Comparison of acute thrombogenicity for magnesium versus stainless steel stents in a porcine arteriovenous shunt model

Abstract

Aims: The present study aimed to investigate whether the Magmaris resorbable magnesium scaffold (RMS) has platelet-repelling properties by comparing its acute thrombogenicity with an equivalent stainless steel stent in an arteriovenous shunt model.

Methods and results: An ex vivo porcine carotid jugular arteriovenous shunt was established and connected to Sylgard tubing containing the Magmaris RMS with sirolimus-eluting PLLA coating and an equivalent 316L stainless steel stent with sirolimus-eluting PLLA coating. Six shunts (two shunt runs per pig) were run comparing the two scaffolds (n=9) in alternating order. Nested generalised linear mixed models were employed to compare variables between scaffold groups. Confocal fluorescent microscopy containing CD61/CD42b demonstrated that the 316L equivalent stent had significantly greater platelet coverage of the total scaffold compared with Magmaris (5.8% vs. 2.8%, adjusted rate ratio 2.21 [1.41, 3.47], p=0.012). Scanning electron microscopy demonstrated significantly greater thrombus deposition on the 316L equivalent stent as a percentage of the total scaffold compared with Magmaris (8.0% vs. 5.3%, p=0.009). Magmaris also had significantly less CD14 positive monocyte deposition and a trend towards less PM-1 positive neutrophil compared with the 316L equivalent stent.

Conclusions: Magmaris has less thrombogenicity and inflammatory cell deposition compared with the equivalent 316L stainless steel (in geometry and design) stent in a porcine arteriovenous shunt model. These data suggest that resorbable magnesium scaffolds may have inherent properties that reduce adhesion of platelets and inflammatory cells.