 ± 2.7%) as compared to unaffected regions (8.0 ± 1.9%) (p < .001). The mean score of MMP-9 in the area of both the scar and suture was also increased above that observed in normal regions (p < .05). Conversely, MMP-1 was reduced in the scar when compared to the normal region and the area adjacent to the scar (suture region) (p < .05). TIMP-1 was increased in the suture region compared to the normal region (p < .05) while TIMP-2 was reduced in the scar region when compared to the other two regions (p < .05). The membrane repair process was also influenced by the number of previous pregnancies and gestational age at the time of surgery.Conclusion: Reparative activity of the fetal membrane after open fetal surgery involves up-regulation of collagen production and differential involvement of MMPs and TIMPs.

Amniotic membrane and placental histopathological findings after open and fetoscopic prenatal neural tube defect repair

OBJECTIVES

To describe and compare placental and amniotic histology in women who underwent a fetoscopic myelomeningocele repair to those who underwent an open hysterotomy myelomeningocele repair. Also, we intended to compare findings from both prenatal repair groups to age-matched control pregnant patients.

METHODS

Placental and membrane histopathology from 43 prenatally repaired spina bifida cases (17 fetoscopic and 26 open) and 18 healthy controls were retrospectively assessed. Quantitative assessment of histopathology included apoptosis count and maternal and fetal underperfusion scores. Qualitative assessment included the detection of pigmented macrophages and/or signs of placental/amniotic inflammation. Associations between the duration of surgery or the duration of CO₂ insufflation and quantitative histological parameters were tested.

RESULTS

Fetoscopic surgery cases did not show significant differences in any of the studied parameters when compared against controls. No differences were detected either when compared with open repaired cases, except for lower proportion of pigmented laden macrophages in the fetoscopic group (11.8% vs 61.5%, P < 0.01). No associations between the duration of surgery or the duration of CO₂ exposure and any of the quantitative histological parameters were detected.

CONCLUSIONS

These preliminary results support the lack of detrimental effects of the use of heated and humidified CO₂ gas for uterine insufflation to fetal membranes and placenta.

Tissuepatch is biocompatible and seals iatrogenic membrane defects in a rabbit model

OBJECTIVE

To evaluate novel sealing techniques for their biocompatibility and sealing capacity of iatrogenic fetal membrane defects in a pregnant rabbit model.

METHOD

At day 23 of gestation (term = d31), a standardized fetoscopy was performed through a 14G cannula. The resulting fetal membrane defect was closed with condensed collagen, collagen with fibrinogen, Tissuepatch, Duraseal, or a conventional collagen plug (Lyostypt) as reference. At d30, the fetuses were harvested and full thickness fetal membrane samples were analyzed. The study consisted of 2 consecutive parts: (1) biocompatibility testing by fetal survival, apoptosis, and infiltration of polymorphonuclear cells in the membranes and (2) the efficacy to seal fetal membrane defects.

RESULTS

Three sealants (collagen with fibrinogen, Duraseal, or Lyostypt) were associated with a higher fetal mortality compared to control unmanipulated littermates and hence were excluded from further analysis. Tissuepatch was biocompatible, and amniotic fluid levels were comparable to those of control untouched littermates. Compared to the condensed collagen, Tissuepatch was also easier in surgical handling and induced limited cell proliferation.

CONCLUSION

Tissuepatch had the best biocompatibility and efficacy in sealing an iatrogenic fetal membrane defect in the pregnant rabbit compared to other readily available sealants.

Trauma induces overexpression of Cx43 in human fetal membrane defects

Objective

We developed an in vitro model to examine whether trauma induces connexin 43 (Cx43) expression and collagen organisation in the amniotic membrane (AM) of fetal membrane (FM) defects.

Method

Term human FM was traumatised in vitro. Cell morphology and Cx43 were examined in the wound edge AM by immunofluorescence (IMF) confocal microscopy and compared to control AM. Collagen microstructure was examined by second harmonic generation (SHG) imaging. Cell viability was assessed with calcein and ethidium staining.

Results

After trauma, the AM showed a dense region of cells, which had migrated towards the wound edge. In wound edge AM, Cx43 puncta was preferentially distributed in mesenchymal cells compared to epithelial cells with significant expression in the fibroblast layer than epithelial layer (p < 0.001). In the fibroblast layer, the collagen fibres were highly polarised and aligned in parallel to the axis of the wound edge AM. There was an absence of cell migration across the defect with no healing after 168 h. Cell viability of the FM after trauma was maintained during culture.

Conclusion

Cx43 overexpression in wounded AM drives structural changes in collagen that slows down efficacy of cell migration across the FM defect. © 2017 The Authors. Prenatal Diagnosis published by John Wiley & Sons, Ltd.

What's already known about this topic?

After fetal surgery, the human fetal membrane shows limited healing and overexpression of Cx43 at the wound edge.

Cx43 knockdown leads to accelerated wound healing by influencing cell migration and tissue dynamics.

What does this study add?

We developed an artificial fetal membrane model to examine Cx43 expression after trauma and changes in collagen dynamics.

We observed Cx43 overexpression and polarised collagen at the wound edge. These changes were found to be similar to human fetoscopic wounds after fetal surgery.

Connexin 43 is overexpressed in human fetal membrane defects after fetoscopic surgery

OBJECTIVE

We examined whether surgically induced membrane defects elevate connexin 43 (Cx43) expression in the wound edge of the amniotic membrane (AM) and drives structural changes in collagen that affects healing after fetoscopic surgery.

METHOD

Cell morphology and collagen microstructure was investigated by scanning electron microscopy and second harmonic generation in fetal membranes taken from women who underwent fetal surgery. Immunofluoresence and real-time quantitative polymerase chain reaction was used to examine Cx43 expression in control and wound edge AM.

RESULTS

Scanning electron microscopy showed dense, helical patterns of collagen fibrils in the wound edge of the fetal membrane. This arrangement changed in the fibroblast layer with evidence of collagen fibrils that were highly polarised along the wound edge but not in control membranes. Cx43 was increased by 112.9% in wound edge AM compared with controls (p < 0.001), with preferential distribution in the fibroblast layer compared with the epithelial layer (p < 0.01). In wound edge AM, mesenchymal cells had a flattened morphology, and there was evidence of poor epithelial migration across the defect. Cx43 and COX-2 expression was significantly increased in wound edge AM compared with controls (p < 0.001).

CONCLUSION

Overexpression of Cx43 in the AM after fetal surgery induces morphological and structural changes in the collagenous matrix that may interfere with normal healing mechanisms. © 2016 The Authors. Prenatal Diagnosis published by John Wiley & Sons, Ltd.