A polysaccharide, MDG-1, induces S1P1 and bFGF expression and augments survival and angiogenesis in the ischemic heart

Ophiopogon japonicus is a traditional Chinese medicine used to treat cardiovascular disease. Recent studies have confirmed its beneficial properties, but not the mechanism of action. Herein, we investigate the anti-ischemic properties of a water-soluble beta-d-fructan (MDG-1) from Ophiopogon japonicus, and assess the cytoprotective and proangiogenic effects of MDG-1. MDG-1 protects cardiomyocyte and microvascular endothelial cells (HMEC-1) against oxygen glucose deprivation (OGD)-induced cell death, as well as protect myocardial cells from ischemia-induced death occurring after coronary artery ligation in rats. Meanwhile, MDG-1 stimulates the differentiation of HMEC-1 cells into capillary-like structures in vitro and functions as a chemoattractant in migration assays, and promotes neovascularization in ischemic myocardium. In addition, MDG-1 upregulates sphingosine kinase 1 and sphingosine-1-phosphate (S1P) receptor 1 expression. Both MDG-1 and S1P induce basic fibroblast growth factor (bFGF) expression in HMEC-1 cells. Further study revealed that both MDG-1 and S1P induce Akt and ERK phosphorylation in a dose- and time-dependent manner, an effect that is attenuated by pre-treatment with either the Akt inhibitor wortmannin or the ERK inhibitor PD98059, and MDG-1 can also induce eNOS phosphorylation and increases in production of NO. These data indicate that MDG-1 presented remarkable anti-ischemic activity and protects cardiomyocyte and HMEC-1 cells from ischemia-induced cell damage by inducing S1P1 and bFGF cytoprotective and proangiogenic effects via the S1P/bFGF/Akt/ERK/eNOS signaling pathway.