Safety and Efficacy of MSC-EVs in the Prevention of BPD in Extremely Preterm Infants

Inclusion Criteria: * From birth up to 10 days chronological age. * From 23 weeks up to 28 weeks (27 week+6 days) gestational age at birth. * Birth weight ≥ 500g but ≤1500g. * Endotracheally intubated and receiving mechanical ventilation with FiO2 \> 25% anytime between 3 and 10 days postnatally or needing re-intubation due to respiratory complications, - Not expected to be extubated within the next 24/48 hours after enrolment. * Written informed consent from parents/legally designated representative. Exclusion Criteria: * Surfactant administration less than 24 hours prior to (first) IMP administration. * Has a congenital heart defect, except for patent ductus arteriosus (PDA), atrial septal defect or a small/moderate, restrictive ventricular septal defect. * Has a serious malformation of the lung, such as pulmonary hypoplasia/aplasia, congenital diaphragmatic hernia, or any other congenital lung anomaly. * Being treated with inhaled nitric oxide. * Has a known chromosomal abnormality (e.g., Trisomy 18, Trisomy 13, or Trisomy 21) or a severe congenital malformation (e.g., hydrocephalus and encephalocele, trachea-oesophageal fistula, abdominal wall defects, and major renal anomalies). * Has had a known severe congenital infectious disease (i.e., herpes, toxoplasmosis rubella, syphilis, human immunodeficiency virus, cytomegalovirus, etc.). * Active systemic infection, severe sepsis, or septic shock at Screening up to baseline (phase I) or randomization (phase II). * Underwent a surgical procedure (requiring admission to an operating room) within 72 hours before baseline (phase I)/randomization (phase II) or who is anticipated to have a surgical procedure (requiring admission to an operating room) within 72 hours before or following baseline (phase I)/randomization (phase II). * Has had a Grade 3 or 4 intraventricular haemorrhage (IVH). * Has active pulmonary haemorrhage. * Has periventricular leukomalacia (PVL). * The subject is currently participating in any other interventional clinical study. * The subject is, in the opinion of the Investigator, so ill that death is inevitable, or is considered inappropriate for the study such as an infant that received thoracic compressions and/or adrenaline administration during stabilization in the delivery room and for any reason(s) other than those listed above.