The cytotoxicity of corrosion products of nitinol stent wire on cultured smooth muscle cells

Although nitinol is one of most popular materials of intravascular stents, there are still few confirmative biocompatibility data available, especiall y in vascular smooth muscle cells. in this report, the nitinol wires were c orroded in Dulbecco's modified Eagle's medium with constant electrochemical breakdown voltage and the supernatant and precipitates of corrosion produc ts were prepared as culture media. The dose and time effects of different c oncentrations of corrosion products on the growth and morphology of smooth muscle cells were evaluated with [H-3]-thymidine uptake ratio and cell cycl e sorter. Both the supernatant and precipitate of the corrosive products of nitinol wire were toxic to the primary cultured rat aortic smooth muscle c ells. The growth inhibition was correlated well with the increased concentr ations of the corrosion products. Al-though small stimulation was found wit h released nickel concentration of 0.95 +/- 0.23 ppm, the growth inhibition became significant when the nickel concentration was above 9 ppm. The corr osion products also altered cell morphology, induced cell necrosis, and dec reased cell numbers. The cell replication was inhibited at the G0-G1 to S t ransition phase. This was the first study to demonstrate the cytotoxicity o f corrosion products of current nitinol stent wire on smooth muscle cells, which might affect the postimplantation neointimal hyperplasia and the pate ncy rate of cardiovascular stents. (C) 2000 John Wiley & Sons, Inc.