Treatment with stem cells facilitate the return to arterial basal levels of blood gases and hemodynamics. (A) The most appropriate dose of endotoxin for the control group (no treatment) was first determined; 1 (solid line) and 3.5 μg/kg (dotted line). (B) Similarly, the dose of MultiStem for the experimental group was determined according to their ability to maintain the PO2 levels after instillation. Doses of 4 (solid line), 10 (dotted line) and 40 million (red line) MultiStem were delivered intrabronchially a half hour after the end of LPS injection. The time of highest pulmonary injury (lowest arterial PO2) is expressed as time zero. (C) Measurement of the PCO2 levels similarly demonstrated a protective effect in the experimental group (solid line) compared to the control (dotted line). Arterial (D) and pulmonary artery (E) pressures stabilize earlier in animals treated with stem cells. The control group (no treatment) is represented with a dotted line. Forty million stem cells were instilled intrabronchially in the experimental group (solid black) 30 minutes after the end of LPS injection. The time of highest PAP is expressed as time zero. LPS, lipopolysaccharide; PAP, pulmonary artery pressure; PCO2, partial pressure of CO2.