Late administration of antenatal vitamin A promotes pulmonary structural maturation and improves ventilation in the lamb model of congenital diaphragmatic hernia

Impact of fetal treatments for congenital diaphragmatic hernia on lung development

The extent of lung hypoplasia impacts the survival and severity of morbidities associated with congenital diaphragmatic hernia (CDH). The alveoli of CDH infants and in experimental models of CDH have thickened septa with fewer type II pneumocytes and capillaries. Fetal treatments of CDH-risk preterm birth. Therefore, treatments must aim to balance the need for increased gas exchange surface area with the restoration of pulmonary epithelial type II cells and the long-term respiratory and neurodevelopmental consequences of prematurity. Achievement of sufficient lung development in utero for successful postnatal transition requires adequate intra-thoracic space for lung growth, maintenance of sufficient volume and appropriate composition of fetal lung fluid, regular fetal breathing movements, appropriate gas exchange area, and ample surfactant production. The review aims to examine the rationale for current and future therapeutic strategies to improve postnatal outcomes of infants with 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.

Protective effect of baicalin on fetal lung development in a rabbit model of congenital diaphragmatic hernia

Bacalin has been reported to improve fetal lung growth by increasing fetal lung surfactant phospholipids. Therefore, the present study evaluated the effect of transplacental treatment of baicalin during lung development in rabbits with congenital diaphragmatic hernia (DH) rabbit. DH was induced in fetal rabbit on gestational day 23 and baicalin injections were administered daily until term period. Fetal survival rate, body weight and lung-to-body weight ratio (LBWR) were subsequently measured, and the expression of surfactant protein B (SPB) and Ki-67, and morphometry analysis was determined in lung tissues. It was observed that in baicalin treated group the fetal survival rate and LBWR were decreased compared with the control without DH group. Lung morphometry results suggested that treatment with baicalin did not significantly ameliorate congenital DH, and adventitial and medial thickness were similar to those in the control groups, and less muscularization of vessels measuring 30–60 µm. Furthermore, baicalin treatment did not markedly affect the expressions of Ki-67 and SPB in fetuses with DH. Baicalin was demonstrated to improve the morphology of lung in rabbits; however, as it did not induce marked airway changes this present study suggests that baicalin is not suitable for the management of congenital DH.

Congenital diaphragmatic hernias: from genes to mechanisms to therapies

Congenital diaphragmatic hernias (CDHs) and structural anomalies of the diaphragm are a common class of congenital birth defects that are associated with significant morbidity and mortality due to associated pulmonary hypoplasia, pulmonary hypertension and heart failure. In ∼30% of CDH patients, genomic analyses have identified a range of genetic defects, including chromosomal anomalies, copy number variants and sequence variants. The affected genes identified in CDH patients include transcription factors, such as GATA4, ZFPM2, NR2F2 and WT1, and signaling pathway components, including members of the retinoic acid pathway. Mutations in these genes affect diaphragm development and can have pleiotropic effects on pulmonary and cardiac development. New therapies, including fetal endoscopic tracheal occlusion and prenatal transplacental fetal treatments, aim to normalize lung development and pulmonary vascular tone to prevent and treat lung hypoplasia and pulmonary hypertension, respectively. Studies of the association between particular genetic mutations and clinical outcomes should allow us to better understand the origin of this birth defect and to improve our ability to predict and identify patients most likely to benefit from specialized treatment strategies.

Avoiding the prenatal programming effects of glucocorticoids: are there alternative treatments for the induction of antenatal lung maturation?

BACKGROUND

The long-term outcomes of antenatal glucocorticoids (GCs) vary between reports, and have generated controversy in terms of repeated and single-course events, causing irreversible effects on endocrine set points.

AIM

This study aimed to assess the effects of alternative therapeutic agents other than synthetic glucocorticoid GC administration for fetal lung maturation.

METHODS

A review of literature from PubMed, EMBASE, Cochrane Library, and Google Scholar was conducted to assess the use of alternative therapies to synthetic GCs using recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA). End points included the rates of respiratory distress syndrome (RDS), mRNA expression for pneumocyte type II, concentration of surfactant proteins in alveolar lavage, morphological differences, histological proof of lung maturation, and angiogenesis or quantification of the surfactant pool.

RESULTS

In all 41 studies examined, we found that ambroxol showed positive effects on lung maturation, but it has yet to be analyzed with sufficient significance in humans. Interleukins and TNF-alpha produce accelerated lung maturation, but have only been evaluated in basic research/experimental studies. Growth factors promote structural and functional growth in all phases of lung maturation, but little is known about their reciprocal effects and exact mechanisms as therapeutics. Thyroid releasing hormone or vitamin A cause detrimental side effects or were less effective for lung maturation.

CONCLUSIONS

The efficacy and safety of these alternative agents are differentiated and none up to now can be recommended as an alternative to GCs.

The Effect of Transplacental Administration of Glucagon-Like Peptide-1 on Fetal Lung Development in the Rabbit Model of Congenital Diaphragmatic Hernia

Objective: Glucagon-like peptide-1 (GLP-1) increases surfactant protein expression in type 2 pneumocytes. Herein, we determine if transplacental GLP-1 treatment accelerates lung growth in the fetal rabbit model of congenital diaphragmatic hernia (DH). Methods: Time-mated does had an induction of DH on day 23 followed by daily GLP-1 or placebo injection until term. At that time, the does were weighed, fetal blood was obtained for GLP-1 assay, and the lungs were dissected. Fetal outcome measures were lung-to-body-weight ratio (LBWR), morphometry, and Ki67 and surfactant protein B (SPB) expression. Results: Maternal weight loss in the GLP-1 group was 7.1%. Fetal survival was lower in GLP-1 fetuses compared to placebo controls (27/85, 32% vs. 35/57, 61%; p < 0.05). Fetal GLP-1 levels were increased 3.6-fold. The LBWR of GLP-1 DH fetuses fell within the range of DH placebo fetuses (1.166 ± 0.207% vs. 1.312 ± 0.418%), being significantly lower than that of placebo-exposed unoperated fetuses (2.280 ± 0.522%; p < 0.001). GLP-1 did not improve airway morphometry. GLP-1 DH lungs had a reduced adventitial and medial thickness within the range of controls, and lesser muscularization of vessels measuring 30-60 µm. There were no differences in Ki67 and SPB expression. Conclusion: GLP-1 at this dosage improves peripheric pulmonary vessel morphology in intra-acinar vessels with no effect on airway morphometry but with significant maternal and fetal side effects. Thus, it is an unlikely medical strategy.

