Suxiao Jiuxin pill promotes exosome secretion from mouse cardiac mesenchymal stem cells in vitro.

Cardiac mesenchymal stem cells (C-MSCs) are endogenous cardiac stromal cells that play a role in heart repair after injury. C-MSC-derived exosomes (Exo) have shown protective effects against apoptosis induced by acute myocardial ischemia/reperfusion. Suxiao Jiuxin pill (SJP) is a traditional Chinese medicine (TCM) formula used in China for the treatment of acute myocardial ischemia, which contains tetramethylpyrazine (TMP) and borneol (BOR) as major components. In this study, we investigated whether SJP treatment affected exosome release from C-MSCs in vitro. C-MSCs prepared from mice were treated with SJP (62.5 µg/mL), TMP (25 µg/mL) or BOR (15 µg/mL). Using an acetylcholinesterase activity assay, we found that both SJP and TMP treatment significantly increased exosome secretion compared to the control ethanol treatment. The neutral sphingomyelinase 2 (nSMase2) pathway was important in exosome formation and packaging. But neither the level of nSMase2 mRNA nor the level of protein changed following SJP, TMP or BOR treatment, suggesting that SJP stimulated exosome release via an nSMase2-independent pathway. The Rab27a and Rab27b GTPases controlled different steps of the exosome secretion pathway. We showed that SJP treatment significantly increased the protein levels of Rab27a, SYTL4 (Rab27a effector) and Rab27b compared with the control treatment. SJP treatment also significantly upregulated the mRNA level of Rab27b, rather than Rab27a. Moreover, SJP-induced increase of C-MSC-exosome release was inhibited by Rab27b knockdown, suggesting that SJP promotes exosome secretion from C-MSCs via a GTPase-dependent pathway. This study reveals a novel mechanism for SJP in modulating cardiac homeostasis.

Exosomes from Suxiao Jiuxin pill-treated cardiac mesenchymal stem cells decrease H3K27 demethylase UTX expression in mouse cardiomyocytes in vitro.

Suxiao Jiuxin pill (SJP) is a traditional Chinese medicine for the treatment of acute coronary syndrome in China, which contains two principal components, tetramethylpyrazine (TMP) and borneol (BOR). Thus far, however, the molecular mechanisms underlying the beneficial effects of SJP on the cardiac microenvironment are unknown. Cardiac mesenchymal stem cells (C-MSCs) communicate with cardiomyocytes (CMs) through the release of microvesicles (exosomes) to restore cardiac homeostasis and elicit repair, in part through epigenetic regulatory mechanisms. In this study, we examined whether SJP treatment altered C-MSC-derived exosomes (SJP-Exos) to cause epigenetic chromatic remodeling in recipient CMs. C-MSC isolated from mouse hearts were pretreated with SJP (SJP-Exos), TMP (TMP-Exos) or BOR (BOR-Exos). Then, HL-1 cells, a mouse cardiomyocyte line, were treated with exosomes from control C-MSCs (Ctrl-Exos), SJP-Exos, TMP-Exos or BOR-Exos. Treatment with SJP-Exos significantly increased the protein levels of histone 3 lysine 27 trimethylation (H3K27me3), a key epigenetic chromatin marker for cardiac transcriptional suppression, in the HL-1 cells. To further explore the mechanisms of SJP-Exo-mediated H3K27me3 upregulation, we assessed the mRNA expression levels of key histone methylases (EZH1, EZH2 and EED) and demethylases (JMJD3 and UTX) in the exosome-treated HL-1 cells. Treatment with SJP-Exo selectively suppressed UTX expression in the recipient HL-1 cells. Furthermore, PCNA, an endogenous marker of cell replication, was significantly higher in SJP-Exo-treated HL-1 cells than in Ctrl-Exo-treated HL-1 cells. These results show that SJP-Exos increase cardiomyocyte proliferation and demonstrate that SJP can modulate C-MSC-derived exosomes to cause epigenetic chromatin remodeling in recipient cardiomyocytes; consequently, SJP-Exos might be used to promote cardiomyocyte proliferation.

Rosuvastatin enhances angiogenesis via eNOS-dependent mobilization of endothelial progenitor cells.

Circulating endothelial progenitor cells (circEPCs) of bone marrow (BM) origin contribute to postnatal neovascularization and represent a potential therapeutic target for ischemic disease. Statins are beneficial for ischemia disease and have been implicated to increase neovascularization via mechanisms independent of lipid lowering. However, the effect of Statins on EPC function is not completely understood. Here we sought to investigate the effects of Rosuvastatin (Ros) on EPC mobilization and EPC-mediated neovascularization during ischemic injury. In a mouse model of surgically-induced hindlimb ischemia (HLI), treatment of mice with low dose (0.1 mg/kg) but not high dose (5 mg/kg) significantly increased capillary density and accelerated blood flow recovery, as compared to saline-treated group. When HLI was induced in mice that had received Tie2/LacZ BM transplantation, Ros treatment led a significantly larger amount of endothelial cells (ECs) of BM origin incorporated at ischemic sites than saline. After treatment of mice with a single low dose of Ros, circEPCs significantly increased from 2 h, peaked at 4 h, declined until 8 h. In a growth-factor reduced Matrigel plug-in assay, Ros treatment for 5 d induced endothelial lineage differentiation in vivo. Interestingly, the enhanced circEPCs and post-HLI neovascularization stimulated by Ros were blunted in mice deficient in endothelial nitric oxide synthase (eNOS), and Ros increased p-Akt/p-eNOS levels in EPCs in vitro, indicating these effects of Ros are dependent on eNOS activity. We conclude that Ros increases circEPCs and promotes their de novo differentiation through eNOS pathway.

Oral L-arginine supplementation in acute myocardial infarction therapy: a meta-analysis of randomized controlled trials.

OBJECTIVE: The objective was to analyze completed trials assessing the effect of oral L-arginine supplementation on clinical outcomes of patients with acute myocardial infarction (AMI). BACKGROUND: Prior trials suggest that oral L-arginine administration improves endothelial function in patients with stable coronary artery disease (CAD). However, it is still unclear whether oral supplementation of L-arginine has any effect on clinical outcomes in patients with unstable CAD, such as AMI. METHODS: We systematically searched PubMed, Cochrane Library, Embase, reviews, and reference lists of relevant articles. The search strategy paired the term "arginine" with the following: "coronary heart disease," "myocardial infarction," "cardiovascular disease," "ischemia," and "trial." We conducted a meta-analysis of randomized, placebo-controlled L-arginine supplementation trials that evaluated clinical outcomes in AMI patients. Two reviewers independently assessed the trials. Differences were resolved by consensus. RESULTS: Only 2 trials (927 participants) were included. None of the 2 studies showed a significant difference in event rate between the L-arginine and placebo groups. In an overall pooled estimate, there was a 7% reduction in mortality in the L-arginine treatment group (105/459, 22.9%) compared with the control group (111/455, 24.4%), which did not reach statistical significance (risk ratio [RR]: 0.93, 95% confidence interval [CI]: 0.74-1.17; P = 0.54). CONCLUSION: Oral L-arginine supplementation has no effect on the clinical outcomes of patients with AMI.