Both Airspace Ang-2 and airspace RAGE were positively correlated with airspace total protein [38]; in experimental models of MSC therapy for ARDS and clinical studies of ARDS, the concentration of total protein in the airspaces is a good biomarker of lung endothelial cell and epithelial protein permeability [42–46]. This evidence concerns the gene ANGPT2 and acute respiratory distress syndrome.