RETROVIRAL-MEDIATED GENE TRANSDUCTION ALTERS INTEGRIN EXPRESSION ON VASCULAR ENDOTHELIAL-CELLS

Genetically recombinant endothelial cells (rEC) may improve the patenc y of small diameter vascular grafts by preventing thrombosis or limiti ng neointimal hyperplasia. Previous work has shown that rEC have reduc ed adhesion to vascular bypass grafts in vivo. Poor adhesion may be du e to altered adhesion (integrin) receptors. This study evaluated the e xpression of the alpha(5) beta(1) (fibronectin), alpha(2) beta(1) (col lagen IV), and alpha(v) beta(3) (vitronectin) integrin subunits on rEC . Human umbilical vein EC or canine jugular vein EC were transduced wi th neoR, neoR and human tPA or hygromycin resistance genes using retro viral vectors. Naive EC and EC exposed to empty viral particles (mEC) were controls. Naive EC, mEC, and all rEC's were evaluated for alpha a nd beta subunits for each integrin receptor studied using immunoblotti ng, Blotting for alpha(2), alpha(5), and alpha(v) exhibited expression of the alpha integrin subunits in all cells. The beta(1) and beta(3) subunits were present in mEC and nEC but were absent or truncated in a ll rEC. The decreased adhesion of rEC's to synthetic vascular grafts m ay be accounted for by their altered beta(1) and beta(3) integrin subu nit expression. The beta subunit is critical for organization of the c ytoskeleton and cellular signal transduction. Diminished beta subunit expression in rEC is neither vector specific nor related to retroviral exposure alone. Alteration of beta integrin expression may be to asso ciated with the over-expression of phosphotransferase genes such as ne oR or hygromycin B used as selectable markers in gene transfer protoco ls. (C) 1997 Academic Press.