Severe Lung Hypoplasia Research Articles

Effect of prenatal diaphragmatic hernia on pulmonary arterial morphology.

Congenital diaphragmatic hernia (CDH) is a major cause of severe lung hypoplasia and pulmonary hypertension in the newborn. While the pulmonary hypertension is thought to result from abnormal vascular development and arterial vasoreactivity, the anatomical changes in vascular development are unclear. We have examined the 3D structure of the pulmonary arterial tree in rabbits with a surgically induced diaphragmatic hernia (DH). Fetal rabbits (n= 6) had a left-sided DH created at gestational day 23 (GD23), delivered at GD30, and briefly ventilated; sham-operated litter mates (n= 5) acted as controls. At postmortem the pulmonary arteries were filled with a radio-opaque resin before the lungs were scanned using computed tomography (CT). The 3D reconstructed images were analyzed based on vascular branching hierarchy using the software Avizo 2020.2. DH significantly reduced median number of arteries (2,579 (8440) versus 576 (442), p= .017), artery numbers per arterial generation, mean total arterial volume (43.5± 8.4 vs. 19.9± 3.1μl, p= .020) and mean total arterial cross-sectional area (82.5± 2.3 vs. 28.2± 6.2 mm2 , p=.036). Mean arterial radius was increased in DH kittens between the eighth and sixth branching generation and mean arterial length between the sixth and 28th branching generation. A DH in kittens resulted in threefold reduction in pulmonary arterial cross-sectional area, primarily due to reduced arterial branching. Thus, the reduction in arterial cross-sectional area could be a major contributor to pulmonary hypertension infants with CDH.

Lateral Thoracic Expansion for Jeune's Syndrome, Surgical Approach, and Technical Details

Jeune's syndrome, or asphyxiating thoracic dystrophy (ATD), is a rare autosomal recessive disorder characterized by skeletal dysplasia. Ribs are typically short and horizontal resulting-in lethal variant-in severe lung hypoplasia, progressive respiratory failure, and death. Lateral thoracic expansion (LTE) consists in staggered bilateral ribs osteotomy leading to chest expansion and lung development. Studies on LTE in ATD patients report encouraging data, but the rarity of ATD implies the lack of a standardized surgical path. The aim of this report is to present our experience with LTE, the technical modification we adopted, and patients' clinical outcome. We retrospectively reviewed data of 11 LTE performed in 7 ATD patients with lethal variant. Information regarding pre- and postoperative clinical conditions and surgical details was collected. We adopted a single-stage or a two-stage approach based on patient clinical condition. Computed tomography (CT) scan was performed before and after surgery and lung volume was calculated. Five patients are alive, while two died in intensive care unit for other than respiratory cause (sepsis). Most patients experienced clinical improvement in terms of decreased respiratory infections rate, need for ventilation, and improved exercise tolerance. Postoperative CT scan demonstrated a median lung volume increase of 88%. Mortality in ADT patients is high. However, LTE is a feasible and safe surgical approach, which could improve clinical conditions and survival rate. Survived patients showed postoperatively less oxygen requirement and improved clinical conditions.

Operative mortality after Society of Thoracic Surgeons–European Association for Cardio-Thoracic Surgery Mortality Category 1 to 3 procedures: Deficiencies and opportunities for quality improvement

