It is very difficult for doctors to measure the evolution of tumors and if chemotherapy is actually working on cancer patients. This is why MIT researchers have developed a minuscule device that can be implanted directly into a tumor and containing nanoparticles designed to test for different substances associated with tumor growth. As the implant can stay inside the patient for a long time, it will help doctors to see if a treatment is working. This could avoid repetitive MRI (magnetic resonance imaging) exams. But the implant has to go through extensive preclinical testing before being approved.
How will work the nanoparticles contained in the new MIT implant?
Such nanoparticles have been used before, but for the first time, the MIT researchers have encased the nanoparticles in a silicone delivery device, allowing them to remain in patients' bodies for an extended period of time. The device can be implanted directly into a tumor, allowing researchers to get a more direct look at what is happening in the tumor over time.
Below are three images showing how these nanoparticles will be used. (Credit: Michael Cima research group in this slide show)
|"In this image, nanoparticles tailored to detect a particular molecule, or analyte, are suspended within a device that allows them to be delivered into a patient's body."|
|"Next, analytes enter the device through a porous membrane."|
|"As a result, the nanoparticles attach to the analytes and clump together. Those clumps can be detected by magnetic resonance imaging."|
Cima's tumor monitor is a silicone rod about eight microliters in volume filled with sensing nanoparticles. At the center of each particle is iron oxide, a good contrast agent for MRI scans. However, because the particles are so small, it's only when they clump together that they are easy to see on an MRI scan. The iron-oxide particles are coated with the carbohydrate dextran, to which the researchers can attach multiple antibodies for whatever molecule in the tumor environment they want the device to detect. When the target molecule enters the device, several nanoparticles will attach to it and become visible as a dark speck on an MRI scan.
And what cancer patients can expect from such a device? At least less intrusive exams.
Looking to the future, Cima says he hopes the process won't involve running patients through an MRI scanner again and again. His group is working to modify a portable MRI machine to function with the detecting implant. About the size of a box of tissues, the scanner could be waved over the part of the body that harbors the device and take a quick image.
But right now, "the next step for the research group is to start more extensive preclinical testing."
Sources: Massachusetts Institute of Technology press release, via EurekAlert!, December 18, 2006; Katherine Bourzac, Technology Review, December 14, 2006; and various websites
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