A method for preparing a cultured cell sheet for use in treatment of suppressing air leakage, blood leakage, or bodily fluid leakage from a surface layer of an organ, which has tissue adhesiveness and flexibility, the method comprising obtaining a cultured cell sheet by culturing cells including any one type or combination of two or more types of cells selected from the group consisting of fibroblasts, cells of alveolar tissue, cells of myocardial tissue, cells of hepatic tissue, cells of vascular tissue, mesenchymal stem cells, and adipose derived cells, on a cell culture support having a surface coated with a temperature responsive polymer having an upper or lower critical solution temperature of 0° C. to 80° C. in water, in the range of 0.5 μg/cm2 to 5.0 μg/cm2;
- and further comprising:
- (1) adjusting culture medium to a temperature above the upper critical solution temperature or below the lower critical solution temperature;
- and
- (2) detaching the cultured cell sheet.