In vitro sealing of punctured fetal membranes: potential treatment for midtrimester premature rupture of membranes

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...

The Future of Fetal Surgery

The field of fetal medicine has evolved significantly over the past several decades. Our ability to identify and treat the unborn patient has been shaped by advancements in imaging technology, genetic diagnosis, an improved understanding of fetal physiology, and the development and optimization of in utero surgical techniques. The future of the field will be shaped by medical innovators pushing for the continued refinement of minimally invasive surgical technique, the application of pioneering technologies such as robotic surgery and in utero stem cell and gene therapies, and the development of innovative ex utero fetal support systems.

Why Do the Fetal Membranes Rupture Early after Fetoscopy? A Review

Iatrogenic preterm premature rupture of the fetal membranes (iPPROM) remains the Achilles' heel of keyhole fetal surgery (fetoscopy) despite significant efforts in preclinical models to develop new therapies. This limited success is partially due to incomplete understanding why the fetal membranes rupture early after fetoscopy and notable differences in membrane physiology between humans and domestic species. In this review, we summarize aspects of fetoscopy that may contribute to iPPROM, the previous efforts to develop new therapies, and limitations of preclinical models commonly used in fetal membrane research.

Application of Tissue Engineering and Regenerative Medicine in Prelabor Rupture of Membranes: a Review of the Current Evidence

Preterm prelabor rupture of membranes (PPROM) is the main cause of preterm delivery, resulting in increased perinatal morbidity and mortality. Several techniques have been studied for the healing of ruptured membranes, with some success. Before new techniques using tissue/organ engineering are applied in clinical practice, these techniques must be validated in clinical trials. To address this issue, the objective of this study was to summarize the current literature on interventions to seal or heal the amniotic membranes after PPROM. An electronic search was conducted using the keywords "fetal membranes," "premature rupture," "amnion," "tissue engineering," "fibrin tissue adhesive," "regenerative medicine," "tissue adhesive," "wound healing," and "fetoscopy" through the MEDLINE, Embase, and Cochrane CENTRAL databases, with the limitation of English-language studies. Through a review of the identified studies, it was found that spontaneous healing of the fetal membrane has not been successful. Several efforts have been made to seal membranes before or after rupture using different methods, including amniopatches, collagen, tissue patches, fibrin sealant, mussel-mimetic sealant, engineered cell matrix, and immunological supplements. However, most studies have been conducted in ex vivo or in vivo settings, so the safety and applicability of these techniques to spontaneous rupture of membranes in clinical settings have not been sufficiently tested. Overall, the current evidence is limited regarding the safety and effectiveness of interventions against PPROM.

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.

Cryopreserved human amniotic membrane and a bioinspired underwater adhesive to seal and promote healing of iatrogenic fetal membrane defect sites

INTRODUCTION

We investigated the ability of cryopreserved human amniotic membrane (hAM) scaffold sealed with an underwater adhesive, bio-inspired by marine sandcastle worms to promote healing of iatrogenic fetal membrane defects in a pregnant swine model.

METHODS

Twelve Yucatan miniature pigs underwent laparotomy under general anesthesia at 70 days gestation (term = 114 days). The gestational sacs were assigned to uninstrumented (n = 24) and instrumented with 12 Fr trocar, which was further randomized into four different arms-no hAM patch, (n = 22), hAM patch secured with suture (n = 16), hAM patch with no suture (n = 14), and hAM patch secured with adhesive (n = 9). The animals were euthanized 20 days after the procedure. Gross and histological examination of the entry site was performed for fetal membrane healing.

RESULTS

There were no differences in fetal survival, amniotic fluid levels, or dye-leakage from the amniotic cavity between the groups. The fetal membranes spontaneously healed in instrumented sacs without hAM patches. In sacs with hAM patches secured with sutures, the patch was incorporated into the swine fetal membranes. In sacs with hAM patches without sutures, 100% of the patches were displaced from the defect site, whereas in sacs with hAM patches secured with adhesive 55% of the patches remained in place and showed complete healing (p = 0.04).

