Prospective Isolation of Mesenchymal Stem Cells from Human Bone Marrow and Placenta Using a Frizzled-9-Specific Monoclonal Antibody.

We have recently shown that Frizzled-9 (FZD9) is expressed on the cell surface of multipotential mesenchymal stromal cells derived from human bone marrow (BM) and placenta (PL). To test whether FZD9 is also expressed on primary mesenchymal stem cells (MSC) with CFU-F (colony forming unit fibroblast) capacity, we used the FZD9-specific monoclonal antibody W3C4E11 to fractionate BM and PL cells into FZD9+ and FZD9- populations. Defined numbers of sorted cells were then cultured in a serum free bFGF-containing medium, originally designed fur the culture of human ES cells. 14 days after culture, the resulting fibroblastoid cells were stained with Giemsa staining solution and colonies consisting of > 50 cells were enumerated. In the FZD9+ fraction, a 70 fold increase of the CFU-F frequency in PL and a 80–90 fold increase in BM was observed. Cultured FZD9+ cells also expressed the stem cell markers Oct-4, nanog-3, and nestin, as well as SSEA-4, TRA1-2-49/6E, CD105, CD13, CD164, CD318, and W8B2B10 antigen. After culture under appropriate conditions, FZD9+ cells could be differentiated into cells of the ectodermal (neuronal like cells), endodermal (pancreatic like cells), and mesodermal (adipocytes and osteoblasts) lineages, indicating the multi-lineage differentiation capacity of these cells. In conclusion, FZD9 is a novel marker for the prospective isolation of MSC from human BM and PL.