Pretreatment with an angiotensin II receptor blocker abolished ameliorating actions of adipose-derived stem cell sheets on cardiac dysfunction and remodeling after myocardial infarction

Abstract

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.

Esm1 and Stc1 as Angiogenic Factors Responsible for Protective Actions of Adipose-Derived Stem Cell Sheets on Chronic Heart Failure After Rat Myocardial Infarction

“…Isolation and coronary perfusion of hearts were conducted by using a Langendorff perfusion system (Model 7523-40; Masterflex, Barrington, IL, USA), as described previously. 18 Coronary arteries were perfused with a modified Tyrode's solution (NaCl 144, KCl 5, CaCl2 1.5, MgCl2 0.9, HEPES 6, and D-glucose 5 [in mmol/L]; pH 7.4 with NaOH) equilibrated with 100% oxygen. D-luciferin (Toyobo, Osaka, Japan) of 25 μmol (1 mL of 25 mmol/L solution) was injected into coronary arteries of MI hearts through the aorta.…”

“…ADSCs were isolated from the inguinal subcutaneous fat tissue of 8-week-old wild-type (WT) Lewis rats and Tg rats of the same strain, and cultured as described previously. 18,19 To prepare cell sheets, ADSCs were cultured on 35-mm temperature-responsive culture dishes (UpCell, Cell Seed Inc., Tokyo, Japan) in an incubator at 37°C for 48 h. They were then maintained at 20°C for 1 h and were detached as an intact sheet.…”

“…For the 3 MI groups, acute MI was induced by ligation of the left anterior descending artery, as described previously. 12,18,19 Sheet transplantation, as described in our previous report, 12 was performed for the Tg-ADSC and WT-ADSC group rats 7 days after MI.…”

Stem cell-derived cell sheet transplantation for heart tissue repair in myocardial infarction

“…Some studies showed that ADSC-derived cell sheet could attenuate cardiac dysfunction with scarred myocardium repair, cardiac remodeling attenuation, increased cellular engraftment, upregulated growth factor and cytokine expression, decreased interstitial fibrosis, and increased capillary density in border areas [66,67]. Interestingly, an angiotensin II receptor blocker, irbesartan, was observed to abolish the effects of rat ADSC-derived cell sheet on the attenuation of cardiac dysfunction and remodeling in a 5-week AMI rat model [68]. Moreover, Imanishi and his colleagues reported that the transplantation of adipocyte-derived sheet 5 min after AMI surgery ameliorated inflammation and inhibited fibrosis in a mouse AMI model after 2 days or 28 days [47].…”

“…Hypoxia, as a major stress-inducing angiogenesis, can enhance the therapeutic effects of cell sheet in MI via increased vascularization [45]. An angiotensin II receptor blocker, irbesartan, observably abolished the effects of rat ADSC-derived cell sheet on the attenuation of cardiac dysfunction and remodeling in a 5-week MI rat model [68]. It is known that SMs do not easily develop synchronized beating with the host heart; however, studies have shown that improved systolic and diastolic functions exist in the host AMI heart after myoblast transplantation, even without contraction of the transplanted myoblasts, and observable angiogenesis was detected in the transplanted regions, indicating a plausible reason for the role of cell sheet in heart contraction recovery after MI [89,90].…”