The respiratory system (i.e., oral-nasal-laryngeal tract, bronchus, trachea, and alveolar sacs in the lungs) is critical for maintenance of an adequate oxygen supply and excretion of carbon dioxide (CO2). For this purpose, the lung parenchyma has a dense capillary network mediating gaseous exchange. The lung is vulnerable to damage from a variety of causes, including viruses, bacteria, toxic chemicals/smoke, food aspiration, septic or cardiogenic shock, resuscitation after circulatory arrest, alveolar-type pulmonary edema, massive blood transfusion, and ischemia-reperfusion injury after bypass surgery or organ transplantation. Moreover, sustained insults may ultimately develop into clinical acute respiratory distress syndrome (ARDS) . Despite pharmacologic advances and continuous renewal of management strategies, in-hospital mortality from ARDS remains unacceptably high. Consequently, there is an urgent need for a safe and efficacious alternative treatment for this high-risk group of patients.