Can maternal vitamin e supplementation prevent lung hypoplasia in the nitrofen-induced rat model of congenital diaphragmatic hernia?

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.

Is there a role for antioxidants in prevention of pulmonary hypoplasia in nitrofen-induced rat model of congenital diaphragmatic hernia?

BACKGROUND/PURPOSE

Many studies suggest a role for antioxidants in the prevention of lung hypoplasia in nitrofen-induced rat models with congenital diaphragmatic hernia (CDH). This study investigates the oxidative status and the histological outcome of prenatal administration of vitamins E and C with synergistic effect, and effect of N-acetylcysteine (NAC) to improve lung maturation of nitrofen-induced rats.

METHODS

CDH was induced by maternal administration of a single oral dose of nitrofen on day 9.5 of gestation, and the Sprague-Dawley rats were randomly divided into five groups: nitrofen (N), nitrofen + vitamin C (NC), nitrofen + vitamin E (NE), nitrofen + vitamin C + vitamin E (NCE) and nitrofen + NAC (NNAC). A control group in which only vehicle was administered was included. Cesarean section was performed on day 21. Body weight (BW) and total lung weight (LW) of all fetuses with CDH were recorded; lung histological evaluation was performed, and protein content of lungs, determination of thiobarbituric acid reactive substances, and the protein carbonyls in tissue samples were determined.

RESULTS

A total of 133 rat fetuses with CDH were investigated. The body weight and the lung weight of fetuses of all groups that were exposed to nitrofen were significantly decreased than of the control group (P < 0.05). The animals exposed to nitrofen with different antioxidants showed increased protein levels in lung tissue. However, in the NCE and the NNAC groups, protein levels were significantly increased than in the others. Malondialdehyde levels significantly decreased in the NCE and the NNAC groups when compared with the NC and the NE groups. In addition, the NCE and NNAC groups decreased protein oxidation to control levels, and no significant difference was observed between control and these two antioxidants groups. The N, NC, NE and NNAC groups showed minimal improvement in lung histology; the NCE groups showed the most improvement in lung histology when compared with the other nitrofen plus antioxidant groups.

CONCLUSION

Prenatal administration of NAC and vitamin E in combination with vitamin C represented the best effects to avoid oxidative damage and protein content of the lungs in rat pups with CDH at birth.

Improvement of pulmonary hypoplasia associated with congenital diaphragmatic hernia by in utero CFTR gene therapy

Congenital diaphragmatic hernia (CDH) may be an ideal candidate disease for in utero gene therapy as disrupted fetal lung growth plays a significant role in disease outcome. We previously demonstrated that transient in utero overexpression of CFTR during fetal development resulted in lung epithelial proliferation and differentiation. We hypothesized that gene therapy with CFTR would improve the pulmonary hypoplasia associated with congenital diaphragmatic hernia (CDH). CDH was induced by the herbicide 2,4-dichlorophenyl-4-nitrophyl ether (nitrofen) following maternal ingestion at either 10 or 13 days gestation. In utero gene transfer of the CFTR gene was subsequently performed at 16 days gestation. Examination of the fetuses at 22 days gestation revealed little improvement in the CFTR-treated lungs following induction of hernias with nitrofen at 10 days gestation. However, the CFTR gene treatment significantly improved internal surface area, saccular density, overall saccular number, and amount of saccular air space in the lungs that were treated with nitrofen at 13 days gestation. RT-PCR demonstrated that gene transfer occurred following treatment at 13 days gestation but not in the lungs treated with nitrofen at 10 days gestation, despite gene transfer at the same gestational age (16 days) in both groups. As disruption of lung development correlates with the gestational stage at which nitrofen exposure occurs, these results confirmed previous findings that in utero gene transfer efficiency depends on the stage of lung development. Lung development may be significantly delayed in human CDH to allow for successful gene transfer later in gestation, providing a substantial therapeutic window.

Neonatal lung remodeling: structural, inflammatory, and ventilator-induced injury

The developing lung is subject to events, both prenatal and postnatal, that alter the normal developmental process. The degree of insult or injury affects how the lung functions at birth and then responds to the insult throughout childhood. In this article, only 3 of the influences are examined: structural, inflammatory, and mechanical. It is recognized that there is a plethora of other factors that influence lung remodeling.