Abstract: Disclosed is a method for evaluating cell differentiation state, including inducing pluripotent stem cells to differentiate into mesodermal cells in a liquid medium by a first differentiation treatment for inducing pluripotent stem cells to differentiate into mesodermal cells and a second differentiation treatment for inducing the mesodermal cells to differentiate into cardiomyocytes; collecting a supernatant of the liquid medium comprising cells induced to differentiate by the second differentiation treatment; and measuring miRNA-3p in miR-1/133a cluster in the supernatant, where the miRNA-3p is at least one selected from a group consisting of miR-1-3p and miR-133a-3p, and the measured value of miRNA-3p is an index of differentiation into cardiomyocytes.

Abstract: The object of the present invention is to improve the post-transplantation engraftment rate of cardiomyocytes that have been purified to such an extent that they are free from non-cardiomyocytes and any components derived from other species. To solve this problem, the present inventors studied the possibility of constructing cell masses from the purified cardiomyocytes. As a result, they revealed that the stated problem could be solved by providing a method of preparing cell masses of cardiomyocytes derived from pluripotent stem cells, characterized in that cell masses of aggregated cells containing cardiomyocytes that had been differentiated and induced from pluripotent stem cells were dispersed to single cells to thereby obtain purified cardiomyocytes, which were then cultured in a culture medium under serum-free conditions so that they were reaggregated.

Abstract: An object of the present invention is to provide an agent for improving quality of an iPS cell, a method for producing an iPS cell, an iPS cell produced by such a method for production, and a composition for producing an iPS cell. The method for producing an iPS cell according to the present invention comprises the step of introducing (a) a nuclear reprogramming substance and (b) an H1foo gene or a gene product thereof into a somatic cell. High-quality iPS cells can be produced in greater quantity by introducing not only a nuclear reprogramming substance but also an H1foo gene or a gene product thereof into a somatic cell.

Abstract: An object of the present invention is to provide an agent for improving quality of an iPS cell, a method for producing an iPS cell, an iPS cell produced by such a method for production, and a composition for producing an iPS cell. The method for producing an iPS cell according to the present invention comprises the step of introducing (a) a nuclear reprogramming substance and (b) an H1foo gene or a gene product thereof into a somatic cell. High-quality iPS cells can be produced in greater quantity by introducing not only a nuclear reprogramming substance but also an H1foo gene or a gene product thereof into a somatic cell.

Abstract: The present invention has as its object to find out new conditions that make it possible to induce cell death of non-cardiomyocytes or undifferentiated stem cells more completely and to select cardiomyocytes only. In order to achieve this object, there are provided in the present application: a cell culture medium for use in inducing cell death of undifferentiated stem cells, wherein the cell culture medium is free of glutamine in the amino acid profile; and also a method for inducing cell death of non-cardiomyocytes by performing cell culture in said cell culture medium. Further provided in this application are: a cell culture medium for use in selecting cardiomyocytes, wherein the cell culture medium is supplemented with lactate, pyruvate or a fatty acid, free of sugar, and free of glutamine in the amino acid profile; and also a method for selecting cardiomyocytes by culturing a mixture of cardiomyocytes and non-cardiomyocytes in said cell culture medium.