Abstract: The characteristics of mesenchymal stem cell （MSC）, including immuno-regulatory, hematopoiesis-supporting and angiogenesis-promoting activities endow it to be the second candidate of adult stem cells beyond hematopoietic stem cells in clinical application. MSC, as a cellular drug, has been officially approved by some governments to treat graft-versus- host disease, Crohn＇s disease and osteoarthritis. Meanwhile, hundreds of clinical trials have been ongoing and thousands of subjects have received MSC therapy. However, it should be noted that serious or even fatal side effects and complications might occur, being aroused by MSC itself and the process of MSC therapy. Therefore, the informed consent of the subjects enrolled in a clinical trial should be reinforced especially the efficacies of MSC therapy on a disease are still in controversy. To rigorously protect the interest of the patients, the details of the therapy including the rationale of the treatment, the potential risks and the measurements that will be taken, and the current managements and their differences from the tested trial, should be readily accessible and comprehensible to the enrolled subjects.

Key words: Mesenchymal stem cells, Ethical issues, Safety