Abstract 10618: Modified Rna Ccnd2 Promotes Myocardial Remuscularizationin Lv Infarct by Regulating Cardiomyocyte Cell Cycle

Abstract

The adult mammalian heart has limited capacity to regenerate, due to postnatal cardiomyocyte cell cycle arrest. This study examined whether the cardiomyocyte cell-cycle reactivation can enhance myocardial remuscularization in hearts with acute myocardial infarction (AMI). Because the G1-to-S phase transition of the cell cycle is critically regulated by cyclin D proteins, and the expression of cyclin D2 (CCND2) could regenerate injured myocardium, we hypothesized that a transient and exclusive overexpression of CCND2 in cardiomyocytes can result in myocytes proliferation and therefore, remuscularize myocardial infarct. The transient and exclusive myocyte overexpression of CCND2 was achieved by Specific ModRNA Translation system (SMRTs) 1 . In vitro assessments were performed in hiPSC-derived cardiomyocytes (hiPSC-CMs) by immunofluorescence staining of cell proliferation markers (Ki67, BrdU, PH3, and Aurora B) to evaluate whether cardiomyocyte-specific modified RNA CCND2 ( CMS modRNA-CCND2) could reactivate cell cycle. Using a mouse model of AMI, normal and infarcted mice were compared 4 weeks after AMI to assess the structural and functional outcomes of myocardial injection 100μg CMS modRNA-CCND2. In vitro , the, CMS modRNA-CCND2 resulted in significantly higher CMs cell cycle activity as evidenced by significantly higher percentage of hiPSC-CMs that expressed Ki67 (8.68 ± 1.64 VS 36.68 ± 2.61 , p<0.01), BrdU (8.44 ± 1.14% VS 17.59 ± 0.84%, p<0.01), PH3 (0.51 ± 0.04% VS 1.68 ± 0.09%, p<0.01), and Aurora B (0.47 ± 0.03% VS 1.59 ± 0.07%, P<0.01), CMS modRNA-Luciferase vs CMS modRNA-CCND2, respectively. In vivo, CMs cell cycle activity was significantly increased in SMRT treated hearts 4 weeks post AMI as evidenced by: Ki67 (0.41 ± 0.04% VS 2.00 ± 0.17%, p<0.01), PH3 (0.039 ± 0.004% VS 0.30 ± 0.006%, p<0.01), AMI VS AMI + SMRT, respectively. LV Infarct size also decreased significantly 4 weeks after AMI in AMI + SMRT group of hearts (50.04 ± 1.42% VS 31.28 ± 1.28%, p<0.01). Thus, CMS modRNA-CCND2 could induce myocardial remuscularization by re-activating CM cell- cycle in hearts with AMI. *, equal contribution first author