BACKGROUND/AIMS: CD117(+) stem cell (SC) based therapy is considered an alternative therapeutic option for terminal heart disease. However, controversies exist on the effects of CD117(+) SC implantation. In particular, the link between CD117(+) SC function and angiotensin-II-type-2 receptor (AT2R) after MI is continuously discussed. We therefore asked whether 1) AT2R stimulation influences CD117(+) SC properties in vitro and, 2) which effects can be ascribed to AT2R stimulation in vivo. METHODS: We approached AT2R stimulation with Angiotensin II while simultaneously blocking its opponent receptor AT1 with Losartan. CD117 effects were dissected using a 2D-Matrigel assay and HL-1 co-culture in vitro. A model of myocardial infarction, in which we implanted EGFP(+) CD117 SC, was further applied. RESULTS: While we found indications for AT2R driven vasculogenesis in vitro, co-culture experiments revealed that CD117(+) SC improve vitality of cardiomyocytes independently of AT2R function. Likewise, untreated CD117(+) SC had a positive effect on cardiac function and acted cardioprotective in vivo. CONCLUSIONS: Therefore, our data show that transient AT2R stimulation does not significantly add to the beneficial actions of CD117(+) SC in vivo. Yet, exploiting AT2R driven vasculogenis via an optimized AT2R stimulation protocol may become a promising tool for cardiac SC therapy.
BACKGROUND/AIMS: CD117(+) stem cell (SC) based therapy is considered an alternative therapeutic option for terminal heart disease. However, controversies exist on the effects of CD117(+) SC implantation. In particular, the link between CD117(+) SC function and angiotensin-II-type-2 receptor (AT2R) after MI is continuously discussed. We therefore asked whether 1) AT2R stimulation influences CD117(+) SC properties in vitro and, 2) which effects can be ascribed to AT2R stimulation in vivo. METHODS: We approached AT2R stimulation with Angiotensin II while simultaneously blocking its opponent receptor AT1 with Losartan. CD117 effects were dissected using a 2D-Matrigel assay and HL-1 co-culture in vitro. A model of myocardial infarction, in which we implanted EGFP(+) CD117 SC, was further applied. RESULTS: While we found indications for AT2R driven vasculogenesis in vitro, co-culture experiments revealed that CD117(+) SC improve vitality of cardiomyocytes independently of AT2R function. Likewise, untreated CD117(+) SC had a positive effect on cardiac function and acted cardioprotective in vivo. CONCLUSIONS: Therefore, our data show that transient AT2R stimulation does not significantly add to the beneficial actions of CD117(+) SC in vivo. Yet, exploiting AT2R driven vasculogenis via an optimized AT2R stimulation protocol may become a promising tool for cardiac SC therapy.