Tuesday, April 29, 2008

Magnets in cancer treatments - a new oncology tool or a bad idea?

Biopsy results can be ambiguous: sometimes they can be negative simply because there are too few malignant cells in the sample to be detected - not because all trace of disease has gone. Researchers from the University of New Mexico and the company Senior Scientific, both in Albuquerque, have devised a solution that harnesses the power of magnetic attraction.

The idea is to use magnetic iron oxide nanoparticles encased in a biocompatible material. These in turn can be coated with antibodies that bind to chemicals found only in cancerous cells. When injected into the body, thousands of the particles stick to cancer cells, turning them into miniature magnets. The cells can then be drawn towards magnets encased in the tip of a biopsy needle (Source: Physics in Medicine and Biology, vol 52, p 4009).

A mathematical model of the system confirmed that significant numbers of cancer cells, laden with nanoparticles, could be attracted to a needle within two or three minutes. In the lab, the researchers showed that a magnetised needle could attract leukemia cells surrounded by nanoparticles and suspended in blood or other synthetic materials designed to mimic bodily fluids. Nanoparticles have been used before to destroy diseased cells, but this was the first time they actually retrieved cells.

More recently, researchers have been wondering if cancer treatments be enhanced by something as simple as a magnet. A promising way to tackle some diseases is to deliver cells with modified genes to diseased tissue. Getting enough of the modified cells to the affected area can be tricky.

Claire Lewis and colleagues from the University of Sheffield inserted magnetic nanoparticles, as well as cancer-fighting genes, into monocytes, the white blood cells commonly used in gene therapy, and injected them into mice with tumours. A magnet placed above the tumour caused the cancer-fighting monocytes to congregate there (Source: Gene Therapy, DOI: 10.1038/gt.2008.57).

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