Abstract 16382: Hyperhomocysteinemia Suppresses Endothelial Progenitor Cells Homing via β1 Integrin Inhibition Post Vascular Injury in Cystathionice-β Synthase Deficient Mice
Objective: To examine the effect of HHcy on endothelial progenitor cells (EPCs) and evaluated the therapeutic effect of bone marrow (BM)-derived CD34+ progenitor cells (PCs) on vascular remodeling.
Methods and Results: Severe HHcy (Hcy, ≈150μ M) was induced in mice with heterozygous deficiency of cystathionice-β synthase (CBS-/+) by fed a high methionine diet for 8 weeks. Carotid artery air-dry endothelium denudation was performed. CD34+ PCs were isolated from enhanced green fluorescent protein (EGFP) transgenic mice and intravenously transfused into CBS mice immediately after injury. EPC population was determined by flow cytometry analysis using antibodies against CD34 and VEGFR2. HHcy reduced EPCs in BM from 0.71±0.08% in control mice to 0.52±0.06% (P=0.04), inhibited circulating EPC restoration 3 days post injury (0.21±0.03% versus 0.33±0.05% in control mice, P=0.029), and suppressed CD34+/VEGFR2+ cell mobilization post endothelial denudation. Further, HHcy reduced the homing of GFP+ cells to the injury site by 55% as compared with control mice7 days after injury (P=0.026) in the mice with CD34+ PCs transfusion. CD34+ PC transfusion improved endothelial repair from 69% to 89% (P=0.043) 7 days post-injury, and reduced neointimal formation from 0.42±0.06 to 0.30±0.04 (P=0.01) 28 days after injury in HHcy mice. In cultured EPCs derived from human peripheral blood (PB), L-Hcy (50-250μ M) inhibited EPC proliferation as measured by [3H] thymidine incorporation, adhesion to fibronectin coated plates and migration in a scratch wound assay in a dose dependent manner. L-Hcy (250μ M) inhibited β1 integrin expression and activation in human EPCs. The inhibitory effect of Hcy on EPC adhesion was largely rescued from 58% to 82% by using a function-activating anti-β1 antibody.
Conclusions: Our findings suggest that HHcy reduces EPC generation in the BM, suppresses EPC mobilization and homing after vascular injury via β1 integrin inhibition, thus contributes to impaired reendothelialization and accelerated neointima formation. These results support the notion of using CD34+ PC transfusion as an effective cell therapy in vascular injury.
Key words: Hyperhomocysteinemia, endothelial progenitor cell, progenitor cell therapy, vascular injury, integrin
- © 2012 by American Heart Association, Inc.