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Iron is considered as an attractive alternative material for bioresorbable scaffolds (BRS). The sirolimus eluting iron bioresorbable scaffold (IBS), developed by Biotyx Medical (Shenzhen, China), is the only iron-based BRS with an ultrathin-wall design. The study aims to investigate the long-term efficacy, safety, biocompatibility, and lumen changes during the biodegradation process of the IBS in a porcine model. A total of 90 IBSs and 70 cobalt-chromium everolimus eluting stents (EES) were randomly implanted into nonatherosclerotic coronary artery of healthy mini swine. The multimodality assessments including coronary angiography, optical coherence tomography, micro-computed tomography, magnetic resonance imaging, real-time polymerase chain reaction (PCR), and histopathological evaluations, were performed at different time points. There was no statistical difference in area stenosis between IBS group and EES group at 6 months, 1year, 2 years and 5 years. Although the scaffolded vessels narrowed at 9 months, expansive remodeling with increased mean lumen area was found at 3 and 5 years. The IBS struts remained intact at 6 months, and the corrosion was detectable at 9 months. At 5 years, the iron struts were completely degraded and absorbed in situ, without in-scaffold restenosis or thrombosis, lumen collapse, aneurysm formation, and chronic inflammation. No local or systemic toxicity and abnormal histopathologic manifestation were found in all experiments. Results from real-time PCR indicated that no sign of iron overload was reported in scaffolded segments. Therefore, the IBS shows comparable efficacy, safety, and biocompatibility with EES, and late lumen enlargement is considered as a unique feature in the IBS-implanted vessels.

This study aimed to investigate the long-term biocompatibility, safety, and degradation of the ultrathin nitrided iron bioresorbable scaffold (BRS) in vivo, encompassing the whole process of bioresorption in porcine coronary arteries. Fifty-two nitrided iron scaffolds (strut thickness of 70 μm) and 28 Vision Co–Cr stents were randomly implanted into coronary arteries of healthy mini-swine. The efficacy and safety of the nitrided iron scaffold were comparable with those of the Vision stentwithin 52 weeks after implantation. In addition, the long-term biocompatibility, safety, and bioresorption of the nitrided iron scaffold were evaluated by coronary angiography, optical coherence tomography, micro-computed tomography, scanning electron microscopy, energy dispersive spectrometry and histopathological evaluations at 4, 12, 26, 52 weeks and even at 7 years after implantation. In particular, a large number of struts were almost completely absorbed in situ at 7 years follow-up, which were first illustrated in this study. The lymphatic drainage pathway might serve as the potential clearance way of iron and its corrosion products.

Iron is considered as an attractive alternative material for bioresorbable scaffolds (BRS). The sirolimus eluting iron bioresorbable scaffold (IBS), developed by Biotyx Medical (Shenzhen, China), is the only iron-based BRS with an ultrathin-wall design. The study aims to investigate the long-term efficacy, safety, biocompatibility, and lumen changes during the biodegradation process of the IBS in a porcine model. A total of 90 IBSs and 70 cobalt-chromium everolimus eluting stents (EES) were randomly implanted into nonatherosclerotic coronary artery of healthy mini swine. The multimodality assessments including coronary angiography, optical coherence tomography, micro-computed tomography, magnetic resonance imaging, real-time polymerase chain reaction (PCR), and histopathological evaluations, were performed at different time points. There was no statistical difference in area stenosis between IBS group and EES group at 6 months, 1year, 2 years and 5 years. Although the scaffolded vessels narrowed at 9 months, expansive remodeling with increased mean lumen area was found at 3 and 5 years. The IBS struts remained intact at 6 months, and the corrosion was detectable at 9 months. At 5 years, the iron struts were completely degraded and absorbed in situ, without in-scaffold restenosis or thrombosis, lumen collapse, aneurysm formation, and chronic inflammation. No local or systemic toxicity and abnormal histopathologic manifestation were found in all experiments. Results from real-time PCR indicated that no sign of iron overload was reported in scaffolded segments. Therefore, the IBS shows comparable efficacy, safety, and biocompatibility with EES, and late lumen enlargement is considered as a unique feature in the IBS-implanted vessels., Competing Interests: H. Qiu and R. L. Gao received institutional research grants from Biotyx Medical (Shenzhen) Co. Ltd., Shenzhen. China. G. Zhang, D. Y. Zhang, H. P. Qi, and Y. D. Lu are employees of Biotyx Medical (Shenzhen) Co. Ltd. Y. F. Zheng is an editor-in-chief for Bioactive Materials and was not involved in the editorial review or the decision to publish this article. All other authors have no relationships relevant to the contents of this paper to disclose., (© 2024 The Authors.)

This study aimed to investigate the long-term biocompatibility, safety, and degradation of the ultrathin nitrided iron bioresorbable scaffold (BRS) in vivo, encompassing the whole process of bioresorption in porcine coronary arteries. Fifty-two nitrided iron scaffolds (strut thickness of 70 μm) and 28 Vision Co-Cr stents were randomly implanted into coronary arteries of healthy mini-swine. The efficacy and safety of the nitrided iron scaffold were comparable with those of the Vision stentwithin 52 weeks after implantation. In addition, the long-term biocompatibility, safety, and bioresorption of the nitrided iron scaffold were evaluated by coronary angiography, optical coherence tomography, micro-computed tomography, scanning electron microscopy, energy dispersive spectrometry and histopathological evaluations at 4, 12, 26, 52 weeks and even at 7 years after implantation. In particular, a large number of struts were almost completely absorbed in situ at 7 years follow-up, which were first illustrated in this study. The lymphatic drainage pathway might serve as the potential clearance way of iron and its corrosion products., Competing Interests: R. L. Gao and H. Qiu received institutional research grants from Lifetech Scientific (Shenzhen) Co. Ltd. and BiotyxMedical (Shenzhen) Co. Ltd., Shenzhen, China. H. P. Qi, L. Qin, W. Q. Zhang, G. Zhang and D. Y. Zhang are employees of BiotyxMedical (Shenzhen) Co. Ltd.. X. L. Shi is employee of Lifetech Scientific (Shenzhen) Co. Ltd.. All other authors have no relationships relevant to the contents of this paper to disclose., (© 2022 The Authors.)