Hypoxia-preconditioned mesenchymal stem cell-derived exosomes attenuate myocardial ischemia/reperfusion injury by miR-29b-3p via PINK1/Parkin-mediated mitophagy

Figure 4 miR-29b-3p alleviates mitochondrial damage. A: Schematic protocol for transfection of cardiomyocytes with miR-NC and miR-29b-3p; B: Gene Ontology enrichment analysis of differentially expressed target genes between the model and miR-29b-3p treatment groups (P < 0.05); C: Transmission electron microscopy images showing mitochondrial damage; D: Double immunofluorescence staining of mitochondria and LC3B. Scale bar: 10 μm; E: MitoSOX Red staining of myocardial cells. Scale bar: 10 μm; F and G: Study of myocardial cells labeled with MitoSOX Red using flow cytometry; H: Mitochondrial membrane potential staining. Red, JC-1 aggregates. Green, JC-1 monomers; I and J: Representative flow cytometry plots showing the effects of different treatments on mitochondrial membrane potential (I) and quantitative analysis of JC-1 monomers (J); K and L: Western blot assay revealed the protein expression of PINK1, Parkin, and Tim23 and quantitative analysis. ^aP < 0.05, ^bP < 0.01, ^cP < 0.001, ^dP < 0.0001. Con: Control; H/R: Hypoxia/reperfusion; DAPI: 4’,6-diamidino-2-phenylindole; JC-1: 5,5‘,6,6’-Tetrachloro-1,1‘,3,3’-tetraethylbenzimidazolylcarbocyanine iodide; MFI: Mean fluorescent intensity; miR: MicroRNA; NC: Negative control; NS: Not significant.