gms | German Medical Science

Objective: To assess a novel embolisation material in experimental aneurysms whereby intra-arterial administration of magnetic nanoparticles are navigated into the lumen of vascular aneurysms with assistance from an external magnetic field.

Methods: A magnetically steerable substance (Magseal, APG Ltd., Newbury, UK) was used to fill experimentally induced aneurysms in rabbits. The substance consisted of Core-Shell (CS) Particles suspended in saline. The particles had a shell made of a polymeric material and a core made of magnetite (Fe₃O₄). The diameter of the CS particles was 1.4 micrometers. To stabilize the CS particles in suspension, they were coated layer by layer (LBL) with a positively charged polymer and a negatively charged polymer such that the outer layer was negative. To prevent the magnetite cores from becoming permanently magnetized, they were comprised of a multiplicity of nanoparticles. During Magseal administration via a microcatheter, a magnetic field (0.125 T, 0.013 Tesla/mm) was applied to the aneurysm. The magnetic field was generated using solid-state neodymium magnets. The magnets were placed externally to the animal’s body.

Results: It was possible to steer and hold the nanoparticles within the aneurysmal cavity where they occluded the lumen progressively. After removal of the external magnetic field, the results remained stable for the remainder of the observational period (30 minutes), however, after a 4-week observational period, recanalization of the aneurysm occurred. Multi-organ histological examination did not identify any adverse findings.

Conclusions: Magseal can be magnetically directed into aneurysms allowing short-term obliteration. Although the method has yet to show reliable long-term stability, these experiments provide the proof of concept encouraging further investigation of intravascular magnetic compounds. The small size of the particles allows capillary penetration without occlusion.