Abstract:
PURPOSE:Our aim was to compare different magnet arrangements for magnetic cell delivery to human lower leg arteries and investigate the theoretical targeting efficiency under realistic flow conditions as a possible treatment after angioplasty. Additionally the potential of scaling down or translating the magnetic actuation device for preclinical studies was explored. METHODS:Using finite element methods, the magnetic field distribution was calculated in 3D for the optimization of magnet arrangements. Computational fluid dynamics simulations were performed for the human posterior tibial artery with the geometry and boundary condition data derived from magnetic resonance imaging (MRI) studies. These simulations were used to trace the trajectories of cells for an optimized magnet arrangement. Additionally the behavior of cells close to the vessel wall was investigated using a fluid-structure interaction model. RESULTS:The optimal magnet for the lower leg arteries was a Halbach cylinder k3 variety (12 elements with 900 rotation steps for the magnetization orientation). With this magnet, numerical simulations predict a targeting efficiency of 6.25% could be achieved in the posterior tibial artery for cells containing 150 pg iron. Similar simulations, which were scaled down to rabbit dimensions while keeping the forces acting on a cell constant, lead to similar predicted targeting efficiencies. Fluid dynamic and fluid-structure interaction simulations predict that magnetically labeled cells within a 0.5% radii distance to the vessel wall would be attracted and remain at the wall under physiological flow conditions. CONCLUSIONS:First pass capture of magnetically labeled cells under pulsatile flow conditions in human lower leg arteries leads to low targeting efficiencies. However, this can be increased to almost 100% by stopping the blood flow for 5 min. A magnetic actuation device can be designed for animal models that generate magnetic forces achievable for cells in human leg arteries.
journal_name
Med Physjournal_title
Medical physicsauthors
Riegler J,Lau KD,Garcia-Prieto A,Price AN,Richards T,Pankhurst QA,Lythgoe MFdoi
10.1118/1.3593363subject
Has Abstractpub_date
2011-07-01 00:00:00pages
3932-43issue
7eissn
0094-2405issn
2473-4209journal_volume
38pub_type
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