Fig. 2

Preparation of hUC-MSC sheets. a Cells were cultured on conventional tissue culture plastic (TCP) or temperature-responsive cell culture dish (TRCD) for 4–5 days. b Cell number was counted using hemocytometer when cultured on TCP or TRCD for 100 h. c Cells cultured on TRCD were detached in sheet form by temperature reduction. d-e Histological analysis of cell sheets was performed by H&E stain and IHC. f–i Cell surface morphology was observed using SEM. j–m Microstructures of hUC-MSC sheets and single hUC-MSCs were analyzed using TEM. White arrows indicated cell junction, red arrows indicated ECMs and yellow arrows indicate endoplasmic reticulum in b. Scale bars indicate 200 μm (a, d, and e), 10 mm (c), and 5 μm (j–m)