Liposome-mediated gene transfer into human vascular smooth muscle cells

Abstract

Background: Complexing recombinant DNA with cationic liposomes is a convenient means of introducing foreign genes into cells (lipofection) and could potentially form the basis for genetically modifying diseased blood vessels in patients. The mechanism of lipofection is incompletely understood, but it is recognized that the degree of successful gene transfer is highly dependent on cell type. To date, there has been no reported experience with lipofection of human vascular smooth muscle cells. Methods and Results: Primary cultures of human vascular smooth muscle cells were transfected under optimized conditions with a plasmid expressing either firefly luciferase (Luc) or nuclear-localized β-galactosidase (NL-β-gal). Cells were derived from either normal human internal mammary arteries (n=6), fragments of primary atherosclerotic plaque (n=4), or fragments of restenotic lesions (n=5). Concurrent lipofection of rabbit vascular smooth muscle cells and NIH 3T3 cells was performed as well. Cultures derived from 15 patients all demonstrated positive expression of the reporter gene. Compared with NIH 3T3 cells, however, expression in human vascular smooth muscle cells was markedly reduced: in cells derived from internal mammary artery, Luc expression, normalized for protein content, was 123-fold lower than in NIH 3T3 cells, whereas the proportion of cells expressing NL-β-gal was 30-fold lower. Luc expression in cells derived from restenotic tissue was significantly greater than from cells derived from primary plaque (P