Maternal administration of betamethasone inhibits proliferation induced by fetal tracheal occlusion in the nitrofen rat model for congenital diaphragmatic hernia: a placebo-controlled study

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.

Results of fetal endoscopic tracheal occlusion for congenital diaphragmatic hernia and the set up of the randomized controlled TOTAL trial

In isolated congenital diaphragmatic hernia, lung size and/or the position of the liver are predictive of neonatal outcome. Percutaneous Fetal Endoscopic Tracheal Occlusion (FETO) by a balloon can be undertaken to prompt lung growth in the worst cases. The feasibility and safety of FETO is no longer at stake, and it is associated with an apparent increase in neonatal survival. The gestational age at birth, the pre-existing lung size, the ability to remove the balloon prior to birth, and the lung response are predicting outcome. The most frequent complication is preterm premature rupture of the membranes, and as a consequence preterm delivery, which also complicates balloon removal. We have set up a randomized trial for the formal evaluation of FETO in Europe, including criteria for fetoscopy centers. Training of European as well as North American centers is taking place, so that the procedure could be safely and more widely offered.

Antenatal steroid and tracheal occlusion restore vascular endothelial growth factor receptors in congenital diaphragmatic hernia rat model

OBJECTIVE

Investigate the effects of antenatal steroids and tracheal occlusion on pulmonary expression of vascular endothelial growth factor receptors in rats with nitrofen-induced congenital diaphragmatic hernia.

STUDY DESIGN

Fetuses were exposed to nitrofen at embryonic day 9.5. Subgroups received dexamethasone or were operated on for tracheal occlusion, or received combined treatment. Morphologic variables were recorded. To analyze vascular endothelial growth factor receptor 1 and vascular endothelial growth factor receptor 2 expression, we performed Western blotting and immunohistochemistry. Morphologic variables were analyzed by analysis of variance and immunohistochemistry by Kruskal-Wallis test.

RESULTS

Congenital diaphragmatic hernia decreased body weight, total lung weight, and lung-to-body weight ratio. Tracheal occlusion increased total lung weight and lung-to-body weight ratio (P < .05). Fetuses with congenital diaphragmatic hernia had reduced vascular endothelial growth factor receptor 1 and vascular endothelial growth factor receptor 2 expression, whereas steroids and tracheal occlusion increased their expression. Combined treatment increased expression of receptors, but had no additive effect.

CONCLUSION

Vascular endothelial growth factor signaling disruption may be associated with pulmonary hypertension in congenital diaphragmatic hernia. Tracheal occlusion and steroids provide a pathway for restoring expression of vascular endothelial growth factor receptors.

Albumin as an adjunct to tracheal occlusion in fetal rats with congenital diaphragmatic hernia: a placebo-controlled study

OBJECTIVE

We sought to investigate effects of intratracheal albumin injection prior to tracheal occlusion (TO) on lung proliferation in fetal rats with nitrofen-induced congenital diaphragmatic hernia.

STUDY DESIGN

On embryonic day 19, nitrofen-exposed fetuses underwent TO, TO and 50 microL of either intratracheal albumin 20% or saline, or remained untouched. Main outcome at embryonic day 21.5 was expression of the proliferation marker Ki-67. Secondary outcomes were lung-to-bodyweight ratio (LBWR), tropoelastin expression, density and spatial distribution of elastin, pulmonary/alveolar morphometry, and fetal survival.

RESULTS

TO increased Ki-67 messenger RNA and LBWR. Albumin further increased LBWR and density of Ki-67-positive cells but also fetal mortality. TO with or without adjuncts induced elastin deposits at the tips of arising secondary crests, increased air space size, and decreased septal thickness.

CONCLUSION

TO had effects on lung proliferation and advanced the morphologic appearance. Addition of albumin increased density of proliferating cells and LBWR, yet at the expense of additional fetal loss.