Transcatheter aortic valve replacement is a well-established treatment option for high- and intermediate-risk patients with severe symptomatic AVS. However, a specific role for circulating microRNAs in the improvement of cardiac function for patients after TAVR has not yet been investigated. Methods: Circulating EV-associated miRNAs were investigated by using an unbiased Taqman-based human miR array. Several EV-miRNAs were significantly deregulated in AVS patients on day seven after TAVR in comparison to the pre-procedural levels in patients without LVEF-improvement. The higher levels of miR-122-5p were negatively correlated with LVEF improvement at both day seven (r=-0.264 and p=0.015) and at six months (r=-0.328 and p=0.0018). Results: By utilization of patient-derived samples and a murine AVS model, we observed that the expression of miR-122-5p correlates negatively with cardiac function, which is associated with LVEF. Graded wire-injury-induced AVS mice demonstrated a higher level of miR-122-5p, which was related to cardiomyocyte dysfunction. Murine ex vivo experiments revealed that miR-122-5p is highly enriched in ECs in comparison to cardiomyocytes. Co-culture, copy-number analysis, and immunofluorescence demonstrated that miR-122-5p can be shuttled via large EVs from ECs into cardiomyocytes. Gain- and loss-of-function suggested that EV-shuttling of miR-122-5p increases the level of miR-122-5p in recipient cardiomyocytes. Mechanistically, mass spectrometry, miR-pull down, EMSA, and RNA-IP experiments confirmed that miR-122-5p interacts with the RBP, hnRNPU, in a sequence-specific manner to encapsulate miR-122-5p into large EVs. Upon shuttling, miR-122-5p reduces the expression of the anti-apoptotic gene BCL2 , by binding to its 3' untranslated region to inhibit its translation. Conclusion: Increased levels of circulating pro-apoptotic EV-incorporated miR-122-5p are associated with reduced LVEF after TAVR.
Read full abstract