Phenotypic analysis of C57Bl/6 MSCs. (A) Mesemchymal stromal cells (MSCs) were analyzed by flow cytometry analysis for surface expression of CD31, CD34, CD44, CD45, CD73, CD105, and CD11b. The dotted line and the solid line represent the isotype and the specific antibody, respectively. (B) MSCs were tested for their differentiation potential into osteocytes, adipocytes, or chondrocytes in the presence of bone, fat, or cartilage differentiation medium, respectively. The left panel shows a light microscopy picture of Alizarin Red S–stained osteocyte-differentiated MSC at a magnification of ×50, the middle panel shows Oil red–stained lipid droplets in adipocyte-differentiated MSC at ×50 and ×100, and the right panel shows a Alcian blue–stained-chondrocyte-differentiated MSC as ×50.