Myocardial regeneration therapy has emerged as an alternative therapy for heart failure and is expected to replace current conventional therapies. As a cell source, the presence of resident cardiac stem cells (RCSC) in the heart has been reported by many researchers. These RCSC show multi-potency and are considered to differentiate into myocytes. On the other hand, bone marrow stem cells have received the greatest attention as a source of cell transplantation therapy in the current era, with a larger number of clinical applications reported because of their ease and safety. Myoblasts have also emerged as a possible cell source for clinical applications. We previously found that myoblast-cell-sheet implantation improved cardiac function and ventricle thickness in a rat MI model. Furthermore, we conducted a pre-clinical large animal study using porcine MI and dog DCM models, and confirmed the effectiveness of skeletal myoblast sheets. Thereafter, we conducted clinical applications of skeletal myoblast implantation. It may eventually be possible to perform regeneration therapy as a routine therapeutic method.