ObjectivesWe examined cases of operative mortality at a single quaternary academic center for patients undergoing relatively lower-risk (Society of Thoracic Surgeons–European Association for Cardio-Thoracic Surgery Mortality Category 1-3) procedures, as a means of identifying systemic weaknesses and opportunities for quality improvement. MethodsA retrospective review of all operative mortality events for patients who underwent a Society of Thoracic Surgeons–European Association for Cardio-Thoracic Surgery Mortality Category 1, 2, or 3 index procedure (2009-2020) at our institution was performed. After a detailed chart review was performed by 2 independent faculty for each case, factors and system deficiencies that contributed to mortality were identified. ResultsA total of 42 mortalities were identified. A total of 37 patients (88%) had at least 1 Society of Thoracic Surgeons–designated risk factor, including prior cardiac operations (48%), extracardiac malformations (43%), and preoperative ventilation (33%). Eight patients (19%) had non–Society of Thoracic Surgeons–designated preoperative patient-level variables considered as at potential risk, including severe ventricular dysfunction, pulmonary hypertension, lung hypoplasia, and undiagnosed severe coronary abnormalities. Four patients (10%) had no identified preoperative risk factors. After detailed chart review, 5 broad categories were identified: patient-related factors (n = 33; 78%), postoperative infection (n = 13; 31%), postoperative residual lesions (n = 7; 17%), Fontan physiology failure (n = 4; 10%), and unexplained left ventricular failure after tetralogy of Fallot repair (n = 3; 7%). A total of 74% of patients had at least 1 preoperative, intraoperative, or postoperative system deficiency. A total of 50% of surgeries were urgent or emergency. ConclusionsOperative mortality after Society of Thoracic Surgeons–European Association for Cardio-Thoracic Surgery Mortality Category 1 to 3 procedures is related to the presence of multifactorial risk patterns (Society of Thoracic Surgeons and non–Society of Thoracic Surgeons-designated patient-level risk factors and variables, broad risk categories, system deficiencies, emergency surgery). A multidisciplinary approach to care, with early recognition and treatment of modifiable additional burdens, could reduce this risk.

Randomized Trial of Fetal Surgery for Severe Left Diaphragmatic Hernia

(Engl J Med. 2021;385:107–118) Congenital diaphragmatic hernia (CDH) can lead to serious lifelong complications, but may be treated if diagnosed before birth. In fetoscopic endoluminal tracheal occlusion (FETO), a balloon is inserted into the fetal trachea in utero to stimulate fetal lung growth and is removed prior to birth. One study of 210 fetuses undergoing FETO for severe lung hypoplasia due to isolated CDH found a nearly doubled survival rate among fetuses who received FETO compared with controls (49% vs. 24%). This current study, Tracheal Occlusion to Accelerate Lung Growth (TOTAL), aimed to test whether fetuses with surgical treatment of severe left CDH had superior survival rates compared with fetuses who received expectant prenatal care.

Respiratory Support of Infants With Congenital Diaphragmatic Hernia

Optimisation of respiratory support of infants with congenital diaphragmatic hernia (CDH) is critical. Infants with CDH often have severe lung hypoplasia and abnormal development of their pulmonary vasculature, leading to ventilation perfusion mismatch. It is vital that lung protective ventilation strategies are employed during both initial stabilisation and post-surgical repair to avoid ventilator induced lung damage and oxygen toxicity to prevent further impairment to an already diminished gas-exchanging environment. There is a lack of robust evidence for the routine use of surfactant therapy during initial resuscitation of infants with CDH and thus administration cannot be recommended outside clinical trials. Additionally, inhaled nitric oxide has been shown to have no benefit in reducing the mortality rates of infants with CDH. Other therapeutic agents which beneficially act on pulmonary hypertension are currently being assessed in infants with CDH in randomised multicentre trials. The role of novel ventilatory modalities such as closed loop automated oxygen control, liquid ventilation and heliox therapy may offer promise for infants with CDH, but the benefits need to be determined in appropriately designed clinical trials.

Knowledge Gaps in the Fetal to Neonatal Transition of Infants With a Congenital Diaphragmatic Hernia.

Clinical research for infants born with a congenital diaphragmatic hernia (CDH) has until recently mainly focused on advances in prenatal and postnatal treatment. However, during the early perinatal transition period there are major physiological adaptations. For most infants these changes will happen uneventfully, but for CDH infants this marks the beginning of serious respiratory complications. In recent years, there is emerging evidence that the clinical management during the perinatal stabilization period in the delivery room may influence postnatal outcomes. Herein, we discuss major knowledge gaps and novel concepts that aim to optimize fetal to neonatal transition for infants with CDH. One such novel and interesting approach is performing resuscitation with an intact umbilical cord, the efficacy of this procedure is currently being investigated in several clinical trials. Furthermore, close evaluation of neonatal physiological parameters in the first 24 h of life might provide early clues concerning the severity of lung hypoplasia and the risk of adverse outcomes. We will provide an overview of trending concepts and discuss potential areas for future research.

Home management by remote self-monitoring in intermediate- and high-risk pregnancies: A retrospective study of 400 consecutive women.

