Original Articles

Circulating and Urinary miR-210 and miR-16 Increase during Cardiac Surgery Using Cardiopulmonary Bypass – A Pilot Study

^* Cardiac Surgery Research and Perfusion, Cardiac and Thoracic Surgical Unit, Flinders Medical Centre, Adelaide, Australia
^† School of Medicine, Flinders University, Adelaide, Australia
^‡ Flinders Centre for Epidemiology and Biostatistics (FCEB), Flinders University, Adelaide, Australia; and the Departments of
^§ Gastroenterology and
^¶ Renal Medicine, Flinders Medical Centre, Adelaide, Australia

Address correspondence to: Annette L. Mazzone, BSc (Hons), CCP (Aust), Dip Perf, Cardiac Surgery Research and Perfusion, Cardiac and Thoracic Surgical Unit, Flinders Medical Centre, Bedford Park, South Australia 5042, Australia. E-mail: annette.mazzone@sa.gov.au

Received: 24 March 2017
Accepted: 8 October 2017

Abstract

A pilot study to measure and compare blood and urine microRNAs miR-210 and miR-16 in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) and off-pump coronary artery bypass grafting surgery. Frequent serial blood and urine samples were taken from patients undergoing cardiac surgery with CPB (n = 10) and undergoing off-pump cardiac surgery (n = 5) before, during, and after surgery. Circulating miR-210 and miR-16 levels were determined by relative quantification real-time polymerase chain reaction. Levels of plasma-free haemoglobin (fHb), troponin-T, creatine kinase, and creatinine were measured. Perioperative serum miR-210 and miR-16 were elevated significantly compared to preoperative levels in patients undergoing cardiac surgery with CPB (CPB vs. Pre Op and Rewarm vs. Pre Op; p < .05 for both). There were increases of greater than 200% in miR-210 levels during rewarming and immediately postoperatively and a 3,000% increase in miR-16 levels immediately postoperatively in urine normalized to urinary creatinine concentration. Serum levels of miR-16 were relatively constant during off-pump surgery. miR-210 levels increased significantly in off-pump patients perioperatively (p < .05 Octopus on vs. Pre Op); however, the release was less marked when compared to cardiac surgery with CPB. A significant association was observed between both miR-16 and miR-210 and plasma fHb when CPB was used (r = −.549, p < .0001 and r = −.463, p < .0001 respectively). Serum and urine concentrations of hypoxically regulated miR-210 and hemolysis-associated miR-16 increased in cardiac surgery using CPB compared to off-pump surgery. These molecules may have utility in indicating severity of cardiac, red cell, and renal injury during cardiac surgery.