Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide with the characterization of obstructed airflow. In a large number of patients, diffusion function is impaired along with the progression of disease. REGEND001 cell therapy, comprised of airway basal cells with ability to regenerate lung tissue, is promising to COPD treatment. In this study, a multicenter, randomized, single-blind, placebo-parallel-controlled trial is performed to assess the efficacy and safety of REGEND001 cell therapy in treatment of chronic obstructive pulmonary disease with diffusion capacity defect.

Inclusion Criteria:

• Male or female, aged 40 to 75 at the time of signing informed consent.
• Diagnosed with COPD according to the 2021 Global Initiative for Chronic Obstructive Lung Disease (GOLD).
• The ratio of forced expiratory volume in one second (FEV1)/forced vital capacity (FVC)FEV1/FVC is < 70% after inhalation of bronchodilators.
• The diffusion function of carbon monoxide (DLCO) is ≥ 20% and < 80% of the predicted value at screening.
• Tolerated to pulmonary function tests.
• Tolerated to bronchoscopy
• Voluntary to sign the informed consent, coordinated to finish the trial-related procedures and tests, and capable of recording or stating the change of disease condition in a relatively complete manner.

Exclusion Criteria:

• Females who are pregnant, nursing, or planning to be pregnant within a year after using this product (or males whose spouse planning to be pregnant);

• Subject positive in each of the tests containing treponema pallidum antibody (TP-Ab), human immunodeficiency virus (HIV) antibody, hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibody at screening. But except the followings:

  1. Hepatitis B virus carriers (only HBsAg positive without any hepatitis symptom or sign, and all liver function tests present normal results or abnormal markers without clinical significance by the assessment of investigators);
  2. Cured hepatitis C patients (negative in HCV ribonucleic acid (RNA) test);

• Subject with assessed survival time of < 1 year by investigators at screening;

• Subject with malignant tumors or a history of malignant tumors at screening;

• Subject with infections in lung or other sites, requiring intravenous drug treatment within a week prior to screening;

• Subject with more than 4 moderate-to-severe AECOPD, resulting in hospitalization within a year prior to screening;

• Subject with one or more pathogenetic or serologic findings of the novel coronavirus infection, or symptoms of suspected infection within 6 weeks prior to screening;

• Subject with a history of invasive or noninvasive mechanical ventilation within 4 weeks prior to screening;

• Subject who has taken prednisone tablets orally at a dose of ≥ 20 mg/day (or equivalent amount of other oral corticosteroids) within 4 weeks prior to screening;

• Subject with major lung diseases other than COPD by assessment of investigators at screening;

• Subject with severe systemic diseases other than lung within 6 months prior to screening and assessed to be inappropriate to participate in this trial by investigators;

• Subject with severe anemia or poorly controlled granulocyte deficiency, thrombocytopenia by assessment of investigators;

• Subject with abnormal coagulation and assessed to be negative for the safety of fiberoptic bronchoscopy operations at screening;

• Subject requiring long-term anticoagulation therapy of using antiplatelet coagulant therapeutic agents and disable to discontinue their medications 1 week prior to cell collection and cell infusion as assessed by investigators;

• Subject with a risk of suicide, a history of mental illness or a history of epilepsy at screening;

• Subject with severe arrhythmias or heart conduction disorders (degree II or above) in 12-lead ECG test at screening;

• Subject participated in other clinical trials with interventions within 3 months prior to screening;

• Investigators, co-investigators, research coordinators, employees of research participants or research centers, or their family members;

• Any circumstance considered to probably increase the risk of patients or interfere with the clinical trial.