Human Term Placenta-Derived Mesenchymal Stromal Cells Are Less Prone to Osteogenic Differentiation Than Bone Marrow-Derived Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSC) can be isolated from different tissues. They are capable of differentiating in vitro, for example, to osteoblasts, chondrocytes, or adipocytes. In contrast to CD34 for hematopoietic stem cells, a distinct MSC-defining antibody is not available. Further, for hematopoietic cells lineage-defining antigens such as CD3 or CD20 are known. In contrast, for MSC-derived cells lineage-associated cell surface markers are far from being established. We therefore investigated expression of cell surface antigens on human term placenta-derived MSC (pMSC) in more detail and correlated expression pattern to the osteogenic differentiation capacity of the MSC. We report that pMSC expressed the typical cell surface antigens at levels comparable to bone marrow-derived MSC (bmMSC), including CD73, CD90, and CD105, but did not express CD11b, CD34, and CD45. Further, CD164, TNAP, and the W5C5 antigens were detected on pMSC, whereas CD349 was not observed. Some pMSC expressed CD146 at low or moderate levels, and their osteogenic differentiation potential was weak. In contrast, bmMSC expressed CD146 at high levels, expression of alkaline phosphatase was significantly higher, and they presented a pronounced osteogenic differentiation potential. We conclude that MSC from different sources differ in their expression of distinct markers, and that this may correlate in part with their lineage determination. Thus, a higher percentage of bmMSC expressed CD146 at prominent levels and such cells may be better suited for bone repair. In contrast, many pMSC expressed CD146 at low or moderate levels. They, therefore, may be suitable for applications in which osteogenic differentiation is undesirable.