Abnormal lung development in congenital diaphragmatic hernia

The outcomes of patients diagnosed with congenital diaphragmatic hernia (CDH) have recently improved. However, mortality and morbidity remain high, and this is primarily caused by the abnormal lung development resulting in pulmonary hypoplasia and persistent pulmonary hypertension. The pathogenesis of CDH is poorly understood, despite the identification of certain candidate genes disrupting normal diaphragm and lung morphogenesis in animal models of CDH. Defects within the lung mesenchyme and interstitium contribute to disturbed distal lung development. Frequently, a disturbance in the development of the pleuroperitoneal folds (PPFs) leads to the incomplete formation of the diaphragm and subsequent herniation. Most candidate genes identified in animal models have so far revealed relatively few strong associations in human CDH cases. CDH is likely a highly polygenic disease, and future studies will need to reconcile how disturbances in the expression of multiple genes cause the disease. Herein, we summarize the available literature on abnormal lung development associated with CDH.     

Congenital diaphragmatic hernia-associated pulmonary hypertension

Congenital diaphragmatic hernia (CDH) is a complex entity wherein a diaphragmatic defect allows intrathoracic herniation of intra-abdominal contents and both pulmonary parenchymal and vascular development are stifled. Pulmonary pathology and pathophysiology, including pulmonary hypoplasia and pulmonary hypertension, are hallmarks of CDH and are associated with disease severity. Pulmonary hypertension (PH) is sustained, supranormal pulmonary arterial pressure, and among patients with CDH (CDH-PH), is driven by hypoplastic pulmonary vasculature, including alterations at the molecular, cellular, and tissue levels, along with pathophysiologic pulmonary vasoreactivity. This review addresses the basic mechanisms, altered anatomy, definition, diagnosis, and management of CDH-PH. Further, emerging therapies targeting CDH-PH and PH are explored.     

Bilateral congenital diaphragmatic hernia and gastroschisis in a newborn: can low intrathoracic pressure prevent the pulmonary hypoplasia?

Congenital diaphragmatic hernia (CDH) is associated with high mortality and morbidity due to pulmonary hypoplasia (PH) and persistent pulmonary hypertension (PPH). Bilateral CDH is extremely rare with poor prognosis. It is usually accepted that PH in CDH is due to the herniation of abdominal viscera in the thorax leading to compression of the lung and preventing the normal lung development. On the other hand, some authors suggest that the PH occurs independently from the intrathoracic pressure in foetuses with CDH because of embryologic and genetic factors. We report a case of a newborn with bilateral CDH and gastroschisis born without PH, with favourable outcome. We support the hypothesis that a low intrathoracic pressure in patients with CDH allows an improved lung development.     

Hoxa5基因在先天性膈疝大鼠模型胎肺中的表达

目的 研究Hoxa5基因在先天性膈疝(congenital diaphragmatic hernia,CDH)胎肺中的表达特点以及探讨其在CDH肺发育不良发生机制中的可能作用.方法 采用实时荧光定量PCR(real time quantitative PCR,QPCR)方法检测Hoxa5基因在妊娠第17.5天、19.5天、21.5天的nitrofen诱导CDH大鼠模型胎肺及正常对照大鼠胎肺巾的相对表达量.结果 正常对照组胎肺中Hoxa5 mRNA的表达水平随着胎龄的增加旱下降趋势,其中第21.5天胎肺中Hoxa5 mRNA的表达水平显著下降,与其他二胎龄点相比差异有统计学意义(P＜0.05);CDH组中Hoxa5 mRNA的表达趋势与正常胎肺相似,即随胎龄的增加其表达量下降,其当中第21.5天胎肺中Hoxa5 mRNA的表达水平明显降低,与其他二胎龄点相比差异有统计学意义(P＜0.05).第17.5天与19.5天胎龄CDH组胎肺中Hoxa5 mRNA的表达水平分别与相应对照组相比,差异无统计学意义;而妊娠晚期(第21.5天胎龄)CDH组胎肺中Hoxa5 mRNA的表达水平高于对照组.差异具有统计学意义.结论 正常对照组中第21.5天胎龄时Hoxa5 mRNA的表达水平显著降低,提示Hoxa5 mRNA在孕晚期的低表达是正常肺发育的分子基础之一;而CDH组中第21.5天胎龄时Hoxa5 mRNA的表达水平明显高于对照组,提示Hoxa5在孕晚期CDH胎肺中Hoxa5的高表达可能是CDH肺发育不良形成机制之一.     

