Chronic obstructive pulmonary disease (COPD) is a group of disease characterized by obstructed airflow. Usually, the lung structure is gradually impaired along with the progression of the disease. Recently, the treatment of disease is challenged by shortage of approaches for regenerating the injured lung tissue. Here in this study, investigators intend to perform a single-centered, open, concurrent-controlled phase I/II clinical trial with autologous bronchial basal cells on COPD treatment since they were proved to regenerate lung tissue in animal models. The participants is recruited and divided into experiment group and control group. For patients from experiment group, bronchial basal cells will be isolated, expanded, carefully characterized in vitro and transplanted autologously into lung by fiberoptic bronchoscopy. No intervention is performed for patients from control group. During the study, the safety and efficacy will be evaluated on all the subjects by measuring the key indicators.

Inclusion Criteria:

• Subjects aged between 40 to 75;
• Subjects diagnosed with COPD and meet the following standards: a. sustained airway obstruction; b. post-bronchodilator FEV1<80% predicted value;
• Subjects with DLCO<80% predicted value in spirometry;
• Subjects with a smoking history more than 10 pack-years (current smoker and former smoker);
• Subjects with stable condition for more than 4 weeks;
• Subjects tolerant to bronchoscopy;
• Subjects signed informed consent.

Exclusion Criteria:

• Pregnant or lactating women;
• Subjects with syphilis or any of HIV, HBV, HCV positive antibody;
• Subjects with any malignancy;
• Subjects requiring anti-infection (bacteria or virus) treatment by intravenous drugs;
• Subjects suffering from any of the following pulmonary diseases: asthma, active tuberculosis, pulmonary embolism, pneumothorax, pulmonary artery hypertension caused by other diseases;
• Subjects with a history of invasive or non-invasive mechanical ventilation in the past 4 weeks;
• Subjects suffering from other serious diseases, such as diabetes, myocardial infarction, unstable angina, cirrhosis, and acute glomerulonephritis;
• Subjects with leukopenia (WBC less than 4x10^9 / L) or agranulocytosis (WBC less than 1.5x10^9 / L or neutrophils less than 0.5x10^9 / L) caused by any reason;
• Subjects with severe renal impairment, serum creatinine> 1.5 times of the upper limit of normal;
• Subjects with liver disease or liver damage: ALT, AST, total bilirubin> 2 times of the upper limit of normal;
• Subjects with a history of mental illness or suicide risk, with a history of epilepsy or other central nervous system disorders;
• Subjects with severe arrhythmias (such as ventricular tachycardia, frequent superventricular tachycardia, atrial fibrillation, and atrial flutter, etc.) or cardiac degree II or above conduction abnormalities displayed via 12-lead ECG;
• Subjects with a history of alcohol or illicit drug abuse;
• Subjects allergic to products from cattle and pig;
• Subjects accepted by any other clinical trials within 3 months before the enrollment;
• Subjects with poor compliance, difficult to complete the study;
• Any other conditions that might increase the risk of subjects or interfere with the clinical trial.