Cyclin D2 Overexpression Enhances the Efficacy of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes for Myocardial Repair in a Swine Model of Myocardial Infarction.

BACKGROUND

Human induced pluripotent stem cells with normal (wild-type) or upregulated (overexpressed) levels of CCND2 (cyclin D2) expression were differentiated into cardiomyocytes (CCND2CMs or CCND2CMs, respectively) and injected into infarcted pig hearts.

METHODS

Acute myocardial infarction was induced by a 60-minute occlusion of the left anterior descending coronary artery. Immediately after reperfusion, CCND2CMs or CCND2CMs (3×10 cells each) or an equivalent volume of the delivery vehicle was injected around the infarct border zone area.

RESULTS

The number of the engrafted CCND2CMs exceeded that of the engrafted CCND2CMs from 6- to 8-fold, rising from 1 week to 4 weeks after implantation. In contrast to the treatment with the CCND2CMs or the delivery vehicle, the administration of CCND2CM was associated with significantly improved left ventricular function, as revealed by magnetic resonance imaging. This correlated with reduction of infarct size, fibrosis, ventricular hypertrophy, and cardiomyocyte apoptosis, and increase of vascular density and arterial density, as per histologic analysis of the treated hearts. Expression of cell proliferation markers (eg, Ki67, phosphorylated histone 3, and Aurora B kinase) was also significantly upregulated in the recipient cardiomyocytes from the CCND2CM-treated than from the CCND2CM-treated pigs. The cell proliferation rate and the hypoxia tolerance measured in cultured human induced pluripotent stem cell cardiomyocytes were significantly greater after treatment with exosomes isolated from the CCND2CMs (CCND2Exos) than from the CCND2CMs (CCND2Exos). As demonstrated by our study, CCND2Exos can also promote the proliferation activity of postnatal rat and adult mouse cardiomyocytes. A bulk miRNA sequencing analysis of CCND2Exos versus CCND2Exos identified 206 and 91 miRNAs that were significantly upregulated and downregulated, respectively. Gene ontology enrichment analysis identified significant differences in the expression profiles of miRNAs from various functional categories and pathways, including miRNAs implicated in cell-cycle checkpoints (G2/M and G1/S transitions), or the mechanism of cytokinesis.

CONCLUSIONS

We demonstrated that enhanced potency of CCND2CMs promoted myocyte proliferation in both grafts and recipient tissue in a large mammal acute myocardial infarction model. These results suggest that CCND2CMs transplantation may be a potential therapeutic strategy for the repair of infarcted hearts.