Serum From Patients With Erectile Dysfunction and Vascular Risk Factors Triggered an Oxidative Stress-Dependent Mitochondrial Apoptotic Pathway in Ex Vivo Expanded Circulating Angiogenic Cells of Healthy Men

Abstract

IntroductionSerum from men with erectile dysfunction (ED) and vascular risk factors inhibits circulating mononuclear cells (MNCs) from expanding ex vivo and differentiating circulating angiogenic cells (CACs), which are putatively involved in the repair of endothelial damage. AimTo explore the involvement of apoptosis in the inhibition of CAC differentiation from MNCs of healthy men exerted by serum from men with ED and vascular risk factors. MethodsMNCs from healthy men were cultured in serum from 10 healthy men (median age = 45 years, 25th–75th quartiles = 38.5–48.5) and from 14 patients (median age = 58.0 years, 25th–75th quartiles = 52.5–62.0). CACs were identified by the uptake of 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine–labeled acetylated low-density lipoprotein (DiLDL) and concomitant Ulex europaeus agglutinin I binding assessed by fluorescence microscopy. Main Outcome MeasuresFlow cytometric evaluation of mitochondrial membrane potential, assessed with 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethyl-benimidazolyl carbocyanine iodide dye, and of activated caspase-8, -9, and -3 in DiLDL-positive cells. ResultsThe number of CACs was significantly decreased by serum from patients compared with controls. This was associated with suppression of the mitochondrial membrane potential and activation of caspase-9 and -3 but not of caspase-8. This suggests an activation of the intrinsic (mitochondrial) pathway of apoptosis, whereas the death receptor activation of apoptosis was not involved. Activation of caspase-9 and -3 induced by serum from patients with ED was prevented by the exposure of MNCs to Trolox, a hydrophilic cell-permeable vitamin E analog with high antioxidant capacity. ConclusionAn oxidative stress-dependent mitochondrial dysfunction was triggered in ex vivo expanded CACs of healthy men by serum from men with vascular risk factors and ED, the only clinical correlate for diffuse vascular disease. The activation of apoptosis and inhibition of CAC differentiation might generate a defective mechanism of vascular repair.