Oxidized Low-Density Lipoproteins Delay Endothelial Wound Healing: Lack of Effect of Vitamin E

The purpose of this study was to examine the influence of oxidized low-density lipoprotein (oxLDL) on endothelial regrowth in an in vitro wounding model and the possible protection afforded by vitamin E (E). Endothelial cells grown on micropore filters were wounded by scraping and allowed to reestablish growth on denuded areas in the presence of LDL or oxLDL (25-200 micrograms/ml), linoleic acid (FA, 90 microM) or linoleic acid hydroperoxide (OFA, 15 microM) for 24 h. Some monolayers were pretreated with 25 microM E for 24 h. Transendothelial albumin movement was used as a measure of endothelial barrier function and as an indicator of endothelial monolayer regrowth. Exposure to levels of oxLDL as low as 25 micrograms/ml for 24 h resulted in depressed endothelial monolayer regrowth, whereas native LDL was without effect and pre-enrichment with 25 microM E offered no protection. In comparison, E pre-enrichment improved endothelial regrowth to control levels in FA- and OFA-treated cultures, unlike oxLDL-treated cultures. It is concluded that circulating oxLDL may reduce regrowth of wounded endothelium and supplemental E may not offer protection. Moreover, fatty acids or their hydroperoxides are unlikely to be involved in this effect.