Mesenchymal Stromal Cells for Traumatic Brain Injury

Inclusion Criteria: * Age: 18-70 years * Clinical frailty index (CFI) \< 5 * Evidence of TBI confirmed by abnormalities consistent with trauma on CT scan upon admission (Marshall's CT Classification \>1) * Feasibility of study drug (MSC/placebo) administration within 48 hours from TBI * GCS ≤ 8 at recruitment and at least one pupil reactive to light * ICP monitoring already inserted or planned for clinical indications * Weight \< 100 Kg and \> 40 kg Exclusion Criteria: * Motor GCS \> 5 at recruitment * High likelihood (\> 85%) of death in the first 48 h calculated by IMPACT calculator on early admission data * Bilateral mydriasis * Opening ICP \> 40 mmHg * Known history of prior brain injury, psychiatric disorder, neurological impairment and/or deficit * Brain penetrating injury * Spinal cord injury * Previous epilepsy requiring anti-convulsant therapy * Severe organ failure (including PaO2/FiO2\<200 and shock) * Recent serious infectious process * Cancer * Immunosuppression * Human immunodeficiency virus * Positive urine pregnancy test or nursing * Known risk/history of coagulopathy and thromboembolism * Pre-existing and severe: * lung disease (such as asthma, chronic obstructive pulmonary disease), * heart dysfunction (as heart failure and reduced cardiac output), * liver insufficiency (as cirrhosis) * kidney insufficiency * and other organ severe abnormalities * Known hypersensitivity to excipients used in the formulation (Dimethyl sulfoxide (DMSO), Citrate-dextrose solution (ACD)) * Participation in a concurrent interventional study