Chip uses microfluidics to detect circulating breast cancer exosomes from blood

As tumors grow, cancer cells release vesicles in the body that are packed with a wide variety of biomolecules specific to each tumor. These vesicles, called exosomes, have emerged as promising biomarkers for cancer diagnosis and predicting how tumors will respond to treatment. Isolating and detecting these nanoscale structures, however, remains a challenge that often involves time-consuming series of ultracentrifugations.

Chen et al. present a new on-chip device that leverages microfluidics for isolating and detecting circulating exosomes in the blood of breast cancer patients. Using a immunomagnetic beads and highly precise microvalves, the group was able to separate out exosomes containing the tumor marker epithelial cell adhesion molecule (EpCAM) from patients’ blood for direct visualization with fluorescence microscopy.

“The size of exosomes secreted by cells is very small, only tens of nanometers. To study them, we need to ‘fish’ them out of body fluids such as blood and urine,” said author Wentao Su. “Here, we first put some magnetic ‘baits’ for exosomes in the body fluid. After catching the exosomes, we can use magnets to draw them out.”

The group’s chip separated the exosomes in about 1.5 hours – less than one-third the time that the most common ultracentifugation approach takes.

The chip exhibited a strong ability to identify the presence of EpCAM-positive exosomes as well as to discriminate between cancer cells and healthy cells, with a reported sensitivity of 90 percent and specificity greater than 95 percent respectively.

The cancerous exosomes could then be analyzed using immunoassay, western blot analysis and electron microscopy.

Su said the group looks to expand their work to detecting more biomarkers with the hopes of determining cancer type and stage.

Source: “Microfluidic device for on-chip isolation and detection of circulating exosomes in blood of breast cancer patients,” by Wenwen Chen, Hongjing Li, Wentao Su, and Jianhua Qin, Biomicrofluidics (2019). The article can be accessed at https://doi.org/10.1063/1.5110973 .