Bronchiolitis obliterans (BO) is a chronic lung disease which was initiated with injury of the bronchiolar epithelium and resulted in nonuniform luminal obliteration or narrowing. Among children, the most common form of BO is post-infectious BO with a lack of treatment guidelines or standard therapy. In this study, an open, single-armed study is performed to preliminarily evaluate the safety and efficacy of airway basal stem cells on treatment of pediatric BO.

The study is co-sponsored by Regend Therapeutics and Shanghai Children's Hospital.

Inclusion Criteria:

• Males and females, aged between 28 days and 18 years;
• Diagnosed with bronchiolitis obliterans according to the guidelines;
• Meeting at least one of the following: FEV1 < 55% of predicted value; requiring continuous assisted mechanical ventilation or oxygen therapy;
• None of acute infections within the past four weeks;
• Tolerating bronchoscopy;
• The child and/or parent(s) provide informed consent, and are able to understand and adhere to scheduled visits, treatments, laboratory tests, and other study procedures.

Exclusion Criteria:

• Subjects with bronchiolitis obliterans syndrome (BOS) who are on a current cGVHD treatment regimen at screening.
• At the time of screening, subject who is positive in each of treponema pallidum antibody (TP-Ab), human immunodeficiency virus (HIV) antibody, hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibody test. Hepatitis B virus carriers with stable current condition can be enrolled. Cured hepatitis C patients with negative result in HCV ribonucleic acid (RNA) test can be enrolled as well.
• Subject who is assessed to have major lung diseases other than BO by investigators at screening or who has other severe systemic diseases within 6 months prior to screening and is considered to be unsuitable for this study by investigators.
• Presence of severe coagulation dysfunction at screening and may compromise the safety of bronchoscopy in the investigator's judgment.
• Subjects requiring long-term maintenance anticoagulant therapy or antiplatelet aggregation therapy, and for whom, in the investigator's assessment, the medication cannot be discontinued within a week prior to cell collection and infusion.
• Subjects with suicide risk or a history of psychiatric disorders at screening.
• Participation in another interventional clinical study within 3 months prior to screening.
• Poor compliance, making him or her difficult to complete the study.
• Subjects who is considered to be unsuitable for this study in in the opinion of the investigator.