DISCUSSION

In contrast to humans, swine fetal membranes heal spontaneously after an iatrogenic injury and thus not an adequate model. hAM patches became incorporated into the defect site by cellular ingrowth from the fetal membranes. The bioinspired adhesive adhered the hAM patches within the defect site.

In vitro sealing of iatrogenic fetal membrane defects by a collagen plug imbued with fibrinogen and plasma

OBJECTIVES

We aimed to demonstrate local thrombin generation by fetal membranes, as well as its ability to generate fibrin from fibrinogen concentrate. Furthermore, we aimed to investigate the efficacy of collagen plugs, soaked with plasma and fibrinogen, to seal iatrogenic fetal membrane defects.

METHODS

Thrombin generation by homogenized fetal membranes was measured by calibrated automated thrombography. To identify the coagulation caused by an iatrogenic membrane defect, we analyzed fibrin formation by optical densitometry, upon various concentrations of fibrinogen. The ability of a collagen plug soaked with fibrinogen and plasma was tested in an ex vivo model for its ability to seal an iatrogenic fetal membrane defect.

RESULTS

Fetal membrane homogenates potently induced thrombin generation in amniotic fluid and diluted plasma. Upon the addition of fibrinogen concentrate, potent fibrin formation was triggered. Measured by densiometry, fibrin formation was optimal at 1250 µg/mL fibrinogen in combination with 4% plasma. A collagen plug soaked with fibrinogen and plasma sealed an iatrogenic membrane defect about 35% better than collagen plugs without these additives (P = 0.037).

CONCLUSIONS

These in vitro experiments suggest that the addition of fibrinogen and plasma may enhance the sealing efficacy of collagen plugs in closing iatrogenic fetal membrane defects.

Fetal membrane patch and biomimetic adhesive coacervates as a sealant for fetoscopic defects

Iatrogenic preterm premature rupture of membranes after fetoscopic procedures affects 10-47% of patients, secondary to the non-healing nature of membranes and the separation of layers during the entry. In this study we developed an in vitro model to mimic the uterine wall-fetal membrane interface using a water column with one end sealed with human fetal membranes and poultry breast, and a defect was created with an 11 French trocar. Further, a fetal membrane patch in conjunction with multiphase adhesive coacervates modeled after the sandcastle worm bioadhesive was tested for sealing of an iatrogenic defect. The sealant withstood an additional traction of 12 g for 30-60 min and turbulence of the water column without leakage of fluid or slippage. The adhesive is non-toxic when in direct contact with human fetal membranes in an organ culture setting. A fetal membrane patch with multiphase adhesive complex coacervates may help to seal the defect and prevent iatrogenic preterm premature rupture of the membranes.

Management of oligohydramnios in pregnancy

The finding of oligohydramnios in pregnancy is problematic. The various mechanisms that control amniotic fluid, the inability to precisely measure and quantify the amount, and the relevance of a "decreased" amount of fluid make the management of this finding unclear. Given the limited amount of data, the single deepest vertical pocket may be a better method than the amniotic fluid index to define oligohydramnios. A large prospective study is needed to develop the most optimal management recommendations, especially for idiopathic oligohydramnios at or near term.

Amniopatch for iatrogenic rupture of the fetal membranes

With the increased use of invasive fetal procedures, the number of women facing post-procedure membrane rupture is increasing. Here we review the use of platelets and fresh frozen plasma for sealing iatrogenic fetal membrane defects by describing the mechanisms of action of the amniopatch procedure as well as published experience. In cases of iatrogenic preterm pre-labour rupture of the membranes, amniopatch effectively seals the fetal membranes in over two-thirds of cases. There is a risk of 16% of in utero fetal death, which may occur at varying intervals from the procedure and often for unknown reasons. Amniopatch has also been used as a treatment of chorionic membrane separation. In summary, current experience suggests that in cases of early onset but persistent amniotic fluid leakage following an invasive fetal procedure, amniopatch is an option.

Precipitated egg white as a sealant for iatrogenic preterm premature rupture of the membranes

OBJECTIVE

The objective of the study was to investigate whether precipitated egg white could be used as a sealant for iatrogenic injury to fetal membranes.

