Sauer H, Ravindran F, Beldoch M, Sharifpanah F, Jedelská J, Strehlow B, Wartenberg M. α2-Macroglobulin enhances vasculogenesis/angiogenesis of mouse embryonic stem cells by stimulation of nitric oxide generation and induction of fibroblast growth factor-2 expression.
Stem Cells Dev 2013;
22:1443-54. [PMID:
23379699 DOI:
10.1089/scd.2012.0640]
[Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
α2-macroglobulin (α2M) is an acute-phase protein released upon challenges like cardiac hypertrophy and infarction. α2M signals via the low density lipoprotein receptor-related protein (LRP-1) and may induce stem cell activation. In the present study, the effects of α2M on vasculogenesis/angiogenesis and underlying signaling cascades were investigated in mouse embryonic stem (ES) cells. LRP-1 was expressed in ES cells and upregulated during differentiation. α2M dose dependently increased CD31-positive vascular structures in ES cell-derived embryoid bodies, the early cardiovascular markers isl-1, Nkx-2.5, and flk-1 as well as numbers of VE-cadherin and flk-1-positive cells, but downregulated α-smooth muscle actin. Enhancement of vasculogenesis/angiogenesis by α2M was abolished by the LRP-1 antagonist receptor-associated protein (RAP) and LRP-1 blocking antibody. Notably, α2M stimulated vascular growth in the chicken chorioallantois membrane assay, but not in a human umbilical vein endothelial cell spheroid model. α2M increased fibroblast growth factor-2 (FGF-2) protein expression, which was abolished by RAP, induced nitric oxide (NO) generation as determined by 4,5-diaminofluorescein diacetate microfluorometry, and activated nitric oxide synthase-3 (NOS-3) as well as extracellular-regulated kinase 1,2 (ERK1/2) and phosphatidyl inositol 3-kinase (PI3K). NO generation, the increase in FGF-2 expression, and the stimulation of vasculogenesis/angiogenesis by α2M were blunted by the NO synthase inhibitor L-NAME, the ERK1/2 inhibitor PD98059, and the PI3K inhibitor LY294002. Furthermore, vasculogenesis/angiogenesis by α2M was inhibited in the presence of the FGF receptor 1 antagonist SU5402. In conclusion, α2M stimulates endothelial and early cardiac, but not smooth muscle differentiation of ES cells through generation of NO, activation of ERK1/2 as well as PI3K, and induction of FGF-2 expression.
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