Fetal intervention for congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a condition that results from incomplete diaphragm formation during embryogenesis. The diaphragmatic defect allows for herniation of abdominal viscera into the chest, and the resulting pulmonary hypoplasia and pulmonary hypertension can lead to cardiorespiratory failure in the neonatal period. There is a wide spectrum of disease severity in CDH, and while advances in neonatal care and the introduction of extracorporeal membrane oxygenation have improved outcomes in many cases, the most severe defects are still associated with high morbidity and mortality. Improvements in prenatal diagnostic and prognostic capabilities have created an opportunity to select high risk patients for fetal intervention. Three decades of refinements in the fetal surgical therapy for CDH have led to the current technique of Fetoscopic Endoluminal Tracheal Occlusion (FETO). Herein, we review the current considerations for selecting patients for fetal intervention, and the contemporary fetal surgical operation for CDH, FETO, with a focus on early outcomes and ongoing studies.     

Diaphragm development and congenital diaphragmatic hernia

Advances in the understanding of normal diaphragm embryogenesis have provided the necessary foundation for novel insights into the pathogenesis of congenital diaphragmatic hernia (CDH). Although diaphragm formation is still not completely understood, we have identified key structures and periods of development that are clearly abnormal in animal models of CDH. The pleuroperitoneal fold (PPF) is a transient structure which is the target for the neuromuscular component of the diaphragm. The PPF has been shown to be abnormal in multiple animal models of Bochdalek CDH; specifically, a malformation of the nonmuscular component of this tissue is thought to underlie the later defect in the complete diaphragm. Based on data from animal models and the examination of human postmortem tissue, we hypothesize that abnormal PPF development underlies Bochdalek CDH. Further, the understanding of the pathogenesis of rarer subtypes of CDH will be advanced by the study of various new animal models discussed in this review.     

The embryology of the diaphragm

Despite the progress in prenatal diagnosis and intervention as well as postnatal therapeutic strategies, congenital diaphragmatic hernia (CDH) is still associated with a meaningful mortality because of the induced pulmonary hypoplasia. An essential key in understanding the pathogenesis of CDH is the underlying embryology, which has been neglected during the last decades. Likewise, the development of the normal diaphragm is still poorly understood. Obsolescent perceptions, mainly formed from histologic sections, are still propagated. In this review we present an atlas of scanning electron microscopy images that depict the normal and defective development of the diaphragm in the nitrofen rat model for CDH. Our findings suggest that the normal diaphragm mainly develops from the posthepatic mesenchymal plate. If the development of the posthepatic mesenchymal plate is impaired, a diaphragmatic defect occurs.     

A clinical analysis of prognostic parameters of survival in children with congenital diaphragmatic hernia.

BACKGROUND: Congenital diaphragmatic hernia (CDH) still has a high mortality because of accompanying lung hypoplasia and persistent pulmonary hypertension. Although prognostic parameters based on perinatal measurements have been proposed, our ability to accurately predict the surgical results remains insufficient. METHODS: We treated 55 infants with CDH from 1981 to 2004. Among them, 46 patients presented respiratory distress within the first 24 hours of life. Results of surgical treatment in the 46 infants were retrospectively correlated with gender, birth weight, gestational age at diagnosis, laterality, cardiac anomalies, diaphragmatic defect area, contents of herniated viscera, and the great vessel diameters measured by echocardiography. RESULTS: Out of 46 CDH neonates, 27 (58.7 %) survived and 19 (41.3 %) died aged 3 to 17 days. Non survivors had a significantly larger diaphragmatic defect and more frequent liver herniation. Out of possible predictive parameters studied, an index of the main pulmonary artery (cross-sectional area/diaphragmatic defect area ratio) most closely correlated with the surgical outcomes. CONCLUSIONS: The postoperative prognosis of CDH infants does not depend only on pulmonary hypoplasia, but also on other factors including the magnitude of abdominal visceral herniation. In this series of patients, the most reliable prognostic predictor was a clinical index reflecting the degree of both pulmonary hypoplasia and diaphragmatic maldevelopment.     

