Potential sealing and repair of human FM defects after trauma with peptide amphiphiles and Cx43 antisense.

OBJECTIVE: We examined whether peptide amphiphiles functionalised with adhesive, migratory or regenerative sequences could be combined with amniotic fluid (AF) to form plugs that repair fetal membrane (FM) defects after trauma and co-culture with connexin 43 (Cx43) antisense. METHODS: We assessed interactions between peptide amphiphiles and AF and examined the plugs in FM defects after trauma and co-culture with the Cx43antisense. RESULTS: Confocal microscopy confirmed directed self-assembly of peptide amphiphiles with AF to form a plug within minutes, with good mechanical properties. SEM of the plug revealed a multi-layered, nanofibrous network that sealed the FM defect after trauma. Co-culture of the FM defect with Cx43 antisense and plug increased collagen levels but reduced GAG. Culture of the FM defect with peptide amphiphiles incorporating regenerative sequences for 5 days, increased F-actin and nuclear cell contraction, migration and polarization of collagen fibers across the FM defect when compared to control specimens with minimal repair. CONCLUSIONS: Whilst the nanoarchitecture revealed promising conditions to seal iatrogenic FM defects, the peptide amphiphiles need to be designed to maximize repair mechanisms and promote structural compliance with high mechanical tolerance that maintains tissue remodeling with Cx43 antisense for future treatment.

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.

Oxidative stress damage-associated molecular signaling pathways differentiate spontaneous preterm birth and preterm premature rupture of the membranes.

STUDY HYPOTHESIS: In women with preterm premature rupture of the membranes (PPROM), increased oxidative stress may accelerate premature cellular senescence, senescence-associated inflammation and proteolysis, which may predispose them to rupture. STUDY FINDING: We demonstrate mechanistic differences between preterm birth (PTB) and PPROM by revealing differences in fetal membrane redox status, oxidative stress-induced damage, distinct signaling pathways and senescence activation. WHAT IS KNOWN ALREADY: Oxidative stress-associated fetal membrane damage and cell cycle arrest determine adverse pregnancy outcomes, such as spontaneous PTB and PPROM. STUDY DESIGN, SAMPLES/MATERIALS, METHODS: Fetal membranes and amniotic fluid samples were collected from women with PTB and PPROM. Molecular, biochemical and histologic markers were used to document differences in oxidative stress and antioxidant enzyme status, DNA damage, secondary signaling activation by Ras-GTPase and mitogen-activated protein kinases, and activation of senescence between membranes from the two groups. MAIN RESULTS AND THE ROLE OF CHANCE: Oxidative stress was higher and antioxidant enzymes were lower in PPROM compared with PTB. PTB membranes had minimal DNA damage and showed activation of Ras-GTPase and ERK/JNK signaling pathway with minimal signs of senescence. PPROM had higher numbers of cells with DNA damage, prosenescence stress kinase (p38 MAPK) activation and signs of senescence. LIMITATIONS, REASONS FOR CAUTION: Samples were obtained retrospectively after delivery. The markers of senescence that we tested are specific but are not sufficient to confirm senescence as the pathology in PPROM. WIDER IMPLICATIONS OF THE FINDINGS: Oxidative stress-induced DNA damage and senescence are characteristics of fetal membranes from PPROM, compared with PTB with intact membranes. PTB and PPROM arise from distinct pathophysiologic pathways. Oxidative stress and oxidative stress-induced cellular damages are likely determinants of the mechanistic signaling pathways and phenotypic outcome. STUDY FUNDING AND COMPETING INTERESTS: This study is supported by developmental funds to Dr R. Menon from the Department of Obstetrics and Gynecology at The University of Texas Medical Branch at Galveston and funds to Dr M. Kacerovský from the Ministry of Health Czech Republic (UHHK, 001799906). The authors report no conflict of interest.

About puncture testing applied for mechanical characterization of fetal membranes.

Puncture testing has been applied in several studies for the mechanical characterization of human fetal membrane (FM) tissue, and significant knowledge has been gained from these investigations. When comparing results of mechanical testing (puncture, inflation, and uniaxial tension), we have observed discrepancies in the rupture sequence of FM tissue and significant differences in the deformation behavior. This study was undertaken to clarify these discrepancies. Puncture experiments on FM samples were performed to reproduce previous findings, and numerical simulations were carried out to rationalize particular aspects of membrane failure. The results demonstrate that both rupture sequence and resistance to deformation depend on the samples' fixation. Soft fixation leads to slippage in the clamping, which reduces mechanical loading of the amnion layer and results in chorion rupturing first. Conversely, the stiffer, stronger, and less extensible amnion layer fails first if tight fixation is used. The results provide a novel insight into the interpretation of ex vivo testing as well as in vivo membrane rupture.

