? Doctors decided that it was not in the best interests of the subjects to participate in the study, or there was any situation that could not follow the agreement safely, ? there was a history of pulmonary embolism, ? there were patients with human immunodeficiency virus (HIV) infection, ? there were severe organ failure, such as severe liver disease (such as child Pugh score = grade C, AST more than 5 times of the upper limit of normal, or severe renal insufficiency (estimated glomerular filtration rate = 30ml / min / 1.73m2) or patients undergoing continuous renal replacement therapy, hemodialysis, peritoneal dialysis, severe shock or other situations that clinicians think are not suitable for use. (Note: due to the newly discovered disease, clinicians can't give up the hope of treatment at will based on the principle of rescuing the dead and supporting the wounded) ? pregnant and lactating women, or positive pregnancy test before medication, ? human immunodeficiency virus (HIV) infected patients, ? Patients with malignant tumors, except those with cervical carcinoma in situ, skin non metastatic squamous or basal cell carcinoma who have been treated completely, ? any experimental treatment for lung injured cells or stem cells within 28 days before screening and evaluation.

? Doctors decided that it was not in the best interests of the subjects to participate in the study, or there was any situation that could not follow the agreement safely, ? there was a history of pulmonary embolism, ? there were patients with human immunodeficiency virus (HIV) infection, ? there were severe organ failure, such as severe liver disease (such as child Pugh score = grade C, AST more than 5 times of the upper limit of normal, or severe renal insufficiency (estimated glomerular filtration rate = 30ml / min / 1.73m2) or patients undergoing continuous renal replacement therapy, hemodialysis, peritoneal dialysis, severe shock or other situations that clinicians think are not suitable for use. (Note: due to the newly discovered disease, clinicians can't give up the hope of treatment at will based on the principle of rescuing the dead and supporting the wounded) ? pregnant and lactating women, or positive pregnancy test before medication, ? human immunodeficiency virus (HIV) infected patients, ? Patients with malignant tumors, except those with cervical carcinoma in situ, skin non metastatic squamous or basal cell carcinoma who have been treated completely, ? any experimental treatment for lung injured cells or stem cells within 28 days before screening and evaluation.