Home management in general is considered to improve patient well-being, patient involvement and cost-effectiveness, for obstetric patients as well. But concerns regarding inclusion of intermediate- and high-risk pregnant women are an issue and a limitation for clinical implementation. This retrospective study evaluated the outcome and safety of extended remote self-monitoring of maternal and fetal health in intermediate- and high-risk pregnancies. The study reports on 400 singleton pregnancies complicated by preterm premature rupture of membranes (PPROM), fetal growth restriction, preeclampsia, gestational diabetes mellitus, high-risk of preeclampsia, or a history of previous fetal or neonatal loss. Remote self-monitoring was performed by pregnant women and included C-reactive protein, non-stress test by cardiotocography, temperature, blood pressure, heart rate, and a questionnaire concerning maternal and fetal wellbeing. Data were transferred to the hospital using a mobile device platform and evaluated by healthcare professionals. In case of non-reassuring registrations, the pregnant women were invited for assessment at the hospital. Primary outcome was perinatal death. Secondary outcomes were other maternal and perinatal complications. No severe maternal complications were observed. Nine fetal or neonatal deaths occurred, all secondary to malformations, severe fetal growth restriction, extreme prematurity or lung hypoplasia in cases of PPROM before 24weeks. Even in the latter group, fetal and neonatal survival was 78% (18/23) and rose to 97% (60/62) when PPROM occurred after a gestational age 23+6 weeks. None of the fetal or neonatal deaths were attributable to the home-management setting. Home-monitoring including remote self-monitoring of fetal and maternal well-being in intermediate- and high-risk pregnancies seems to be a safe alternative to inpatient or frequent outpatient care, which sets the stage for a new way of thinking of hospital care. The implementation process included staff training workshops and development of patient enrollment practice with clarification of expectations and responsibilities, which can be crucial to the results.

The randomized Tracheal Occlusion To Accelerate Lung growth (TOTAL)-trials on fetal surgery for congenital diaphragmatic hernia: reanalysis using pooled data

Two randomized controlled trials compared the neonatal and infant outcomes after fetoscopic endoluminal tracheal occlusion with expectant prenatal management in fetuses with severe and moderate isolated congenital diaphragmatic hernia, respectively. Fetoscopic endoluminal tracheal occlusion was carried out at 27+0 to 29+6 weeks' gestation (referred to as "early") for severe and at 30+0 to 31+6 weeks ("late") for moderate hypoplasia. The reported absolute increase in the survival to discharge was 13% (95% confidence interval,-1 to 28; P=.059) and 25% (95% confidence interval, 6-46; P=.0091) for moderate and severe hypoplasia. Data from the 2 trials were pooled to study the heterogeneity of the treatment effect by observed over expected lung-to-head ratio and explore the effect of gestational age at balloon insertion. Individual participant data from the 2 trials were reanalyzed. Women were assessed between 2008 and 2020 at 14 experienced fetoscopic endoluminal tracheal occlusion centers and were randomized in a 1:1 ratio to either expectant management or fetoscopic endoluminal tracheal occlusion. All received standardized postnatal management. The combined data involved 287 patients (196 with moderate hypoplasia and 91 with severe hypoplasia). The primary endpoint was survival to discharge from the neonatal intensive care unit. The secondary endpoints were survival to 6 months of age, survival to 6 months without oxygen supplementation, and gestational age at live birth. Penalized regression was used with the following covariates: intervention (fetoscopic endoluminal tracheal occlusion vs expectant), early balloon insertion (yes vs no), observed over expected lung-to-head ratio, liver herniation (yes vs no), and trial (severe vs moderate). The interaction between intervention and the observed over expected lung-to-head ratio was evaluated to study treatment effect heterogeneity. For survival to discharge, the adjusted odds ratio of fetoscopic endoluminal tracheal occlusion was 1.78 (95% confidence interval, 1.05-3.01; P=.031). The additional effect of early balloon insertion was highly uncertain (adjusted odds ratio, 1.53; 95% confidence interval, 0.60-3.91; P=.370). When combining these 2 effects, the adjusted odds ratio of fetoscopic endoluminal tracheal occlusion with early balloon insertion was 2.73 (95% confidence interval, 1.15-6.49). The results for survival to 6 months and survival to 6 months without oxygen dependence were comparable. The gestational age at delivery was on average 1.7 weeks earlier (95% confidence interval, 1.1-2.3) following fetoscopic endoluminal tracheal occlusion with late insertion and 3.2 weeks earlier (95% confidence interval, 2.3-4.1) following fetoscopic endoluminal tracheal occlusion with early insertion compared with expectant management. There was no evidence that the effect of fetoscopic endoluminal tracheal occlusion depended on the observed over expected lung-to-head ratio for any of the endpoints. This analysis suggests that fetoscopic endoluminal tracheal occlusion increases survival for both moderate and severe lung hypoplasia. The difference between the results for the Tracheal Occlusion To Accelerate Lung growth trials, when considered apart, may be because of the difference in the time point of balloon insertion. However, the effect of the time point of balloon insertion could not be robustly assessed because of a small sample size and the confounding effect of disease severity. Fetoscopic endoluminal tracheal occlusion with early balloon insertion in particular strongly increases the risk for preterm delivery.

