Poly(ethylenimine)-mediated gene delivery affects endothelial cell function and viability

Poly(ethylenimine) (PEI) was used to transfect the endothelial cell line EA .hy 926, and the secreted levels of three gene products, tissue-type plasmi nogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1), and von Willebrand Factor (VWF), were assessed via ELISA. We found that the lev els of these gene products in cell supernatants increased by factors up to 16.3 (tPA), 8.3 (PAI-1), or 6.7 (vWF) times the levels recorded for untreat ed cells. and roughly correlated with the percentage of cells that expresse d the reporter plasmid. Transfections carried out using promotorless constr ucts of the same reporter plasmid also yielded increases in tPA. PAI-1. and vWF to similar extents. Additionally, data regarding cell viability were g athered and found to inversely relate to both the effectiveness of the PEI used for transfection and the secreted levels of the three mentioned produc ts. There appeared to be two distinct types of cell death, resulting from t he use of either free PEI (which acts within 2 h) or PEI/DNA complexes (whi ch cause death 7-9 h after transfection). Cells were also transfected by po ly(L-lysine) and liposomal carriers, and increases in secreted tPA similar to those seen with PEI-mediated transfection were observed for positively t ransfected cells. The results of these investigations indicate that non-vir al gene delivery can induce a state of endothelial cell dysfunction, and th at PEI-mediated transfection can lead to two distinct types of cell death. (C) 2001 Elsevier Science Ltd. All rights reserved.