The objective of this study is to evaluate the efficacy and safety of a single intratracheal administration of Pneumostem® for treatment of Bronchopulmonary Dysplasia (BPD) in high-risk premature infants by comparing Pneumostem-treated group with a control group.

Inclusion Criteria:

• Age: 5 - 14 days since birth
• Fetal gestational age: ≥23 weeks and <29 weeks
• Birth weight: ≥500g and ≤1250g
• Premature infant of equal to or less than 2 weeks of age who is receiving a ventilator therapy at a rate of > 12 breath/min and > 25% oxygen
• Patient whose ventilator setting has not been changed and who has shown aggravation of the illness within the 24 hours prior to the study enrollment
• Patient with a written consent form signed by a legal representative or a parent upon explanation of the clinical trial

Exclusion Criteria:

• Patient with concurrent cyanotic or acyanotic congenital heart diseases, except for patent ductus arteriosus
• Patient with a concurrent severe lung malformation (i.e. Pulmonary hypoplasia, congenital diaphragmatic hernia, congenital cystic lung disease)
• Patient with a concurrent severe lung malformation with chromosome anomalies (i.e. Edward syndrome, Patau syndrome, Down syndrome, etc) or severe congenital malformation (Hydrocephalus, Encephalocele, etc)
• Patient with a concurrent severe congenital infection (i.e. Herpes, Toxoplasmosis, Rubella, Syphilis, AIDS, etc)
• Patient withCRP > 30 mg/dL; Severe sepsis or shock
• Patient who is scheduled for or expected to undergo a surgical procedure 72 hours prior to/following the administration of the study drug
• Patient who has been administered with a surfactant within the 24 hours prior to the administration of the study drug
• Patient with severe intracranial hemorrhage ≥ grade 3 or 4
• Patient with active pulmonary hemorrhage or active air leak syndrome at the time of screening
• Patient with a history of participating in other clinical studies
• Patient who is allergic to Gentamicin
• Patient who is considered inappropriate to participate in the study by the investigator