Mesenchymal stem cells (MSCs) comprise a subpopulation with multipotent differentiation capacity. Their culture has been established in the early 1960s when fibroblastoid cells were discussed as supportive stromal cells within the hematopoietic bone marrow niche. Initially, application of MSC was based on the hope to cure defects of cartilage or bone. Later, MSCs were also administered in myocardial infarction or in diseases of the central nervous system as well as in liver or kidney failure. Varying outcomes in these studies might be a result of the heterogeneity of MSC cultures and due to absence of reliable protocols for isolation of the naïve stem cell. However, the immunomodulatory function of MSC resulted in further clinical perspectives: studies have demonstrated that human MSCs reduce allorecognition, interfere with antigen-presenting cells and T-cell function, and generate a local immunosuppressive microenvironment by cytokines. This paved the way for MSC-based treatment of autoimmune diseases and graft-versus-host disease after HLA-mismatched allogeneic hematopoietic stem cell transplantation.

This special issue will become an international forum to summarize recent developments in MSC biology and clinical research. We especially ask for manuscripts that describe molecular characteristics of MSCs or their application in animal models or clinical trials. Reviews that summarize the results of basic research with clinical impact are also welcome. Potential topics include, but are not limited to:

• Optimization of MSC isolation, characterization, and expansion
• Basic research: studies on MSC biology
• Preclinical research: application of MSC in animal models of diseases
• Clinical research: background and results of studies about MSC application in humans

Before submission authors should carefully read over the journal's Author Guidelines, which are located at http://www.hindawi.com/journals/sci/guidelines/. Prospective authors should submit an electronic copy of their complete manuscript through the journal Manuscript Tracking System at http://mts.hindawi.com/ according to the following timetable: