Treatment of Pediatric Bronchiolitis Obliterans by Airway Basal Stem Cells

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.