he efficacy of pharmacological and surgical treatments for chronic heart failure after myocardial infarction (MI) is limited. Cell-based regenerative therapy (cell transplantation) improved the blood supply to the damaged heart, and minimized the area of infarc-tion. 1-3 These beneficial effects are mediated, in part, by cytokines, such as hepatocyte growth factor (HGF) and Editorial p ????

IntroductionCell sheets using myoblasts have been developed for the treatment of heart failure after myocardial infarction (MI) bridging to heart transplantation. Stem cells are supposed to be better than myoblasts as a source of cells, since they possess a potential to proliferate and differentiate into cardiomyocytes, and also have capacity to secrete angiogenic factors. Adipose-derived stem cells (ASCs) obtained from fat tissues are expected to be a new cell source for ASC sheet therapies. Administration of angiotensin II receptor blockers (ARBs) is a standard therapy for heart failure after MI. However, it is not known whether ARBs affect the cell sheet therapy. This study aimed to examine ameliorating effects of ASC sheets on heart failure and remodeling after MI, and how pretreatment with ARBs prior to the creation of MI and ASC sheet transplantation modifies the effects of ASC sheets.MethodsASCs were isolated from fat tissues of wild-type rats, and ASC sheets were engineered on temperature-responsive dishes. In in vitro studies using cultured cells, mRNA levels of vascular endothelial growth factor (VEGF) in ASCs were determined by RT-PCR in the presence of angiotensin II and/or an ARB, irbesartan, under normoxia and hypoxia; mRNA and protein levels of angiotensin II receptor type 1a (AT1aR), type 1b (AT1bR) and type 2 (AT2R) were also determined by RT-PCR and western blotting. In in vivo studies using a rat MI model, effects of transplanted ASC sheets and/or irbesartan on cardiac functions and remodeling after MI were evaluated by echocardiography, histological analysis and molecular biological techniques.ResultsIn the in vitro studies, ASCs expressed higher levels of VEGF mRNA under hypoxia. They also expressed mRNA and protein of AT1aR but not AT1bR or AT2R. Under normoxia, angiotensin II increased the level of VEGF mRNA in ASCs, which was abolished by irbesartan. Under hypoxia, irbesartan reduced the level of VEGF mRNA in ASCs regardless of whether angiotensin II was present or not. In the in vivo studies, ASC sheets improved cardiac functions after MI, leading to decreased interstitial fibrosis and increased capillary density in border zones. These effects of ASC sheets were abolished by oral administration of irbesartan before MI and their transplantation.ConclusionsASC sheets ameliorated cardiac dysfunctions and remodeling after MI via increasing VEGF expression, which was abolished by pretreatment with irbesartan before the creation of MI and transplantation.

Clinical studies have shown that β-blockers could reduce incidence of cardiovascular events, as well as the mortality of patients with chronic heart failure. 7 Carvedilol is a non-selective AR antagonist that blocks β1-and β2-ARs, as well as α1-AR. 8 Carvedilol suppresses SNS activities, and decreases heart rate (HR) and contractility. This action is beneficial to patients with heart failure whose SNS is activated. 9 Carvedilol also causes vasodilation and decreases peripheral vascular resistance without reflex tachycardia by concomitant blockade of α1-and β1-ARs. 10

Topiroxostat showed protective effects against I/R injury with higher potency than allopurinol or NAC. It dramatically inhibited XO activity and TBARS production, suggesting suppression of ROS generation.

Background: Activation of angiotensin receptor type1 (AT1R) and xanthine oxidase (XO) generates reactive oxygen species (ROS), that causes cardiac dysfunction after myocardial infarction (MI). However, it remains unknown whether its inhibition could restore the cardiac function after MI. In the present study, we examined effects of irbesartan and topiroxostat on cardiac function after MI. Methods and results: We studied blood pressure and cardiac function in a rat myocardial infraction model using tail cuff system and echocardiography. Irbesartan and topiroxostat as well as vehicle were orally administered for 35 days to rats 7 days before MI induction. Neither irbesartan nor topiroxostat altered mean blood pressure and heart rate after MI. Treatment with either drugs significantly improved cardiac function after MI. The potency of topiroxostat to restore the cardiac function was approximately half of that of irbesartan. Conclusions: A nonpurine XO inhibitor, topiroxostat improved cardiac function after MI, suggesting that like irbesartan, topiroxostat may be a promising drug to treat congestive heart failure after MI.Effect of topiroxostat on cardiac function after MI in rats Vascular Failure 2018; 2(2): 74-79 75