Early intramyocardial implantation of exogenous mitochondria effectively preserved left ventricular function in doxorubicin-induced dilated cardiomyopathy rat

This study tested the hypothesis that early implantation of mitochondria (Mito) into left myocardium could effectively protect heart against doxorubicin/12 mg/kg-induced dilated cardiomyopathy (DCM) in rat. Adult-male SD rats (n = 18) were equally categorized into group 1 (sham control), group 2 (DCM) and group 3 [DCM + Mito (500 μg/rat intramyocardial injection by day-21 after DCM induction)] and euthanized by day 60. In vitro studies showed that exogenously-transferred Mito was abundantly identified in H9C2 cells. The q-PCR showed significant increase in relative number of mitDNA in Mito-transferred H9C2 cells than in control group (P<0.001). The mRNA-gene and protein expressions of NRF1/NRF2/Tfam/PGC-1α/ERRα/Mfn2 were significantly increased in low-dose Mito-transferred and more significantly increased in high-dose Mito-transferred H29C2 cells than in control group (all P<0.01). Day-60 left-ventricular-ejection-fraction (LVEF) was significantly lower in group 2 than in groups 1 and 3, and significantly lower in group 3 than in group 1 (P<0.0001). The ratios of lung and heart weights to tibial length and myocardial histopathological findings of fibrotic area/myocardial injured score/γ-H2AX+ cells exhibited an opposite pattern to LVEF among the three groups (all P<0.0001). The myocardial protein expressions of oxidative-stress (NOX-1/NOX-2/oxidized protein/p22phox), autophagic (beclin-1/Atg-5/ratio of CL3B-II/CL3B-I), and apoptotic/mitochondrial-damaged (cleaved-caspase-3/mitochondrial Bax/cleaved-PARP/cytosolic-cytochrome-C/DRP1/ cyclophilin D1) biomarkers exhibited an opposite pattern, whereas the protein expressions of mitochondrial integrity (mitochondrial-cytochrome-C/mitochondrial-complex I/II/III/IV and Mfn2/PGC-1) exhibited an identical pattern to LVEF among the groups (all P<0.001). In conclusion, early Mito therapy effectively preserved LVEF and myocardial integrity in DCM rat.