Endothelial progenitor cell-derived exosomes facilitate vascular endothelial cell repair through shuttling miR-21-5p to modulate Thrombospondin-1 expression.

Background: Our previous studies observed that administration of exosomes from endothelial progenitor cells (EPC) facilitated vascular repair in the rat model of balloon injury. However, the molecular events underlying this process remain elusive. Here, we aim to interrogate the key miRNAs within EPC-derived exosomes (EPC-exosomes) responsible for the activation of endothelial cell (EC) repair. Methods: The efficacy of EPC-exosomes in re-endothelialization was examined by Evans Blue dye and histological examination in the rat model of balloon-induced carotid artery injury. The effects of EPC-exosomes on human vascular EC (HUVEC) were also studied by evaluating the effects on growth, migratory and tube formation. To dissect the underlying mechanism, RNA-sequencing assays were performed to determine miRNA abundance in exosomes and mRNA profiles in exosome-treated HUVECs. Meanwhile, in vitro loss of function assays identified an exosomal miRNA and its target gene in EC, which engaged in EPC-exosomes-induced EC repair. Results: Administration of EPC-exosomes potentiated re-endothelialization in the early phase after endothelial damage in the rat carotid artery. The uptake of exogenous EPC-exosomes intensified HUVEC in proliferation rate, migration and tube-forming ability. Integrative analyses of miRNA-mRNA interactions revealed that miR-21-5p was highly enriched in EPC-exosomes and specifically suppressed the expression of an angiogenesis inhibitor Thrombospondin-1 (THBS1) in the recipient EC. The following functional studies demonstrated a fundamental role of miR-21-5p in the pro-angiogenic activities of EPC-exosomes. Conclusions: The present work highlights a critical event for the regulation of EC behavior by EPC-exosomes, which EPC-exosomes may deliver miR-21-5p and inhibit THBS1 expression to promote EC repair.

Wedelolactone, a plant coumarin, prevents vascular smooth muscle cell proliferation and injury-induced neointimal hyperplasia through Akt and AMPK signaling.

Wedelolactone (WDL) is a natural compound derived from Chinese herbal medicine Eclipta prostrate L, and has been reported to exhibit various effects potentially beneficial for human health. However, the possible preventive effects of WDL toward vascular remodeling and mechanisms involved have not been investigated to date. In this study, we investigated the effects of WDL on proliferation induced by platelet-derived growth factor (PDGF) in primary rat aortic smooth muscle cells (VSMCs) and on neointimal hyperplasia resulted from balloon injury in rats. WDL exhibited strong inhibitory effects against PDGF-induced VSMC proliferation. Cell cycle analysis revealed that WDL induced G0/G1 arrest and prevented cell cycle from entering S phase. Immunoblot analysis suggested that the cell cycle arrest induced by WDL was through Akt suppression and adenosine 5'-monophosphate-activated protein kinase (AMPK) activation, with a subsequent cyclin-dependent kinase inhibitor p21 induction and cyclin D1 inhibition. We also observed that WDL notably reduced neointima-to-media area ratio of balloon-injured rat common carotid arteries (CCAs) in comparison with those untreated balloon-injured CCAs. The regulation of WDL on protein expressions of Akt, AMPK and cyclin D1 in vivo were also consistent with that in vitro. Taken together, our results suggest WDL exhibits potential preventive effects toward vascular remodeling and neointimal hyperplasia through the reduction of VSMC proliferation via inhibition of Akt and activation of AMPK.

Effects of isosorbide mononitrate on the restoration of injured artery in mice in vivo.

The pharmacological basis of isosorbide mononitrate (ISMN), a widely used drug for cardiovascular diseases, is that it is metabolized to nitric oxide (NO). However, NO is a double-edged sword that results in either beneficial or detrimental effect. Vascular injury is the common consequence of many cardiovascular diseases, but it is not determined whether ISMN influences the restoration of injured artery in vivo. Carotid artery injury was induced by electric stimulation in mice. Vasoconstriction and endothelium-dependent and -independent relaxation were recorded by a multichannel acquisition and analysis system. ISMN (10 mg/kg, p.o.) treatment for 1 week and 1 month had no effect on reendothelialization, histology and function of carotid artery injured by electric stimulation. L-arginine (500 mg/kg, p.o.) and Nomega-nitro-L-arginine methyl ester (L-NAME) (50 mg/kg, p.o.) treatment for 1 week did not affect the reendothelialization process, but L-NAME treatment induced neointimal hyperplasia and inhibited endothelium-dependent relaxation in electrically injured artery. These results suggest that supplement of exogenous or endogenous NO has no effect on the restoration of injured artery, but inhibition of endogenous NO induces neointimal hyperplasia in injured artery. ISMN treatment does not affect the restoration of injured artery.

Competitive NMDA receptor antagonists and agonists: effects on spontaneous alternation in mice exposed to cerebral oligemia.

The purpose of the present study was to investigate the effects of competitive NMDA receptor antagonists,D,L-(E)-2-amino-4-methyl-5-phosphono-3-pentenoic acid (CGP 37849) and its ethyl ester (CGP 39551), or agonist, N-methyl-D-aspartate (NMDA) on spontaneous alternation in mice exposed to cerebral oligemia. Alternation behavior was evaluated in an Y-maze. Transient cerebral oligemic hypoxia was induced by bilateral clamping of carotid arteries (BCCA) for 30 min under pentobarbital anesthesia. In BCCA mice, CGP 37849 (5 mg/kg, ip) impaired spontaneous alternation when given 48 h or 7 days after surgery. CGP 39551 (5 mg/kg, ip) had no effect.NMDA (50 mg/kg, sc) improved performance of the task in BCCA mice when tested 48 h after surgery. These results suggest that cerebral oligemic hypoxia induced by BCCA leads to functional disturbances in the central nervous system, such as spontaneous alternation impairment and increased susceptibility to NMDA receptor-related drugs. Adverse potential of cerebral oligemia may limit a therapeutic use of NMDA receptor antagonists.