Perfusion Bioreactor: A New Pulsatile System for the Perfusion of Tissue Engineered Cardiovascular Prostheses

The aim of this study was to evaluate cell adhesion and pro-inflammatory cytokine expression of human vascular cells seeded on polyurethane grafts (PUG) under physiological conditions in a newly developed closed perfusion system. Human vascular fibroblasts (FBs) and endothelial cells (ECs) were isolated from saphenous vein segments and expanded in culture. PUG (n= 17, A= 38 +/- 3 cm(2)) were either seeded with ECs (n= 9) or pre-seeded with FBs (n= 8), followed by colonization with ECs. Seeded PUGs were then divided into four groups and exposed for 4 hours to variable flow conditions. Samples were taken before and after perfusion and evaluated by scanning electron microscopy (SEM) and reverse transcription-polymerase chain reaction (RT-PCR) for the expression of the cytokines interleukin 1-alpha (IL-1a), interleukin 6 (IL-6), interleukin 8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1). Conditioning of colonized vascular cells in a pulsatile Bioreactor significantly decreases pro-inflammatory cytokine expression. Pre-seeding with FBs enhance the adhesion of ECs to PUG. Microbiological tests of perfusion medium after 4 hours perfusion revealed no bacterial contamination. Bioreactors with pulsatile flow can be used for an in-vitro conditioning of tissue-engineered cardiovascular prostheses.