While non-invasive imaging technologies such as mammograms or CT scans are capable of detecting tumors, identifying whether they are malignant or benign usually involves getting out the scalpel and conducting a biopsy. Now researchers at Johns Hopkins University have developed a technique that uses magnetic resonance imaging (MRI) to noninvasively detect cancerous cells, offering the potential of supplementing biopsies or maybe one day replacing them altogether.
The team's study, conducted on test tube-grown cells and mice, took advantage of recent findings by other research groups indicating that glucose can be detected without the use of injectable dyes by a fine-tuned MRI technique. Because the outer membranes of certain cancerous cells shed sugar molecules, the Johns Hopkins researchers were able to use this technique to image cancerous cells.
"We think this is the first time scientists have found a use in imaging cellular slime," says Jeff Bulte, Ph.D., a professor of radiology and radiological science in the Institute for Cell Engineering at the Johns Hopkins University School of Medicine. "As cells become cancerous, some proteins on their outer membranes shed sugar molecules and become less slimy, perhaps because they’re crowded closer together. If we tune the MRI to detect sugars attached to a particular protein, we can see the difference between normal and cancerous cells."
Although other research efforts have used MRI to image proteins on the outside of cells that have lost their sugar, these have relied on injectable contrast dyes. The new technique can provide a more comprehensive view by relying on the way glucose interacts with surrounding water molecules. After comparing MRI scans of proteins called mucins with and without sugars attached to discern how the signal changed, the researchers then looked for the signal in four types of lab-grown cancer cells. The technique revealed mucin-attached sugars at markedly lower levels in cancerous cells than in normal cells.
"The advantage of detecting a molecule already inside the body is that we can potentially image the entire tumor," says Xiaolei Song, Ph.D., the lead author on the study and a research associate in Bulte’s laboratory. "This often isn’t possible with injected dyes because they only reach part of the tumor. Plus, the dyes are expensive."
Song says this is the first technique to use an integral property of the cells, rather than an injected dye, to detect cancer cells. Having demonstrated the technique in test tube-grown cells and mice, the team will next explore whether it can be used to distinguish more types of cancerous tumors from benign tumors in live mice.
If further testing goes the way they hope it does, the researchers say the technique could help detect cancer in people at earlier stages and be used to monitor a patient's response to chemotherapy. It could also help ensure the most malignant part of a tumor is sampled for biopsies, and potentially replace at least some biopsies altogether.
The team's research appears in the online journal Nature Communications.
Source: Johns Hopkins Medicine
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