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Diagnosing Cancer From a Single Drop of Blood

Harvard lab develops microfluidic device

What if a physician could effectively diagnose cancer from one drop of a patient’s blood?

Harvard University student Neil Davey, A.B., Class of 2018, has developed a technique that pushes the possibility of noninvasive cancer diagnosis one step closer to reality. The process involves injecting a tiny amount of blood into a microfluidic device to encapsulate single cells from the bloodstream in individual microfluidic drops. Once the cells have been encapsulated, Davey uses a polymerase chain reaction (PCR), a common technique in molecular biology, to target and amplify fragments of cancer DNA within the drops.

By linking DNA amplification to a fluorescent output, he can shine a laser onto the drops to detect and quantify brightness, which would indicate the presence of cancer DNA in a circulating tumor cell. Davey developed this technique in the lab of mentor Dr. David Weitz, Mallinckrodt Professor of Physics and Applied Physics at the John A. Paulson School of Engineering and Applied Sciences.

“The advantage of this technology is that it is ultrasensitive, so I can detect as few as one cancer cell from a billion normal cells in the blood,” Davey said. “The process is also very specific. One can uniquely detect a wide range of cancers using this DNA amplification technology.”

The technique could hold huge implications in the world of cancer diagnostics, which currently relies primarily on invasive and dangerous tumor biopsies. Microfluidics is much easier and cheaper than traditional methods, since the test uses only tiny amounts of reagents and takes 30 to 60 minutes to complete. The technology is currently about 90% accurate, but that accuracy can be improved if the test is refined to target more genes of the cancer cell, Davey said.

“Because this technology is in an engineering platform, it is pretty universal. We tested the platform itself on prostate cancer and colorectal cancer, but it can be used on any disease, as well,” he said.

Davey is looking forward to studying additional applications of microfluidics. The technology can be used to isolate specific cancer genomes by sorting bright drops out of the mix, allowing scientists to learn more about the nature of the disease. It can also be used to identify specific mutations of the cancer genome, which could help doctors determine which medications would be most effective for a patient.

Source: Harvard University; January 5, 2016.

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