Featured Science and Innovations
Tensegrity in a Cell
What do the human body, a sailboat's rigging and a circus tent have in common? If you happened to catch the title of this page, you won't be surprised at the answer: Tensegrity.
A tensegrity structure is composed of parts, or elements, that are "tensed," working in opposition to other elements that resist being compressed. These elements are balanced in such a way that they tense and stabilize the entire structure. In the human body, bones are compression struts that oppose the tension created by muscles, tendons and ligaments. In a sailboat, the mast, spreaders and hull act as compressional elements working in opposition to wire cables that tense and stabilize the entire structure. Likewise, tensed canvas fabric pulls against rigid pegs in the ground and vertical poles to give the circus tent its shape.
Thirty years ago, while still an undergraduate student at Yale, Donald Ingber, MD, PhD, began to think that cells, too, might be tensegrity structures. In the years since, he and his colleagues at Children's Hospital Boston and Harvard University have gone on to substantiate the idea. They have shown that contractile microfilaments in the cell's molecular skeleton, or cytoskeleton, act like stretched rubber bands as they compress hollow cytoskeletal fibers called microtubules and pull on molecular pegs that anchor the cell to an underlying scaffold -- the extracellular matrix. Moreover, they have found that physical distortion of the cell and cytoskeleton can alter cellular biochemistry and gene expression. This form of "mechanobiology," says Dr. Ingber, is as important to body function as hormones and other chemical interactions. An example of mechanobiology in action occurs after an injury in which cells are removed. Freed from their normally crowded context, the cytoskeletons and nuclei of cells that were adjacent to the removed cells distort, which triggers genes and chemical reactions that cause them to multiply until they get so tightly packed and compressed that they stop growing. This is how tissue regenerates.
Here, you can experiment with the counteracting forces inside the molecular skeleton of a single cell by selectively changing the length or tension of cytoskeletal filaments and by altering the rigidity of the extracellular matrix. See how your actions affect the various structural elements inside the cells, as well as the overall shape of the cell.
Interactive Feature: Tensegrity in a Cell (700 K)
Manipulate the forces, structural restraints and molecular elements of a cell's cytoskeleton and see how your changes affect the cell's shape. Requires Flash plugin.
More on Tensigrity
These three animated gifs, provided by Eddy Y. Xuan of Biomedical Communications, University of Toronto, Canada, shows how hierarchical tensegrity structures, such as a cell with a nucleus, behave when pulled, stretched and sheared.
Articles on the Web
The Mechanical Cell, by Nancy Fliesler
From Dream magazine, published by Children's Hospital Boston.
The Architecture of Life, by Donald Ingber
From Scientific American, January 1998 [Requires payment to view.]
Tensegrity I. Cell structure and hierarchical systems biology, by Donald E. Ingber.
From the Journal of Cell Science.
Tensegrity II. How structural networks influence cellular information processing networks, by Donald E. Ingber. From the Journal of Cell Science.
Mechanochemical Basis of Cell and Tissue Regulation, Donald E. Ingber
From the National Academy of Engineering, Fall 2004
Ingber DE. Tensegrity: The Architectural Basis of Cellular Mechanotransduction. Annual Review of Physiology, Vol. 59, pages 575-599; 1997.
Ingber DE. The origin of cellular life. Bioessays 22: 1160-1170; 2000.
Chen CS, Mrksich M, Huang S, Whitesides G, Ingber DE. Geometric control of cell life and death. Science, 276:1425-1428; 1997.
Wang N, Butler JP, Ingber DE. Mechanotransduction across the cell surface and through the cytoskeleton. Science, 260:1124-1127; 1993.
Ingber, DE. Cellular Tensegrity: defining new rules of biological design that govern the cytoskeleton. J. Cell Sci., 104:613-627; 1993.
D'Arcy W. Thompson. On Growth and Form. Revised Edition. Cambridge University Press, 1942 (Reprinted 1992).
Credits -- Interactive Feature
Subject Matter Expert: Donald E. Ingber, MD, PhD, Children's Hospital Boston
Writer/Producer: Rick Groleau, Children's Hospital Boston
Illustrator: Chesley Lowe
Designer: Sonali Patel, WGBH Interactive
Developer: Daniel Bulli, WGBH Interactive
Additional images and movies provided by Sui Huang,
Keiji Naruse, Ben Matthews, and Don Ingber.