Abstract 12425: MicroRNA-494 is Released From Endothelial Cells and Transferred to Cardiomyocytes via Extracellular Vesicles to Mediate Anti-Apoptotic Effects

Introduction: Experimental studies suggest that a disrupted coordination of cardiac hypertrophy and angiogenesis contributes to the transition to heart failure indicating that endothelial-cardiomyocyte (CM) communication may be important in maintaining tissue homeostasis. Recent studies demonstrated that microRNAs (miRs) can be transferred between cells via microvesicles (MV) to mediate cell-to-cell communication. Results: To determine whether endothelial cells (EC) can transfer microvesicle embedded miRs to CMs, we overexpressed c.elegans-specific miRs in EC and co-cultured EC with CM in a Boyden chamber to prevent direct cell-to-cell communication (pore size 0.4 µm). C.elegans miRs were significantly enriched in CM with a maximal level at 24h. Moreover, incubation of CM with MV isolated from c.elegans miR overexpressing EC led to an increase in c.elgans miR-expression in CM. Next, we determined whether EC can transfer functionally active miRs. EC showed high expression of miR-494 particularly after being transduced with the flow-dependent transcription factor KLF2. Since miR-494 was shown to inhibit CM apoptosis, we determined whether miR-494 can be transferred and provide an anti-apoptotic activity in CM. Indeed, isolated MV of KLF2-transduced EC, flow-exposed or miR-494 overexpressing EC contain significantly increased miR-494 levels (1.44+-0.11-fold, 4.54+-2.08-fold and 32.61+-7.63-fold, respectively). miR-494 enriched MV further significantly reduced H2O2 or ischemia/reperfusion injury dependent apoptosis of CM (2.28+-0.20-fold lower in miR-494 enriched CM vs control CM). Mechanistically, Western blot results indicate that the miR-494 targets PTEN, CamK 2δ and Rock1 are reduced in MV-treated CM. Summary: Together our results indicate a cross-talk between ECs and CMs based on transfer of miRs in microvesicles, which is enhanced by flow-induced KLF2. MVs might be used as a carrier for miR-494 to induce cardioprotective effects after ischemia in the heart.