The main purpose at the early phase of septic shock on the evolution of organ failure judged by the SOFA (Sepsis Organ Failure Assessment score) score on Day 7 (or the day of death or the day of discharge from the intensive care unit if before Day 7) compared to SOFA score observed in patients in the control group. The secondary purpose is to assess the role of heterologous mesenchymal stem cells on the occurrence and duration of failure of each organ and on the mortality at day 28 and day 90. The safety of administration will be also assessed.

Patients hospitalized in recovery unit and having a very severe septic shock with community origin (≥ 2 organ failures other than hemodynamic) since less than 12 hours, will receive 10^6/kg heterologous mesenchymal stem cells in 250 ml albumin 4%, infused for 30 minutes in central venous line or 250 ml albumin 4% alone.

Inclusion Criteria:

• Septic shock of community origin since less than 12 hours. The onset time of septic shock is the time of catecholamine introduction( adrenaline, noradrenaline, or dopamine > 8μg/kg/min)
• At least 2 organ failure other than hemodynamic
• Occurrence between Monday 8am and Friday 8am (for availability reasons of staff)
• Signature of informed consent (patient/close relative or reliable person)
• Affiliation to social security plan

Exclusion Criteria:

• Non-septic shock
• Nosocomial septic shock
• PaO2/FiO2 <100
• Pregnant or breast-feeding woman
• Brain death
• Dying person
• Therapeutic limitations
• Participation to another current interventional clinical trial or since less than 30 days