Expansion of SP cells by preculture. (A-a) Synovial tissue-derived SP cells were cultured in the DMEM (solid rectangles) or StemPro-34SFM (SFM; shaded rectangles) with different concentration of FBS. Data represent the mean ± S.D. of 6 experiments. Asterisks indicate statistically significant difference (P < 0.01) between control (tissue) evaluated by Dunnet's test. Different characters indicate statistically significant difference (P < 0.05) determined by ANOVA and Tukey's multiple comparison tests. (A-b) SP region expanded by preculture in 1%FBS supplemented SFM (upper panel). The regions were determined by verapamil treatment (lower panel). (B) Phase-contrast images of precultured cells in SFM supplemented with 1% FBS. In the condition, small cell colonies could be observed (arrow). Phase-contrast images of the sorted cells (right). Right-upper panels show SP cells (scale bar = 200 μm) and high-magnification image of these (scale bar = 100 μm). Right-lower panels show NSP cells and high-magnification images of these.