STUDY DESIGN

Membranes were collected, washed, and affixed to the bottom of glass cylinders filled with second-trimester amniotic fluid. An iatrogenic defect with an 8-gauge needle was created in the test column, and precipitated egg white was added. Fluid levels in test and control columns were compared over a 14 day period. The amount of fluid added to columns was compared using the Wilcoxon rank sum test; P < .05 was considered significant.

RESULTS

Test columns (20/21) maintained seal integrity for 14 days and required less amniotic fluid to be added as compared with controls: median: 55.1 mL (range, 20-137 mL) vs 61.6 mL (range, 22-159 mL), respectively (P < .01).

CONCLUSION

Precipitated egg white has the potential to seal iatrogenic membrane defects for up to 14 days' duration.

Injectable candidate sealants for fetal membrane repair: bonding and toxicity in vitro

OBJECTIVE

This study was undertaken to test injectable surgical sealants that are biocompatible with fetal membranes and that are to be used eventually for the closure of iatrogenic membrane defects.

STUDY DESIGN

Dermabond (Ethicon Inc, Norderstedt, Germany), Histoacryl (B. Braun GmbH, Tuttlingen, Germany), and Tissucol (Baxter AG, Volketwil, Switzerland) fibrin glue, and 3 types of in situ forming poly(ethylene glycol)-based polymer hydrogels were tested for acute toxicity on direct contact with fetal membranes for 24 hours. For the determination of elution toxicity, extracts of sealants were incubated on amnion cell cultures for 72 hours. Bonding and toxicity was assessed through morphologic and/or biochemical analysis.

RESULTS

Extracts of all adhesives were nontoxic for cultured cells. However, only Tissucol and 1 type of poly(ethylene glycol)-based hydrogel, which is a mussel-mimetic tissue adhesive, showed efficient, nondisruptive, nontoxic bonding to fetal membranes. Mussel-mimetic tissue adhesive that was applied over membrane defects that were created with a 3.5-mm trocar accomplished leak-proof closure that withstood membrane stretch in an in vitro model.

CONCLUSION

A synthetic hydrogel-type tissue adhesive that merits further evaluation in vivo emerged as a potential sealing modality for iatrogenic membrane defects.

The management of preterm premature rupture of the membranes near the limit of fetal viability

Preterm premature rupture of the membranes near the limit of fetal viability is an uncommon complication of pregnancy, affecting approximately 4 in 1000 gravidas. However, maternal, fetal, and neonatal complications resulting from this condition are significant and include chorioamnionitis, pulmonary hypoplasia, restriction deformities, fetal loss, and complications of extreme prematurity among surviving infants. In this article, we review the literature regarding pregnancy outcomes after preterm premature rupture of the membranes near the limit of viability, and the data on traditional and nontraditional interventions to improve outcomes. An approach to patients who present with preterm premature rupture of the membranes near the limit of viability will be proposed.

In vitro evaluation of the ability of platelet-rich plasma to seal an iatrogenic fetal membrane defect

OBJECTIVES

The purpose of the study is to evaluate the ability of platelet-rich plasma (PRP) to seal an iatrogenic fetal membrane defect.

METHODS

First, we evaluated the stability of a PRP plug in an amniotic fluid environment. Further, we evaluated the sealing capability of PRP plugs in an in vitro model that mimics a fetoscopic membrane defect. Finally, we examined its influence on membrane repair and cell proliferation in monolayer cell cultures and amnion-chorion tissue explants.

RESULTS

PRP plugs persisted in an amniotic fluid for a median time of 7 weeks. PRP plugs also provided waterproof sealing of a fetoscopic membrane defect. Finally, PRP stimulated cell proliferation in a monolayer cell culture and provided a good matrix for cell proliferation and migration in amnion-chorion tissue explants.

CONCLUSION

Our in vitro experiments suggest that PRP plugs may provide a long-lasting, waterproof sealing of fetal membrane defects and stimulate fetal membrane repair.

Presealing of the chorioamniotic membranes prior to fetoscopic surgery: preliminary study with unfertilized chicken egg models

BACKGROUND

Fetoscopic surgical techniques continue to develop. However, progress has been hindered by premature rupture of membranes (PROM), which complicates 5-30% of fetoscopic procedures. Several membrane closure techniques have been devised but none proven reliable.

