June 6, 2008 Developing fundamental math and mechanics to explain life processes like embryo development, cellular migration and growth could open doors to a new frontier in biology, many researchers say.
A group of these scientists and engineers will gather in Woods Hole, Mass. June 18-21 for the Symposium on Cellular, Molecular and Tissue Mechanics. The University of Michigan is leading the organization of this event.
Symposium participants will present current research on ways mechanics is being used to study and explain biology. Mechanics, one of the earliest branches of physics, is the study of how forces affect matter. It appears that faint pushes and pulls play a much larger role in cellular signaling than previously thought, researchers say.
"The dominant view in biology has been that cellular behavior is largely chemistry-driven, but there's a growing recognition of something else at work. A lot of what the cell does is mechanical. It needs to move things around. It migrates," said Krishna Garikipati, an associate professor in the U-M Department of Mechanical Engineering and the Michigan Center for Theoretical Physics.
For a few decades, biophysicists and other scientists have been examining these forces that measure just one-trillionth of the weight of an average person. But now engineers are getting involved, as the tools of nanotechnology allow them to observe with greater detail and advancements in tissue engineering demand a greater understanding of biology.
"People have known for a long time that mechanics is important, but very little work has been done to nail down what's going on at the cellular level," said Jacques Dumais, associate professor of organismic and evolutionary biology at Harvard University. At the symposium, Dumais will present research on the mechanics of cell growth in plants and fungi.
Dumais says more researchers are looking to math now as a way to connect and comb through decades worth of observational molecular biology data. "Now, there is enough data to make meaningful models," Dumais said. "Models tell us there's something predictable about a system."
A mathematical model of growth could help researchers understand, for example, how a synthetic tissue will interact with the body and change over time.
Cell-generated forces could be involved in many processes, including the spread of cancer in the body. Cells' ability to migrate is central to cancer metastasis. Perhaps there's a way to mechanically prevent the spread of cancer, Garikipati said.
Garikipati will present research that suggests there are simple but universal ways that cells exploit forces to control the growth and motion of focal adhesions, sticky feet that cells develop to help them attach and navigate. They are believed to help guide the differentiation of stem cells into various types of tissues in an embryo.
How mechanics and chemistry work together in embryo formation and growth is a central question of developmental biology, says Larry Taber, a professor of biomedical engineering at Washington University in St. Louis. Taber develops computational models to study the role of mechanical forces in the formation of tissues and organs in embryos. He will present related research at the symposium.
"Some people think that the genes turn on in certain ways and cells just obey," Taber said. "But the genes aren't quite that smart. They may start a process, but then mechanics and chemistry may take over."
A gene may cause a part of a cell to contract, for example. The cells next to it feel that stress and respond to it, perhaps contracting too and generating stress that more cells feel. This stress could act as a signal. In embryo development, Taber said, cells tend to take the shape of an organ, such as a heart, before they differentiate into the proper type of tissue.
Taber is seeking a mechanical source for laws of biology that would explain tissue responses and growth.
"Biological systems have to obey the laws of physics, but I believe there are additional laws that govern the behavior of cells and proteins," Taber said. "But it's a very complex system. In physics, objects don't have a mind of their own."
Growth challenges some of the basic notions of mechanics, researchers say.
"When you look at growth mathematically, you have to get rid of certain assumptions about mechanics. You have to start from scratch. Solid bodies like bridges and buildings aren't gaining or losing mass," Garikipati said.
Close to 40 participants will give 30-minute talks during the symposium, which is at the Jonsson Conference Center in Woods Hole, Mass.
Garikipati and U-M mechanical engineering professor Ellen Arruda are the main organizers of this symposium. In addition to U-M, organizers include Brown University, Stanford University and several international institutions. It is sponsored by the International Union of Theoretical and Applied Mechanics (IUTAM), and supported in part by the National Science Foundation (NSF).
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