Iatrogenic perforation of intertwin membrane after laser surgery for twin-to-twin transfusion syndrome.

OBJECTIVE: To evaluate management and outcome of iatrogenic monoamniotic twins (iMAT) compared with twins with intact intertwin dividing membranes after laser surgery for twin-to-twin transfusion syndrome (TTTS). METHODS: This was a retrospective analysis of twins with and without iatrogenic rupture of the intertwin membranes that had been treated for TTTS with laser surgery at our center between 2004 and 2012. Primary outcomes were perinatal survival and severe neonatal morbidity. Secondary outcomes were mode of delivery, gestational age at birth and cord entanglement. RESULTS: In total, 338 pregnancies were included. In 67/338 (20%) pregnancies, iMAT was suspected antenatally. In 47 of these 67 (70%), a preterm Cesarean section was performed for monoamnionicity. Perinatal survival was 108/134 (81%) vs 396/542 (73%) in twins with intact intertwin membranes (P = 0.13). Mean gestational age at birth in iMAT was 31 completed weeks, compared to 33 weeks in twins with intact membranes (P < 0.01). At birth, cord entanglement was present in 8/67 (12%) iMAT pregnancies. Severe neonatal morbidity was assessed in 106/110 (96%) in iMAT cases and 392/416 (94%) in controls. The incidence of severe neonatal morbidity was 28/106 (26%) in iMAT vs 72/392 (18%) in controls (P = 0.25). Severe cerebral injury was significantly increased in the iMAT group as compared with controls, at 16/106 (15%) vs 18/392 (5%) (P < 0.01). CONCLUSIONS: Iatrogenic rupture of intertwin membranes was suspected in 20% of pregnancies treated with laser therapy for TTTS and was associated with a lower gestational age at birth and increased neonatal morbidity.

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.

Manual rupture versus transvaginal ultrasound-guided aspiration of allanto-amniotic fluid in multiple pregnancies: a clinical approach to embryo reduction in dairy cattle.

To avoid the problems associated with twinning in dairy cattle, one of the embryos may be eliminated. This study compares the effect on pregnancy maintenance of two embryo reduction techniques, manual rupture (MR) and transvaginal ultrasound-guided aspiration (TUGA) of allanto-amniotic fluid, in Holstein-Friesian cows with multiple pregnancies. In the first experiment, 61 lactating cows bearing unilateral twins (n=27), bilateral twins (n=30) or triplets/quadruplets (n=4) were subjected to MR (n=45) or TUGA using a 17-G neddle (n=16) on day 28-34 of gestation. In 21 and 10 cows undergoing MR and TUGA embryo reduction, respectively, pregnancy loss occurred before day 90 (46.7 vs. 62.5%, P= 0.28). Through binary logistic regression, the type of pregnancy was identified as the only variable significantly affecting pregnancy maintenance (P=0.03). Based on the odds ratio, the risk of pregnancy loss was 4.1 times higher for unilateral twins than for bilateral twins (70.4 vs. 36.7%, respectively, P=0.01). No effect was detected on pregnancy maintenance of the technique used (P=0.17) or of the interaction technique by type of pregnancy (P=0.22). In the second experiment, a 22-G needle was used to perform TUGA on 22 lactating cows. The pregnancy loss rates were 44.4% (4/9), 18.2% (2/11) and 50% (1/2) for cows bearing unilateral twins, bilateral twins and triplets, respectively. The total pregnancy loss rate following TUGA using the 22-G needle tended to be lower than that using the 17-G needle (31.8 vs. 62.5%; P=0.06). Our results suggest that TUGA using a 22-G needle could be the method of choice to perform embryo reduction in cows carrying multiple pregnancies.

Gestational age-dependent repair kinetics of microsurgical defects in monolayers of human amniocytes.

