Researchers from Yale’s Mechanical Engineering Department recently developed a technique to control the movement of immune system cells by taking advantage of how these cells track bacteria.

Knowing that immune system cells follow chemical trails released by bacteria, post-doctoral researcher Holger Kress and mechanical engineering professor Eric Dufresne ’96 developed artificial bacteria that released chemicals typically tracked by the immune system. By moving these artificial bacteria with beams of light in a microscope, Kress and Dufresne were able to guide the immune system cells.

“The motion of cells in response to external stimuli is a key part of our immune system.” Kress said in an e-mail. “If we learn more about this motion in response to stimuli, we will get a deeper understanding of our immune systems and diseases like cancer.”

If scientists can understand how the immune system tracks down harmful bacteria, Kress said, researchers will be able to understand how immune system cells process chemical information. This will give scientists new ways to comprehend and investigate how other cells in the human body communicate using chemicals.

“We believe that the technique can be applied to a wide range of research areas in cell biology and in developmental biology.” Kress said. “Such a deeper understanding will hopefully lead to better cures for diseases such as cancer or autoimmune diseases.” Kress and Dufresne worked with biomedical engineering professor Tarek Fahmy to create artificial bacteria that mimicked the size and chemical signature of the average bacteria. Previously, scientists understood that immune system cells tracked bacteria by their chemical trails, Kress said. But they were unable to create artificial bacteria that released the correct chemical trails until now.

Creating the artificial bacteria was only half of the task, Kress said. In order to guide immune cells using these artificial bacteria, the lab also needed to find out how to control their movement.

To do this, Kress said, the lab used very focused beams of light to physically move the artificial bacteria.

Dufresne and his team next hope to investigate new ways of tracking and directing the motion of immune cells by varying the types and concentrations of chemicals released by the artificial bacteria.

The paper describing the procedure and results was published online in the Nov. 15 issue of Nature Methods. The research was funded by the German Academy of Sciences Leopoldina, the National Institutes of Health and the National Science Foundation.