Aberrant pulmonary lymphatic development in the nitrofen mouse model of congenital diaphragmatic hernia

Characterization of the congenital diaphragmatic hernia model in C57BL/6J fetal mice: a step toward lineage tracing experiments

PURPOSE

Lineage tracing is key to study the fate of individual cells and their progeny especially in developmental biology. To conduct these studies, we aimed to establish a reproducible model of CDH in the most commonly used genetic background strain that is C57BL/6J mice.

METHODS

CDH was induced in C57BL/6J dams by maternal administration of nitrofen + bisdiamine at E8.5. Fetuses from olive oil-gavaged mothers served as controls. Lungs from CDH and control fetuses were compared for (1) growth via radial airspace count (RAC), mean linear intercept (MLI) and gene expression for Fgf10, Nrp1, and Ctnnb1; (2) maturation (Pdpn, Spc, Ager, Abca3, Eln, Acta2, Pdgfra) via gene and protein expression; (3) vascularization via gene and protein expression (CD31, Vegfa, Vegfr1/2, Epas1, Enos).

STATISTICS

unpaired t-test or Mann-Whitney test.

RESULTS

Nitrofen + bisdiamine administration resulted in 36% left-sided CDH (31% mortality). CDH fetuses had hypoplastic lungs and impaired growth (lower RAC, higher MLI, lower Fgf10, Nrp1, Ctnnb1), maturation (decreased Pdpn, Ager, Eln gene expression), and vascularization (decreased Cd31, Vegfr1/2; Epas1 and Enos). Lower protein expression was confirmed for PDPN, ELN and CD31.

CONCLUSION

Modeling CDH in C57BL/6J mouse fetuses is effective in reproducing the classical CDH hallmarks. This model will be critical for lineage tracing experiments.

The proportion of alveolar type 1 cells decreases in murine hypoplastic congenital diaphragmatic hernia lungs

BACKGROUND

Pulmonary hypoplasia, characterized by incomplete alveolar development, remains a major cause of mortality and morbidity in congenital diaphragmatic hernia. Recently demonstrated to differentiate from a common bipotent progenitor during development, the two cell types that line the alveoli type 1 and type 2 alveolar cells have shown to alter their relative ratio in congenital diaphragmatic hernia lungs.

OBJECTIVE

We used the nitrofen/bisdiamine mouse model to induce congenital diaphragmatic hernia and accurately assess the status of alveolar epithelial cell differentiation in relation to the common bipotent progenitors.

STUDY DESIGN

Pregnant Swiss mice were gavage-fed with nitrofen/bisdiamine or vehicle at embryonic day 8.5. The administered dose was optimized by assessing the survival, congenital diaphragmatic hernia and facial abnormality rates of the exposed mouse pups. NanoCT was performed on embryonic day 11.5 and 16.5 to assess the embryonic and early canalicular stages of lung development. At embryonic day 17.5 corresponding to late canalicular stage, congenital diaphragmatic hernia lungs were characterized by measuring the lung weight/body weight ratio, morphometry, epithelial cell marker gene expression levels and alveolar cell type quantification.

RESULTS

Nitrofen/bisdiamine associated congenital diaphragmatic hernia lungs showed delayed development, hypoplasia with morphologic immaturity and thickened alveolar walls. Expression levels of distal epithelial progenitor marker Id2 increased, alveolar type 1 cell markers Pdpn and Hopx decreased, while type 2 cell markers pro-SPC and Muc1 remained constant during the canalicular stage. The number of Pdpn+ type 1 alveolar cells also decreased in congenital diaphragmatic hernia lungs.

CONCLUSION

The mouse nitrofen/bisdiamine model is a potential model allowing the study of congenital diaphragmatic hernia lung development from early stages using a wide array of methods. Based on this model, the alveolar epithelium showed a decrease in the number of alveolar type 1 cell in congenital diaphragmatic hernia lungs while type 2 cell population remains unchanged.

New Insights into Congenital Diaphragmatic Hernia - A Surgeon's Introduction to CDH Animal Models

In recent decades, new research into the developmental defects and pathophysiological basis of congenital diaphragmatic hernia (CDH) has revealed opportunities for the development of innovative therapies. Importantly, the use of animal models to represent this anomaly in the laboratory has resulted in the discovery of many important genetic, epigenetic, and other molecular contributors to this condition. In this review, the most commonly used and newly devised animal models of CDH are presented to familiarize the reader with the latest innovations in the basic sciences.