New Non-invasive Technology Can View And Track Cells

Magnetic resonance imaging (MRI) isn't just for capturing detailed images of the body's anatomy. Thanks to novel imaging reagents and technology, MRI can be used to visualize with "exquisite" specificity - cell populations of interest in the living body. 

The ability to non-invasively locate and track cells, such as immune cells, and betacells will greatly aid the study and treatment of cancer, inflammation, and autoimmune diseases, diabetes, as well as provide a tool for advancing clinical translation of the emerging field of cellular regenerative medicine, by tracking stem cells for example.

Dr. Ahrens will present research on this new approach, called fluorocarbon labeling on Aug. 21 at the 236th national meeting of the American Chemical Society in Philadelphia.

"With our technology we can image specific cells in real-time with exquisite selectivity, which allows us to track their location and movement and to count the apparent number of cells present. We then use conventional MRI to obtain a high-resolution image that places the labeled cells in their anatomical context," said Ahrens, an associate professor of biological sciences at the Mellon College of Science.

The ability to track the movement and eventual location of specific immune cells is critical for understanding the cells' role in disease and therapeutic mechanisms, and for developing effective cell-based therapeutics. Other MRI methods for visualizing cells use metal-based contrast agents, which can make it difficult to clearly identify labeled cells in the body, according to Ahrens.

"The large background signal from mobile water and intrinsic tissue contrast differences can often make it challenging to unambiguously identify regions containing these metal-ion labeled cells throughout the body, which is the current state of the art," Ahrens said.

Ahrens's new approach - fluorocarbon labeling - solves this problem by producing images that clearly show the labeled cells at their precise location in the body. Ahrens first labels the cells of interest with a perfluoropolyether (PFPE) nanoemulsion, which is a colloidal suspension of tiny fluorocarbon droplets. Then, he introduces the labeled cells into an animal subject and tracks the cells in vivo using 19F MRI.

Recent advances in cell-based therapeutics research have focused on training immune cells to counteract diseases including cancer and diabetes and on directing stem cells to regenerate damaged tissues. Non-invasively visualizing these therapeutic cells in patients after transfer can be a vexing problem, according to Ahrens, and any approach that can speed up the testing of these treatments will be extremely useful.

"Ideally we would label therapeutic cells with our cellular MRI agents before they are implanted into a patient. In this way, we could use MRI to visualize the movement of the therapeutic cells in the patient to monitor whether they migrate to and remain in the desired tissues," explained Ahrens.

Source: Diabetes In Control: Carnegie Mellon University (2008, August 22). MRI Technology Developed That Non-invasively Locates, Quantifies Specific Cells In The Body. ScienceDaily. Retrieved August 22, 2008, from http://www.sciencedaily.com /releases/2008/08/080821110109.htm