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The construction of tissue-engineered parts such as heart valves and arteries requires more than just the seeding of cells onto a biocompatible/biodegradable polymeric scaffold. It is essential that the functionality and mechanical integrity of the cell-seeded scaffold be investigated in vitro prior to in vivo implantation. The correct hemodynamic conditioning would lead to the development of tissues with enhanced mechanical strength and cell viability. Therefore, a bioreactor that can simulate physiological conditions would play an important role in the preparation of tissue-engineered constructs. In this article, we present and discuss the design concepts and criteria, as well as the development, of a multifunctional bioreactor for tissue culture in vitro. The system developed is compact and easily housed in an incubator to maintain sterility of the construct. Moreover, the proposed bioreactor, in addition to mimicking in vivo conditions, is highly flexible, allowing different types of constructs to be exposed to various physiological flow conditions. Initial verification of the hemodynamic parameters using Laser doppler anemometry indicated that the bioreactor performed well and produced the correct physiological conditions.

SUMMARYIn this paper, the commercial CFD package Ansys workbench 11 was used to analyse the three-dimensional haemodynamics of a typical stenotic Coronary Artery Bypass Grafting (CABG). Two end-to-side CABG configurations with anastomosis angle of 20 • and 40 • and graft-artery diameter ratios of 1/0.6, 1/1 and 1/1.6 were examined. The flow measurements from in vitro Doppler guide wire technique acquired in left interior mammary artery (LIMA) and grafted to the left anterior descending artery (LAD) were used to impose the physiologically flow conditions at proximal and distal CABG inlet and outlet, respectively. The blood flow was considered to be incompressible, pulsatile, Newtonian, and laminar rheology. The main objective was to determine the effect of anastomosis angle and graft-artery diameter ratio on the flow patterns and the long-term functionality of the graft. In analysing the results, the distributions of temporal and spatial wall shear stress (WSS) gradient and oscillating shear index (OSI) in the critical regions of CABG such as heel, toe and the centre of the junction were presented and the vortex motions and the occurrence of recirculation zones were examined. The findings showed asymmetrically disturbed flows in the localized regions of the proximal and distal host artery for all models considered and the movement of the recirculation zones from heel to toe was found to depend on the time at the cardiac cycle. These regions are known as susceptible sites to thrombosis and re-stenosis due to their association with low values of WSS.

and is currently working with Biomechanics and Tissue Engineering Group at Swinburne. Her area of interest is hemodynamic studies especially of blood vessels.

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