Abstract
Although epicardial blood flow can be restored by an early intervention in most cases, a lack of adequate reperfusion at the microvascular level is often a limiting prognostic factor of acute myocardial infarction (AMI). Our group has recently found that paracrine factors secreted from apoptotic peripheral blood mononuclear cells (APOSEC) attenuate the extent of myocardial injury. The aim of this study was to determine the influence of APOSEC on microvascular obstruction (MVO) in a porcine AMI model. A single dose of APOSEC was intravenously injected in a closed chest reperfused infarction model. MVO was determined by magnetic resonance imaging and cardiac catheterization. Role of platelet function and vasodilation were monitored by means of ELISA, flow cytometry, aggregometry, western blot and myographic experiments in vitro and in vivo. Treatment of AMI with APOSEC resulted in a significant reduction of MVO. Platelet activation markers were reduced in plasma samples obtained during AMI, suggesting an anti-aggregatory capacity of APOSEC. This finding was confirmed by in vitro tests showing that activation and aggregation of both porcine and human platelets were significantly impaired by co-incubation with APOSEC, paralleled by vasodilator-stimulated phosphoprotein (VASP)-mediated inhibition of platelets. In addition, APOSEC evidenced a significant vasodilatory capacity on coronary arteries via p-eNOS and iNOS activation. Our data give first evidence that APOSEC reduces the extent of MVO during AMI, and suggest that modulation of platelet activation and vasodilation in the initial phase after myocardial infarction contributes to the improved long-term outcome in APOSEC treated animals.Electronic supplementary materialThe online version of this article (doi:10.1007/s00395-012-0292-2) contains supplementary material, which is available to authorized users.
Highlights
We provide evidence that intravenous application of APOSEC attenuates myocardial infarction by reducing microvascular obstruction (MVO) in a porcine closed chest ischemia/reperfusion acute myocardial infarction (AMI) model
Based on recent observations showing that the infusion of cultured apoptotic peripheral blood mononuclear cells (PBMC) was able to prevent experimental AMI in rodents [4, 38] we speculated whether paracrine factors secreted from PBMC—termed APOSEC— are capable to attenuate AMI in a rodent and in a closed chest porcine ischemia/reperfusion AMI model
APOSEC is a compound made of soluble factors secreted by irradiated PBMC and has previously been shown to abrogate myocardial damage in a large animal ischemia reperfusion AMI model
Summary
We provide evidence that intravenous application of APOSEC attenuates myocardial infarction by reducing MVO in a porcine closed chest ischemia/reperfusion AMI model. Based on recent observations showing that the infusion of cultured apoptotic peripheral blood mononuclear cells (PBMC) was able to prevent experimental AMI in rodents [4, 38] we speculated whether paracrine factors secreted from PBMC—termed APOSEC (abbreviation for APOptotic cell SECretoma)— are capable to attenuate AMI in a rodent and in a closed chest porcine ischemia/reperfusion AMI model. A possible mode of action was suggested by showing that co-incubation of primary human cardiomyocytes with APOSEC led to an activation of pro-survival signalling-cascades (AKT, Erk1/2, CREB, c-Jun), and increased anti-apoptotic gene products (Bcl-2, BAG-1) in vitro, protecting cardiomyocytes from starvation-induced cell death [39]
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