Fibrate treatment of eEOCs in murine AKI

Early endothelial outgrowth cells (eEOCs) protect mice from acute kidney injury (AKI). Peroxisome proliferator-activated receptor-alpha (PPAR-alpha) has been shown to mediate renoprotective effects under different experimental conditions. The aim of the study was to investigate consequences of fibrate treatment of murine eEOCs in a cell-based therapeutic approach to AKI. Male C57/Bl6N mice, subjected to unilateral renal ischemia (40 min) post-uninephrectomy, were systemically injected with 0.5 x 10(6) untreated or fenofibrate (FF 1, 5, 10 or 50 mu m)/clofibrate (CF 1 mm) pretreated syngeneic murine eEOCs. Renal function and morphology were analyzed 48 h later. Cellular consequences of eEOC treatment with fibrates (FF 1, 5, 10, 50 mu m, CF 1 mm) were evaluated using different in vitro assays (direct cell migration, apoptosis/necrosis, ELISA studies). Administration of untreated eEOCs did not protect mice from AKI. Injection of eEOCs treated with CF (1 mm) or FF 50 mu m did not result in any protection from ischemia-induced renal dysfunction. In vitro analysis showed reduced cellular secretion of vasoprotective vascular endothelial growth factor (VEGF), an effect that was more pronounced with CF; FF increased percentages of apoptotic/necrotic eEOCs, and both substances failed to stimulate migration of cultured cells. With lower FF concentrations (1, 5, 10 mu m) cell survival was increased and 10 mu m FF stimulated VEGF secretion. In vivo administration of FF-treated eEOCs (10 mu m) also did not result in any renoprotective effect. PPAR-alpha activation using fibrates does not stimulate renoprotective effects of syngeneic murine eEOCs in ischemic AKI, although lower fibrate concentrations significantly activate eEOCs in vitro.