Nanoparticles May Help Identify, Treat Tumors

A new technique may in the near future help clinicians detect tumors during the initial stages of growth. The technique allows nanoparticles to congregate inside cancerous tumors, creating masses with enough of a magnetic signal to be identifiable by magnetic resonance imaging (MRI) scanning.

The study, performed by engineers from the Massachusetts Institute of Technology (MIT; Boston, MA, USA), was published in the May 2006 issue of the journal Angewandte Chemie International Edition. The research, which is just going into animal trials, involves injecting nanoparticles (billionths of a meter in size) made of iron oxide into the body, where they flow through the bloodstream and enter tumors.

Solid tumors must form new blood vessels to grow in a process called angiogenisis. But because this growth is so fast in cancerous tumors, there are gaps in the endothelial cells that line the inside of the blood vessels. The nanoparticles can slide through these gaps to enter the tumors. Once inside the tumor, the nanoparticles can be prompted to group together by a process devised by the MIT engineers.

Specifically, specific enzymes called proteases inside the tumors cause the nanoparticles to "self-assemble,” or bind together. The resulting nanoparticle clusters are too large to get back out of the gaps. Furthermore, the clusters have a stronger magnetic signal than do individual nanoparticles, allowing detection by MRI.

"We inject nanoparticles that will self-assemble when they are exposed to proteases inside of invasive tumors,” said Sangeeta N. Bhatia, M.D., Ph.D., associate professor of the Harvard (Boston, MA, USA)-MIT Division of Health Sciences & Technology (HST) and Electrical Engineering and Computer Science (EECS). "When they assemble, they should get stuck inside the tumor and be more visible on an MRI. This might allow for noninvasive imaging of fast-growing cancer ‘hot spots' in tumors.”

The technique initially is being used to evaluate breast tumors. Dr. Bhatia added that it ultimately may be applied to many different types of cancers and to study the "triggers” that turn a benign mass in the body into a cancerous tumor. Nanoparticles also have the potential to deliver agents that could destroy cancer cells, replacing radiation or chemotherapy treatments that cause debilitating side effects such as hair loss or nausea.

The researchers hold a provisional patent on their work.



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