In recent years, regenerative medicine in which a cell or a tissue of skin, cartilage, bone, blood vessel, organ or the like in human body is removed and cultured, and thereafter used in a treatment of the same person or other person has been developed. The practical application of this technique has been initiated in part. In such regenerative medicine, a small amount of cells collected from a human body are cultured ex vivo, and the cell culture is conducted using a culture vessel such as a petri dish via several times of passage operations. In the passage operation of adhesive cells, the cultured cells attached to the bottom face of the culture vessel are detached using a detachment solution containing, for example, trypsin or the like, and a part thereof is transferred to another culture vessel including a fresh medium. In such procedure, since trypsin used in detachment of the cultured cells leads to degradation of proteins, it is necessary to stop the degradation of proteins by adding a detachment stop solution after executing the detachment of the cultured cells for a short period of time.
However, since detachment of the cultured cells from a culture vessel requires visual observation using a microscope, variation among individual operators is likely to occur. Additionally, also in cases in which automation of the culture apparatus is intended, there still involves a problem that human intervention cannot be avoided in the step of evaluating the detachment of the cultured cell.
In order to solve this problem, a method has been investigated in which an attached cell and a detached cell are discriminated on the basis of the size of the cell area on an image in view of the phenomenon that the cultured cell attached to the culture vessel is found to cover a larger area viewed on the image, while the detached cell is found to cover a smaller area viewed on the image since it takes an approximately spherical shape due to surface tension. However, it is necessary to identify the area before the detachment and the area during/following a detachment treatment for each cell in this method, and thus this method is accompanied by many problems in practical use for cell culture, although it can be used for just research purposes.
Patent Document 1: Japanese Unexamined Patent Application, First Publication No. Hei 2003-235540
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