Changes of Plasma microRNAs in Heart Transplantation Patients Do Not Reflect microRNA Changes in the Cardiac Allograft Vasculopathy Vessel Wall

Abstract

Purpose A limiting factor for long term survival after heart transplantation (HTx) is cardiac allograft vasculopathy (CAV). CAV is characterized by hyperplasia of the intima in coronary arteries. Recently the importance of microRNAs (miRs) was described in multiple vascular diseases. The aim of our study was to determine whether changes in miR expression in plasma post HTx reflect changes in the coronary vessel wall of patients with CAV. Methods and Materials Pooled plasma of HTx patients (two pools, each n=3) was analyzed at 6 and 52 weeks after HTx and compared to healthy control plasma. CAV vessels (n=6) were obtained after autopsy and the intimal layer was isolated by tissue laser microdissection. MiR expression in plasma and vessel wall was determined using Q-PCR arrays. Eight miRs were selected from both array analyses (plasma & vessel wall). Criteria for selection were: fold change >2x, Cq-values Results Array analyses showed miR expression changes over time after HTx and in intimal tissue. Within the Q-PCR validation of plasma 1 miR (1/8) showed a significant up-regulation over time (miR-132). The intimal tissue analysis showed 5 miRs (5/8) to have a significant up- (miR-21, -223, and -146b-5p) or down-regulation (miR-886-5p and -214). Within the top 8 of plasma and intima array analysis no overlap was found in the detected miRs. Conclusions MiRs in CAV patients do alter both in plasma and vessel wall. However, the changes in plasma do not reflect changes in the CAV vessel wall. Q-PCR validation on tissue samples confirmed more miRs than validation in plasma, indicating that miRs in tissue show a more representative pattern in array analysis. The miRs selected from the neo-intimal layer might have a role in CAV development and could be considered potential therapeutic targets in the future.