Mesenchymal Stromal Cell Therapy to Prevent Bronchopulmonary Dysplasia in Extreme Preterm Infants

Inclusion Criteria: * Gestational age (GA) less than 28+0 weeks * Post-natal age between 4 and 14 days of life * Invasive ventilation with oxygen requirement: * On mechanical ventilation: intubated patient with any of the following ventilation modes: conventional, HFO or Jet ventilation: * With requirement of FiO2: FiO2 \>= 30% and for at least 12 hours over 24 hours (i.e. flowsheets, FiO2 histogram) Exclusion Criteria: 1. Congenital anomaly: * Genetic and chromosomal syndromes (e.g., Trisomy 13, Trisomy 18, Trisomy 21): either patient with high suspicion (antenatal findings, clinical features) or documented syndrome by genetic testing. * Major congenital anomalies including cardiac (i.e., congenital heart defects, NB. PDA is not considered an exclusion criterion), neurological (e.g., holoprosencephaly, anencephaly), gastrointestinal (e.g., gastroschisis, omphalocele), pulmonary (e.g., congenital diaphragmatic hernia) anomalies. * Inborn errors of metabolism. 2. Hemodynamic instability (shock): * Hemodynamic instability with impaired end-organ perfusion (metabolic acidosis with increased lactate and/or decreased urine output). * Requirements for fluid bolus, inotrope or vasopressor medication 3. Severe sepsis: * Signs of hemodynamic instability and requiring at least one fluid bolus. * And a positive blood or cerebrospinal fluid culture. 4. Pneumothorax: Pneumothorax with a chest tube in place 5. Severe pulmonary hemorrhage: * Active pulmonary hemorrhage (i.e., frank blood coming from the endotracheal tube. * And at least one of the following criteria: a)hemodynamic instability. b) blood product transfusion (packed red blood cells, platelets, fresh frozen plasma) 6. Extubation: If Extubation planned within the next 24 hours (post first uc-MSC administration/sham procedure). 7. Patient is not expected to survive: * Redirection of care. * Patient is moribund