The relationship of diaphragmatic defect,liver growth,and lung hypoplasia in nitrofen-induced congenital diaphragmatic hernia in the rat

Reduced lung size (lung hypoplasia, LH) is the main cause of mortality in newborns with congenital diaphragmatic hernia (CDH). However, it is unclear which mechanisms lead to LH. To assess this, we analyzed the relationship of LH and liver mass in correlation to the size of the diaphragmatic defect in rats with nitrofen-induced CDH. A total of 266 newborn Sprague-Dawley rats (30 litters) were exposed to nitrofen on day 11.5 of pregnancy. After spontaneous delivery at term (22 days), all newborns were microdissected. Using a computerized morphometric device, the area of the thoracic cavity, the lung, the intrathoracic liver, and the diaphragmatic defect were measured. The lungs, the intrathoracic, and the extrathoracic portion of the liver were weighed. After nitrofen exposure, 160 newborn rats presented with CDH (60.2%). They were divided into five groups according to the intrathoracic content of intraabdominal organs. We observed a significant increase of the total liver and decrease of the lung weight in the severely affected groups. A significant correlation between the size of the defect and the weight of the intrathoracic part of the liver could be demonstrated. Nitrofen alone had no effect on liver weight. Our results indicate that (1) the presence of liver inside the thoracic cavity is not the result of dislocation but rather of growth of liver tissue through the defect, and (2) the observed correlation between the size of the defect and the intrathoracic liver weight may be part of the pathogenesis of LH in CDH.     

Prenatal intervention for the management of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is the result of incomplete formation of the diaphragm that occurs during embryogenesis. The defect in the diaphragm permits the herniation of abdominal organs into the thoracic cavity contributing to the impairment of normal growth and development of the fetal lung. In addition to the hypoplastic lung, anomalies of the pulmonary arterioles worsen the pulmonary hypertension that can have detrimental effects in severe cases. Most cases of CDH can be effectively managed postnatally. Advances in neonatal and surgical care have resulted in improved outcomes over the years. When available, extracorporeal membrane oxygenation can provide temporary cardiorespiratory support for those not effectively supported by mechanical ventilation. In spite of these advances, very severe cases of CDH still carry a very high mortality and morbidity rate. Advances in imaging and evaluation now allow for early and accurate prenatal diagnosis of CDH, thereby identifying those at greatest risk who may benefit from prenatal intervention. This review article discusses some of the surgical and non-surgical prenatal interventions in the management of isolated severe congenital diaphragmatic hernia.     

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a lethal human birth defect. Hypoplastic lung development is the leading contributor to its 30-50% mortality rate. Efforts to improve survival have focused on fetal surgery, advances in intensive care and elective delivery at specialist centres following in utero diagnosis. The impact of abnormal lung development on affected infants has stimulated research into the developmental biology of CDH. Traditionally lung hypoplasia has been viewed as a secondary consequence of in utero compression of the fetal lung. Experimental evidence is emerging for a primary defect in lung development in CDH. Culture systems are providing research tools for the study of lung hypoplasia and the investigation of the role of growth factors and signalling pathways. Similarities between the lungs of premature newborns and infants with CDH may indicate a role for antenatal corticosteroids. Further advances in postnatal therapy including permissive hypercapnia and liquid ventilation hold promise. Improvements in our basic scientific understanding of lung development may hold the key to future developments in CDH care.     

Heparin and in-vitro experimental lung hypoplasia

 Pulmonary hypoplasia (PH) is a leading contributor to the lethality of congenital diaphragmatic hernia (CDH). Studies now suggest that PH arises prior to visceral herniation. Growth factors (GF) are pivotal to this embryonic lung growth. With striking in-vitro effects on lung morphogenesis, GF are under investigation as therapies for PH. Heparin modulates the kinetics of heparan-sulphate binding ligands that drive lung development. We hypothesised that heparin may rescue PH by favourable alteration of endogenous pulmonary GF activity. Normal and hypoplastic lung primordia were microdissected on day 13.5 of gestation and cultured for up to 78 h in plain media with and without heparin. In-vitro morphological development was studied by serial measurements of terminal bud count, lung area, and lung perimeter. Nitrofen-exposed lungs cultured with heparin showed no significant improvements in terminal bud count, lung area, and lung perimeter at 30, 54, and 78 h compared to untreated hypoplastic lungs maintained in vitro. In normal lungs heparin demonstrated no sustained significant morphological effects compared to untreated control lungs. In this study, heparin did not stimulate branching morphogenesis of normal or hypoplastic lungs in our organ culture system. Known at higher concentrations to inhibit smooth-muscle proliferation, heparin may ameliorate pulmonary vascular hypermuscularisation with the prospect of benefiting CDH infants on extracorporeal membrane oxygenation. Future studies will address the impact of exogenous GF on hypoplastic lung development in organ culture.     