OBJECTIVES: There is paucity of data on the capacity of fetal membranes to repair surgical defects following trauma. We aimed at developing an in vitro model using monolayers of human amnion epithelial cells to study fetal membrane healing. METHODS: Term (n = 6) and preterm (n = 3) fetal membranes were collected at caesarean section. The amnion was digested twice in a trypsin solution. Amniocytes were seeded (250,000-750,000/ml) and incubated at 37 degrees C and 5% CO(2) and 21 or 5% O(2). A microsurgical injury was made centrally in the monolayers and the cultures were incubated for 48 h. Every 6 h, slides were fixed and immunohistochemical staining was performed to quantify proliferation at the site of the defect and centrally in the monolayer. The closure rate was evaluated by measuring the defect size every 6 h. RESULTS: The closure rate of the defects was higher in preterm versus term cultures. Proliferation was significantly higher in the defect zone versus the peripheral zone, and also higher in the preterm group. CONCLUSION: We describe a new model for the study of fetal membrane healing and observed gestational age-dependent repair capacity of the amnion.

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.

Enrichment of collagen plugs with platelets and amniotic fluid cells increases cell proliferation in sealed iatrogenic membrane defects in the foetal rabbit model.

OBJECTIVES: The purpose of this study was to evaluate cell proliferation in platelet-enriched collagen plugs with and without addition of amniotic fluid-derived heterologous foetal cells to seal an iatrogenic membrane defect in the foetal rabbit model. METHODS: Amniotic fluid cells were harvested from three donor does at 23 days of gestation (term = 32 days) and labelled with carboxyfluorescein diacetate succinimidyl ester (CFDA-SE). In 42 other does, foetal membrane defects were induced by foetoscopic needle puncture at 23 days of gestation, and closed with either a platelet-enriched collagen plug with (n = 44) or without (n = 32) amniotic fluid cells. At 30 days of gestation, the defects were harvested and assessed microscopically. RESULTS: The plugs enriched with heterologous amniotic fluid cells more commonly had proliferating cells in the centre of the plug than those without cell addition. CFDA-SE labelling confirmed the presence of heterologous amniotic fluid cells over the entire membrane plug. Cell typing showed a mixture of fibroblasts and epithelial cells at the wound edges, whereas in the centre, there was an abundance of fibroblasts. CONCLUSION: When sealing iatrogenic membrane defects in the foetal rabbit model, enrichment of collagen plugs with platelets and amniotic fluid-derived heterologous foetal cells increases local cell proliferation.

Fetoscopic closure of punctured fetal membranes with acellular human amnion plugs in a rabbit model.

OBJECTIVE: To explore a surgical plug formed from decellularized term human amnion membrane for fetoscopic closure of iatrogenic defects in fetal membranes in a rabbit model. METHODS: The study was performed in eight rabbit does. Punctures were created at midgestational day 23 by 14-gauge needle fetoscopy on surgically exposed rabbit amniotic sacs. The entry sites were fetoscopically plugged either with decellularized term human amnion membrane (n=10) or previously successful commercial collagen matrix foil (n=10), followed by their primary fixation with fibrin glue and myometrial suturing. Seven punctured sacs without any plugging and 31 sacs without any manipulation served as two reference groups. Amniotic integrity and fetal parameters were assessed at gestational day 30. RESULTS: We established a facile method to prepare sheets of decellularized term human amnion membrane and verified its nontoxicity and cell compatibility in vitro. Decellularized term human amnion membrane sheets could be delivered precisely and controlled by fetoscopy as compact plugs into amniotic defects. The surgical handling characteristics of decellularized term human amnion membrane were better than the commercial collagen matrix foil. Treatment with human decellularized term human amnion membrane was comparable to treatment with the collagen matrix with regard to efficiency in restoring amniotic integrity. Seventy-five percent and 71.4% of amniotic sacs treated with decellularized term human amnion membrane or the commercial collagen matrix foil, respectively, showed amniotic integrity, compared with 25% in the left-open study group. Histology at the 1 week experimental endpoint showed no evidence for inflammation or beginning of anatomic healing of grafted, decellularized term human amnion membrane. CONCLUSION: Fetoscopic delivery of plugs made of decellularized term human amnion membrane presents a potentially practical surgical method to restore amniotic integrity of punctured fetal membranes. LEVEL OF EVIDENCE: III.

Enhancing sealing of fetal membrane defects using tissue engineered native amniotic scaffolds in the rabbit model.

