Figure 1.

Characterization of bone marrow-derived mesenchymal stromal cells (BMSCs). (a) Morphology of BMSCs at 5 d; after cell culture for 24 h, only several adherent cells were found. Five to seven days later, a colony made of hundreds of cells was recognized and mononuclear cell's shapes were fusiformis or polygon. Magnification: ×100. (b) Optical imaging of β-actin-Fluc⁺ BMSCs and the linear correlation between cell number and densities of Fluc signals; the densities of Fluc signals were strongly correlated to the number of cells (R ² = 0.95, P < 0.01). (c) Flow cytometry analysis of mouse BMSCs labeled with phycoerythrin/allophycocyanin-conjugated CD34, CD45, CD44, and CD90; most BMSCs expressed typical stem cell markers CD90 (89.2%) and CD44 (87.6%) and low levels of hematopoietic markers CD45 (2.3%) and CD34 (1.8%). Bar scale = 100 μm; n = 6.