Cyclosporin A Suppresses Proliferation of Endothelial Progenitor Cells: Involvement of Nitric Oxide Synthase Inhibition

Abstract

To investigate the effects of the potent immunosuppressive agent cyclosporin A (CsA) on the proliferation of human endothelial progenitor cells (EPCs) and endothelial nitric oxide synthase (eNOS) expression in EPCs. The EPCs were obtained from cultured mononuclear cells, which were isolated from the peripheral blood of healthy adults, and stimulated with CsA (10 microg/mL) in the presence or absence of either vascular endothelial growth factor (VEGF; 50 ng/mL) or L-arginine (1 mM). To explore the effect of different concentrations of CsA alone on EPC proliferation, some cells were treated with CsA in a series of final concentrations ranging from 0 to 10 microg/mL. Cell proliferation and apoptosis were determined, respectively, by the Cell Counting Kit-8 assay and terminal deoxynucleotidyl transferase-mediated nick end labeling staining. The expression of eNOS was assayed by reverse transcription-polymerase chain reaction analysis while nitric oxide (NO) generation was detected using the Griess method. The effects of CsA on EPC proliferation, apoptosis, and eNOS/NO production were dose dependent in the concentration ranging from 0.1 microg/mL to 10 microg/mL. Treatment with VEGF (50 ng/mL) significantly promoted EPC proliferation and eNOS/NO production, which were completely abrogated by pre-incubation with CsA (10 microg/mL). The supplement of L-arginine (1 mM) promoted NO production that enhanced EPC proliferation and attenuated the effect of CsA on EPC proliferation and apoptosis. CsA significantly inhibited proliferation, eNOS mRNA expression and NO production of human EPCs, in a dose-dependent manner.