Simvastatin reduces endothelial activation and damage but is partially ineffective in inducing endothelial repair in systemic sclerosis.

OBJECTIVE: To investigate whether statins may improve endothelial function in systemic sclerosis (SSc) by evaluating the effects of simvastatin on vasculogenesis [indicated by the expansion of circulating endothelial progenitor cells (EPC)] and the markers of vascular injury in the peripheral blood of patients with SSc. METHODS: Twenty SSc patients with normal cholesterol concentrations and 20 hypercholesterolemic subjects were allocated to receive 20 mg/day simvastatin for 12 weeks. Peripheral blood samples were collected before and 12 weeks after initiation of treatment, and 4 weeks after discontinuation. Five-parameter, 3-color flow cytometry was performed with a FacScan to enumerate EPC and mature circulating endothelial cells (CEC). Levels of soluble E-selectin, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, interleukin 6, and endothelin-1 were assessed by commercial ELISA. RESULTS: Simvastatin treatment significantly increased EPC in the hypercholesterolemic group, but failed to improve the EPC levels in the SSc patients, mainly in patients with late disease. Baseline levels of CEC were significantly higher in SSc patients compared with controls and at the end of the treatment they were significantly decreased. Regarding other markers of endothelial activation, we found that all the cytokine levels decreased in a statistically significant manner in the treated patients. CONCLUSION: Treatment with simvastatin results in rapid and significant improvement of measures of endothelial activation, suggesting a potential role of statins in the treatment of peripheral vascular disease in SSc. The lack of effect on increase of EPC confirms our previous findings of a defective endothelial stem cell recruitment in the bone marrow of SSc patients. This could indicate that the potential effectiveness of statins in SSc could mainly be ascribed to their effectiveness in modulating endothelial activation mechanisms.

Effects of simulated altitude (normobaric hypoxia) on cardiorespiratory parameters and circulating endothelial precursors in healthy subjects.

BACKGROUND: Circulating Endothelial Precursors (PB-EPCs) are involved in the maintenance of the endothelial compartment being promptly mobilized after injuries of the vascular endothelium, but the effects of a brief normobaric hypoxia on PB-EPCs in healthy subjects are scarcely studied. METHODS: Clinical and molecular parameters were investigated in healthy subjects (n = 8) in basal conditions (T0) and after 1 h of normobaric hypoxia (T1), with Inspiratory Fraction of Oxygen set at 11.2% simulating 4850 mt of altitude. Blood samples were obtained at T0 and T1, as well as 7 days after hypoxia (T2). RESULTS: In all studied subjects we observed a prompt and significant increase in PB-EPCs, with a return to basal value at T2. The induction of hypoxia was confirmed by Alveolar Oxygen Partial Pressure (PAO2) and Spot Oxygen Saturation decreases. Heart rate increased, but arterial pressure and respiratory response were unaffected. The change in PB-EPCs percent from T0 to T1 was inversely related to PAO2 at T1. Rapid (T1) increases in serum levels of hepatocyte growth factor and erythropoietin, as well as in cellular PB-EPCs-expression of Hypoxia Inducible Factor-1alpha were observed. CONCLUSION: In conclusion, the endothelial compartment seems quite responsive to standardized brief hypoxia, possibly important for PB-EPCs activation and recruitment.

Bone marrow endothelial progenitors are defective in systemic sclerosis.

OBJECTIVE: Vascular abnormalities represent the main component of the pathobiology of systemic sclerosis (SSc), progressing from structural derangements of the microcirculation with abortive neoangiogenesis to final vessel loss. Since circulating endothelial progenitor cells (EPCs) are important in the vascular repair process, we undertook this study to examine their numbers in the peripheral blood (PB) of SSc patients and to evaluate whether their status is related to impaired quantitative and/or qualitative aspects of the bone marrow (BM) microenvironment. METHODS: Circulating EPCs from 62 SSc patients were evaluated by flow cytometry and characterized as CD45 negative and CD133 positive. BM EPCs, identified as CD133 positive, were isolated from 14 SSc patients and grown to induce endothelial differentiation. In addition, progenitor numbers and functional properties of hematopoietic and stromal compartments were analyzed by various assays. RESULTS: We found that EPCs were detectable in the PB of patients with SSc, and their number was significantly increased in patients with early-stage disease but not in those with late-stage disease. All of the examined BM samples contained reduced numbers of EPCs and stromal cells, both of which were functionally impaired. Both endothelial and stromal progenitors expressed vascular endothelial growth factor receptor, indicating that BM is strongly induced to differentiate into the endothelial lineage; furthermore, only BM EPCs from patients with early disease led to endothelial differentiation in vitro. CONCLUSION: This study provides the first demonstration that in SSc, there is a complex impairment in the BM microenvironment involving both the endothelial and mesenchymal stem cell compartments and that this impairment might play a role in defective vasculogenesis in scleroderma.

Endothelial colony forming capacity is related to C-reactive protein levels in healthy subjects.

The majority of clinical studies on endothelial progenitor cells (EPCs) focuses on the role of these cells in cardiovascular diseases and no systematic studies exist regarding their variations in healthy subjects. In order to define the burden of angiogenesis in physiological conditions we assessed the frequency of peripheral blood endothelial colonies (PB-ECs) and their relation with other factors possibly involved in their function such as high-sensitivity C-reactive protein (hs-CRP), endothelial cell-specific mitogen factor (VEGF) and tissue inhibitor of metalloproteinases-1 (TIMP-1) in a highly selected healthy population. A PB sample was obtained from 37/47 healthy subjects (age 40.2+/-15.0yrs; M/F 15/22) without known cardiovascular risk factors. The serum level of hs-CRP, VEGF, TIMP-1, the frequency of PB-ECs by clonogenic assay, and the number of early EPCs and late EPCs by flow cytometry analysis were evaluated. PB-ECs were formed by 40.5% of studied subjects with a mean of 0.40+/-0.82 colonies/10(6) cells. The differences in the frequency of colony formation between genders were not statistically significant. The subjects with PB-ECs were characterized by higher values of hs-CRP, when compared with those not forming colonies, 0.276+/-0.230 vs 0.095+/-0.077 mg/l (p=0.003) respectively, and of VEGF, 328.3+/-162.9 vs 202.68+/-118.53 pg/ml (p=0.02). No significant differences were found in TIMP-1 values. The EPC clonogenic potential seems to be related to hs-CRP and VEGF levels even in healthy population supporting the concept that these mediators are involved in physiological ECs function.