Effects of Nicotine on the Number and Activity of Circulating Endothelial Progenitor Cells

Abstract

Recently, some studies have shown that nicotine increased neovascularization, which involves endothelial progenitor cells (EPCs). The effects of nicotine on EPCs are still unclear at present. Therefore, the authors investigated whether nicotine had influences on EPC number and activity. The EPCs were stimulated with nicotine (to make a series of final concentrations: 10(-12) mol/L, 10(-10) mol/L, 10(-8) mol/L, 10(-6) mol/L, 10(-4) mol/L) or vehicle control for the respective time points(12, 18, 24, 32, and 48 hours). The EPCs were characterized as adherent cells double positive for DiLDL uptake and lectin binding by direct fluorescent staining under a laser-scanning confocal microscope. They were further documented by demonstrating the expression of KDR, VEGFR-2, and AC133 with flow cytometry. The EPC proliferation, migration, and in vitro vasculogenesis activity were assayed with the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay; the modified Boyden chamber assay; and the in vitro vasculogenesis kit, respectively. The EPC adhesion assay was performed by replating those on fibronectin-coated dishes and then counting the adherent cells. As a result, nicotine dose dependently increased the EPC number and the proliferative, migratory, adhesive, and in vitro vasculogenesis capacity at nicotine concentrations of 10(-12) to 10(-8) mol/L. The peak effects on EPCs were observed at concentrations of nicotine 10(-8) mol/L, similar to those in the blood of smokers. In addition, nicotine (10(-8) mol/L) time dependently increased the EPC number and activity. However, cytotoxicity was seen at higher nicotine concentrations (> 10(-6) mol/L). In conclusion, nicotine had complex effects on EPCs: nicotine might induce the augmentation of EPCs with enhanced functional activity at relatively low concentrations. However, cytotoxicity was seen at higher nicotine concentrations.

Influence of Cardiovascular Risk Factors on Endothelial Progenitor Cells

“…59 Smoking has been identified as an important risk factor for reduced EPC numbers in one of the first studies on cardiovascular risk factors by Vasa et al 46 However, Wang et al recently demonstrated that the role of nicotine is more complex than initially expected. 60 In an experimental study, they demonstrated that low concentrations of nicotine (10 Ϫ8 Ϫ10 Ϫ12 mol/L) increased EPC number and activity, whereas higher (toxic) concentrations (Ͼ10 Ϫ6 mol/L) were associated with cytotoxicity. In humans, Kondo et al demonstrated that chronic smokers (nϭ15) exhibit reduced EPC levels that can be restored after smoking cessation within 4 weeks.…”

Clinical and therapeutical implications of EPC biology in atherosclerosis

“…Chronic smok- ers have reduced EPC levels which can recover after smoking cessation within 4 weeks [28]. Wang et al recently demonstrated that nicotine may be a two-edged sword [29]. Low concentrations of nicotine increased EPC levels while higher concentrations (>10 -6 mol/L) were associated with decreased EPC levels.…”

Endothelial Progenitor Cells in Diabetic Vasculopathy

“…However, Wang et al recently demonstrated that the r ole o f nicotine i s more complex than initially expected (94). In an experimental study, they demonstrated that low concentrations of nicotine (10-8-10-12 mol/L) increased EPC number and activity, whereas higher (toxic) concentrations (>10-6 mol/L) were associated with cytotoxicity.…”