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IntroductionSepsis is characterized by systemic microvascular dysfunction. Endothelial progenitor cells (EPCs) are critically involved in maintaining vascular homeostasis under both physiological and pathological conditions. The aim of the present study was to analyze the endothelial progenitor cell system in patients suffering from sepsis with acute renal dysfunction.MethodsPatients with newly diagnosed sepsis were recruited from the ICU in a nonrandomized prospective manner. Blood samples were obtained within the first 12 hours after the diagnosis of sepsis. For quantifying endothelial progenitor cells (EPCs), CD133+/Flk-1+ cells were enumerated by cytometric analysis. Analysis of EPC proliferation was performed by a colony-forming units (CFU) assay. Blood concentrations of proangiogenic mediators were measured by ELISA. Acute renal dysfunction was diagnosed according to the Acute Kidney Injury Network (AKIN) criteria. Depending on the overall mean creatinine concentration during the stay at the ICU, patients were either assigned to a 'normal creatinine group' or to a 'high creatinine group'. Survival rates, frequency of dialysis, the simplified acute physiology score (SAPS) II scores, and different laboratory parameters were collected/used for further clinical characterizationResultsCirculating EPCs were significantly higher in all sepsis patients included in the study as opposed to healthy controls. Patients within the 'high creatinine group' showed an even more pronounced EPC increase. In contrast, EPC proliferation was severely affected in sepsis. Neither total circulating EPCs nor EPC proliferation differed between patients requiring dialysis and patients without renal replacement therapy. Cell numbers and cell proliferation also did not differ between surviving patients and patients with sepsis-related death. Serum levels of vascular endothelial growth factor (VEGF), stromal derived factor-1 (SDF-1), and Angiopoietin-2 were higher in sepsis than in healthy controls. Sepsis patients within the 'high creatinine group' showed significantly higher mean serum levels of uric acid.ConclusionsSepsis significantly affects the endothelial progenitor cell system, as reflected by increased EPC numbers, increased concentrations of proangiogenic mediators, and reduced proliferative capacity of the cells. This occurs independently from the frequency of dialysis and from patient survival. Increased serum levels of uric acid are possibly responsible for stronger EPC mobilization in sepsis patients with higher average creatinine levels.

Endothelial progenitor cells (EPCs) protect the kidney from acute ischemic injury. The aim of this study was to analyze whether pretreatment of murine "early outgrowth" EPCs (eEPCs) with the hormone melatonin increases the cells' renoprotective effects in the setting of murine acute ischemic renal failure. Male (8-12 wk old) C57Bl/6N mice were subjected to unilateral ischemia-reperfusion injury postuninephrectomy (40 min). Postischemic animals were injected with either 0.5×10(6) untreated syngeneic murine eEPCs or with cells, pretreated with melatonin for 1 h. Injections were performed shortly after reperfusion of the kidney. While animals injected with untreated cells developed acute renal failure, eEPC pretreatment with melatonin dramatically improved renoprotective actions of the cells. These effects were completely reversed after cell pretreatment with melatonin and the MT-1/-2 antagonist luzindole. In vitro analysis revealed that melatonin reduced the amount of tumor growth factor-β-induced eEPC apoptosis/necrosis. Secretion of vascular endothelial growth factor by the cells was markedly stimulated by the hormone. In addition, migratory activity of eEPCs was enhanced by melatonin and supernatant from melatonin-treated eEPCs stimulated migration of cultured mature endothelial cells. In summary, melatonin was identified as a new agonist of eEPCs in acute ischemic kidney injury.

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Objective: To quantify 18-fluorodeoxyglucose (FDG) accumulation in large vessels in patients with polymyalgia rheumatica by positron emission tomography (PET), and to compare these data with serological markers of inflammation. Methods: 13 untreated patients with active polymyalgia rheumatica underwent FDG positron emission tomography; eight were analysed in a second PET when in clinical remission. Six patients with other highly inflammatory conditions served as controls. For quantitative analysis, FDG uptake over nine defined vascular regions, divided by an individual background value, was expressed as a region of interest (ROI) index. These data were compared with the clinical status of the patient and with erythrocyte sedimentation rate (ESR), C reactive protein, haemoglobin, and platelet and leucocyte counts. Results: By visual evaluation, 12 of the 13 patients showed an increased tracer uptake of the aorta or its major branches. By quantitative analysis, FDG uptake was significantly increased in polymyalgia rheumatica. In patients with active disease, the mean ROI index for all vascular regions exceeded that of controls by 70% (mean (SD): 1.58 (0.37) v 0.93 (0.12); p,0.001). In the eight patients who underwent follow up PET, the index declined substantially. In active polymyalgia rheumatica, FDG uptake was significantly correlated with C reactive protein (r = 0.8), ESR (r = 0.79), and platelet counts (r = 0.68). Conclusions:The observed FDG accumulation in the aorta and its branches and a strong correlation between tracer uptake and markers of inflammation is suggestive of large vessel arteritis. Quantitative ROI analysis appears to be a sensitive tool for detecting such inflammation.