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Window of Opportunity:
Bill Messner sees possibilities in bio-engineering collaboration

By Heather Wax

On a typical day, we encounter any number of control systems—devices that regulate the behavior of other devices: the cruise control in our cars, which maintains the vehicle's speed whether it is going uphill or downhill or there's a headwind; or the thermostat in our homes, which maintains the temperature inside regardless of how hot or cold it is outside. And there are the biological control systems in the cells of our bodies, such as those that—if everything is functioning as it should—maintain our blood sugar within a certain range regardless of what we eat or whether our stomachs are full or empty.

Bill Messner, acting chair of mechanical engineering, sees possibilities in the collaboration between biology and mechanical engineering.

Bill Messner, acting chair of mechanical engineering, sees possibilities in the collaboration between biology and mechanical engineering.

Control systems are Bill Messner's specialty. He has worked on controls for data storage and robotic systems, and in recent years, he has begun to apply his work to biological research. “The interest that I have in this area is twofold,” says Messner, the acting chair of the Department of Mechanical Engineering.* “One is building instrumentation to probe blood cells, tissues, and maybe other things—for examining the biological system. And the other thing is to see what the biological system itself is doing. So we build control systems for the instruments and then we also are interested in how the biological systems control themselves.”

What Messner is now trying to understand, more specifically, is how cells and tissues respond to chemical stimuli. To that end, he is designing and building instruments that can be used to investigate the mechanics of cells using microfluidics.

A biological controls system experiment with microfluidics goes something like this: Researchers place pieces of frog embryo in microfluidic channels, which are very small pipes about a millimeter wide or even narrower. Because the channels are narrow, fluids that flow down them don't mix. Instead, they stay in separate lanes, flowing side by side. As a result, researchers can treat different parts of the embryo with different chemicals; and by changing the flow rates of the chemicals, they can move what they call the “interface” between them, so that part of the embryo always gets stimulus, part never gets stimulus, and the part in the middle is stimulated on and off.

To do this, scientists would use a syringe pump. The trouble is that the amount of liquid a syringe can hold is limited, and it is difficult to control flow rates accurately inside the channels. That meant researchers could only do these microfluidic experiments slowly and only as long as the amount of chemical in the syringe lasted. One of the systems Messner helped devise is a new control mechanism that lets researchers manipulate the fluids more precisely, very quickly, and on the scale of hours, days, or even weeks. The innovation was to replace the syringe pump with a coupled variable resistance and squeeze pump, allowing researchers to use a supply of fluid from a “reservoir of essentially arbitrary size—gallons, in fact we could use a swimming pool,” Messner says.

“That's a huge reservoir we can run for a long time,” he explains. “But we've also got this mechanism that allows us to change things really fast, faster than once per second, like probably closer to 10 times per second. That capability is very, very handy for doing the kind of experiments we like to do because we don't have to wait very long for moving this interface across the embryo or tissue. We can almost instantly move the interface from one side to the other. So we know very precisely how long a particular part of the tissue has been stimulated.” Eventually, he says, knowledge about how biological systems respond to stimuli and control themselves might help scientists develop human therapies to facilitate wound healing or arrest or slow down the growth of cancer.

At Tufts School of Engineering, “Messner's work in applying control theory to biological systems will be a strong addition to our department's current activities in dynamics, controls, and sensor systems,” Robert J. Hannemann, formerly the acting chair of the mechanical engineering department and director of Tufts Gordon Institute, observes, “especially in our collaborative research in soft-body robotics and the new IGERT program in this area.” Messner says he's particularly excited to partner with biomedical engineer and Chair David Kaplan, co-PI of that program, as well as Michael Levin, director of the Tufts Center for Regenerative and Developmental Biology.

“Mike has done just amazing stuff. I'm really hoping that I will be able to collaborate with him and be a part of his research on embryonic development—and I think where I will jump in, at least initially, is helping him to create the instrumentation to do more sophisticated experiments that he's already started doing,” says Messner. “Definitely the biology is kind of the hot thing for me right now. It's got a lot going on at Tufts, great collaborators, and technologies that allow us to have capabilities that formally were very difficult or impossible.”

*Dr. Bill Messner is currently acting chair and visiting professor. He will be instated as chair of Mechanical Engineering pending approval by the Tufts University Trustees.

Heather Wax is a science writer living in Brookline. She has written for Scientific American, Ode, The Boston Globe, and MIT's Technology Review, among other publications.

[posted September 20, 2012]