Bone marrow cell therapy may be effective in conditions that currently lack effective treatment. Stem cells isolated from different anatomic niches of lungs [34, 35, 43, 44, 45] have been shown to differentiate into multiple epithelial cell types following lung injury. Our lab and Wong and colleagues [13] demonstrated the existence of progenitor epithelial cells in the bone marrow of pigs and humans respectively which are capable of differentiating into type I and II pneumocytes suggesting that these cells will be valuable for lung therapies. Functionally, type I pneumocytes are important for gas exchange, water permeability and the regulation of alveolar fluid homeostasis whereas type II pneumocytes produce lung surfactants that reduce the alveolar surface tension [46] . The isolation and expansion of lung-derived autologous cells from humans is difficult, whereas bone marrow progenitor cells can be easily isolated and expanded. In other preliminary studies, we have isolated progenitor epithelial cells from the lung of pigs. Future in vivo experiments in pigs will be designed to compare the lung repair potential of bone marrow-and lung-derived progenitor epithelial cells following infection and/or LPS-induced lung injury.