A NOVEL SIROLIMUS-ELUTING BIODEGRADABLE MAGNESIUM-BASED ALLOY SCAFFOLD: SIX-MONTH RESULTS IN PORCINE PERIPHERAL ARTERIES

Abstract

Purpose: Magnesium-based alloy scaffold is a promising biodegradable stent due to its intrinsic mechanical performance and biocompatibility. Based on our preliminary experiments, we designed a novel sirolimus-elut-ing magnesium-based alloy scaffold. This work aimed to assess its safety and degradation performance in vivo. Methods: The scaffolds were implanted in the lower limb arteries of Bama mini-pigs. Safety was defined as no immediate thrombosis or >30% residual stenosis, which was assessed with optical coherence tomography and digital subtraction angiography. Blood biochemical analyses were performed to evaluate hepatorenal toxicity. The degradation process of the scaffolds, the endothelialization, and lumen loss of the stented-vessels were detected with scanning electron microscopy, immunohistochemical, hematoxylin-eosin staining and optical coherence tomography. Results: Twenty-four scaffolds were successfully implanted in six pigs with no signs of immediate thrombosis or >30% residual stenosis. The scaffolds were covered by endothelium at one month and absolutely resorbed at six months post implantation. Blood analysis showed that the hepatorenal function except for alanine aminotransferase and γ-glutamyl transpeptidase was normal. Obvious intimal hyperplasia and lumen loss were found in the stented vessels at three months, while the diameters and inner lumen areas of stented segments had increased significantly at six months (p<0.001). Conclusion: The scaffolds can be safely implanted in the porcine peripheral arteries and fully resolved at six months after implantation. The stented vessels present positive vascular reconstruction when the scaffolds were fully resorbed. Future improvement for this scaffold should focus on the inhibition of intimal hyperplasia.