Cardiosphere-derived cell exosomes delivered IM decrease scarring, halt adverse remodelling and improve LVEF in porcine AMI and CMI. While conceptually attractive as cell-free therapeutic agents for myocardial infarction, exosomes have the disadvantage that IM delivery is necessary.

Cardiosphere‐derived cells (CDCs) reduce myocardial infarct size via secreted extracellular vesicles (CDC‐EVs), including exosomes, which alter macrophage polarization. We questioned whether short non‐coding RNA species of unknown function within CDC‐EVs contribute to cardioprotection. The most abundant RNA species in CDC‐EVs is a Y RNA fragment (EV‐YF1); its relative abundance in CDC‐EVs correlates with CDC potency in vivo. Fluorescently labeled EV‐YF1 is actively transferred from CDCs to target macrophages via CDC‐EVs. Direct transfection of macrophages with EV‐YF1 induced transcription and secretion of IL‐10. When cocultured with rat cardiomyocytes, EV‐YF1‐primed macrophages were potently cytoprotective toward oxidatively stressed cardiomyocytes through induction of IL‐10. In vivo, intracoronary injection of EV‐YF1 following ischemia/reperfusion reduced infarct size. A fragment of Y RNA, highly enriched in CDC‐EVs, alters Il10 gene expression and enhances IL‐10 protein secretion. The demonstration that EV‐YF1 confers cardioprotection highlights the potential importance of diverse exosomal contents of unknown function, above and beyond the usual suspects (e.g., microRNAs and proteins).

Background The pathogenesis of HFpEF is unclear, but fibrosis, inflammation and hypertrophy have been put forth as likely contributors. CDCs are heart-derived cell products with anti-fibrotic and anti-inflammatory properties. Objectives We questioned whether allogeneic rat CDCs might be able to decrease manifestations of HFpEF in hypertensive rats. Methods Starting at 7 weeks of age, Dahl salt-sensitive rats were fed a high-salt diet for 6–7 weeks and randomized to receive intracoronary CDCs or placebo. Dahl rats fed normal chow served as controls. Results High-salt rats developed hypertension, left ventricular (LV) hypertrophy and diastolic dysfunction, without impairment of ejection fraction. Four weeks after treatment, diastolic dysfunction resolved in CDC-treated rats but not in placebo. The improved LV relaxation was associated with lower LV end-diastolic pressure, decreased lung congestion and enhanced survival in CDC-treated rats. Histology and echocardiography revealed no decrease in cardiac hypertrophy after CDC treatment, consistent with the finding of sustained, equally-elevated blood pressure in CDC- and placebo-treated rats. Nevertheless, CDC treatment decreased LV fibrosis and inflammatory infiltrates. Serum inflammatory cytokines were likewise decreased after CDC treatment. Whole-transcriptome analysis revealed major HFpEF-related, CDC-reversed changes in numerous transcripts, including many involved in inflammation and/or fibrosis. Conclusion CDCs normalized LV relaxation and LV diastolic pressure while improving survival in a rat model of HFpEF. The benefits of CDCs occurred despite persistent hypertension and cardiac hypertrophy. By selectively reversing inflammation and fibrosis, CDCs may be beneficial in the treatment of HFpEF.

Objective The aim of this study was to evaluate the distribution, concentration and toxicity of cinnamaldehyde in electronic cigarette (e-cigarette) refill fluids and aerosols. Methods The distribution and concentration of cinnamaldehyde were determined in 39 e-cigarette refill fluids plus 6 duplicates using gas chromatography and mass spectrometry (GC/MS). A cinnamaldehyde toxicity profile was established for embryonic and adult cells using a live cell imaging assay, immunocytochemistry, the comet assay and a recovery assay. Results Twenty of the 39 refill fluids contained cinnamaldehyde at concentrations that are cytotoxic to human embryonic and lung cells in the MTT assay. Cinnamon Ceylon aerosol produced in a cartomizer-style e-cigarette was cytotoxic. Cinnamon Ceylon aerosols and refill fluid aerosols (80% propylene glycol or cinnamaldehyde/propylene glycol) made using a tank/boxmod e-cigarette were more cytotoxic at 5 V than 3 V. Using GC/MS, aerosols produced at 5 V contained 10 additional peaks not present in aerosol generated at 3 V. One of these, 2,3-butandione (diacetyl), was confirmed with an authentic standard. Cinnamaldehyde depolymerised microtubules in human pulmonary fibroblasts. At concentrations that produced no effect in the MTT assay, cinnamaldehyde decreased growth, attachment and spreading; altered cell morphology and motility; increased DNA strand breaks; and increased cell death. At the MTT IC50 concentration, lung cells were unable to recover from cinnamaldehyde after 2 hours of treatment, whereas embryonic cells recovered after 8 hours. Conclusions Cinnamaldehyde-containing refill fluids and aerosols are cytotoxic, genotoxic and low concentrations adversely affect cell processes and survival. These data indicate that cinnamaldehyde in e-cigarette refill fluids/aerosols may impair homeostasis in the respiratory system.

BACKGROUND Cardiosphere-derived cells (CDCs) mediate therapeutic regeneration in patients after myocardial infarction and are undergoing further clinical testing for cardiomyopathy. The beneficial effects of CDCs are mediated by the secretion of exosomes and possibly other extracellular membrane vesicles (EMV). OBJECTIVES We investigated the effect of cardiosphere-derived EMVs (CSp-EMV) on fibroblasts in vitro and tested whether priming with CSp-EMV could confer salutary properties on fibroblasts in vivo. METHODS CSp-EMVs were isolated from serum-free media conditioned for 3 days by cardiospheres. Dermal fibroblasts were primed with CSp-EMV for 24 h followed by exosomal micro-ribonucleic acid (miRNA) profiling. In vivo, we injected CSp-EMV-primed or -unprimed dermal fibroblasts (or CSp-EMV) in a chronic rat model of myocardial infarction and defined the functional and structural consequences. RESULTS CSp-EMV amplified their own biological signals: exposure of “inert” fibroblasts to CSp-EMV rendered the fibroblasts therapeutic. Intramyocardially-injected CSp-EMV-primed (but not unprimed) fibroblasts increased global pump function and vessel density while reducing scar mass. CSp-EMV priming caused fibroblasts to secrete much higher levels of stromal-cell derived factor 1 and vascular endothelial growth factor, and dramatically changed the microRNA profile of fibroblast-secreted EMVs in vitro. The priming was followed by significant angiogenic and cardioprotective effects. CONCLUSIONS CSp-EMVs alter fibroblast phenotype and secretome in a salutary positive-feedback loop. The phenotypic conversion of inert cells to therapeutically-active cells reveals a novel mechanism for amplification of exosome bioactivity.