Magnesium-based bioresorbable flow diverter for intracranial aneurysms: a pilot study of biocompatibility and bioresorption in a rabbit vascular model

Sep 29, 2026

Bioresorbable flow diverters (BRFDs) aim to address limitations of permanent flow diverters. This research compares bare and poly-L-lactic acid (PLLA)-coated magnesium BRFDs (MgBRFDs) fabricated from a high-strength corrosion-resistant magnesium alloy. In a rabbit vascular model, constructs are evaluated for mechanical properties, structural resolution using OCT, micro-CT, and SEM, and vascular tissue responses via SEM and histopathology. Results show PLLA coating delays bioresorption and supports better stent preservation, with both types demonstrating excellent biocompatibility.

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New devices and techniques Original research Magnesium-based bioresorbable flow diverter for intracranial aneurysms: a pilot study of biocompatibility and bioresorption in a rabbit vascular model Ryo Akiyama , 1 Akira Ishii ,2 Natsuhi Sasaki ,3 So Matsukawa , 1 Shinichi Yagi ,4 Hideo Chihara , 1 Hidehisa Nishi ,2 Kiyotaka Iwasaki ,5 Shinichi Sakurai ,4 Yoshihito Kawamura ,6 Yoshiki Arakawa 1 ► Additional supplemental material is published online only. To view, please visit the journal online ([https://doi.org/](https://doi.org/)[ ](https://doi.org/)[10.1136/jnis-2024-022527](10.1136/jnis-2024-022527)) . 1Neurosurgery, Kyoto University Graduate School of Medicine Faculty of Medicine, Kyoto, Japan 2Neurosurgery, Juntendo University School of Medicine Graduate School of Medicine, Tokyo, Japan 3Neurosurgery, Fukui Red Cross Hospital, Fukui, Japan 4Biobased Materials Science, Kyoto Institute of Technology Faculty of Textile Science, Kyoto, Japan 5Cooperative Major in Advanced Biomedical Sciences, Waseda University School and Graduate School of Advanced Science and Engineering, Tokyo, Japan 6Magnesium Research Center, Kumamoto University, Kumamoto, Japan Correspondence to Professor Akira Ishii; ishiiakira@ [gmail.com](gmail.com) Received 20 September 2024 Accepted 5 November 2024 © Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. To cite: Akiyama R, Ishii A, Sasaki N, et al. J NeuroIntervent Surg Epub ahead of print: [please include Day Month Year] . doi:10 . 1136/jnis-2024- 022527 ABSTRACT Background Bioresorbable flow diverters (BRFDs) have the potential to solve several problems associated with conventional permanent flow diverters. We have constructed bare and poly-L-lactic acid (PLLA)-coated magnesium BRFDs (MgBRFDs) using a high-strength corrosion-resistant magnesium alloy. This study aimed to compare bioresorption and biocompatibility between the two types in a rabbit vascular model to determine which is more clinically feasible in humans. Methods Bare and PLLA-coated MgBRFDs were fabricated by braiding 48 thin magnesium alloy wires. Mechanical testing was conducted. Bare (n=13) and PLLA-coated (n=13) MgBRFDs were implanted into rabbit aortas and harvested 14, 30, and 90 days after implantation. The physical structure of the resolution process was examined using optical coherence tomography (OCT), micro-computed tomography, and scanning electron microscopy (SEM) . The biological response of the vascular tissue was examined using SEM and histopathological analysis. Results The porosity and pore density of the bare MgBRFD were 64% and 16 pores/mm2, respectively; corresponding values for the PLLA-coated MgBRFD were 63% and 12 pores/mm2, respectively. The OCT attenuation score was significantly higher for the PLLAcoated MgBRFD at all time points (14 days, P=0 .01; 30 days, P=0 .02; 90 days, P=0 .004) . OCT, micro-computed tomography, and SEM demonstrated better stent structure preservation with the PLLA-coated MgBRFD. Neointimal thickness did not significantly change overtime in either type of MgBRFD (bare, P=0 .93; PLLAcoated, P=0.34); however, the number of inflammatory and proliferative cells peaked at 14 days and then decreased. Conclusions Both bare and PLLA-coated MgBRFDs had excellent biocompatibility. The PLLA-coated MgBRFD has greater clinical feasibility because of its delayed bioresorption. INTRODUCTION The introduction of flow diverters (FDs) for the treatment of unruptured intracranial aneurysms (IAs) has markedly improved patient outcomes.1–4 However, currently available FDs, constructed WHAT IS ALREADY KNOWN ON THIS TOPIC | ⇒ Bioresorbable flow diverters (BRFDs) can potentially solve the problems associated with conventional permanent flow diverters. Although magnesium is an excellent bioresorbable material, the development of a magnesium BRFD (MgBRFD) has been limited o

FAQs

What is the goal of this pilot study of magnesium BRFDs?

The study compares bioresorption and biocompatibility between bare and PLLA-coated magnesium BRFDs in a rabbit vascular model to determine which is more clinically feasible for humans.

How were the bare and PLLA-coated MgBRFDs prepared and evaluated?

Bare and PLLA-coated MgBRFDs were braided from 48 thin magnesium alloy wires. Mechanical testing was performed, and the devices were implanted into rabbit aortas and harvested at 14, 30, and 90 days for structural and biological assessments using OCT, micro-CT, SEM, and histopathology.

What did the study find regarding bioresorption and biocompatibility?

Both device types showed excellent biocompatibility. The PLLA-coated MgBRFD had delayed bioresorption, better preservation of stent structure, and higher OCT attenuation scores across time points.

Sep 29, 2026

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