Behavior of arterial wall cells cultured on periodically stretched substrates.

Cells in vital tissues align to form the most efficient configuration for functioning. Vascular cells of arterial walls are constantly exposed to fluid shear stress and pressure-induced periodic strain component, both of which are induced by pulsatile flow. In the present study, the effect of cyclic strain on the cellular orientation response and morphological changes of bovine arterial wall cells such as endothelial cells (ECs), smooth muscle cells (SMCs) and fibroblasts (FCs) was studied. Cells seeded onto transparent elastomeric films were subjected to periodic stretch-relaxation under various amplitudes ranging from 5 to 20% and at frequencies ranging from 15 to 120 RPM for up to 24 h. Time-lapse video-recorded images of stress-loaded cells were analyzed by a computer-aided morphometric system to quantitatively evaluate the cellular orientation responses and morphological changes. The stress-loaded cells tended to align perpendicularly to the direction of stretch with time, regardless of cellular species. More pronounced orientation was attained under operating conditions with higher amplitude and frequency of stretching. The response of SMCs and FCs advanced more rapidly than that of ECs. Meanwhile, little morphological change was observed, irrespective of stress-loading or nonloading. Understanding of mechanically induced orientation response provides a fundamental basis on tissue engineering and biomechanics.