(475ad) On the Use of a Ferromagnetic Stent for Implant Assisted Magnetic Drug Targeting

Authors: 
Aviles, M. O., Northwestern University
Ebner, A. D., University of South Carolina
Ritter, J. A., University of South Carolina


Implant assisted (IA) magnetic drug targeting (MDT) is a new drug targeting approach that utilizes a ferromagnetic implant, magnetic drug carrier particles (MDCPs) and an external magnetic field source. The ferromagnetic implant is placed within the body near a target site or zone. The external magnetic field source is then located near this target zone. Finally, the MDCPs are injected into the body near this target zone, and because of their magnetic properties, they become attracted to and are retained by the ferromagnetic implant. The objective of the research that has been carried out by the authors over the past few years is to convincingly demonstrate for a wide range of physical conditions and physiologically relevant situations that more MDCPs are collected when the implant is in place compared to the situation where the implant is not used.

A very effective ferromagnetic implant could be based on the properties of a therapeutic stent. A therapeutic stent is an expandable tube made of a metallic mesh that is used as a prosthesis in a variety of medical situations. Using minimal invasive techniques, such as catheterization, a stent can be placed in the lumen of a blood vessel almost anywhere in the body.

As a first attempt to analyze the effectiveness of a stent as a ferromagnetic implant, an in vitro flow system was devised and used to study the conditions relevant to sequestration of MDCPs from flow fields associated with typical arterial and/or venous blood velocities. Two approaches have been used to study the feasibility of a stent as a MDT device. The first approach encompassed using a ferromagnetic coil placed inside a glass tube while a suspension of MDCP surrogates flowed through it. The second approach encompassed using a metallic mesh to better simulate the multi-wire arrangement of a real intravascular stent.

This in vitro study is being done first to guide a future in vivo study with rat models. Some theoretical work is being done to guide both the in vitro and in vivo studies to gain a fundamental understanding of the underlying and controlling principles. Key parameters that are being studied, as they are considered to be fundamental to the IA-MDT approach, include the velocity of the suspension flow, the external magnetic field strength, the coil wire and mesh properties, and the properties of the MDCP surrogates.

This presentation will provide an overview of the different approaches where IA-MDT can be used to enhance the collection of MDCPs at targeted sites. It will also provide a summary of the most recent findings from this in vitro study.