Chip Performs Blood 'Biopsy'

CHARLESTOWN, Mass., Dec. 19, 2007 -- A microchip-based device the size of a business card uses 80,000 posts smeared with an antibody "glue" to capture hard-to-find tumor cells in blood samples, providing new information about the cells to help monitor and guide future cancer treatments.

The device, called the CTC-chip, was developed by a team from the Massachusetts General Hospital (MGH) Biomicroelectromechanical Systems (BioMEMS) Resource Center and the MGH Cancer Center. It can isolate, count and analyze circulating tumor cells (CTCs) -- viable cells from solid tumors carried in the bloodstream at a level of one in a billion cells -- from a blood sample. Because of their rarity and fragility, it has previously not been possible to get information from CTCs that could help clinical decision-making.
“This use of nanofluidics to find such rare cells is revolutionary, the first application of this technology to a broad, clinically important problem,” said Daniel Haber, MD, director of the MGH Cancer Center and a co-author of the report in the Dec. 20 issue of Nature. “While much work remains to be done, this approach raises the possibility of rapidly and noninvasively monitoring tumor response to treatment, allowing changes if the treatment is not effective, and the potential of early detection screening in people at increased risk for cancer.”

The existence of CTCs has been known since the mid-19th century, but since they are so hard to find, it has not been possible to adequately investigate their biology and significance. Microchip-based technologies have the ability to accurately sense and sort specific types of cells, but have only been used with microliter-sized fluid samples, the amount of blood in a fingerprick. Since CTCs are so rare, detecting them in useful quantities requires analyzing samples that are 1000 to 10,000 times larger.