Constructing Biological Machines

Research has implications for industry, medicine, energy, environment.

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By Marlene Cimons, National Science Foundation

Imagine clusters of living cells that behave like “machines,” doing many jobs that today’s standard mechanical devices cannot perform, or doing them better.

For example, picture a collection of neurons that signals when a plant needs water. Or an “organ,” made up of cells implanted under the skin, that senses when someone’s blood pressure is too high, then dispenses a drug to lower it. Or a “nose” that crawls into a tiny space and detects a toxin in the water supply, or a hidden explosive.

A science fiction fantasy? Not necessarily.

“We want to create a new biology to, for the first time, build biological machines made purely from cells, whether human cells or those from other animals and organisms,” says Roger D. Kamm, professor of biological and mechanical engineering at the Massachusetts Institute of Technology, and director of the Center for Emergent Behaviors of Integrated Cellular Systems. “We’re not trying to make something that nature already makes very well, but we want to take advantage of what nature has developed over the years, and improve upon it, or use it for other purposes."

The idea behind the center’s research is to understand cells and their environment, and how these cells work together to incorporate biochemical and mechanical cues to perform a wide variety of functions. The center’s approach for constructing biological machines is similar to the engineering techniques employed in making non-biological machines. “Many members of our team are engineers, and we think like engineers, building machines up from individual parts,” Kamm says.

The center, which is based at MIT, is a National Science Foundation (NSF) Science and Technology Center, with research partners at the University of Illinois at Urbana-Champaign, the Georgia Institute of Technology and minority-serving partners at City College of New York, University of California at Merced, and Morehouse College. NSF is funding the Center with $5 million annually over five years.

If successful, the research could have dramatic applications in industry, medicine, energy and the environment, among others. “Just like you can use gears, motors, and sensors, for example, in making a conventional machine, you can use their biological equivalents for a cell-based one,” Kamm says.

Biological robots in an assembly line, for example, could repair themselves and adapt to optimize their performance; new “organs” could be designed and implanted, with the ability to sense drug or glucose levels in the bloodstream, and respond appropriately by turning on or off drug secretion; organisms could swim to an oil spill, and “eat” the damaging substance, replicate if needed, then swim home to the “host” ship for processing; “smart” plant-based machines could release the correct amount of controlled energy to produce heat, light or mechanical work.

“Your imagination could run wild with this once you start thinking of the possibilities,” Kamm says. “Much of what we are planning to do may sound way out there, and futuristic, but we can already accomplish many of the individual steps. For example, we can make a collection of muscle cells contract on demand. The next challenge is to figure out how to keep these cells functioning collectively as a muscle. Right now the cells will start to lose their muscle-like characteristics, and become unable to function."

To be sure, the idea of creating living systems with important new roles raises certain ethical issues which center scientists plan to address.

“Will these machines be endowed with the capability to self-repair, adapt, and self-replicate?” Kamm says. “If so, they become indistinguishable from natural organisms and need to be considered in a similar light. If stem cells are used, from what source may they be taken? What protections and regulations need to be in place? These and many other questions will be openly debated within the center, and with the larger community as we develop these advancing technologies.’’