Over-expression of microRNA-499 within donor heart reduces cardiac ischemia-reperfusion injury

Abstract

Objective To explore the role of over-expression of microRNA-499 (miR-499) within donor heart against ischemia-reperfusion injury.Methods Polymerase chain reaction (PCR) was used to identify the miR-499 transgenic mice (Tg).Donor hearts were obtained from wild-type C57BL/6 (WT) and Tg mice and stored in 4 ℃ saline for 16 h.The release of creatine kinase (CK) and lactate dehydrase (LDH) were detected.Both stored donor hearts were transplanted heterotopieally into syngeneie WT recipient mice.The recovery of graft function indicated by its contraction or beating,was assessed by direct palpation and inspection.The transplanted hearts were harvested at 24 h,then histopathology was observed by haematoxylin-eosin staining.Results Tg mice showed positive stripe,which highly expressed miR-499 gene.Donor hearts from Tg mice significantly reduced the release of CK and LDH as compared to WT donors (3 667.0±194.7) vs.(5 043.0±523.8) U/L; (684.2 ±19.1) vs.(1 068.0±150.0) U/L,respectively) and exhibited lower degree of perivascular inflammation,leukocyte infiltration and myocyte necrosis 24 h after transplantation.The scores of graft function for WT heart grafts were significantly lower than those for Tg heart grafts at the same time-points (0.9 vs.2.3 at 15 min and 2.1 vs.3.4 at 24 h) (P ＜ 0.05).Conclusion Over-expression of miR-499 within donor heart can attenuate inflammatory injury and myocardial cell apoptosis caused by cold ischemia and hot reperfusion,benefit for heart function recovery and have a protective role in heart transplantation. Key words: MicroRNA 499; Ischemia-reperfusion injury; Heart transplantation