The animals were assigned to one of four experimental groups (at a ratio of 1:1:1:1): sham-operated control group (CONTROL, n = 8), control group treated with MSCs (MSC-CONTROL, n = 8), sham-operated sepsis group (SEPSIS, n = 8), and septic group treated with MSCs (MSC-SEPSIS, n = 8). The intervention was open-labeled. In septic animals, peritonitis was induced by inoculating 1 g/kg of autologous feces (collected preoperatively and suspended in 200 mL of isotonic saline at 38°C) into the abdominal cavity followed by a 6-h recovery period (baseline). When sepsis-associated hypotension developed, fluid boluses (10 ml/kg of Ringerfundin solution) were administered in a goal-directed manner guided by filling pressures and cardiac output response as part of hemodynamic resuscitation. Fluid resuscitation was discontinued if there was no further increase in cardiac output (10% threshold) and/or when the pulmonary artery occlusion pressure (PAOP) reached more than 15 mmHg. Continuous infusion of norepinephrine was administered if the mean arterial pressure (MAP) fell below 65 mmHg and no further positive hemodynamic response was elicited via fluid resuscitation. Norepinephrine was titrated to maintain MAP between 65 and 70 mmHg. In MSC-CONTROL and MSC-SEPSIS groups, MCSs were infused in a clinically relevant dose (1 × 106/kg) over 10 min via the central venous line 6 h from the baseline. The MSC dose was chosen on the basis of several previous clinical (5, 6) as well as experimental rodent (1, 2) and large animal studies (7). At the end of the experiment, the animals were euthanized by anesthetic overdose and excision of the heart. Experimental protocol scheme is shown in Figure 1.