Transfected synthetic DNA Enzyme Gene specifically inhibits Egr-1 gene expression and reduces Neointimal Hyperplasia following balloon injury in rats

Background: Early growth response factor-1 (Egr-1) controls the gene expression involved in postangioplasty restenosis. In the present study we synthesized specific catalytic DNA targeting sequences in human Egr-1 mRNA to investigate the effects on artery balloon injury. Methods: The catalytic DNA, ED5, was synthesized and transfected into the arterial wall of Wistar rats using the FuGENE6 transfection reagent. The animals were euthanized at day 3, 7, 14 and 21 following artery balloon injury. Serum nitric oxide (NO), nitric oxide synthase (NOS), and endothelin (ET) levels were measured before sacrifice. Histopathological changes to the arterial tissue were evaluated by H&E staining and observed via transmission electromicroscopy. Egr-1, PCNA and TGF-beta 1 expression was detected by immunohistochemistry, RT-PCR, and western-blot. Results: Compared with the control groups, ED5-treated rats exhibited increased levels of both NO and NOS (p<0.05); by contrast, plasma ET levels were decreased relative to controls (p<0.05). Neointimal hyperplasia (NH) was significantly reduced and vascular smooth muscle cells (VSMCs) in the neointima exhibited a general contractile phenotype. Both protein and mRNA expression of Egr-1, PCNA, and TGF-beta(1) in the ED5-treated group were decreased at each time point (p<0.001). Conclusions: ED5 may specifically inhibit Egr-1 gene expression and reduce NH after balloon injury in rats; the latter effect may be mediated by a down-regulation of TGF-beta(1) and up-regulation of NOS to inhibit NH following balloon injury. (C) 2007 Elsevier Ireland Ltd. All rights reserved.