Tracheobronchial innervation is deficient in infants and rats with congenital diaphragmatic hernia and it is rescued by retinoic acid and amniotic fluid stem cells

Resumen

Congenital diaphragmatic hernia (CDH) still causes high mortality in newborns because of severe respiratory failure secondary to pulmonary hypoplasia. In addition, the ensuing chronic pulmonary disease continues to be the most significant source of morbidity in survivors. Pulmonary hypoplasia and lung injury caused by mechanical ventilation have been recognized as the major determinants of respiratory morbidity. However, pulmonary symptoms are also experienced by patients with mild to moderate lung hypoplasia, suggesting that other causes might be involved. Autonomic nerves control tracheobronchial smooth muscle whose contractility modulates lung growth and regulates airway patency. We therefore hypothesized that impaired trachebronchial innervation might interfere with lung development and contribute to induce long-term bronchopulmonary symptoms. Using the nitrofen experimental rat model of CDH, we studied the tracheobronchial innervation and we were able to demonstrate that it was deficient in embryos and fetuses with CDH. We investigated the development of the tracheobronchial innervation, pointing out that it was delayed in embryos and fetuses with CDH and that the neural deficiency was partially compensated by an increase of the supporting glial tissue. In an attempt to translate these findings to the human condition as a partial explanation for chronic lung disease of survivors, we looked for the same lesions in infants with CDH and could confirm their presence. We then undertook to demonstrate that prenatal interventions could improve the above-mentioned deficiencies and demonstrated in cultured hypoplastic rat lungs that both the deficient bronchial innervation and the poor tracheobronchial peristalsis could be rescued by the addition of retinoic acid. Finally, we explored in vitro, in cultured lung explants, and in vivo, using intra-amniotic injection, the possible beneficial effects of amniotic fluid stem cells on hypoplastic lungs and demonstrated the viability of this approach.