Mesenchymal stem cell treatment in hyperoxia‐induced lung injury in newborn rats

The aim of this study was to evaluate the effectiveness of tracheally delivered mesenchymal stem cells (MSC) on lung pathology in a hyperoxia-induced lung injury (HILI) model in neonatal rats.For the HILI model, rat pups were exposed to 85-95% oxygen during the first 10 days of life. Rats were divided into six groups: room-air normoxia (n = 11); room air, sham (n = 11); hyperoxia exposed with normal saline as placebo (n = 9); hyperoxia exposed with culture medium of MSC (n = 10); hyperoxia exposed with medium remaining after harvesting of MSC (n = 8); and hyperoxia exposed with MSC (n = 17). Pathologic changes, number and diameter of alveoli, α-smooth muscle actin (α-SMA) expression and localization of MSC in the lungs were assessed.Number of alveoli increased and alveolar diameter decreased in the mesenchymal stem cell group so that there were no differences when compared with the normoxia group (P = 0.126 and P = 0.715, respectively). Expression of α-SMA decreased significantly in the mesenchymal stem cell group compared with the placebo group (P < 0001). Green fluorescent protein-positive cells were found in lung tissue from all rats given MSC. Some green fluorescent protein-positive MSC also expressed surfactant protein-C.Mesenchymal stem cells became localized in damaged lung tissue, and recovery approximated the room air control.