[Problematic issues in clinical trials of mesenchymal stem cells and unraveling strategies]

With the capacities of multiple differentiation, immunoregulatory activities and easy handling for isolation and culture expansion, human bone marrow mesenchymal stem cells (MSCs) have been utilized in clinical trials for the prevention and treatment of graft-versus-host disease in allogeneic bone marrow transplantation, repair of bone and cartilage defects and treatment of cardiac infarction and liver injury. However, increasingly experimental data indicate that a great deal of issues, such as intra-neutralization of calf serum proteins into cultured MSCs, survival of engrafted cells and subsequent cell differentiation tendency, should be in stringent consideration before clinical trials are designed. In this paper, these issues that should be raised and solved in clinical trials with MSCs were reviewed.