Circulating endothelial progenitor cells in systemic sclerosis: association with disease severity.

BACKGROUND: Heterogeneous data have been reported regarding the detection and number of circulating endothelial progenitor cells (EPCs) in systemic sclerosis (SSc). OBJECTIVE: We investigated the number of circulating EPCs using recent recommendations and we quantified their late outgrowth in patients with SSc and healthy controls. PATIENTS AND METHODS: EPCs, defined as Lin-/7AAD-/CD34+/CD133+/VEGFR-2+ cells, were quantified in 50 patients with SSc (mean age: 55 (16) years, disease duration: 9 (9) years) and 26 controls (mean age: 53 (19) years) by cell sorting/flow cytometry and by counting late outgrowth colony-forming units (CFU). RESULTS: Patients with SSc displayed higher circulating EPC counts than controls (median 86 (5-282) vs 49 (5-275)) EPCs for 1 million Lin- mononuclear cells; p = 0.01). Lower EPC counts were associated with the higher Medsger's severity score (p = 0.01) and with the presence of past and/or current digital ulcers (p = 0.026). There was no difference for the number of late outgrowth EPC-CFUs between patients with SSc and controls in cell culture evaluation. The formation of colonies was associated with higher levels of circulating EPCs (p = 0.02) and the number of colonies correlated with levels of EPCs (R = 0.73, p = 0.0004), validating our combination of fluorescence-activated cell sorter surface markers. CONCLUSIONS: We quantified circulating EPCs with an accurate combination of markers herein validated. Our data demonstrate increased circulating EPC levels in SSc, supporting their mobilisation from bone marrow. Furthermore, the subset of patients with digital vascular lesions and high severity score displayed low EPC counts, suggesting increased homing at this stage. The predictive value of this biomarker now warrants further evaluation.

Autoxidation of rat brain homogenate: evidence for spontaneous lipid peroxidation. Comparison with the characteristics of Fe2+- and ascorbic acid-stimulated lipid peroxidation.

Aerobically-incubated brain homogenates are known to undergo autoxidation characterized by spontaneous TBARS production, presumably as a result of lipid peroxidation. However, TBARS measurement alone, because of its lack of specificity, is not sufficient to demonstrate the occurrence of lipid peroxidation in complex biological systems. This study, undertaken to determine whether or not spontaneous oxidation of rat brain homogenate is due to lipid peroxidation, measured different specific markers of this process (fatty acids, lipid aldehydes and the formation of fluorescence products) and studied changes in alpha-tocopherol. Incubation of rat brain homogenates at 37 degrees C under air led to spontaneous TBARS formation, which was accompanied by lipid aldehydes and lipid fluorescence products as well as polyunsaturated fatty acid (PUFA) degradation. Alpha-tocopherol was also consumed. On the whole, these results demonstrate that autoxidation of brain homogenate is a spontaneous lipid peroxidation process. When homogenates were exposed to Fe2+ and ascorbic acid-induced oxidative stress, lipid peroxidation was enhanced. However, spontaneous and stimulated peroxidation showed similar patterns not characteristic of classical lipid peroxidation, i.e. without the lag and accelerating phases typical of a propagating chain reaction. PUFA degradation was limited despite stimulation of peroxidation.