Background: Tissue engineering represents a promising new method for treating\r\nheart valve diseases. The aim of this study was evaluate the importance of\r\nconditioning procedures of tissue engineered polyurethane heart valve prostheses\r\nby the comparison of static and dynamic cultivation methods.\r\nMethods: Human vascular endothelial cells (ECs) and fibroblasts (FBs) were obtained\r\nfrom saphenous vein segments. Polyurethane scaffolds (n = 10) were primarily seeded\r\nwith FBs and subsequently with ECs, followed by different cultivation methods of cell\r\nlayers (A: static, B: dynamic). Group A was statically cultivated for 6 days. Group B was\r\nexposed to low flow conditions (t1= 3 days at 750 ml/min, t2= 2 days at 1100 ml/min)\r\nin a newly developed conditioning bioreactor. Samples were taken after static and\r\ndynamic cultivation and were analyzed by scanning electron microscopy (SEM),\r\nimmunohistochemistry (IHC), and real time polymerase chain reaction (RT-PCR).\r\nResults: SEM results showed a high density of adherent cells on the surface valves from\r\nboth groups. However, better cell distribution and cell behavior was detected in Group\r\nB. IHC staining against CD31 and TE-7 revealed a positive reaction in both groups.\r\nHigher expression of extracellular matrix (ICAM, Collagen IV) was observed in Group B.\r\nRT- PCR demonstrated a higher expression of inflammatory Cytokines in Group B.\r\nConclusion: While conventional cultivation method can be used for the development\r\nof tissue engineered heart valves. Better results can be obtained by performing a\r\nconditioning step that may improve the tolerance of cells to shear stress. The novel\r\npulsatile bioreactor offers an adequate tool for in vitro imp
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