Automatically Controlled Flow and Pressure Conditions in a Bioreactor System for Medium- to Large-Sized Tissue-Engineered Vascular Grafts

To support vascular tissue generation and maturation in vitro, a suitable environment providing dynamic cultivation is essential and can be achieved within specialized bioreactor systems. This paper describes the implementation and evaluation of a fluid circuit for automatically controlled flow and pressure conditions in medium to large vascular grafts with an inner diameter of up to 8 mm. Shear stresses exerted on the cultivating vascular graft’s inner wall and fluid flow patterns were computed using Computational Fluid Dynamic simulations. Adjustment of the nutrient medium’s viscosity ensures laminar flow and reduces the required flow rate for shear stresses of at least 20 dyn/cm
²
. A custom pressure sensor suited for steam sterilization with an accuracy of 0.1 mmHg was developed and optimized with regard to its impact on the laminar velocity profile. The presented system provides comprehensive conditioning for the cultivation of medium to large vessels to meet the clinical needs of viable tissue grafts but also for physiological research applications.