Epigenetic alterations in chronically ischemic porcine myocardium
Introduction: Research has shown epigenetic change via alternation of the methylation profile of human skeletal muscle DNA after CPB. In this study we investigated the change in epigenome-wide DNA methylation profiles of porcine myocardium after ischemic insult in the setting of treatment with extracellular vesicle (EV) therapy in normal vs high-fat diet (HFD) pigs.Methods: Four groups of three pigs underwent ameroid constrictor placement to the left circumflex artery (LCx) and were assigned to the following groups: (1) normal diet saline injection, (2) normal diet EV injection, (3) HFD saline injection, and (4) HFD EV injection. DNA methylation was profiled via reduced-representation bisulfite sequencing (RRBS) and compared using a custom bioinformatic pipeline.Results:After initial analysis 441 loci had a nominal p value < 0.05 when examining the effect of ischemia vs. normal heart tissue on a normal diet in absence of treatment. 426 loci at p value threshold < 0.05 were identified when comparing the ischemic vs. normal tissue from high-fat diet animals. When examining the effect of EV treatment in ischemic tissue in normal diet there were 574 loci with nominal P value < 0.05 with two loci FN3KRP (P < 0.001) and SNTG1 (P = 0.03) significant after Bonferroni correction. When examining the effect of EV treatment in ischemic tissue in HFD there were 511 loci with nominal p values < 0.05. After Bonferroni correction two loci had P values less than 0.05, BTC (p=0.008) and PCSK7 (P=0.01)Conclusions: Alterations in DNA methylation were identified in pig myocardium after ischemic insult, change in diet, and treatment with EVs. Hundreds of differentially methylated loci were detected, but the magnitude of the effects was low. These changes represent significant alterations in DNA methylation and merit further investigation.