Intrauterine surgery: how far we have come in 30 years.

Intrauterine surgery: how far we have come in 30 years.

Branch pulmonary artery Doppler parameters predict early survival-non-survival in premature rupture of membranes.

Preterm premature rupture of membrane (pPROM) leads to high neonatal mortality due in part to severe lung hypoplasia (LH). In other causes of severe LH, fetal echo-based parameters of smaller branch pulmonary arteries (PA), shorter acceleration to ejection time ratio (AT/ET), increased peak early diastolic reverse flow (PEDRF), and higher pulsatility index (PI) are predictive of worse neonatal outcome. We sought to determine whether these parameters correlated with worse clinical outcome in pPROM. Twenty-five pregnancies complicated by pPROM were prospectively recruited. Fetal echocardiography was used to evaluate branch PA diameters and Doppler parameters. Clinical records were reviewed. Fetal echo findings were compared between early survivors and non-survivors. Of 25 pPROM cases, 5 had early neonatal demise (≤3 days) due to respiratory insufficiency. While gestational age at pPROM, fetal echo, and at birth did not differ, amniotic fluid index (AFI) was significantly lower in early non-survivors compared to survivors (p = 0.05). No difference was observed in PA diameter, PEDRF, or PI; however, branch PA AT/ET was significantly shorter in non-survivors (right PA median 0.12 (0.11-0.16) vs. survivors 0.17 (0.14-0.21), p = 0.046 and left PA 0.12 (0.09-0.13) vs. survivors 0.16 (0.11-0.21), p = 0.042). We found a significantly lower AFI and shorter fetal bilateral branch PA AT/ET to be associated with early neonatal demise following pPROM.

Mesenchyme-specific deletion of Tgf-β1 in the embryonic lung disrupts branching morphogenesis and induces lung hypoplasia

Proper lung development depends on the precise temporal and spatial expression of several morphogenic factors, including Fgf10, Fgf9, Shh, Bmp4, and Tgf-β. Over- or under-expression of these molecules often leads to aberrant embryonic or postnatal lung development. Herein, we deleted the Tgf-β1 gene specifically within the lung embryonic mesenchymal compartment at specific gestational stages to determine the contribution of this cytokine to lung development. Mutant embryos developed severe lung hypoplasia and died at birth due to the inability to breathe. Despite the markedly reduced lung size, proliferation and differentiation of the lung epithelium was not affected by the lack of mesenchymal expression of the Tgf-β1 gene, while apoptosis was significantly increased in the mutant lung parenchyma. Lack of mesenchymal expression of the Tgf-β1 gene was also associated with reduced lung branching morphogenesis, with accompanying inhibition of the local FGF10 signaling pathway as well as abnormal development of the vascular system. To shed light on the mechanism of lung hypoplasia, we quantified the phosphorylation of 226 proteins in the mutant E12.5 lung compared with control. We identified five proteins, Hrs, Vav2, c-Kit, the regulatory subunit of Pi3k (P85), and Fgfr1, that were over- or under-phosphorylated in the mutant lung, suggesting that they could be indispensable effectors of the TGF-β signaling program during embryonic lung development. In conclusion, we have uncovered novel roles of the mesenchyme-specific Tgf-β1 ligand in embryonic mouse lung development and generated a mouse model that may prove helpful to identify some of the key pathogenic mechanisms underlying lung hypoplasia in humans.

The impact of fetal endoscopic tracheal occlusion in isolated left-sided congenital diaphragmatic hernia on left-sided cardiac dimensions.

