Inclusion Criteria:  Age above 18 years. Male and female Must understand and voluntarily sign an Informed Consent for study participation obtained prior to undergoing any study-specific procedures Diagnosed as COVID-19 based upon SARS-CoV-2 RT-PCR test positive Clinical diagnosis meets severe and/or critical parameters Male participants must be willing to ensure their partners do not become pregnant either by practicing abstinence or the use of condoms during sexual activity  Exclusion Criteria:  Participation in another clinical study (with use of another Investigational Medical Product) within 3 months prior to study treatment start Unwillingness or inability to comply with study procedures Patients with serious basic diseases that affect survival, including blood diseases, cachexia, active bleeding, severe malnutrition, etc. Clinically active malignant disease Subjects who are receiving ECMO and CRRT currently History of known pulmonary embolism or known secondary anti-phospholipid syndrome Known or suspected hypersensitivity to any components used to culture the AdMSCs, e.g. BSA and sulfur containing products (e.g., DMSO) Known or suspected allergic to diphenhydramine. Major trauma or surgery within 14 days of study treatment start Mental condition rendering the subject (or the subject's legally acceptable representative[s]) unable to understand the nature, scope and possible consequences of the study Alcohol, drug, or medication abuse within one year prior to study treatment start Any condition that, in the Investigator's opinion, is likely to interfere with evaluation of the AdMSC therapy or satisfactory conduct of the study Irreversible severe end organ failure, such as heart failure/attack, stroke, liver and renal failure due to other disease conditions Patients or family history with hypercoagulable status, such as protein C/protein S deficiency, factor V Leiden, prothrombin gene mutation, dysfibrinogenemia, etc. History of long-term use of immunosuppressive agents Organ transplants in the past 6 months Pregnant, breastfeeding, or desire to become pregnant or unwilling to practice birth control during participation in the study duration, unless surgically sterilized or postmenopausal during the study. Patients with previous pulmonary obstructive pneumonia, severe pulmonary interstitial fibrosis, alveolar proteinosis, allergic alveolitis, and other known viral pneumonia or bacterial pneumonia before COVID-19 infection. The pulmonary imaging revealed the interstitial damage of lungs before the COVID-19 confirmed. QT interval shows greater than 450 ms in males and 470 ms in females in the medical histories or during screen EKG test. Subjects are not medically unstable at time of infusion including but not limiting unstable hypertension, pulse, oximetry, etc.