Stem-cell angiogenesis and regeneration of the heart: review of a saga of 2 decades

Pro-Angiogenic Actions of CMC-Derived Extracellular Vesicles Rely on Selective Packaging of Angiopoietin 1 and 2, but Not FGF-2 and VEGF

While the fundamental mechanism by which cardiac cell therapy mitigates ventricular dysfunction in the post ischemic heart remains poorly defined, donor cell paracrine signaling is presumed to be a chief contributor to the afforded benefits. Of the many bioactive molecules secreted by transplanted cells, extracellular vesicles (EVs) and their proteinaceous, nucleic acid, and lipid rich contents, comprise a heterogeneous assortment of prospective cardiotrophic factors-whose involvement in the activation of endogenous cardiac repair mechanism(s), including reducing fibrosis and promoting angiogenesis, have yet to be fully explained. In the current study we aimed to interrogate potential mechanisms by which cardiac mesenchymal stromal cell (CMC)-derived EVs contribute to the CMC pro-angiogenic paracrine signaling capacity in vitro. Vesicular transmission and biological activity of human CMC-derived EVs was evaluated in in vitro assays for human umbilical vein endothelial cell (HUVEC) function, including EV uptake, cell survival, migration, tube formation, and intracellular pathway activation. HUVECs incubated with EVs exhibited augmented cell migration, tube formation, and survival under peroxide exposure; findings which paralleled enhanced activation of the archetypal pro-survival/pro-angiogenic pathways, STAT3 and PI3K-AKT. Cytokine array analyses revealed preferential enrichment of a subset of prototypical angiogenic factors, Ang-1 and Ang-2, in CMC EVs. Interestingly, pharmacologic inhibition of Tie2 in HUVECs, the cognate receptors of angiopoietins, efficiently attenuated CMC-EV-induced HUVEC migration. Further, in additional assays a Tie2 kinase inhibitor exhibited specificity to inhibit Ang-1-, but not Ang-2-, induced HUVEC migration. Overall, these findings suggest that the pro-angiogenic activities of CMC EVs are principally mediated by Ang-1-Tie2 signaling.

Exercise Training Potentiates The Cardioprotective Effects of Stem Cells Post-infarction

BACKGROUND

Preconditioning of cell recipients may exert a significant role in attenuating the hostility of the infarction milieu, thereby enhancing the efficacy of cell therapy. This study was conducted to examine whether exercise training potentiates the cardioprotective effects of adipose-derived stem cell (ADSC) transplantation following myocardial infarction (MI) in rats.

METHODS

Four groups of female Fisher-344 rats were studied: Sham; non-trained rats with MI (sMI); non-trained rats with MI submitted to ADSCs transplantation (sADSC); trained rats with MI submitted to ADSCs (tADSC). Rats were trained 9 weeks prior to MI and ADSCs transplantation. Echocardiography was applied to assess cardiac function. Myocardial performance was evaluated in vitro. Protein expression analyses were carried out by immunoblotting. Periodic acid-Schiff staining was used to analyse capillary density and apoptosis was evaluated with terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay.

RESULTS

Echocardiography performed 4 weeks after the infarction revealed attenuated scar size in the both sADSC and tADSC groups compared to the sMI group. However, fractional shortening was improved only in the tADSC group. In vitro myocardial performance was similar between the tADSC and Sham groups. The expression of phosphoSer473Akt1 and VEGF were found to be higher in the hearts of the tADSC group compared to both the sADSC and sMI groups. Histologic analysis demonstrated that tADSC rats had higher capillary density in the remote and border zones of the infarcted sites compared to the sMI rats.

CONCLUSIONS

Preconditioning with exercise induces a pro-angiogenic milieu that may potentiate the therapeutic effects of ADSCs on cardiac remodelling following MI.

Role of miR-199b-5p in regulating angiogenesis in mouse myocardial microvascular endothelial cells through HSF1/VEGF pathway

Our study explored effects of miR-199b-5p on angiogenesis in mouse myocardial microvascular endothelial cells (MMVECs) and the involved working mechanisms. We applied explant culture to incubate C57/BL6 mouse MMVECs. Lipofection was used to transfect miR-199b-5p mimic, miR-199b-5p inhibitor and miR-199b-5p scramble respectively. MMVECs were divided into miR-199b-5p up-regulation, miR-199b-5p down-regulation and control groups based on above sequence. Expressions of miR-199b-5p, heat shock factor protein 1 (HSF1) mRNA were assessed by real-time quantitative polymerase chain reaction (RT-QPCR). Expressions of HSF1 and vascular endothelial growth factor (VEGF) were assessed by Western Blotting. Cell proliferation was assessed by CCK8. Tubule formation assay was conducted to assess formation of blood vessels. Results showed that miR-199b-5p up/down-regulation groups exhibited no obvious differences in the expressions of HSF1 mRNA compared to control group. However, miR-199b-5p up-regulation group recorded lower expressions of HSF1 and VEGF in the level of protein, and reduced cell proliferation and tubule formation. Whereas, miR-199b-5p down-regulation group presented the contrary results. The experiment indicated that miR-199b-5p can regulate proliferation and angiogenesis in mouse MMVECs through the pathway of HSF1/VEGF.

Developments in the management of Chagas cardiomyopathy

Over 100 years have elapsed since the discovery of Chagas disease and there is still much to learn regarding pathogenesis and treatment. Although there are antiparasitic drugs available, such as benznidazole and nifurtimox, they are not totally reliable and often toxic. A recently released negative clinical trial with benznidazole in patients with chronic Chagas cardiomyopathy further reinforces the concerns regarding its effectiveness. New drugs and new delivery systems, including those based on nanotechnology, are being sought. Although vaccine development is still in its infancy, the reality of a therapeutic vaccine remains a challenge. New ECG methods may help to recognize patients prone to developing malignant ventricular arrhythmias. The management of heart failure, stroke and arrhythmias also remains a challenge. Although animal experiments have suggested that stem cell based therapy may be therapeutic in the management of heart failure in Chagas cardiomyopathy, clinical trials have not been promising.