FIG. 2.

MSCs reorganize their cytoskeleton in response to TGF-β1 after 24 h. (A) Confocal images of soluble-factor-treated MSCs stained with Phalloidin (F-actin, red), anti-α-tubulin (microtubules, green), and 4′,6-diamidino-2-phenylindole (DAPI, nucleus, blue). The shape and cytoskeletal organization of CM and PDGF-treated MSCs were similar, whereas TGF-β1 with or without PDGF-treated MSCs were elongated with condensed cytoskeletal filaments (scale bar=20 μm). (B, C) Cytoskeletal parameters were determined by analysis of confocal images with custom MATLAB routine. The nuclear shape factors (B) were used to characterize the elongation of the nucleus, respectively, with a shape factor of 1 indicating a perfect circle and 0 indicating a straight line. The stress fiber density (C) was used to characterize the density of actin stress fibers per cell area. Cytoskeletal changes observed in TGF-β1-treated (with or without PDGF) MSCs were confirmed using the cytoskeletal parameters, which indicated reduction in nuclear shape factor and increase in stress fiber densities. Results are reported as average±SEM (n=3). Statistical significances were indicated as (*) for p<0.05, (**) for p<0.005, and (***) for p<0.0005. Color images available online at www.liebertpub.com/scd