It can pick cancer cells out of a blood sample and let them go later, enabling further tests that can show whether the therapy is successfully ridding the patient of the most dangerous cancer cells.
Cells released into the bloodstream by tumors could be used to monitor cancer treatment, but they are very difficult to capture, accounting for roughly one in a billion cells, says Sunitha Nagrath, U-M assistant professor of chemical engineering.
Nagrath and her collaborators pioneered technologies for capturing these cells from blood samples. Their devices trapped the cells on chips made with graphene oxide, a single layer of carbon and oxygen atoms. But all analysis had to be done on the chip because the cells were firmly stuck.
"We could grow the cells on the chip or analyze them all together, but research has shown that cancer cells are not all the same," she said. "Hence, it is important to study cells individually, and our new device makes this possible."
The stem cell theory of cancer holds that relapses occur because chemotherapy and radiation therapy are not very effective at killing cancer stem cells, which can make up as much as 10 percent of a tumor. As a result, the cancer stem cells left behind are able to regrow the tumor or spread to other areas of the body.
New treatments in clinical trials attack the stem cells, but killing this smaller population does not immediately shrink the tumor. Doctors need a good way to monitor whether the cancer stem cells are on the decline. This may be possible through blood tests, but clinicians need to study captured cells individually, and that means removing them from the chip.
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