Single Intraluminal Delivery of a Nitric Oxide-Donor Results in Inhibition of Intimal Thickening in the Rabbit...

Vascular smooth muscle cell (SMC) proliferation and vascular homeostasis are thought to be regulated by nitric oxide and prostaglandins. The loss of these endogenous mediators seems to play an important role for the development of restenosis following balloon angioplasty.

We examined the effect of exogenous linsidomine, a nitric oxide (NO) releasing compound, in a model of balloon injury iliac arteries of rabbits. On the cellular levels, NO can exert effects like cell survival, growth, and proliferation inhibition, has effects on transcription and proteasome effects and mitochondria-related effects in SMCs. SMC proliferation was quantified as a change of intima-media ratio. Linsidomine injection or its vehicle was performed with an infusion-balloon catheter directly into the dilated vessel wall.

Balloon angioplasty resulted in a significant increase of intima-media ratio during the first 3 weeks. Linsidomine treatment decreased the intima-media ratio significantly compared to vehicle treated animals 3 weeks after balloon angioplasty (0.65 ± 0.05 vs 1.2 ± 0.2 intima-media ratio, p < 0.05). However, control vessels had an intima-media ratio of 0.15 ± 0.02. This effect was similar to NOS-2 transfected vessels following angioplasty. Immunohistochemical analysis demonstrated the expression of the proliferating cellular nuclear antigen in dilated vessel of vehicle treated animals, which was reduced in linsidomine-treated rabbits. In in vitro experiments, linsidomine inhibited significantly and dose-dependently rabbit SMC proliferation measured by BrdU incorporation. Further linsidomine increased rate of apoptotic SMCs, however, this effect was p53 independent.

Simultaneous angioplasty of the rabbit iliac artery and direct injection of linsidomine into the vessel wall seem to be an effective strategy to reduce neointima formation. Similar, local application of liposome encapsulation of human nitric oxide synthase-2 transfection resulted in potent inhibition of intima proliferation and SMC proliferation due to local restoration NO within the injured vasculature.