OBJECTIVE

We propose a new approach that of presealing the chorioamniotic membrane prior to membrane disruption-a so called Amnioseal. A set of pilot experiments were designed using unfertilized chicken egg models to test our proposal.

STUDY DESIGN

Two novel unfertilized chicken egg models were developed. Model 1 simulated the chorioamniotic membrane and amniotic cavity. Model 2 simulated the uterine muscle/chorioamniotic membrane interface and amniotic cavity. Four sealants (100% petroleum jelly, FloSeal Hemostatic Matrix, CoSeal Hemostatic Matrix and BioGlue Surgical Adhesive) were tested against untreated controls. The sealants were applied directly to the egg membranes followed by biopsy needle puncture and needle membrane manipulation.

RESULTS

BioGlue adhered strongly to the membrane correlating with the smallest defect size, greatest resistance to rupture, lowest degree of leakage and formed a water tight seal around the needle during membrane manipulation. In comparison, the weak adherence of FloSeal correlated with a larger defect size and higher degree of leakage. 100% petroleum jelly was non-adhesive, provided no membrane support and resulted in membrane rupture.

CONCLUSION

Adhesive sealants confer mechanical support to the membrane and form a water tight seal. Experiments show that Sealant properties greatly affect outcomes. As such the Amnioseal's success will be determined by the properties of the sealant used. Specifically designed sealants are being developed along side a delivery device and will be tested using an in vitro human chorioamniotic membrane model.

Fetal membrane healing after spontaneous and iatrogenic membrane rupture: a review of current evidence

In view of the important protective role of the fetal membranes, wound sealing, tissue regeneration, or wound healing could be life saving in cases of preterm premature rupture of the membranes. Although many investigators are studying the causes of preterm premature rupture of membranes, the emphasis has not been on the wound healing capacity of the fetal membranes. In this review, the relevant literature on the pathophysiologic condition that leads to preterm premature rupture of membranes will be summarized to emphasize a continuum of events between rupture and repair. We will present the current knowledge on fetal membrane wound healing and discuss the clinical implications of these findings. We will critically discuss recent experimental interventions in women to seal or heal the fetal membranes after preterm premature rupture of membranes.

Premature rupture of membranes at 20 weeks: report of a successful outcome after transcervical application of fibrin glue

A 30-year-old primigravida was admitted to hospital at 20 weeks of gestation because of premature rupture of membranes and oligohydramnios. The patient was maintained in bed rest and given intravenous ampicillin. Forty-eight hours later, after documenting the absence of infection and maintenance of the oligohydramnios, fibrin glue was applied transcervically under ultrasound control. There was subjective improvement in amniotic fluid volume after treatment, but always within the criteria of oligohydramnios. Fibrin glue application was repeated twice due to reported increase in fluid loss and diminished amniotic fluid volume on ultrasound. Amoxicillin per os was started at 23 weeks, and clavulanic acid was added at 26 weeks due to the isolation of an Escherichia coli on cervical-vaginal cultures. No signs of infection ensued until 34 weeks, when an axillary temperature of 39.5 degrees C was detected together with a non-reassuring cardiotocographic pattern, the latter leading to the performance of an urgent cesarean section. The newborn had an Apgar score of 9/10/10, umbilical artery pH of 7.32, and no external deformities. He showed no signs of lung hypoplasia and required no oxygen supplementation. Oropharyngeal and blood cultures revealed an E. coli infection and antibiotic treatment was started. No further complications occurred and he was discharged home on the 8th day of life. At 12 months, the child reveals a normal development. The mother had a mild and short-lasting wound infection and was discharged on the 8th postoperative day.

Port insertion and removal techniques to minimize premature rupture of the membranes in endoscopic fetal surgery

BACKGROUND

Premature rupture of membranes (PROM) remains a significant complication of fetal surgery. Rates of 40% to 100% have been reported after both open and endoscopic fetal surgery. We describe a technique of endoscopic port insertion and removal that minimizes trauma to the membranes.

