A Novel Design Testing the Effects of Static and Dynamic Equibiaxial Stretch Gradients on Fibroblast Cell Migration

The study of mechanobiology and the cellular response to the mechanical environment plays a vital role in the understanding of the atherogenesis and the treatment of the disease state through interventions such as stent placement. Cell migration in response to complex stresses also plays a critical role in wound healing. Modeling the mechanical environment as a circular membrane with a center defect can be an accurate representation of in vivo stress gradients. In this study, we created a novel cell stretching device that exposed cells to both static and 1 Hz dynamic stretch. Using NIH 3T3 fibroblasts stained with DiI membrane stain, we were able to expose cells to the two stretch regimes for 48 hours and observe the cellular response via live cell imaging. Cells were observed at 0, 12, 24, and 48 hour time points, and analysis of the change in their radial position was used to determine if cell migration occurred. Cell displacement was calculated using both the kinematic equation and the NeoHookean constitutive model. Uncertainty of the cell displacement calculation was used in determining whether or not there was cell migration. In this study, we were able to prescribe successfully the stretch regimes and observe the cellular response to stretch. Within the bounds of our uncertainty based on the error in the hole radius estimation and our measurement of cell and membrane displacement, however, we cannot say conclusively that cell migration occurred. This study established the methods and protocols necessary for further investigation into mechanobiology, in particular, the cell response to stress environments that more closely resemble the in vivo conditions.