An alternative approach is to use systemically delivered cells to deliver genes to the lung. Th is approach has been used to enhance the therapeutic potential of stem cellssuch as mesenchymal stem/stromal cells, which demon strate promise in preclinical ALI/ARDS models [39] . Fibroblasts have also been used to successfully deliver genes to the lung to attenuate ALI [40] . Preliminary data from a clinical trial in pulmonary hypertension show that endothelial progenitor cells overexpressing endothelial nitric oxide synthase (NOS3) decrease pulmonary vascular resistance [41] , highlighting the potential of cell-delivered gene therapy for ALI/ARDS.