Figure 4. C23 attenuates DOX-induced cardiac apoptosis in mice.

DOX uptake in the heart was assessed by reflectance fluorescence imaging, and the resultant apoptosis was simultaneously imaged with Anx-750, a near-infrared fluorescent annexin V probe. (A) DOX fluorescence in a phantom calibration study increased linearly with increasing concentration. (B) Representative ex vivo short-axis heart slices of mouse hearts showing differential DOX uptake 24 hours after a 15 mg/kg DOX injection. (C) Representative ex vivo images of Anx-750 accumulation showed marked reduction in Anx fluorescence after cotreatment with C23 at a dose of 2 mg/kg. A significant reduction in apoptosis was seen with all 3 doses of C23 tested. (D) Cardiac annexin uptake increased significantly in the DOX-only group (DOX+carrier) compared with the control mice injected with saline. Annexin uptake was reduced significantly with treatment with C23. C23 administered at doses of 0.1, 1, and 2 mg/kg all conferred a significant cardioprotective effect. Positive DOX uptake in the heart was confirmed by direct imaging. A total of 45 mice were included in the study as follows: 0.9% saline, i.p. injection (n = 7); 15 mg/kg DOX in saline, and carrier only, i.p. (n = 17); 15 mg/kg DOX in saline, and 0.1 mg/kg 23, i.p. (n = 7); 15 mg/kg DOX in saline, and 1 mg/kg 23, i.p. (n = 7); and 15 mg/kg DOX in saline, and 2 mg/kg 23, i.p. (n = 7). Data are represented as mean ± SEM. *P < 0.05, **P < 0.01, and ***P < 0.001, 1-way ANOVA followed by the Tukey’s test. Carrier, 10% DMSO + 90% olive oil. (E) DOX retention in the heart was assessed by direct reflectance fluorescence imaging, and quantified as an increase in signal/noise ratio (SNR) compared with the control mice without DOX injection. No significant difference in DOX fluorescence increase was seen between the DOX only and any of the C23-treated mice. P > 0.05, 1-way ANOVA. Veh., 10% DMSO.