Ribozyme oligonucleotides against transforming growth factor-β inhibited neointimal formation after vascular injury in rat model -: Potential application of ribozyme strategy to treat cardiovascular disease

Background-Because the mechanisms of atherosclerosis or restenosis after angioplasty have been postulated to involve an increase in transforming growth factor (TGF)-beta, a selective decrease in TGF-beta may have therapeutic value. Thus, we used the ribozyme strategy to actively cleave the targeted gene to selectively inhibit TGF-beta expression. Methods and Results-We constructed ribozyme oligonucleotides (ONs) targeted to the sequence of the TGF-beta gene that shows 100% homology among the human, rat, and mouse species, The specificity of ribozyme against TGF-beta gene was confirmed by selective inhibition of TGF-beta mRNA in cultured vascular smooth muscle cells as well as balloon-injured blood vessels in vivo. Importantly, the marked decrease in TGF-beta resulted in significant inhibition of neointimal formation after vascular injury in a rat carotid artery model (P < 0.01), whereas DNA-based control ONs and mismatched ribozyme ONs did not have any inhibitory effect on neointimal formation. Inhibition of neointimal formation was accompanied by (I) a reduction in collagen synthesis and mRNA expression of collagen I and III and (2) a significant decrease in DNA synthesis as assessed by proliferating cell nuclear antigen staining, Moreover, we modified ribozyme ONs containing phosphorothioate DNA and RNA targeted to the TGF-beta gene, Of importance, modified ribozyme ONs showed a further reduction in TGF-beta expression. Conclusions-Overall, this study provides the first evidence that selective blockade of TGF-beta resulted in inhibition of neointimal formation, accompanied by a reduction in collagen synthesis and DNA synthesis in a rat model, We anticipate that modification of ribozyme ON pharmacokinetics will facilitate the potential clinical utility of the ribozyme strategy.