Approaches of translational medicine to face bronchopulmonary dysplasia

Background High-flux oxygen supplementation is provided to extremely preterm babies soon after birth, to ensure appropriate blood oxygenation and help the immature lung to thrive in extrauterine life. This treatment is necessary, but its burden is not insignificant. The oxygen supplementation causes mild-to-severe damage to the immature lungs of the newborns, affecting their development. The most relevant pathological findings are interstitial fibrosis, morphogenic alterations, altered gas exchange and dysmorphic vessels and capillaries (impaired angiogenesis), and pulmonary hypertension caused by the thickening of the muscle layer of the arterioles. Pulmonary hypertension is the main cause of death for BronchoPulmonary Dysplasia. Aims of the study The focus of this thesis is BronchoPulmonary Dysplasia (BPD), a life-threatening chronic disease that affects many preterm newborns every year, 15-35% of the babies born at <32 weeks of gestation, and to find a therapy to prevent severe life-long consequences among them. An oxidative damage has been created to mimic the hyperoxic environment of BPD. Nanoparticles have been used as an anti-oxidative drug starting from the recent clinical trial EVENEW, which applies Extracellular Vesicles derived from Mesenchymal Stromal Cells (MSC-EVs) to prevent BPD in premature babies. Gene and protein analysis aimed to shed light on the MSC-EVs mechanism of action in preventing BPD. Materials and Methods Two translational models were assessed to study the impact of this disease on the lungs and more specifically in the alveoli. Alveolar Epithelial cells and Lung Fibroblasts were cultured in three-dimensional (3D) models: lung spheroids and organoids. Evaluating the 3D structures after oxidative damage carried out with H2O2 or Rotenone, we analyzed the rescue achieved with a classic antioxidant molecule (Vitamin C) or with an experimental therapy with MSC-EVs. Results We observed a reduction in oxidation and death in spheroids treated with MSC-EVs in all the assays performed. Protein detection analysis for Cleaved Caspase 3 showed a reduction in cell death which was statistically significant (p<0.0261) and for 8-Oxo-2’deoxyguanosine (DNA damage caused by ROS) the decrease was even more relevant (p<0.0001). Gene expression analysis confirmed these results: elevated levels of antioxidant enzymes like SOD2 were detected, and also DNA repair enzymes like Ogg1. Conclusions Our translational models to face BPD confirmed their relevance and usefulness and strengthened the importance of the employment of MSC-EVs as a therapeutic tool.