Transplantation of CREG modified embryonic stem cells improves cardiac function after myocardial infarction in mice

Engraftment of embryonic stem cells (ESC) has been proposed as a potential therapeutic approach for post-infarction cardiac dysfunction. However, only mild function improvement has been achieved due to low survival rate and paracrine dysfunction of transplanted stem cells. Cellular repressor of E1A stimulated genes (CREG) has been reported to be a secreted glycoprotein implicated in promoting survival and differentiation of many cell types. Therefore we hypothesized that transplantation of genetically modified ESC with CREG (CREG-ESC) can improve cardiac function after myocardial infarction in mice. A total of 2 × 10⁵ CREG-ESC or EGFP-ESC were engrafted into the border zone in a myocardial infarction model in mice. Cardiac function, infarct size and fibrosis at 4 weeks, survival of transplanted ESC, apoptosis and cytokine level of heart tissue, and teratoma formation were assessed in vivo. Apoptosis of ESC under inflammatory stimuli and cardiac differentiation of ESC were investigated in vitro. After 4 weeks, we found transplantation of CREG-ESC could significantly improve cardiac function, ameliorate cardiac remodeling, and reduce infarct size and fibrosis area. Transplantation of CREG-ESC remarkably increased ESC survival in the border zone and inhibited apoptosis of cardiomyocytes. Furthermore, the decrease of inflammatory factors (IL-1β, IL-6 and TNF-α) and increase of anti-inflammatory factors (TGF-β, bFGF and VEGF165) in the border zone were higher in CREG-ESC transplanted hearts. Safety evaluation showed that all transplantation at 2 × 10⁵ per heart dose produced no teratoma. Surprisingly, the mice with 3.0 × 10⁶ CREG-ESC transplantation was demonstrated teratoma free without cardiac rhythm disturbances in contrast to 100% teratoma formation and rhythm abnormality for the same dose of EGFP-ESC transplantation. In addition, overexpression of CREG inhibits ESC apoptosis and enhanced their differentiation into cardiomyocytes in vitro. Transplantation of CREG-modified ESC exhibits a favorable survival pattern in infarcted hearts, which translates into a substantial preservation of cardiac function after acute myocardial infarction.