Oliver Alexander A, Bilgin Cem, Cortese Jonathan, Bayraktar Esref A, Dai Daying, Ding Yong Hong, Carlson Kent D, Griebel Adam J, Schaffer Jeremy E, Connon Mitchell L, Dragomir-Daescu Dan, Kadirvel Ramanathan, Guillory Roger J, Kallmes David F
Biomedical Engineering and Physiology, Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN, United States.
Radiology, Mayo Clinic, Rochester, MN, United States.
Front Bioeng Biotechnol. 2025 Feb 25;13:1522696. doi: 10.3389/fbioe.2025.1522696. eCollection 2025.
Flow diverters are specialized stents used to treat intracranial aneurysms. Bioresorbable flow diverters (BRFDs) have been proposed as the next-generation of flow diverter technology. BRFDs aim to occlude and heal the aneurysm before safely dissolving into the body, mitigating complications associated with the permanent presence of conventional flow diverters. We previously prototyped BRFDs using an iron-manganese-nitrogen (FeMnN) alloy and demonstrated their flow diversion functionality, radial strength, bioresorbability, and MRI compatibility in benchtop tests. In the current work, we investigated their aneurysm occlusion efficacy .
Elastase induced aneurysms were created in seven rabbits and BRFDs were deployed over the aneurysms for 3 months. Aneurysm occlusion efficacy and the biological response was assessed via angiography, gross dissection microscopy, and histology.
The BRFDs failed to occlude the aneurysms in 5/7 rabbits at the 3-month endpoint. The bioresorbable wires appeared to resorb too rapidly and fragment away from the aneurysm neck prior to becoming entirely encased in tissue and completely occluding the aneurysm. In 3/7 rabbits, some FeMnN wires remained over the aneurysm neck that were encased in tissue, partially covering the aneurysm neck. Histological analysis revealed that the wires, when present, were a suitable substrate over which tissue could develop. Therefore, we attribute the poor aneurysm occlusion efficacy to mechanical failure rather than an impaired biological healing response.
The FeMnN BRFDs degraded too rapidly to effectively treat the rabbit elastase induced aneurysms. Future work will focus on developing BRFDs out of materials with a delayed resorption rate.
血流导向装置是用于治疗颅内动脉瘤的特殊支架。可生物吸收血流导向装置（BRFDs）已被提议作为下一代血流导向技术。BRFDs旨在在安全溶解于体内之前闭塞并治愈动脉瘤，减轻与传统血流导向装置长期存在相关的并发症。我们之前使用铁锰氮（FeMnN）合金制作了BRFDs的原型，并在台式测试中展示了它们的血流导向功能、径向强度、生物可吸收性和MRI兼容性。在当前工作中，我们研究了它们的动脉瘤闭塞效果。
在7只兔子身上制造弹性蛋白酶诱导的动脉瘤，并将BRFDs放置在动脉瘤上3个月。通过血管造影、大体解剖显微镜检查和组织学评估动脉瘤闭塞效果和生物学反应。
在3个月的终点时，7只兔子中有5只的BRFDs未能闭塞动脉瘤。可生物吸收的金属丝似乎吸收过快，在完全被组织包裹并完全闭塞动脉瘤之前就从动脉瘤颈部断裂。在7只兔子中有3只，一些FeMnN金属丝留在被组织包裹的动脉瘤颈部，部分覆盖了动脉瘤颈部。组织学分析表明，这些金属丝在存在时是组织可以生长的合适基质。因此，我们将动脉瘤闭塞效果不佳归因于机械故障而非生物愈合反应受损。
FeMnN BRFDs降解过快，无法有效治疗兔子弹性蛋白酶诱导的动脉瘤。未来的工作将集中于开发具有延迟吸收速率材料的BRFDs。