Medical interventions to reverse pulmonary hypoplasia in the animal model of congenital diaphragmatic hernia: A systematic review

We aimed to systematically review all published pre-clinical research on prenatal medical treatment of pulmonary hypoplasia in congenital diaphragmatic hernia (CDH). Background The neonatal mortality due to isolated CDH remains high. Whether fetal endoscopic tracheal occlusion (FETO) reduces mortality is still to be demonstrated. Therefore more potent preferentially medical therapy would be welcomed. Methods We searched MEDLINE (Pubmed), Embase and the Web of Science including all studies from the earliest date (1951) to December 2013. Article quality was assessed using the modified CAMRADES checklist. Inclusion criteria were those animal studies addressing prenatal medical interventions and principal variables were confirmation of a diaphragmatic defect, lung to body weight ratio (LBWR), formal airway morphometry or DNA/protein content. Results In total 983 articles were identified. Following abstract review, 96 articles were assessed by two authors in agreement with a third for eligibility. Of these, 43 were included in the final analysis. The median number of study quality checklist items (maximum 10) scored was 4 (IQ range: 2-5). Thirty (69.8%) of studies were in the nitrofen rat. The majority were treated with vitamins or glucocorticoids. Single studies reported some improvement in lung morphology with alternative therapies. It was impossible to identify a pattern in animal model selection or creation, mode, time point or duration of treatment and readouts. Only one study reported a sample size calculation. Conclusion Comparison in pre-clinical studies in CDH is challenging due to methodological variation. Agreed standardized methods need to be applied in future investigation of new medical therapies.

Effects of antenatal multiple micronutrient supplementation on lung function in mid-childhood: follow-up of a double-blind randomised controlled trial in Nepal

A randomised trial of prenatal multiple micronutrient supplementation in Nepalese women increased birthweight and weight at 2 years of age in offspring, compared to those born to mothers who only received iron and folic acid supplements. Further follow-up of this cohort provided an opportunity to investigate the effect of antenatal multiple micronutrients on subsequent lung function by measuring spirometry at 7-9 years of age in C: hildren born during the trial. 841 children (80% of the cohort) were seen at mean±sd 8.5±0.4 years. Technically successful spirometry results were obtained in 793 (94.3%) children, 50% of whom had been randomised to micronutrient supplementation. Background characteristics, including anthropometry, were similar in the two allocation groups. Lung function was also similar, mean (95% CI) difference in z-scores (supplementation minus control) was -0.08 (-0.19-0.04), -0.05 (-0.17-0.06) and -0.04 (-0.15-0.07) for forced expiratory volume in 1 s (FEV1), forced vital capacity and FEV1/FVC, respectively. Compared with healthy white children, FEV1 and FVC in the "healthy" Nepalese children were ∼1 (∼13%) z-score lower, with no difference in FEV1/FVC. We conclude that, compared with routine iron and folic acid, multiple micronutrient supplementation during pregnancy has no effect on spirometric lung function in Nepalese children at 8.5 years of age.

Novel non-surgical prenatal approaches to treating congenital diaphragmatic hernia

This review focuses on the emerging field of non-surgical in-utero therapies in the management of fetal pulmonary hypoplasia and pulmonary hypertension associated with congenital diaphragmatic hernia (CDH). These experimental approaches include pharmacologic as well as stem-cell-based strategies. Current barriers of non-surgical therapies toward clinical translation are emphasized. As the severity of CDH will likely influence the efficacy of any in-utero therapy, the current status of prenatal imaging and the role of novel biomarkers, especially those related to fetal inflammation, are also reviewed.

Cellular differentiation and proliferation in the ovine lung during gestation and early postnatal development

This study investigates epithelial cell differentiation and proliferation in specific anatomical regions of the ovine lung during prenatal and postnatal development. Immunohistochemistry was used to identify ciliated epithelial cells, Clara cells, neuroepithelial bodies and type II pneumocytes in the lungs of preterm (67, 127 and 140 days of gestation), full-term (147 days) and postnatal (9, 16 and 91 days old) lambs. Differentiation of ciliated epithelial cells was seen at 67 days of gestation and at term for Clara cells. Neuroepithelial bodies were first detected at 127 days of gestation. From 16 to 91 days of age there was a significant (P <0.05) increase in beta-tubulin (present in ciliated epithelial cells) and Clara cell protein (present in Clara cells) in multiple regions of the lung. Detection of Ki67, a marker of proliferation, in preterm lambs showed a reduction in proliferation index in multiple anatomical regions of the lung between 70 days of gestation and term. Cell proliferation increased following parturition, and then decreased between 16 and 91 days of age, with the largest reduction occurring in the alveolar compartment. Knowledge of which cells are present at specific times of lung development provides valuable information on the anatomy of the ovine lung, improving its use as a model for ovine and human neonatal disease. In addition, the antibodies used here will be valuable for future studies requiring the identification and quantification of respiratory epithelial cell phenotypes in the sheep lung.