Article Text
Abstract
Vein graft failure (VGF) following coronary artery bypass grafting occurs through proliferation and migration of vascular smooth muscle cells (VSMC) forming a neointima that blocks the graft lumen. Dysregulated renin angiotensin system (RAS) signalling promotes vascular remodelling through angiotensin II (Ang II) stimulating the angiotensin type 1 receptor. The counter-regulatory RAS peptide angiotensin-(1–9) [Ang-(1–9)], acts via the angiotensin type 2 receptor and inhibits VSMC proliferation and migration.1 Here, gene transfer of Ang-(1–9) was investigated as a novel therapy to inhibit human saphenous vein VSMC (HSVSMC) migration and proliferation in vitro and neointima formation in vivo.
An adenoviral vector [RAdAng-(1–9)] was generated expressing a fusion protein that secretes Ang-(1–9) extracellularly following transduction.2 Transgene expression was confirmed by immunoblotting. HSVSMC migration was evaluated by scratch wound assay. MTS assay was used to determine effects of conditioned media from RAdAng-(1–9) transduced HepG2 cells on HSVSMC proliferation.
Saline, RAdControl or RAdAng-(1–9) (1 × 1011 vp) was administered to C57/Bl6 mice intravenously. After 48 hours the endothelium of the left carotid arteries was denuded by wire injury. After 4 weeks, injured carotid arteries were subjected to histological staining and morphometric analysis performed.
Immunoblotting of cell lysates and conditioned media demonstrated RAdAng-(1–9)-transduced HSVSMC expressed and secreted the fusion protein. RAdAng-(1–9) transduction of HSVSMC inhibited Ang II-induced migration as compared to RAdControl transduced cells [p<0.001]. Treating HSVSMC with conditioned media of RAdAng-(1–9) transduced HepG2 cells inhibited proliferation [p<0.05]. RAdAng-(1–9) delivered intravenously 48 hours before surgery significantly inhibited neointima formation 28 days after carotid wire injury [p<0.001].
These data demonstrate that adenoviral gene therapy with Ang-(1–9) can be used to inhibit HSVSMC migration and proliferation and neointima formation after acute vascular injury in mice.
References
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