Mesenchymal stem cells (MSC) can be isolated from two regions of the placenta, the amniotic mesenchyme and the chorionic mesenchyme. Cells isolated from these placental regions should be confirmed to be of fetal origin.
MSC are defined by three criteria: adherence to plastic, expression of specific antigens, and their ability to differentiate into osteoblasts, adipocytes, and chondroblasts.
More than 95% of the MSC population must express the following markers, CD73, CD105, and CD90. At the same time, less than 2% of the cells should express CD34, CD45, CD14 or CD11b, CD79α or CD19 and HLA class II.