Abstract 11832: Activated Cardiomyocytes in the Cell Cycle Promote Cardiac Engraftment

Abstract

Rationale: The only treatment for drug-resistant heart failure is heart transplantation, however, it has problems such as donor shortages and rejection. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-cardiomyocytes) are promising sources of regenerative medicine that can solve these problems. The engraftment potential of hiPSC-cardiomyocytes following the transplantation into the host heart should be improved to realize this therapy. Objective: We aim to discover a compound to enhance the engraftment of hiPSC-cardiomyocytes following the cell transplantation into the damaged heart. We also aim to realize a larger graft size and recover cardiac function. Methods and Results: We established an iPSC line constitutively expressing Fluorescent Ubiquitination-based Cell Cycle Indicator (FUCCI), which can show the cell cycle phase in real-time. We compared the engraftment capacity of hiPSC-cardiomyocytes in between the S/G2/M (activation) phase and G0/G1 (inactivation) phase for three months after transplantation, finding cell cycle activated hiPSC-cardiomyocytes showed significantly higher engraftment efficiency than those in inactivated. We, thus, conducted the screening to find cell-cycle activating compounds in the hiPSC-cardiomyocytes. The screening identified some candidates from more than 4000 compounds, and we focused on the most effective compound (CCA-1). An EdU assay and cell number count demonstrated the activation of proliferative capacity by CCA-1. Moreover, genetic analysis revealed a group of genes related to CCA-1-induced cell cycle activation. Finally, using in vivo bioluminescent imaging, we confirmed that CCA-1 treated hiPSC-cardiomyocytes showed enhanced graft size after transplantation into mice ischemic heart. Conclusions: This study highlights the effectiveness of the FUCCI system to analyze the cell cycle status in hiPSC-cardiomyocytes, and the cell cycle activation by CCA-1 is the efficient strategy to increase the graft size following the cell transplantation into the damaged heart.