1. pregnancy, lactation, and those who are not pregnant but did not, or unwilling to, take effective contraceptives measures 4 weeks before and after the treatment. 2. patients with malignant tumors or other serious systemic diseases. 3. patients with hemoglobin \< 10 g, alanine aminotransferase (alt) ≥ 5 × uln, aspartate aminotransferase (ast) ≥ 5 × uln, alkaline phosphatase (alp) ≥ 5 × uln, total bilirubin (tbili) ≥ 2 × uln, serum creatinine \> 2.5 mg/dl, platelet counts \< 100,000/μl, wbc \< 3,000 cells/μl, or neutrophil counts \< 1,000/μl at screening. 4. presence of barotrauma or hemodynamic instability defined as hypotension with diastolic blood pressure \< 90 mmhg or mean arterial pressure (map) \< 70 mmhg despite fluid expansion, and vasoactive support or pneumothorax at screening. 5. uncontrolled hypertension with systolic blood pressure \> 170 mmhg and diastolic blood pressure \> 100 mmhg which, in the investigator's judgment, would not make participation appropriate. 6. recent history of (within 2 years) ischemic heart disease or cerebrovascular attack, such as myocardial infarction, unstable angina, or stroke. 7. recent history (within 2 years) of hypercoagulable disorder, antiphospholipid syndrome, pulmonary embolism, or deep venous thrombosis. 8. condition other than covid-19 that is projected to limit lifespan to ≤ 1 year. 9. history of drug or alcohol abuse within the past 24 months. 10. unwilling to commit to follow-up visits. 11. patients who are participating in other clinical trials with an investigational product. 12. co-infection of hiv, tuberculosis, influenza virus, adenovirus, and other respiratory infection virus. 13. patients with other conditions that are not suitable to participate in this clinical study as determined by the investigator.

1. pregnancy, lactation, and those who are not pregnant but did not, or unwilling to, take effective contraceptives measures 4 weeks before and after the treatment. 2. patients with malignant tumors or other serious systemic diseases. 3. patients with hemoglobin \< 10 g, alanine aminotransferase (alt) ≥ 5 × uln, aspartate aminotransferase (ast) ≥ 5 × uln, alkaline phosphatase (alp) ≥ 5 × uln, total bilirubin (tbili) ≥ 2 × uln, serum creatinine \> 2.5 mg/dl, platelet counts \< 100,000/μl, wbc \< 3,000 cells/μl, or neutrophil counts \< 1,000/μl at screening. 4. presence of barotrauma or hemodynamic instability defined as hypotension with diastolic blood pressure \< 90 mmhg or mean arterial pressure (map) \< 70 mmhg despite fluid expansion, and vasoactive support or pneumothorax at screening. 5. uncontrolled hypertension with systolic blood pressure \> 170 mmhg and diastolic blood pressure \> 100 mmhg which, in the investigator's judgment, would not make participation appropriate. 6. recent history of (within 2 years) ischemic heart disease or cerebrovascular attack, such as myocardial infarction, unstable angina, or stroke. 7. recent history (within 2 years) of hypercoagulable disorder, antiphospholipid syndrome, pulmonary embolism, or deep venous thrombosis. 8. condition other than covid-19 that is projected to limit lifespan to ≤ 1 year. 9. history of drug or alcohol abuse within the past 24 months. 10. unwilling to commit to follow-up visits. 11. patients who are participating in other clinical trials with an investigational product. 12. co-infection of hiv, tuberculosis, influenza virus, adenovirus, and other respiratory infection virus. 13. patients with other conditions that are not suitable to participate in this clinical study as determined by the investigator.

pregnancy, lactation, and those who are not pregnant but did not, or unwilling to, take effective contraceptives measures 4 weeks before and after the treatment. patients with malignant tumors or other serious systemic diseases. patients with hemoglobin < 10 g, alanine aminotransferase (alt) ≥ 5 × uln, aspartate aminotransferase (ast) ≥ 5 × uln, alkaline phosphatase (alp) ≥ 5 × uln, total bilirubin (tbili) ≥ 2 × uln, serum creatinine > 2.5 mg/dl, platelet counts < 100,000/μl, wbc < 3,000 cells/μl, or neutrophil counts < 1,000/μl at screening. presence of barotrauma or hemodynamic instability defined as hypotension with diastolic blood pressure < 90 mmhg or mean arterial pressure (map) < 70 mmhg despite fluid expansion, and vasoactive support or pneumothorax at screening. uncontrolled hypertension with systolic blood pressure > 170 mmhg and diastolic blood pressure > 100 mmhg which, in the investigator's judgment, would not make participation appropriate. recent history of (within 2 years) ischemic heart disease or cerebrovascular attack, such as myocardial infarction, unstable angina, or stroke. recent history (within 2 years) of hypercoagulable disorder, antiphospholipid syndrome, pulmonary embolism, or deep venous thrombosis. condition other than covid-19 that is projected to limit lifespan to ≤ 1 year. history of drug or alcohol abuse within the past 24 months. unwilling to commit to follow-up visits. patients who are participating in other clinical trials with an investigational product. co-infection of hiv, tuberculosis, influenza virus, adenovirus, and other respiratory infection virus. patients with other conditions that are not suitable to participate in this clinical study as determined by the investigator.

pregnancy, lactation, and those who are not pregnant but did not, or unwilling to, take effective contraceptives measures 4 weeks before and after the treatment. patients with malignant tumors or other serious systemic diseases. patients with hemoglobin < 10 g, alanine aminotransferase (alt) ≥ 5 × uln, aspartate aminotransferase (ast) ≥ 5 × uln, alkaline phosphatase (alp) ≥ 5 × uln, total bilirubin (tbili) ≥ 2 × uln, serum creatinine > 2.5 mg/dl, platelet counts < 100,000/μl, wbc < 3,000 cells/μl, or neutrophil counts < 1,000/μl at screening. presence of barotrauma or hemodynamic instability defined as hypotension with diastolic blood pressure < 90 mmhg or mean arterial pressure (map) < 70 mmhg despite fluid expansion, and vasoactive support or pneumothorax at screening. uncontrolled hypertension with systolic blood pressure > 170 mmhg and diastolic blood pressure > 100 mmhg which, in the investigator's judgment, would not make participation appropriate. recent history of (within 2 years) ischemic heart disease or cerebrovascular attack, such as myocardial infarction, unstable angina, or stroke. recent history (within 2 years) of hypercoagulable disorder, antiphospholipid syndrome, pulmonary embolism, or deep venous thrombosis. condition other than covid-19 that is projected to limit lifespan to ≤ 1 year. history of drug or alcohol abuse within the past 24 months. unwilling to commit to follow-up visits. patients who are participating in other clinical trials with an investigational product. co-infection of hiv, tuberculosis, influenza virus, adenovirus, and other respiratory infection virus. patients with other conditions that are not suitable to participate in this clinical study as determined by the investigator.