Chimeric DNA–RNA hammerhead ribozyme targeting transforming growth factor-β1 mRNA inhibits neointima formation in rat carotid artery after balloon injury

Abstract

We designed and synthesized a chimeric DNA–RNA hammerhead ribozyme targeting transforming growth factor (TGF)-β1 mRNA and found that this ribozyme effectively and specifically inhibited growth of vascular smooth muscle cells. We examined the effects of the chimeric DNA–RNA hammerhead ribozyme targeting TGF-β1 mRNA on neointima formation and investigated the underlying mechanism to develop a possible gene therapy for coronary artery restenosis after percutaneous transluminal coronary angioplasty. Expression of mRNAs encoding TGF-β1, p27kip1, and connective tissue growth factor (CTGF) in carotid artery increased after balloon injury. Fluorescein-isothiocyanate (FITC)-labeled ribozyme was taken up into the midlayer smooth muscle of the injured carotid artery. Both 2 and 5 mg of ribozyme reduced neointima formation by 65% compared to that of controls. Ribozyme markedly decreased expression of TGF-β1 mRNA and protein in injured vessel. Mismatch ribozyme had no effect on expression of TGF-β1 mRNA protein in injured vessel. Ribozyme markedly decreased expression of fibronectin, p27kip1, and CTGF mRNAs in injured vessel, whereas a mismatch ribozyme had no effect on these mRNAs. These findings indicate that the chimeric DNA–RNA hammerhead ribozyme targeting TGF-β1 mRNA inhibits neointima formation in rat carotid artery after balloon injury with suppression of TGF-β1 and inhibition of extracellular matrix and CTGF. In conclusion, the hammerhead ribozyme against TGF-β1 may have promise as a therapy for coronary artery restenosis after percutaneous transluminal coronary angioplasty.