Cell orientation induced by extracellular signals

Cells like fibroblasts and osteoblasts are oriented by different extracellular guiding signals like an electric field, a bent surface, and a periodically stretched surface. An automatic controller is responsible for the cell alignment. The controller contains both a deterministic and a stochastic signal. The following machine properties were determined:The angle dependence of the cellular signal transformer is cos {ie167-1}.The set point of the automatic controller is {ie167-2}. The cells like to orient their long axis perpendicular to the direction of the applied guiding signal.The signal transformer measures the extracellular signal in a quadratic fashion. The cells cannot register the sign of the guiding field.The stochastic signal in the automatic controller can be quantified by a characteristic time (≈ 130 min for fibroblasts).The extracellular signal is registered in cell-made standards (ratio of the deterministic and stochastic signal equals one): 0.3±0.05 V/mm for human fibroblasts (electric field) and 85±3 μm for human fibroblasts and osteoblasts (cylindrically bent surface).The lag-time in the signal transduction system of fibroblasts is ≈ 4 min.