The test, which is at the proof-of-concept stage, can rapidly screen a drop of blood for biomarkers of pancreatic cancer. It can provide results in less than an hour. The findings were published recently in the journal ACS Nano.
Pancreatic cancer is often difficult to cure because it is not usually detected until it has reached an advanced stage.
“An important step towards being able to cure diseases that come out of nowhere, like pancreatic cancer, is early detection,” said first author Jean Lewis, an assistant project scientist in the Department of Nanoengineering at UC San Diego. “We envision that in the future, physicians might perform this type of test using a quick finger stick to diagnose patients who may not know they have the disease yet.”
Blood tests for early cancer detection, known as liquid biopsies, are a hot topic in research. To screen for pancreatic cancer in the blood, researchers are developing new methods that involve collecting and analyzing nano-sized biological structures called exosomes, which are released from all cells in the body, including cancer cells. Exosomes contain proteins and genetic material that can serve as biomarkers for detecting cancers.
The test developed by UC San Diego researchers uses an electronic chip-based system to extract exosomes directly from blood in minutes. “We can use just a drop of blood as is—no extra processing required,” said Lewis. “We can also analyze the exosomes right there on the spot and show whether they carry any of the cancer biomarkers we are looking for.”
The test is simple. Apply a drop of blood on a small electronic chip, turn the current on, wait several minutes, add fluorescent labels and look at the results under a microscope. If a blood sample tests positive for pancreatic cancer, bright fluorescent circles will appear.
“This test could be used as a primary screening strategy to identify patients who would subsequently need to undergo more expensive and invasive diagnostic methods like a CT scan, MRI or endoscopy,” said Dr. Rebekah White, surgical oncologist and associate professor of surgery at Moores Cancer Center.
The chip used in this test works by applying an alternating electric current, which selectively pulls nano-sized particles like exosomes out of the blood and deposits them onto tiny electrodes on the chip’s surface. Larger blood particles get washed away while smaller ones such as exosomes are left behind. Researchers then apply fluorescently labeled antibodies that specifically target two protein biomarkers for pancreatic cancer: glypican-1 and CD63. If these biomarkers are present, brightly colored circles where the antibodies bind can be seen under a microscope, indicating a positive result. This entire process can be done in less than an hour.
So far, the test has only been performed on a small set of patients. More research is being performed to determine if biomarker levels can be detected in cancer stages between stage 0 and stage 1.
The full study can be found in ACS Nano.
