FIG. 1.

Characterization of chondrocyte cells and chondrocyte cell sheet in vitro. (A) Chondrocyte cells showing expression of collagen II. Green indicates collagen II; blue, nuclei. Representative flow cytometry analysis of collagen II⁺ cells. Black line indicates collagen II⁺ cells. (B) Confluent chondrocyte cells were spontaneously detached from an UpCell^® dish, which is grafted with temperature-responsive polymers (CellSeed). (C) Confluent chondrocyte cells were cultured in a 35-mm UpCell dish at 37°C and 5% CO₂ (left panel, magnification 10×). The dishes were then transferred to another incubator, set at 20°C, to release the cultured cells as an intact cell sheet (middle and right panel, magnification 10×). (D) Chondrocyte cell sheet maintained collagen II⁺ layer in vitro. Green indicates collagen II; blue, nuclei. (E) Scanning electron microscopy revealed the presence of densely adherent cells and the extracellular matrix–cell adhesion without artificial scaffold in a cell sheet. Scale bar = 10 μm. Color images available online at www.liebertpub.com/tea