MIT chip to revolutionise disease management?

The hope, they say, is to integrate the microchip into portable diagnostic devices that can analyse patient blood samples for a range of diseases — 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," he commented. "It's a more gentle process, and the cells are functionally viable." Before flowing blood through the chip, the team first tested the design with a culture of two types of leukemia cells. Through video imaging, they observed that one cell type was drawn out of the stream, attaching and rolling briefly along a sticky gold stripe before jumping to a neighboring line. Eventually, after a series of jumps and rolls, the cells rolled the rest of the way along a stripe, then into a separate gutter, or channel, where they flowed into a collector. Karnik and his team measured the interactions between target cells and the chip's pattern of stripes, and developed a mathematical model to describe the optimal pattern of cell rolling, depending on several factors such as the angle and length of each stripe. "We are able to get a good picture of the separation process, and this should be useful in guiding future devices of this type," Karnik concluded.