Vascular bypass grafts smaller than 6 mm in inner diameter have faced serious constraints due to the limited number of applicable blood vessels in patient's body and incompatibility on the mechanical properties of artificial vessels with small native vessels. A new alternative method to overcome this limitation is tissue engineered blood vessels (TEBV) and the manufacture of tissue engineered scaffolds (TES). In this study, in order to determine the mechanical properties of TES and provide a method for predicting their behavior, a test is performed to measure the scaffold’s outer diameter due to change in the fluid pressure in a bioreactor. We test five similar TES samples and the results are examined individually. For the first, second and third samples, the performance of the bioreactor is evaluated. In addition, bioreactor’s design flaws are resolved. According to the change of fluid pressure, the scaffold’s outer diameter of 4th and 5th samples is measured. The experimental resultillustrate that the change of scaffold’s outer diameter at low pressures is more remarkable than that at high pressures (86% of the change in scaffold’s outer diameter is related to the outlet pressure of 0 to 60 mmHg while only 14% of this change is related to the outlet pressure of 60 to 120 mmHg.). It is also observed that all samples in the pressure range of 120 to 160 mmHg axially rupture at inlet or outlet sections. Anisotropic structural model is chosen based on experimental results to predict the scaffold’s wall behavior and analyze the governing equations of this model with simple assumptions. Material models for TES are determined using curve fitting method on the experimental results and the governing equations which are obtained from the analytical solution. Eventually by using material models, fluid-solid interaction model for TES based on experimental conditions and assumption of incompressible steady state flow was chosen.The numericalresults are validatedwith theexperimentaldata and a good agreement is observed (maximum error of 5%). The simulation results show that, if material models are calculated for TES, it is possible to predict the behavior of scaffold’s wall by using this model. Also, simulation and experiment results indicate that the manufacture of TES should be based on the dimensions of artery which is excised from the real tissue. In order to allow the cells that seeded onto TES to receive the wall shear stress similar to coronary arteries, a fluid with shear-thinning properties resembling to blood should be used instead of distilled water in bioreactor. Keywords: Tissue engineered scaffold, Bioreactor, Fluid-solid interaction simulation, Anisotropic structural model, Holzapfel
