A new way of diagnosing lung cancer with a blood draw is 10 times faster and 14 times more sensitive than earlier methods, according to University of Michigan researchers. The microchip developed at U-M captures exosomes—tiny packages released by cells—from blood plasma to identify signs of lung cancer. Once thought to be trash ejected from cells for cleanup, researchers discovered in the past decade that exosomes are tiny parcels containing proteins or DNA and RNA fragments that are valuable for communication between cells.
Although healthy cell exosomes move important signals throughout the body, cancer cell exosomes can help tumors spread by preparing tissues to accept tumor cells before they arrive. “Cancer exosomes leaving the tumor microenvironment go out and kind of prepare the soil. Later, the cancer cell seeds shed from the tumor and travel through the bloodstream to plant in the conditioned soil and start to grow,” said Sunitha Nagrath, U-M professor of chemical and biomedical engineering and co-corresponding author of the study in the journal Matter.
Exosomes carry proteins both inside the parcel and on their outside surface. Like many biological molecules, these surface proteins are chiral—meaning they have a right- or left-handed twist—which causes them to interact with light in unique ways. In cancer exosomes, surface proteins are often mutated, meaning a genetic change altered the order of the molecules that make up the protein.
Mutations subtly cha.