Congenital Diaphragmatic Hernia: Experimental Approach

Congenital diaphragmatic hernia is the only relatively common congenital malformation which requires operative treatment during the neonatal period, and the incidence is reported to be one in 2,000–5,000 births. Although a diaphragmatic defect can be easily corrected by pulling out the herniated viscera of the chest and closing the diaphragma, the mortality rate of infants with congenital diaphragmatic hernia is high despite improvements in neonatal intensive care, because the hypoplastic lungs on the affected side can not provide life support after birth. The severity of associated pulmonary hypoplasia is the most important factor determining survival in an infant with congenital diaphragmatic hernia. From experimental study, it should be emphasized that retardation in the lung growth, regardless of its potential for further growth, just at the time of pleuroperitoneal canal closure, may result in congenital diaphragmatic hernia; the hypoplastic lung on the side of herniation would not result from the compression of the lung by the herniated organs, but it may be induced by the limited space for further growth.     

Congenital Diaphragmatic Hernia Induced by Nitrofen in Mice and Rats: Characteristics as Animal Model and Pathogenetic Relationship between Diaphragmatic Hernia and Lung Hypoplasia

Abstract Congenital diaphragmatic hernia (CDH) and lung hypoplasia were induced in high frequency and dose-dependently in the offspring from dams, treated orally with 2,4-dichlorophenyl- p -nitrophenyl ether (nitrofen) during pregnancy in CD-I mice and CD rats. Both in mice and rats, CDH found in the fetal and neonatal periods was a posterolateral type of diaphragmatic hernia (DH) showing a distinct side-preponderance: the left-side preponderance in mice and right-side preponderance in rats. CDH in the offspring, surviving after weaning, was mostly of retrosternal type in mice and of pericardial type in rats. CDH induced experimentally in the present study can be regarded as an excellent animal model for human CDH in terms of both anatomical features and the time of appearance of different types of CDH as well as clinical symptoms.
Lung hypoplasia was observed in the offspring with and without CDH; though its severity was greater in those with CDH. The offspring with severe lung hypoplasia died of respiratory insufficiency during the neonatal period, regardless of the presence or absence of CDH. These findings suggest that lung hypoplasia is not a consequence of CDH, but that a common pathogenetic process in the early embryonic stage might involve both lung hypoplasia and CDH.     

Evidence for decreased lipofibroblast expression in hypoplastic rat lungs with congenital diaphragmatic hernia

Purpose

Pulmonary hypoplasia (PH) is a serious condition in newborns with congenital diaphragmatic hernia (CDH). Lipid-containing interstitial fibroblasts (LIFs) play an essential role in fetal lung maturation by stimulating alveolarization and lipid homeostasis. In rodents, LIFs are first evident during the canalicular phase of lung development with a significant increase over the last 4 days of gestation. Adipocyte differentiation-related protein (ADRP), a functional lipogenic molecular marker characterizing LIFs, is highly expressed in fetal lungs during this critical time period. We hypothesized that LIF expression in hypoplastic rat lungs is decreased in the nitrofen-induced CDH model, which is accompanied by reduced alveolar ADRP expression and lipid content.

Methods

On embryonic day 9.5 (E9.5), time-mated rats received either nitrofen or vehicle. Fetuses were sacrificed on selected time points E18.5 and E21.5, and dissected lungs were divided into controls and CDH-associated PH. Pulmonary gene expression levels of ADRP were determined by quantitative real-time polymerase chain reaction. ADRP immunohistochemistry and oil red O staining were used to assess pulmonary protein expression and lipid content. Immunofluorescence double staining for alpha smooth muscle actin, which is known to be absent in LIFs, and lipid droplets was performed to evaluate the pulmonary expression of this specific subset of fibroblasts.

Results

Relative mRNA expression of ADRP was significantly reduced in lungs of CDH-associated PH on E18.5 and E21.5 compared to controls. ADRP immunoreactivity and lipid staining were markedly diminished in alveolar mesenchymal cells of CDH-associated PH on E18.5 and E21.5 compared to controls. Confocal laser scanning microscopy demonstrated markedly decreased LIF expression in alveolar interstitium of CDH-associated PH on E18.5 and E21.5 compared to controls.

Conclusion

Decreased pulmonary LIF expression during late gestation suggests impaired LIF functioning in the nitrofen-induced CDH model, which may cause disruption in fetal alveolarization and lipid homeostasis, and thus contribute to the development of PH.     

