Abstract-Cytokine-induced NO production depresses myocardial contractility and has been shown to be cytotoxic to cardiac myocytes. However, the mechanisms of cytokine-induced cardiac myocyte cell death are unclear. To analyze these mechanisms in detail, we treated neonatal cardiac myocytes in serum-free culture with a combination of the macrophage-derived cytokines interleukin-1␤, tumor necrosis factor-␣, and interferon-␥. These cytokines caused a time-dependent induction of cardiac myocyte apoptosis, but not necrosis, beginning 72 hours after treatment, as determined by nuclear morphology, DNA internucleosomal cleavage, and cleavage of poly(ADP-ribose) polymerase, reflecting caspase activation. Apoptosis was preceded by a Ͼ50-fold induction of inducible NO synthase mRNA and the release of large amounts (5 to 8 nmol/g protein) of NO metabolites (NOx) into the medium. Cell death was completely blocked by an NO synthase inhibitor and attenuated by antioxidants (N-acetylcysteine and DTT) and the caspase inhibitor ZVAD-fmk. Cytokines also mediated an NO-dependent, sustained increase in myocyte expression of the Bcl-2 homologs Bak and Bcl-x(L). The NO donor S-nitrosoglutathione also induced apoptosis and cell levels of Bak, but not of Bcl-x(L). All effects of cytokines, including poly(ADP-ribose) polymerase cleavage, could be attributed to interleukin-1␤; interferon-␥ and tumor necrosis factor-␣ had no independent effects on apoptosis or on NOx production. We conclude that cytokine toxicity to neonatal cardiac myocytes results from the induction of NO and subsequent activation of apoptosis, at least in part through the generation of oxygen free radicals. The rate and extent of this apoptosis is modulated by alterations in the cellular balance of Bak and Bcl-x(L), which respond differentially to cytokine-induced and exogenous NO and by the availability of oxidant species. (Circ Res. 1999;84:21-33.)Key Words: poly(ADP-ribose) polymerase Ⅲ protein kinase G Ⅲ nitric oxide Ⅲ Bcl-x(L) Ⅲ oxidative stress

Background Accumulating evidence shows that microRNA-210 (miR-210) holds great promise to improve angiogenesis for brain tissue repair after cerebral ischemia. However, safe and efficient delivery of miR-210 via intravenous administration is still a challenge. In the past decade, exosomes have emerged as a novel endogenous delivery system. Here, c(RGDyK) peptide is conjugated to exosomes, and they are loaded with cholesterol-modified miR-210 (RGD-exo:miR-210). Results In a transient middle cerebral artery occlusion (MCAO) mouse model, the RGD-exo:miR-210 targets the lesion region of the ischemic brain after intravenous administration, resulting in an increase in miR-210 at the site. Furthermore, RGD-exo:miR-210 are administered once every other day for 14 days, and the expressions of integrin β 3 , vascular endothelial growth factor (VEGF) and CD34 are significantly upregulated. The animal survival rate is also enhanced. Conclusions These results suggest a strategy for the targeted delivery of miR-210 to ischemic brain and provide an angiogenic agent for the treatment of ischemic stroke. Electronic supplementary material The online version of this article (10.1186/s12951-019-0461-7) contains supplementary material, which is available to authorized users.