Activation of MG53 Enhances Cell Survival and Engraftment of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes in Injured Hearts.

Background and Objective: Our previous studies demonstrated that MG53 protein can protect the myocardium, but its use as a therapeutic is challenging due to its short half-life in blood circulation. This study aimed to investigate the cardioprotective role of MG53 on human induced pluripotent stem cell-derived cardiomyocytes (HiPSC-CMs) in the context of myocardial ischemia/reperfusion (I/R). Methods: In vitro: HiPSC-CMs were transfected with adenoviral MG53 (HiPSC-CMs^MG53), in which the expression of MG53 can be controlled by doxycycline (Dox), and the cells were then exposed to H₂O₂ to mimic ischemia/reperfusion injury. In vivo: HiPSC-CMs^MG53 were transplanted into the peri-infarct region in NSG™ mice after I/R. After surgery, mice were treated with Dox (+ Dox) to activate MG53 expression (sucrose as a control of -Dox) and then assessed by echocardiography and immunohistochemistry. Results: MG53 can be expressed in HiPSC-CM^MG53 and released into the culture medium after adding Dox. The cell survival rate of HiPSC-CM^MG53 was improved by Dox under the H₂O₂ condition. After 14 and 28 days of ischemia/reperfusion (I/R), transplanted HiPSC-CMs^MG53 + Dox significantly improved heart function, including ejection fraction (EF) and fractional shortening (FS) in mice, compared to HiPSC-CMs^MG53-Dox, and reduced the size of the infarction. Additionally, HiPSC-CM^MG53 + Dox mice demonstrated significant engraftment in the myocardium as shown by staining human nuclei-positive cells. In addition, the cell survival-related AKT signaling was found to be more active in HiPSC-CM^MG53 + Dox transplanted mice's myocardium compared to the HiPSC-CM^MG53-Dox group. Notably, the Dox treatment did not cause harm to other organs. Conclusion: Inducible MG53 expression is a promising approach to enhance cell survival and engraftment of HiPSC-CMs for cardiac repair. [ABSTRACT FROM AUTHOR]