OBJECTIVE: The purpose of this study was to compare the efficacy of native engineered amniotic scaffolds (AS) and polyesterurethane scaffolds (DegraPol) and document wound healing response when sealing iatrogenic fetal membrane defects in the rabbit model. STUDY DESIGN: Native AS were engineered from freshly harvested membranes of 23 days' gestational age (GA; term = 31-2 d). Acellularity of AS was assessed by histology, light and scanning electron microscopy. Fetal membrane defects were created by 14 gauge-needle puncture at GA 23 days and primarily closed with AS (n = 10) or DegraPol (n = 10) or left unclosed (positive controls; n = 10). Sixty-one sacs served as negative controls. At GA 30 days a second look hysterotomy was performed to assess presence of amniotic fluid (AF) and harvest plugging sites for microscopic evaluation. RESULTS: Engineered AS had a cell-free collagenous fiber network. AF was significantly higher only in the DegraPol group (78%; P < .05) compared to the AF in positive controls (17%). Integration of plugs in the fetal membrane defect was better with AS than DegraPol, with higher reepithelialization rates (AS: 52.5% +/- 6.5%; DegraPol: 11.6% +/- 2.6%; P < .001) and proliferation indices (AS: 0.47 +/- 0.03; DegraPol: 0.28 +/- 0.04; P = .001). In both treatment groups, cell proliferation in the myometrium was increased (P < .05). CONCLUSION: Native AS seal iatrogenic fetal membrane defects better than DegraPol. Within a week, there is abundant reepithelilization and minimal local inflammation. This yields the proof of principle that engineered native, amniotic membrane scaffolds enhance fetal membrane wound healing response.

The force required to rupture fetal membranes paradoxically increases with acute in vitro repeated stretching.

OBJECTIVE: The purpose of this study was to determine whether acute repetitive stretching causes fetal membranes (FM) weakening. STUDY DESIGN: Cesarean or vaginally delivered FM were repeatedly stretched and thereafter subjected to rupture testing. Rupture strength (RS), work to rupture (WR), and stiffness were determined. Unstretched FM were compared with stretched FM. RESULTS: In the cesarean group, FM stretched to 50% or 75% of the baseline (unstretched) RS for 10-20 cycles of 10 seconds each paradoxically showed increased RS and stiffness. WR decreased compared with baseline. Detailed analysis revealed that even a single stretch cycle initiated these changes to physical properties. Vaginally delivered FM showed similar changes in physical properties, as did separated amnion. CONCLUSION: Acute stretch forces do not directly cause FM weakening.

Endoscopic closure of fetal membrane defects: comparing iatrogenic versus spontaneous rupture cases.

OBJECTIVE: Currently, physicians manage preterm premature rupture of membranes (PPROM) by expectant management or termination of the gestation. A therapy aimed at sealing membranes would be optimal to maintain the pregnancy and achieve a normal neonate. Our objective was to compare an endoscopic technique for intrauterine closure of fetal membrane defects after both iatrogenic and spontaneous rupture of membranes. METHODS: Our technique was performed on four patients experiencing PPROM spontaneously and four patients after genetic amniocentesis. Intrauterine endoscopy allowed direct visualization of membrane defects. Rapid sequential injections of platelets, fibrin glue and powdered collagen slurry were administered at the site of the defect and of trocar placement. Sonography for amniotic fluid index, nitrazine and fern testing and pad count were performed after each procedure at three intervals: immediately post-procedure, and after 24 and 48 h. RESULTS: Eight patients underwent endoscopic intrauterine sealing of ruptured membranes between 16 and 24 weeks of gestation: four were spontaneous ruptures and four were ruptures post-amniocentesis. In the post-amniocentesis group, three patients delivered viable infants at 26, 32 and 34 weeks. In one patient, the membranes ruptured again 12 h after the sealing procedure and she decided to undergo termination of pregnancy. Of the four spontaneous rupture patients, two experienced preterm labor and delivery within 2 days of the procedure. One patient was diagnosed with fetal demise 12 h post-procedure, and one patient delivered a neonate at 31 weeks of gestation with severe respiratory distress syndrome. CONCLUSIONS: This technique for sealing ruptured membranes is effective after amniocentesis, but may not be of benefit with spontaneous rupture.

Factors influencing the flow rate through a surgical defect in human fetal membranes.