Pulmonary neuroendocrine cells in nitrofen-induced diaphragmatic hernia and the effect of prenatal glucocorticoids

The high mortality associated with congenital diaphragmatic hernia (CDH) is due to pulmonary hypoplasia and hypertension, structural and functional abnormalities which can to some extent be ameliorated by prenatal administration of glucocorticoids. In the hypoplastic, hypertensive lungs of neonatal rats in which CDH has been induced by nitrofen, those pulmonary neuroendocrine cells (PNCs) containing calcitonin gene-related peptide (CGRP) increase in number, and it has been suggested that this might be due to inhibition of secretion of the peptide, the consequent decrease in its vasodilatory effects contributing to the hypertension. Whether this increase affects the entire population of PNCs, however, and how these cells are affected by administration of prenatal glucocorticoids, is unknown. As revealed by immunolabelling for protein gene product (PGP) 9.5, a general marker of NCs and expressed per cm² tissue section, the total PNC population in rats with nitrofen-induced CDH was significantly greater than in controls receiving only olive oil (672 vs 375/cm², P = 0.03) and was further increased (824 per cm²) in animals treated prenatally with dexamethasone (n = 8 in all groups). The increase in the total PNC population in rats with CDH is similar in magnitude to that described for the CGRP-containing subpopulation. Since the major role of the products of PNCs is now thought to be the regulation of development of pulmonary tissues and their response to injury, it is probable that the expansion of their population in the abnormal lungs associated with CDH is an adaptive response to pulmonary maldevelopment, a response possibly augmented by exogenous corticosteroids.     

Embryology and anatomy of congenital diaphragmatic hernia

Prenatal and postnatal treatment modalities for congenital diaphragmatic hernia (CDH) continue to improve, however patients still face high rates of morbidity and mortality caused by severe underlying persistent pulmonary hypertension and pulmonary hypoplasia. Though the majority of CDH cases are idiopathic, it is believed that CDH is a polygenic developmental defect caused by interactions between candidate genes, as well as environmental and epigenetic factors. However, the origin and pathogenesis of these developmental insults are poorly understood. Further, connections between disrupted lung development and the failure of diaphragmatic closure during embryogenesis have not been fully elucidated. Though several animal models have been useful in identifying candidate genes and disrupted signalling pathways, more studies are required to understand the pathogenesis and to develop effective preventative care. In this article, we summarize the most recent litterature on disrupted embryological lung and diaphragmatic development associated with CDH.     

Acute gastric volvulus and congenital diaphragmatic hernia,case report and review

Congenital diaphragmatic hernia (CDH) is the result of the incomplete fusion and closure of the pleuroperitoneal canal during the fetal development. CDH is usually diagnosed prenatally but, if undiagnosed, the clinical presentation ranges from asymptomatic children to serious respiratory or gastrointestinal symptoms. Acute gastric volvulus associated with CDH is a rare surgical emergency in children. We report two cases of acute gastric volvulus associated with CDH and review the literature.Key words: Acute gastric volvulus, children, congenital diaphragmatic hernia, gastropexy     

Does the developing liver inhibit early lung growth in congenital diaphragmatic hernia?

 It has been hypothesised that the liver induces lung hypoplasia in congenital diaphragmatic hernia (CDH) by non-compressive intrathoracic growth rather than traditional mass herniation. Utilising a co-culture system, we tested the capacity of liver cells to inhibit lung growth by contact rather than compression. Heart, liver, and lungs were microdissected from normal rat embryos (n>20 from at least three litters) on day 13.5 of gestation. Monolayer cultures of enzymatically dispersed livers and hearts were established at the same cell density. Lung primordia were cultured in direct contact with hepatic cells or partitioned from them by a permeable polytetrafluoroethylene membrane. This permits the contributions of diffusable factors and cell contact to be distinguished. Lungs were similarly cultured in direct contact with or partitioned from cardiac cells. Lungs cultured in isolation served as further controls. Daily inspection permitted assessment of in-vitro lung growth. Growth of lungs in direct contact with hepatic cells was equivalent to that of lungs partitioned from liver cells. Lungs in direct contact with cardiac cells and lungs partitioned from cardiac cells were also not inhibited compared to lungs cultured in isolation. Early lung development is thus not inhibited by humoral or contact-mediated interactions with embryonic liver cells. Lung hypoplasia in CDH is therefore unlikely to originate from contact inhibition with the developing liver. An intrinsic pulmonary defect may better explain hypoplastic lung development in CDH.