Evaluation of the biocompatibility of two new diamond-like stent coatings (Dylyn (TM)) in a porcine coronary stent model

Hydrogenated diamond-like carbon films (DLC, a-C:H), deposited using plasma -assisted or ion beam-assisted techniques, offer great potential as self-lu bricating coatings in many tribological applications. Additionally, studies on biocompatibility have shown that DLC is an inert, impervious hydrocarbo n,vith properties suitable for use in the biomedical field. One particular class of modified DLC coatings are diamond-like nanocomposite coatings (DLN or Dylyn(TM), Bekaert, Kortrijk, Belgium), which offer promising solutions for many industrial applications. In this study, the biocompatibility of t wo diamond-like stent coatings are evaluated in a porcine coronary stent mo del. Methods. Either coated or non-coated stents were randomly implanted in two coronary arteries of 20 pigs so that each group contained 13 stented arteri es. Pigs underwent a control angiogram at 6 weeks and were then sacrificed. Quantitative coronary analysis before, immediately after stent implantatio n, and at 6 weeks was performed using the semi-automated Polytron 1000(R) s ystem (Siemens, Erlangen, Germany). Morphometry was performed using a compu terized morphometric program. Angiographic analysis showed similar baseline selected arteries and post-stenting diameters. At 6-week follow-up, there was no significant difference in minimal stent diameter. Histopathology rev ealed a similar injury score in the 3 groups. Inflammation was significantl y increased in the DLN-DLC coating group. Thrombus formation was significan tly decreased in both coated stent groups. Neointimal hyperplasia was decre ased in both coated stent groups; however, the difference with the non-coat ed stents was not statistically significant. Area stenosis was lower in the DLN-coated stent group than in the control group (41 +/- 17% vs. 54 +/- 15 %; p = 0.06). Conclusion. The results indicate that the diamond-like nanocomposite stent coatings are compatible, resulting in decreased thrombogenicity and decreas ed neointimal hyperplasia. Covering this coating with another diamond-like carbon film (DLC) resulted in an increased inflammatory reaction and no add itional advantage compared to the single-layer diamond-like nanocomposite c oating.