Evaluation of the Effect of Retroviral Gene Transduction on Vascular Endothelial Cell Adhesion

Abstract

Genetically modified endothelial cells (ECs) seeded on synthetic vascular grafts offer the potential to improve small diameter vascular graft patency. Despite encouraging results with naive ECs, cells transduced with retroviral vectors appear impaired in their ability to adhere to and stably colonize vascular grafts in vivo. This study addresses changes in retrovirally transduced EC adhesion as the cause of cell loss. Endothelial cells were retrovirally transduced with the bacterial neoR gene or "mock" transduced with empty viral particles. Cells were allowed to adhere to collagen IV (CIV) or fibronectin (FN) prior to exposure to 20 or 90 dyn/cm² using a parallel plate apparatus. Cell detachment was evaluated using time lapse videomicroscopy. Fibronectin was a significantly better adhesive protein for naive EC than CIV at both shear stresses. NeoR-transduced EC had significantly greater detachment from FN than either naive or "mock"-transduced EC. Transduced EC attachment to FN was no greater than to CIV. Flow cytometric analysis of the fibronectin receptor (FNR) showed that transduced cells have reduced receptor expression compared to naive and "mock"-transduced EC. These results indicate retrovirally transduced EC have altered FNR and adhesion to FN and that these changes may account for transduced EC loss in vivo.