New microchip sorts white blood cells from whole blood

Early in 2012, MIT scientists reported on the development of a postage stamp-sized microchip capable of sorting cells through a technique, known as cell rolling, that mimics a natural mechanism in the body. The device successfully separated leukemia cells from cell cultures—but could not extract cells directly from blood.

Now the group has developed a new microchip that can quickly separate white blood cells from samples of whole blood, eliminating any preliminary processing steps—which can be difficult to integrate into point-of-care medical devices. The hope, the researchers say, is to integrate the microchip into a portable diagnostic device that may be used to directly analyze patient blood samples for signs of inflammatory disease such as sepsis—particularly in regions of developing countries where diagnostic lab equipment is not readily available.

In their experiments, the scientists pumped tiny volumes of blood through the microchip and recovered a highly pure stream of white blood cells, virtually devoid of other blood components such as platelets and red blood cells. What's more, the team found that the sorted cells were undamaged and functional, potentially enabling clinicians not only to obtain a white blood cell count, but also to use the cells to perform further genetic or clinical tests.

Rohit Karnik, an associate professor of mechanical engineering at MIT, says the key to recovering such pure, functional cells lies in the microchip's adaption of the body's natural process of cell rolling."We believe that because we're using a very biomimetic process, the cells are happier," Karnik says. "It's a more gentle process, and the cells are functionally viable."