A STRAIN DEVICE IMPOSING DYNAMIC AND UNIFORM EQUI-BIAXIAL STRAIN TO CULTURED-CELLS

The objective of this study is to design a new apparatus to allow the control of the magnitude and frequency of dynamic stretch applied unif ormly to cells cultured on a silicon elastic membrane. The apparatus i s designed to produce equibiaxial dynamic stretches with area changes ranging from 0% to 55% and frequencies ranging from 0 to 2 Hz. Homogen eous finite strain analysis using triangles of markers was performed t o compute the symmetric two-dimensional Lagrangian strain tensor on th e membrane. Measurements of strain in both static and dynamic conditio ns showed that the shear component of the strain tensor (E-rc) was nea r zero, and that there was no significant difference between radial (E -rr) and circumferential (E-cc) components, indicating the attainment of equi-biaxial strain. Bovine aortic endothelial cells were transient ly transfected with a chimeric construct in which the luciferase repor ter is driven by TPA-responsive elements (TRE). The transfected cells cultured on the membrane were stretched. The luciferase activity incre ased significantly only when the cells were stretched by 15% or more i n area. Cells in different locations of the membrane showed similar in duction of luciferase activities, confirming that strain is uniform an d equibiaxial across the membrane. (C) 1998 Biomedical Engineering Soc iety.