Fetal endoscopic tracheal occlusion (FETO) is offered to fetuses with congenital diaphragmatic hernia (CDH) and severe lung hypoplasia to promote lung growth and may secondarily affect left heart growth. The effects of FETO on left heart hypoplasia (LHH) are not described post-CDH repair. A retrospective analysis was performed for fetuses with left-sided CDH who underwent FETO and severity-matched controls from 2007 to 2016 at our institution. Echocardiographic, ultrasound, and MRI data were reviewed. Left heart dimensions were assessed prenatally and postnatally. Primary clinical outcome evaluated was death. Twelve FETO patients and 18 controls were identified. Fetal LHH was noted in both groups and worsened after FETO. Postnatal mitral valve dimensions were larger in the FETO group pre-CDH repair (P=.03). Post-CDH repair, mitral valve and left ventricular dimensions were not significantly different between groups (P=.79 and P=.63 respectively) while FETO aortic valve dimensions were smaller (P=.04). Extracorporeal membrane oxygenation use was lower in the FETO group. No associations were found between left heart dimensions and outcomes. Although increased lung growth was seen after FETO, fetal LHH persisted with relative normalization seen post-repair. Persistent LHH post-FETO could be secondary to a small contribution of pulmonary venous return to the fetal left heart and increased intrathoracic pressures post-FETO.

Parameters of fetal pulmonary vascular health: baseline trends and response to maternal hyperoxia in the second and third trimesters.

Several parameters, including branch pulmonary artery (PA) diameter and Doppler-derived PA acceleration-to-ejection time ratio (AT/ET), peak late-systolic/early-diastolic reversed flow (PEDRF) and pulsatility index (PI) response to maternal hyperoxia, have been used to investigate fetal pulmonary health. Lower AT/ET, increased PEDRF and lack of PI response to hyperoxia have been observed in fetuses with severe lung hypoplasia and are considered markers of pulmonary vascular resistance. We sought to further define the evolution of PA diameter and Doppler parameters and their response to maternal hyperoxia in healthy fetuses. Fifty-four prospectively recruited women with healthy pregnancy underwent fetal echocardiography from 18-36 weeks of gestation. After baseline branch PA diameter and Doppler assessment, oxygen (8-10 L/min) was administered by non-reservoir facemask for 10 min and PA Doppler parameters were reassessed. Branch PA diameters and AT/ET increased linearly with gestational age, while PEDRF increased quadratically (P < 0.001 for all) and PA-PI did not change. In response to maternal hyperoxia, although most fetuses demonstrated a significant decrease in PI for both branch PAs (right PA, P = 0.025; left PA, P = 0.040) ≥ 30 weeks, significant variability was observed in PI response with 31% of cases demonstrating either no response or a slight decrease. No other parameter demonstrated a measurable change in response to maternal hyperoxia. From the mid-trimester, fetal branch PA diameters and AT/ET increase linearly and PEDRF increases quadratically, whereas PI remains unchanged. Although maternal hyperoxia triggers a significant decrease in PA-PI after 30 weeks, variability in this response may reduce its utility in clinical practice. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Increased CaSR and TRPC6 pulmonary vascular expression in the nitrofen-induced model of congenital diaphragmatic hernia

The high morbidity and mortality rates in congenital diaphragmatic hernia (CDH) are attributed primarily to severe lung hypoplasia and/or persistent pulmonary hypertension (PPH). PPH in CDH is characterized by abnormal vascular remodeling with thickening of medial and adventitial layers and extension of smooth muscle into previously nonmuscularized arteries. Excessive proliferation of pulmonary arterial smooth muscle cells (PASMC) is an important contributor to the concentric pulmonary arterial remodeling. An increase in cytosolic-free Ca2+ concentration in PASMC is a major trigger for pulmonary vasoconstriction and a key stimulus for PASMC proliferation and migration. Calcium-sensing receptor (CaSR), a member of the G-protein coupled receptor family, is activated by cations (e.g., Ca2+, Mg2+) and polyamines. Under normal physiological conditions, the expression levels of CaSR in the pulmonary vasculature are very low. Canonical transient receptor potential channels (TRPCs) constitute a series of nonselective cation channels with variable degree of Ca2+ selectivity. TRPC6 has been reported to play a crucial role in the regulation of neo-muscularization, vasoreactivity, and vasomotor tone in the pulmonary vasculature. We hypothesized that CaSR and TRPC6 expression is upregulated in the pulmonary vasculature of nitrofen-induced CDH rats. Following ethical approval (REC1103), time-pregnant Sprague Dawley rats received nitrofen or vehicle on gestational day (D) 9. D21 fetuses were divided into CDH and control (n = 12). Quantitative real-time polymerase chain reaction (QRT-PCR), western blotting, and confocal-immunofluorescence microscopy were performed to detect lung gene and protein expression of CaSR and TRPC6. QRT-PCR and western blot analysis revealed that CaSR and TPRC6 expression was significantly increased in the CDH group compared to controls (p < 0.05). Confocal-immunofluorescence microscopy revealed that CaSR and TRPC6 lung expression was markedly increased in CDH group compared to controls. Increased CaSR and TRPC6 expression in CDH lung suggests that CaSR interacting with TRPC6 may contribute to abnormal vascular remodeling resulting in pulmonary vasoconstriction and development of PPH.