OBJECTIVES: In order to determine factors influencing the flow rate trough a created defect in human fetal membranes, an ex vivo set-up was used with fetal membranes collected from patients undergoing Caesarean section at term. METHODS: The membranes were secured at the bottom of a plastic tube and traumatised with needles ranging from 14-26 Gauges (Ga), under a hydrostatic pressure of 10 to 20 cm H(2)O and an angle of 45 degrees or 90 degrees. The column was filled with amniotic fluid or Hartmann's solution. The duration of the puncture was 1 s or the time it takes to aspirate 10 ml through the needle. The flow rate through the defect in the fetal membranes and size of the defect were measured. RESULTS: The flow rate and defect size increased with increasing diameter of the needle. Increasing the pressure in the column resulted in a significant linear increase in the flow rate. Replacing the saline solution with amniotic fluid did not result in significant changes in the measured flow rates, except for the small needle size (24 Ga). Increasing the duration of the puncture did not result in increased flow rates, except for small needle size (24 Ga). CONCLUSION: These experiments suggest that needle diameter, angle of needle insertion, duration of the procedure, amniotic fluid pressure and composition could influence the incidence of amniotic fluid leakage following amniocentesis.

Endoscopic documentation of unintentional perforation of the dividing membrane during amnioreduction for twin-twin transfusion syndrome.

OBJECTIVE: The purpose of this report is to document endoscopically the occurrence of unintentional piercing of the dividing membrane in a monochorionic twin pregnancy with twin-twin transfusion syndrome (TTTS). MATERIALS AND METHODS: The dividing membrane was visualized endoscopically during laser therapy in a patient with TTTS who had previously undergone therapeutic amniocentesis. The donor twin had no visible bladder, but the amniotic fluid volume had normalized after amniocentesis. RESULTS: The suspected membrane perforation was identified endoscopically during laser surgery. Five areas of vascular communications were identified and photocoagulated. CONCLUSIONS: Sonographic evidence of normalization of the amniotic fluid volumes after therapeutic amniocentesis with persistent nonvisualization of the bladder of the donor twin should not be interpreted as a sign of improvement of TTTS, but rather as indirect evidence of unintentional perforation of the dividing membrane. This complication can be confirmed endoscopically.

An organ-culture for in vitro evaluation of fetal membrane healing capacity.

OBJECTIVES: We aimed to set up an organ culture of human amniochorion to evaluate fetal membrane repair capacity following surgical trauma. METHODS: Fetal membranes were collected from four patients, during elective caesarean section at term. Explants were traumatised at the centre and cultured on collagen support material for a total of 12 days. Viability was assessed by light microscopy and proliferation by detection of 5-Bromo-2' deoxy-Uridine (BrdU) incorporation and immunohistochemistry. Wound healing capacity was assessed trough photographic documentation every 2 days. RESULTS: Cultures showed good survival for 12 days. Increased cellularity, survival and proliferations were observed at the borders of the cultures in contrast to the central trauma site. During the 12 days observation period, no significant closure of the membrane defect could be demonstrated. CONCLUSION: This organ culture system represents a new model for the study of human fetal membrane repair. Despite good survival and localised proliferation, no obvious closure of a surgically created defect was observed in the described culture conditions.

Matrix metalloproteinases -2 and -9 and their endogenous tissue inhibitors in fetal membrane repair following fetoscopy in a rabbit model.

The cellular mechanisms underlying fetal membrane repair are poorly understood. Matrix metalloproteinases (MMP) and the endogenous tissue inhibitors of metalloproteinases (TIMP) play a key role in the control of turnover of extracellular matrix in fetal membranes at normal parturition and preterm prelabour rupture of the fetal membranes (PPROM). The time course of secretion of MMP-2 (72 kDa, gelatinase A) and MMP-9 (92 kDa, gelatinase B) and TIMP into extra-embryonic coelomic, allantoic and amniotic fluids in a rabbit model was examined. Furthermore, to evaluate their role in fetal membrane repair, the changes induced by fetoscopy at mid-gestation (23 days; gestation length is 32 days) were investigated. Zymography showed predominantly secretion of latent MMP-2 at 18, 23 and 30 days of gestation in all gestational compartments. Reverse zymography detected a broad range of TIMP activity with molecular weights of 27-30 kDa (TIMP-1, glycosylated TIMP-3 and TIMP-4), 24 kDa (unglycosylated TIMP-3) and 21 kDa (TIMP-2). Following fetoscopy, both MMP-2 and TIMP increased significantly in amniotic fluid and extra-embryonic coelomic fluid, but not in allantoic fluid, as demonstrated by densitometric analyses. These findings indicate a modulating role for MMP and TIMP in the repair processes following a surgically induced fetal membrane defect.