COPD is a high morbidity disease. There is no cure for COPD and the imperative need is to develop efficient treatment. Mesenchymal stem cell (MSC) may provide a treatment option in pulmonary emphysema because of their immunomodulatory, anti-inflammatory and alveolar repairing effects in preclinical studies. To study the safety and tolerability and maximum feasible dose of UMC119-06, an allogeneic human umbilical cord MSC, after a single dose administration in subjects with moderate COPD, an open-label, dose-escalation, standard 3+3 design, phase I clinical trial were conducted. The designed doses were low dose (1x10^6 cells/kg), intermediate dose (5x10^6 cells/kg), and high dose (1x10^7 cells/kg). Patients were assessed for pulmonary function, biochemical profile and quality of life over 450 days follow-up. This ongoing study is registered with ClinicalTrials.gov, number NCT04206007, and the recruitment was completed. There have been 5 subjects completing the study, 1 subject withdrawing, and 3 subjects are ongoing long-term follow-up in the study. No SAEs occurred during the interim analysis period, and all TEAEs were mild or moderate in severity at the current doses. The maximum tolerated dose was defined as 1x 107 cell per kg. The data indicated the improvements in FEV1/FVC by 5.38 and 6.00, 6MWT by 31.75 and 44.25 meters, and SGRQ total score by 7.24, 11.79, from baseline to Days 28 and 90 after UMC119-06 infusion. All the subjects had ameliorated or remained in the same grade in mMRC dyspnea scale. The interim analysis result demonstrated that UMC119-06 is feasible, safe and promising therapeutic for COPD.