(A) Real time PCR analysis of hMSCs in various culture conditions for 21 days in continuous electric field mode (30 min per day). AGN: aggrecan; Col 2: type II collagen; Col 1: type 1 collagen; Col X: type X collagen; and Sox9. In culture conditions labeled –E–T, +E–T, –E +T, and +E +T, +E and –E represents presence and absence of electric field, respectively, and +T and –T represent presence and absence of TGF-β1, respectively. Images of collagen type I staining for –E+T (B) and +E+T (C) and collagen type II staining for –E+T (D) and +E+T (E) are also shown. The scale bar represents 50 μm for all images.