Circulating microRNAs and cardiomyocyte proliferation in heart failure patients related to 10 years survival.

AIMS: Mechanochemical signalling drives organogenesis and is highly conserved in mammal evolution. Regaining recovery in myocardial jeopardy by inducing principles linking cardiovascular therapy and clinical outcome has been the dream of scientists for decades. Concepts involving embryonic pathways to regenerate adult failing hearts became popular in the early millennium. Since then, abundant data on stem cell research have been published, never reaching widespread application in heart failure therapy. Another conceptual access, using mechanotransduction in cardiac veins to limit myocardial decay, is pressure-controlled intermittent coronary sinus occlusion (PICSO). Recently, we reported acute molecular signs and signals of PICSO activating regulatory miRNA and inducing cell proliferation mimicking cardiac development in adult failing hearts. According to a previously formulated hypothesis, 'embryonic recall', this study aimed to define molecular signals involved in endogenous heart repair during PICSO and study their relation to patient survival.

METHODS AND RESULTS: We previously reported a study on the acute molecular effects of PICSO in an observational non-randomized study. Eight out of the thirty-two patients with advanced heart failure undergoing cardiac resynchronization therapy (CRT) were treated with PICSO. Survival was monitored over 10 years, and coronary sinus blood samples were collected during intervention before and after 20 min and tested for miRNA signalling and proliferation when co-cultured with cardiomyocytes. A numerically lower death rate post-CRT and PICSO as compared with control CRT only, and a non-significant reduction in all-cause mortality risk of 42% was observed (37.5% vs. 54.0%, relative risk = 0.58, 95% confidence interval: 0.17-2.05; P = 0.402). Four miRNAs involved in cell cycle, proliferation, morphogenesis, embryonic development, and apoptosis significantly increased concomitantly in survivors and PICSO compared with a decrease in non-survivors (hsa-miR Let7b, P < 0.01; hsa-miR- 421, P < 0.006; hsa-miR 363-3p, P < 0.03 and hsa-miR 19b-3p P < 0.01). In contrast, three miRNAs involved in proliferation and survival, determining cell fate, and recycling endosomes decreased in survivors and PICSO (hsa miR 101-3p, P < 0.03; hsa-miR 25-3p, P < 002; hsa-miR 30d-5p P < 0.04). In vitro cellular proliferation increased in survivors and lowered in non-survivors showing a pattern distinction, discriminating longevity according to up to 10-year survival in heart failure patients.

CONCLUSIONS: This study proposes that generating regenerative signals observed during PICSO intervention relate to patient outcomes. Morphogenetic pathways induced by periods of flow reversal in cardiac veins in a domino-like pattern transform embryonic into regenerative signals. Studies supporting the conversion of mechanochemical signals into regenerative molecules during PICSO are warranted to substantiate predictive power on patient longevity, opening new therapeutic avenues in otherwise untreatable heart failure.