Lung hypoplasia in newborn rabbits with a diaphragmatic hernia affects pulmonary ventilation but not perfusion

BackgroundA congenital diaphragmatic hernia (DH) can result in severe lung hypoplasia that increases the risk of morbidity and mortality after birth; however, little is known about the cardiorespiratory transition at birth.MethodsUsing phase-contrast X-ray imaging and angiography, we examined the cardiorespiratory transition at birth in rabbit kittens with DHs. Surgery was performed on pregnant New Zealand white rabbits (n=18) at 25 days’ gestation to induce a left-sided DH. Kittens were delivered at 30 days’ gestation, intubated, and ventilated to achieve a tidal volume (Vt) of 8 ml/kg in control and 4 ml/kg in DH kittens while they were imaged.ResultsFunctional residual capacity (FRC) recruitment and Vt in the hypoplastic left lung were markedly reduced, resulting in a disproportionate distribution of FRC into the right lung. Following lung aeration, relative pulmonary blood flow (PBF) increased equally in both lungs, and the increase in pulmonary venous return was similar in both control and DH kittens.ConclusionThese findings indicate that nonuniform lung hypoplasia caused by DH alters the distribution of ventilation away from hypoplastic and into normally grown lung regions. During transition, the increase in PBF and pulmonary venous return, which is vital for maintaining cardiac output, is not affected by lung hypoplasia.

Sepsis risk factors in infants with congenital diaphragmatic hernia

BackgroundCongenital diaphragmatic hernia (CDH) is a rare congenital anomaly and remains among the most challenging ICU-managed disease. Beside severe pulmonary hypertension, lung hypoplasia and major abdominal surgery, infective complications remain major determinants of outcome. However, the specific incidence of sepsis as well as associated risk factors is unknown.MethodsThis prospective, 4-year observational study took place in the pediatric intensive care and neonatal medicine department of the Paris South University Hospitals (Le Kremlin-Bicêtre, France), CDH national referral center and involved 62 neonates with CDH.Main resultsDuring their ICU stay, 28 patients (45%) developed 38 sepsis episodes. Ventilator-associated pneumonia (VAP: 23/38; 31.9 VAP per 1000 days of mechanical ventilation) and central line-associated blood stream infections (CLABSI: 5/38; 5.5 per 1000 line days) were the most frequently encountered infections. Multivariate analysis showed that gestational age at birth and intra-thoracic position of liver were significantly associated with the occurrence of sepsis. Infected patients had longer duration of mechanical and noninvasive ventilation (16.2 and 5.8 days, respectively), longer delay to first feeding (1.2 days) and a longer length of stay in ICU (23 days), but there was no difference in mortality.ConclusionsHealthcare-associated infections, and more specifically VAP, are the main infective threat in children with CDH. Sepsis has a significant impact on the duration of ventilator support and ICU length of stay but does not impact mortality. Low gestational age and intra-thoracic localization of the liver are two independent risk factors associated with sepsis.

Canonical Sonic Hedgehog Signaling in Early Lung Development.

