The considerable therapeutic potential of human multipotent mesenchymal stromal cells
(MSC) has generated markedly increasing interest in a wide variety of biomedical disciplines.
However, investigators report studies of MSC using different methods of isolation
and expansion, and different approaches to characterizing the cells. Thus it is increasingly
difficult to compare and contrast study outcomes, which hinders progress in the field.
To begin to address this issue, the Mesenchymal and Tissue Stem Cell Committee of
the International Society for Cellular Therapy proposes minimal criteria to define
human MSC. First, MSC must be plastic-adherent when maintained in standard culture
conditions. Second, MSC must express CD105, CD73 and CD90, and lack expression of
CD45, CD34, CD14 or CD11b, CD79alpha or CD19 and HLA-DR surface molecules. Third,
MSC must differentiate to osteoblasts, adipocytes and chondroblasts in vitro. While
these criteria will probably require modification as new knowledge unfolds, we believe
this minimal set of standard criteria will foster a more uniform characterization
of MSC and facilitate the exchange of data among investigators.