Inexpensive Filter Isolates Circulating Tumor Cells


Researchers at Kumamoto University in Japan have designed an inexpensive and convenient filter that can isolate circulating tumor cells from as little as 1 mL of patient blood. The highly sensitive filter can successfully work in samples containing as few as five tumor cells in 1 mL of blood, and does not require expensive equipment or reagents, unlike certain pre-existing cell capture technologies. The filter may help in developing diagnostic technologies that can aid clinicians in identifying cancer early.

Circulating tumor cells are those that have detached from a tumor and travel through the blood stream. Although they represent a vector for cancer metastasis, circulating tumor cells are a largely untapped diagnostic resource, with enormous potential in assisting clinicians in early cancer identification. If the cells can be successfully isolated from a patient’s blood, they can provide an early warning sign that cancer is present, as well as a minimally invasive diagnostic marker, requiring only a small blood sample.

However, isolating the cells is easier said than done, as they are typically only present in very low concentrations. There may only be several of the circulating tumor cells in a milliliter of blood, whereas the number of white and red blood cells could easily number in the billions. A needle in a haystack doesn’t even come close.

Despite this, researchers have made some headway in developing technologies that can separate circulating tumor cells from whole blood samples. However, such technology can be bulky or expensive, and may rely on expensive reagents, limiting its use. This latest technology employs nucleic acid aptamers and a unique design that allows regular blood cells to flow through, to make a relatively inexpensive filter.

The new filter deforms in three dimensions when blood is pumped through it, resulting in small slits opening that allow blood cells to flow through. However, this effect also causes some intentional cell clumping and allows circulating tumor cells to come into contact with nucleic acid aptamers that are present on the filter surface, resulting in binding and capture. The new device has already demonstrated impressive sensitivity compared with pre-existing tumor cell isolation technologies.    

“This work demonstrates that our micro-filter device can accurately detect trace amounts of cancer cells in blood,” said Yuta Nakashima, a researcher involved in the study. “We expect it will be adopted for cancer diagnosis and treatment, including for early diagnosis of cancers that cannot be detected by imaging like CT and PET scans, postoperative follow-up, recurrence monitoring, and tailor-made treatments. In the future, we plan to use blood samples donated by cancer patients to verify the practical and clinical application of the method.”

Study in journal Talanta: Detection of cancer cells in whole blood using a dynamic deformable microfilter and a nucleic acid aptamer

Via: Kumamoto University

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