Ten mil­li­liters of blood may not seem like a lot, and coming from healthy indi­vid­uals it isn’t. But for crit­i­cally ill patients with dimin­ished resources, 10mL could be cru­cial. Nonethe­less, that’s what’s cur­rently required to test for cir­cu­lating tumor cells in late-​​stage cancer.

In a recently com­pleted grad­uate thesis, Brian Plouffe employed the com­bined exper­tise of fac­ulty mem­bers Shashi Murthy and Laura Lewis in Northeastern’s Depart­ment of Chem­ical Engi­neering to develop an alter­na­tive testing method.

Diag­nosing metas­tasis in late-​​stage cancer patients requires iden­ti­fying for­eign cells in the blood­stream, known as cir­cu­lating tumor cells. The cur­rent method for doing so involves a costly, inef­fi­cient tech­nique called magnet-​​activated cell sorting (MACS).

As the name implies, clin­i­cians tag the cells of interest with micro­scopic mag­netic beads and then use a large magnet to sep­a­rate them from the rest of the blood sample. The whole pro­ce­dure, which first requires a lengthy sample cleanup process, takes place in a test tube and uses up the entire sample in one run.

Plouffe’s approach shrinks the process to a frac­tion of the size and cost. The method allows clin­i­cians to pass a single mil­li­liter of whole unprocessed blood through a minia­tur­ized ver­sion of a MACS device, which can be tuned to test for a variety of cell types.

In the first two years of his inves­ti­ga­tion, Plouffe “described the whole thing with equa­tions,” says Murthy. They started with exten­sive cal­cu­la­tions that pre­dicted how a par­ticle would move in a mag­netic field with a fluid carrier.

We took a math­e­mat­ical approach first before coming in and trying to build some­thing that may or may not work,” Plouffe said.

Whereas Murthy afforded insight into the fluid dynamics part of the equa­tion, Lewis’ exper­tise in rare-​​earth mag­nets and elec­tro­mag­netism helped Plouffe deter­mine how those ele­ments would affect the system. “I don’t do bio,” Lewis said. “Shashi doesn’t do mag­netism. But at the time Brian was still in the learning mode of both fields. He forged the col­lab­o­ra­tion in order to come up with some­thing new that com­bined them.”

In Jan­uary, the team pub­lished its first proof-​​of-​​concept results. They first fab­ri­cated the devices and then tested them with blood sam­ples con­taining a known con­cen­tra­tion of mag­net­i­cally tagged breast cancer cells. The devices recov­ered up to 95 per­cent of the cancer cells with min­imal non-​​target blood cell contamination.

Not only is Plouffe’s approach effi­cient and inex­pen­sive, it is also portable and extremely user friendly. Plouffe imag­ines that it could one day be used in the field in under­de­vel­oped nations to diag­nose dis­ease in real-​​time.

Murthy expects the device to have far reaching appli­ca­tions, with the poten­tial to make early-​​stage diag­noses from a variety of fluid types (saliva, lym­phatic fluid, etc.), and testing for cell types beyond cancer.