A gravity-based blood test for mesothelioma and other cancers? Scientists say it might pan outResearchers from Johns Hopkins University's Department of Chemical and Biomolecular Engineering recently announced that they have created a microfluidic device that might be used to sift through blood to look for cancer cells, using nothing more than magnetic microbeads and gravity.
If you've ever tried panning for gold, then you'll have an idea of how this new, potentially mesothelioma-detecting device might work.
A ramp, a blood sample and some 'speed bumps'
German Drazer and Jorge Bernate, the scientists that developed this test, emphasized its simplicity. It has no moving parts, being comprised of nothing more than a tiny, slightly tilted plate covered with small parallel "speed bumps." Each bump is a micron high - that is, one millionth of a meter.
By applying blood to this so-called lab-on-chip system, scientists could theoretically separate the sample's cells by weight, in a process that resembles gold panning.
"As different particles are driven over these diagonal speed bumps, heavier ones have a harder time getting over than the lighter ones," Bernate explained. He added that cells stop against a particular bump and then roll along it until they reach a collection trough: "After the particles cross this section of the 'highway,' they end up in different 'lanes' and can take different 'exits,' which allows for their continuous separation."
The key to this process is the specific gravity - or inability to float - of cancer cells. The only problem, as Drazer and Bernate intuited early on, is that bloodborne cancer cells usually are not heavier than other cells.
To solve the problem, they came up with an elegant potential solution: Inject patients with a mixture of tumor-cell-binding magnetic microbeads. These would weigh down bloodborne mesothelioma cells and make them easier to sift out of sample serum.
The applications are promising
One of the reasons that this microfluid test is so appealing to oncologists and patient advocates is that, currently, there is no accurate blood test for detecting mesothelioma at all, much less early.
The only existing tests look not for malignant cells, but for certain proteins - like mesothelin and osteopontin - that are associated with mesothelioma. These tests are notoriously insensitive, making them useful only for tracking the course of previously diagnosed mesothelioma.
However, the creation and fine-tuning of microfluidic assays might change all that. A full description of this technique appears in the journal Physical Review Letters.
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