Vitamin E reduces platelet adhesion to human endothelial cells in vitro.
Although it has been reported that vitamin E (alpha-tocopherol) can reduce platelet adhesiveness and aggregation in vivo, the mechanism is still unknown. Therefore, the aim of the present study was to determine whether incubations of platelet-rich plasma (PRP) with vitamin E influence platelet adhesion to cultured endothelial cells. To exclude blood plasma involvement, also washed platelets were pretreated with alpha-tocopherol. Vitamin E (0.5-1.0 mM) was added to PRP or washed platelets. Endothelial cells in monolayer were incubated with thrombin-activated platelets (1 or 2 U/ml). After 1 hr of incubation, non-adhered platelets were removed and counted. Treating of PRP with alpha-tocopherol inhibited platelet adhesion to endothelial cell monolayer. This effect was dose dependent on concentrations of alpha-tocopherol and thrombin. In our experiments PRP was treated with alpha-tocopherol and endothelial cell monolayer was used as test surface. These findings agree with previous observations on the adhesivity of platelets to synthetic surfaces after dietary vitamin E in healthy volunteers. When washed platelets were incubated with alpha-tocopherol, no significant reduction of adhesion was detectable. As preincubation of washed platelets with alpha-tocopherol does not inhibit platelet adhesion, it may be supposed that the effect of vitamin E does not occur in a directly cellular mechanism. The data suggest that alpha-tocopherol may reduce platelet adhesiveness probably after incorporation by plasma lipoproteins.
Szuwart
T
T
Platelet Research Unit, Institute of Anatomy, University of Münster, Germany.
Brzoska
T
T
Luger
T A
TA
Filler
T
T
Peuker
E
E
Dierichs
R
R
D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology* / Q000502:physiology; D006801:Humans; D010973:Platelet Adhesiveness / Q000187:drug effects*; D013917:Thrombin / Q000494:pharmacology; D014810:Vitamin E / Q000008:administration & dosage / Q000494:pharmacology*
D014810:Vitamin E; D013917:Thrombin