Oxygen transport in bioreactors for engineered vascular tissues

Tissue engineered vascular grafts cultured in vitro are often done so under static conditions, which forces a diffusion-only mass transport regime for nutrient delivery and metabolite removal. Some bioreactor culture methods employ mechanical stimulation to improve material strength and stiffness; however, even with mechanical stimulation, engineered tissues are likely to operate in a diffusional transport regime for nutrient delivery and metabolite removal. In this study, we present an analysis of dissolved oxygen (DO) transport limitations that can arise in statically cultured vascular grafts and highlight bioreactor designs that improve transport, particularly by perfusion of medium through the interstitial space by transmural flow. A computational analysis is provided in conjunction with empirical data to support the models. Our goal was to investigate designs that would eliminate nutrient gradients that are evident using static culture methods in order to develop more uniform engineered vascular tissues, which could potentially improve mechanical strength and stiffness.