Method for producing a cultured cell sheet for tissue regeneration

A method for producing a cell sheet for cartilage repair, the cell sheet being formed from a culture of cells derived from a cartilage tissue, the method comprising:

• culturing for 12 to 16 days cells derived from a cartilage tissue on a surface of a membrane, a temperature-responsive polymer comprising poly(N-isopropylacrylamide) being immobilized on the surface, to produce the cell sheet;
• and evaluating the cell sheet of cultured cells as a cell sheet suitable for cartilage repair, when the cell sheet of cultured cells shows positive in immunostaining using an antibody against type 1 collagen and negative in immunostaining using an antibody against type 2 collagen,
• wherein the culturing is stopped before the cell sheet of cultured cells evaluated as the cell sheet suitable for cartilage repair becomes positive for immunostaining using an antibody against type II collagen;
• and wherein the membrane is a pore membrane, and during culturing, the cells are in contact with a culture medium on an upper side of the pore membrane and in contact with a culture medium on a lower side of the pore membrane through pores in the pore membrane.