Characterization of human adipose tissue-derived stem cells (ASCs). (A) Morphology of ZsGreen-positive ASCs was observed under bright-field and green fluorescence. (B) Immunostaining indicated that ASCs were positive for cell surface markers CD29, CD44, CD90, and CD105 and negative for CD34 and CD133. (C) Flow cytometry confirmed that the cells were negative for CD34 and CD133 but that CD29, CD44, CD90, and CD105 were highly expressed. (D) Triplet differentiation assays revealed that ASCs could differentiate into adipocytes, chondrocytes, and osteocytes. Adipocytes, chondrocytes, and osteocytes were stained by Oil Red O, Alcian blue 8GX, and Alizarin red, respectively. DAPI, 4′,6-diamidino-2-phenylindole.