The canonical hedgehog (HH) signaling pathway is of major importance during embryonic development. HH is a key regulatory morphogen of numerous cellular processes, namely, cell growth and survival, differentiation, migration, and tissue polarity. Overall, it is able to trigger tissue-specific responses that, ultimately, contribute to the formation of a fully functional organism. Of all three HH proteins, Sonic Hedgehog (SHH) plays an essential role during lung development. In fact, abnormal levels of this secreted protein lead to severe foregut defects and lung hypoplasia. Canonical SHH signal transduction relies on the presence of transmembrane receptors, such as Patched1 and Smoothened, accessory proteins, as Hedgehog-interacting protein 1, and intracellular effector proteins, like GLI transcription factors. Altogether, this complex signaling machinery contributes to conveying SHH response. Pulmonary morphogenesis is deeply dependent on SHH and on its molecular interactions with other signaling pathways. In this review, the role of SHH in early stages of lung development, specifically in lung specification, primary bud formation, and branching morphogenesis is thoroughly reviewed.

EP08.06: Prediction of severity of lung hypoplasia in the fetuses with prolonged premature rupture of membrane

EP08.06: Prediction of severity of lung hypoplasia in the fetuses with prolonged premature rupture of membrane

Lung Perfusion MRI After Congenital Diaphragmatic Hernia Repair in 2-Year-Old Children With and Without Extracorporeal Membrane Oxygenation Therapy.

In severe cases of congenital diaphragmatic hernia (CDH), extracorporeal membrane oxygenation (ECMO) therapy improves survival. Later on, lung morbidity mainly defines development. The purpose of this study was to investigate whether 2-year-old children who need ECMO therapy after delivery have reduced perfusion MRI values as a sign of more severe lung hypoplasia than do children who do not need ECMO. After CDH repair, 38 children underwent dynamic contrast-enhanced MRI with a 3D time-resolved angiography with stochastic trajectories sequence. Fifteen (39%) of the children had received ECMO therapy in the neonatal period. Pulmonary blood flow (PBF), pulmonary blood volume (PBV), and mean transit time were calculated for both lungs. In addition, the ratio of ipsilateral to contralateral lung was calculated for all parameters. In all children, those with and those without ECMO requirement, PBF and PBV were significantly reduced on the ipsilateral side (p < 0.05). Children who had received ECMO therapy had significantly reduced PBF and PBV values on the ipsilateral side (p < 0.05) compared with children who had not needed ECMO therapy. The ratios of ipsilateral to contralateral lung for PBF and PBV were also significantly reduced after ECMO. Two-year-old children undergoing CDH repair who had needed neonatal ECMO had significantly reduced perfusion MRI values in the ipsilateral lung in comparison with children who had not needed ECMO. Perfusion MRI measurements are associated with the severity of lung hypoplasia and may therefore be helpful in follow-up investigations.

Unique Tracheal Fluid MicroRNA Signature Predicts Response to FETO in Patients With Congenital Diaphragmatic Hernia.

Our objective was to determine the fetal in vivo microRNA signature in hypoplastic lungs of human fetuses with severe isolated congenital diaphragmatic hernia (CDH) and changes in tracheal and amniotic fluid of fetuses undergoing fetoscopic endoluminal tracheal occlusion (FETO) to reverse severe lung hypoplasia due to CDH. We profiled microRNA expression in prenatal human lungs by microarray analysis. We then validated this signature with real-time quantitative polymerase chain reaction in tracheal and amniotic fluid of CDH patients undergoing FETO. We further explored the role of miR-200b using semiquantitative in situ hybridization and immunohistochemistry for TGF-β2 in postnatal lung sections. We investigated miR-200b effects on TGF-β signaling using a SMAD-luciferase reporter assay and Western blotting for phospho-SMAD2/3 and ZEB-2 in cultures of human bronchial epithelial cells. CDH lungs display an increased expression of 2 microRNAs: miR-200b and miR-10a as compared to control lungs. Fetuses undergoing FETO display increased miR-200 expression in their tracheal fluid at the time of balloon removal. Future survivors of FETO display significantly higher miR-200 expression than those with a limited response. miR-200b was expressed in bronchial epithelial cells and vascular endothelial cells. TGF-β2 expression was lower in CDH lungs. miR-200b inhibited TGF-β-induced SMAD signaling in cultures of human bronchial epithelial cells. Human fetal hypoplastic CDH lungs have a specific miR-200/miR-10a signature. Survival after FETO is associated with increased miR-200 family expression. miR-200b overexpression in CDH lungs results in decreased TGF-β/SMAD signaling.