METHODS

Twenty-seven consecutive patients undergoing endoscopic laser ablation for twin-to-twin transfusion syndrome were reviewed. In each case, a minilaparotomy was performed, and the amniotic cavity was entered under direct vision of the uterus using a Seldinger technique. The entry site was carefully dilated to accommodate a 4.0-mm-diameter cannula. A gelatin sponge plug was placed at port removal. Postoperative management and outcome were evaluated.

RESULTS

Median gestational age at operation was 21.3 weeks. Median operating time was 60 minutes. One patient delivered intraoperatively because of fetal distress. Seventeen (65.4%) patients required postoperative tocolysis (median duration, 12 hours). Median postoperative gestation was 6.5 weeks (range, 1-20 weeks). Only 1 (4.2%) of 24 patients with successful gelatin sponge placement developed PROM.

CONCLUSIONS

Meticulous technique and atraumatic insertion and removal of ports help minimize the risk of postoperative amniotic leak after endoscopic fetal surgery. Our PROM rate of 4.2% contrasts sharply with previously reported rates after similar operations.

Pre-emptive placement of a presealant for amniotic access

OBJECTIVE

Amniotic access for fetal diagnosis and therapy can lead to membrane leaks, separation, and preterm premature rupture of membranes. Morbidity limits the beneficial effects of fetal intervention. We propose to examine a novel preventive "presealant" membrane puncture technique and evaluate it in vitro.

STUDY DESIGN

Fetal membranes from normal term deliveries were fastened to a pressure controlled pump and punctured after presealant placement. Distinct bioadhesives were then compared for sealing efficacy by the measurement of leak pressures. Membranes were also evaluated for changes in tensile rupture strength after treatment.

RESULTS

Preemptive sealing by 2 of the presealants achieved significantly higher leak pressures compared with control membranes (85 and 78, respectively, vs 27 cm of water; P < .05). One of the presealants worked effectively in a membrane-sealant-membrane interface (62 vs 30 cm of water; P < .05). All treated membranes, however, demonstrated diminished tensile rupture forces compared with control membranes (124 vs 170 g/cm2; P > .05).

CONCLUSION

The application of a presealant is effective for the prevention of iatrogenic rupture in an in vitro model and may be beneficial for clinical application. Further studies with different bioadhesives are needed, given the limitations of the glues that are described in this study.

Successful patching of iatrogenic rupture of the fetal membranes

Rupture of the fetal membranes is a common, but potentially serious complication of invasive fetal procedures. Quintero described a technique to seal the fetal membrane defect by means of a bloodpatch, usually called 'amniopatch' in this application. The successful use in two consecutive patients with ruptured membranes after a fetoscopic intervention at respectively 17 and 22 weeks' gestational age is described, together with a literature review of published experience.

Recent evidence associated with the condition of preterm prelabour rupture of the membranes

PURPOSE OF REVIEW

The published literature on preterm prelabour rupture of the membranes is voluminous yet despite advances in obstetric and neonatal care, the problem remains a major cause of perinatal mortality and morbidity. The purpose of this review is to present recent evidence pertaining to the role of inflammatory mediators such as cytokines and the tissue damage and long-term handicap they cause, the molecular biology and physiology of membrane structure, the role of host susceptibility and the genetics of preterm birth and therapeutic options for the management of preterm prelabour rupture, including antibiotics, amnioinfusion and special situations.

RECENT FINDINGS

Neonatal morbidity from preterm prelabour rupture of the membranes is mainly related to oligohydramnios and pulmonary hypoplasia. Occupational factors have a significant effect on the occurrence and outcome following rupture. Matrix metalloproteinases control growth and remodelling of the pregnant uterus, placenta and membranes and are linked to a genetic predisposition to preterm birth through gene expression and variation. Transvaginal ultrasound scan, oncofetal fibronectin and the presence of abnormal genital tract flora (bacterial vaginosis) in pregnancy may help in the prediction of preterm birth.

SUMMARY

Preterm prelabour membrane rupture remains a management problem, particularly at very early gestations, yet obstetric and neonatal care can make a difference to outcome. While at early gestations the prognosis is poor, it is not hopeless. Careful selection of the recent literature on the subject might interest and inform those faced regularly with the problem, prevent therapeutic nihilism, promote confidence in our ability to make a difference and realise that we are not alone when faced with the therapeutic dilemma that is this condition.