The purpose of the present invention is to provide a new medical application using pluripotent stem cells (Muse cells) for regenerative medicine. The present invention provides a cell formulation for treating myocardial infarctions especially severe large scale myocardial infarctions and accompanying heart failure. Said cell formulation contains SSEA3 positive pluripotent stem cells isolated from either mesenchymal tissue from an organism or cultured mesenchymal cells. This cell formulation is based on the following myocardial tissue regeneration mechanism: intravenous administration of Muse cells to subjects with the abovementioned disorders results in said Muse cells selectively accumulating in the damaged myocardial tissue and within said tissue differentiating into cardiac muscle.
