Nanotech News

November 21, 2005

Tracking Human Melanoma Therapy with Magnetic Nanoparticles

The use of the body's own immune system cells and stem cells to fight cancer is one of the novel approaches to cancer therapy now being tested in human clinical trials. The success of this type of therapy relies in part, however, on delivering these cells to target organs. For example, cancer researchers have been keen on delivering what are known as dendritic cells to lymph nodes in order to stimulate the body's immune system to attack melanoma. Now, investigators have demonstrated that they can use magnetic iron oxide nanoparticles injected into dendritic cells to track where these cells go using conventional magnetic resonance imaging (MRI).

Reporting its work in the journal Nature Biotechnology, an international research team headed by Carl Figdor, Ph.D., of the Radboud University Nijmegen Medical Centre in The Netherlands and Jeff Bulte, Ph.D., of the Johns Hopkins University School of Medicine, show how immature dendritic cells will naturally take up iron oxide nanoparticles in amounts that are sufficient to make these labeled cells visible in an MRI scan. The investigators begin with dendritic cells that have been loaded with tumor markers, or antigens, derived from a patient's own melanoma cells. After treating these primed cells with iron oxide nanoparticles, the researchers then injected the dendritic cells into the lymph nodes of eight stage-III melanoma patients.

MRI scans performed two days after the injection showed that up to 40 percent of the dendritic cells migrated to nearby lymph nodes. In the scans, lymph nodes containing the labeled dendritic cells were easily distinguished from empty lymph nodes.

One finding from this study was that the dendritic cells were injected correctly into lymph nodes in only half of the patients despite using ultrasound imaging to guide the injections. The investigators concluded that MRI imaging done in conjunction with dendritic cell therapy could improve the success rate of this therapy by ensuring that the therapy is administered correctly. Indeed, the researchers questioned whether inadequate delivery of dendritic cells to lymph nodes might account for fact that only a limited portion of patients respond to dendritic cell therapy.

This work, which was supported in part by the National Institutes of Health, is detailed in a paper titled, "Magnetic resonance tracking of dendritic cells in melanoma patients for monitoring of cellular therapy." An abstract is available through PubMed.
View abstract.