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To study the effects of physical forces on cell growth and differentiation, researchers must stretch, strain, compress, shear, pull, or apply pressure to tissue culture cells. Numerous procedures have been created to apply force to cells in vitro. Designed to simulate forces encountered in vivo, such methods include cell wounding by cutting a monolayer and the application of tension or compression by means of hydraulic pressure. Now, with the development of the Bio-Stretch System from ICCT Technologies R & D Center Inc. of Markham, Ontario, researchers have a computerized stretch instrument that enables the study of cells in a mechanically active environment. Through the use of highly controlled magnetic forces, the Bio-Stretch device allows researchers to apply user-defined, controlled, static, or variable cyclic stretches to cells cultured in two or three dimensions. As a result, the effects of mechanical stress as a regulator of cell growth, differentiation, structure, and function can be studied in many cells and tissues. The choice of the substratum used for cell culture plays an important role in the Bio-Stretch System. These materials, primarily silicone elastic membranes for two-dimensional cultures or Gelfoam™ sponges for three-dimensional organotypic cultures (Pharmacia and Upjohn), have inherent recoil properties useful in the application of stretch forces to cells. The ability of Bio-Stretch to study organotypic structures is an important feature of the instrument because cell shape and architecture, as influenced by extracellular matrix structures, may play a crucial role in mechanical deformation-induced cellular activity.1 During a typical stretch cycle, the culture dish containing a silicone membrane or Gelfoam sponge supporting an active cell culture is placed in position on a magnet board, one of the components of the Bio-Stretch System. One end of the sponge/membrane is attached to the dish by a locking device, and a plastic-coated metal bar is affixed to the other end using a specially designed clip. When properly positioned on the magnet board, the metal bar is located directly in front of an electromagnetic solenoid. When current flows through the solenoid, the resultant magnetic force attracts the bar, causing the elongation of the sponge and mechanically stretching the cells. When the current is turned off, the recoil properties of the sponge/membrane pull it back to its original size. The system consists of an IBM-compatible computer that runs a program called Bio-Stretch Manager, the Bio-Stretch Controller, and up to three sets of magnet boards. Each magnet board has five platforms for culture dishes; each board is controlled by the Bio-Stretch Controller. The Bio-Stretch Manager software simplifies operation of the Bio-Stretch Controller. Employing an easy-to-use graphic user interface design, the Bio-Stretch Manager allows the programming of precise stretch regimens consisting of various patterns. Each stretch pattern is defined by four parameters: 1) the duration of burst and a rest time; 2) the burst frequency of stretch-relax cycles; 3) the percent on time per stretch-relax cycle; and 4) the stretch strength as a percentage of the maximal power supply output. By varying these parameters, researchers can apply sustained, rhythmic, or irregular stretch patterns to the cells. Rhythmic patterns, for instance, represent forces such as heartbeat, pulse, and conventional mechanical ventilation. Irregular patterns simulate muscle contractions during exercise or conditions like cardiac arrythmia. M. Liu et al., "The effect of mechanical strain on fetal rat lung cell proliferation: comparison of two- and three-dimensional culture systems." In Vitro Cell. Dev. Biol.-Animal, 31:858-66, 1995. For More Information, contact ICCT Technologies R & D Center Inc. at (905) 479-1152 or www.iccttech.com

Forces of Nature: Stretching Cells with ICCT Technologies' Bio-Stretch System

Oct 10, 1999

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