Exosomes Derived from miR-214-Enriched Bone Marrow-Derived Mesenchymal Stem Cells Regulate Oxidative Damage in Cardiac Stem Cells by Targeting CaMKII

Figure 7

Change in CaMKII expression during BMSC-exo-induced antioxidative injury in CSCs under oxidative stress. Cultured CSCs were transfected CaMKII3 overexpression cDNA or siRCaMKII3 for 48 h. Then, the cells were treated with BMSC-exos under different conditions for 24 h and/or cultured with 100 μM H₂O₂ for 2 h. (a) Representative immunofluorescence staining for TUNEL (green), C-kit (red), DAPI (blue), and merged images. Photos were randomly captured using a fluorescence microscope. Scale bar = 20 μm. (b) The panel shows the percentages of TUNEL-positive cells. Compared with H₂O₂, SiRCaMKII3 could significantly decreased the percentage of TUNEL-positive cells. Additionally, compared with Hypoxic-exos, CaMKII3 could partially increase the percentage of TUNEL-positive cells. (c and d) The expression levels of procaspase-3, cleaved caspase-3, Bax, and Bcl-2 were detected by immunoblotting. Compared with Hypoxic-exos or SiRCaMKII3 group, the CaMKII3 group displayed substantially increased cleaved caspase-3 and Bax expression and decreased Bcl-2 expression. In addition, the Hypoxic-exo-induced protective effect against CSC apoptosis under oxidative stress was suppressed by CaMKII3 overexpression. (e and f) Graph represents the SOD and MDA levels in CSCs; compared with H₂O₂ group, Hypoxic-exos or SiRCaMKII3 inhibited MDA levels and increased SOD production, while CSCs were transfected with CaMKII3 increased MDA levels and suppressed SOD production. (g) Transient intracellular Ca²⁺ measurement assays with Fluo-8/AM fluorescent labeling were used to detect Ca²⁺ concentration in CSCs exposed to different treatments. (h) Compared with that in the H₂O₂ or CaMKII3 group, the fluorescence intensity of intracellular Ca²⁺ was significantly decreased in the Hypoxic-exos or siRCaMKII group. Furthermore, CaMKII3 overexpression could suppress the Hypoxic-exo-induced protective effect against CSC oxidative stress injury. ; compared with the H₂O₂ group. compared with the Hypoxic-exos group.

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