Embolization of Blood Vessels as a Cancer Therapy Using Magnetorheological Fluids

This paper demonstrates a possible in vitro cancer therapy by mechanically blocking the blood vessels to a tumor through injecting a model magnetorheological (MR) fluid and applying an external magnetic field. The biocompatible MR fluid is made of magnetite particles coated with starch and suspended in either water or sheep blood. Two particle sizes of 1.0 and 0.25 μm are used. A simple blood network consists of four branches of blood vessels made of silicone tubes of 0.4 mm in diameter. One of the branches contains a tumor made of a cylindrical cavity with a diameter of either 3.0 or 5.0 mm to simulate stage II or III tumors. The cavity is connected with either two or four vessels to the rest of the branch and is placed between two magnetic poles. By measuring the weight of the leaking fluid downstream from the magnets, the sealing quality is monitored. A dilute MR fluid (1.0% particle volume fraction) is pumped slowly through the network. As the fluid goes through the cavity, seals form within seconds after a magnetic field (0.43-0.62 T) is turned on. They block the fluid flow to the tumor. With sheep blood as the suspension medium, both size of magnetite particles form a good quality seal for the 3 mm cavity. Thus, a mechanical method for stopping blood flow is demonstrated in a multi-tube blood network for stage II tumor.