Flow responses of human blood outgrowth endothelial cells adhered to bioartificial tissue

Abstract

Blood outgrowth endothelial cells (BOECs) are isolated by outgrowth of circulating progenitor cells from a patient blood sample and thus could provide a source of autologous endothelial cells for tissue‐engineered vascular grafts. To examine the suitability of these cells for use in vascular tissue engineering, late outgrowth endothelial cells isolated from human peripheral blood were seeded on tissue constructs formed from fibrin remodeled by entrapped neonatal human dermal fibroblasts (NHDFs). BOECs adhered to this surface and remained adherent when exposed to laminar shear flow of cell culture medium, at shear stresses of 15 dynes/cm2.We have examined shear stress effects on human BOEC activation state, by comparing VCAM‐1, ICAM‐1, and Thrombomodulin (TM) expression after activation with TNF‐α. These markers were chosen due to their reported response to changes in shear stress, as well as their implication in endothelial cell activation. BOECs seeded on collagen‐coated slides and tissue constructs were statically cultured or exposed to 5–15 dynes/cm2 shear stress for 24 hours. Expression of the activation markers was altered compared to static controls, while the cell densities did not vary significantly. TM expression was elevated by shear stress, while VCAM‐1 and ICAM‐1 showed decreased expression. These results illustrate the potential utility for BOECs in vascular tissue engineering, as not only do the cells adhere to fibrin‐based tissue constructs and remain adherent under physiological shear stress, they are also responsive to shear stress signaling. Funding from NIH R01 HL083880 (to RTT).