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Grigorescu G.,N Simionescu Of The Romanian Academy | Liehn E.A.,RWTH Aachen
Annals of the Romanian Society for Cell Biology | Year: 2013

Vascular diseases and cancer represent leading causes of mortality worldwide. Elucidating the mechanisms of neovascularization draws major scientific interest, as augmenting or inhibiting blood vessel formation might cure these diseases. Circulating endothelial progenitor cells (EPC) are able to stimulate neovascularization either by paracrine secretion or by proliferation and incorporation into new blood vessels. SDF-1 has been identified as a potent angiogenic chemokine, involved in homing of angiogenic progenitor cells toward an ischemic site. Several clinical trials indicated that cell therapy can improve heart condition after an acute myocardial infarction. While the results are encouraging, choosing the best strategy is still a matter of debate. In this study, we aimed to elucidate whether SDF-1 contributes to paracrine properties of early EPC. To this purpose, we isolated early EPC from human peripheral blood and evaluated SDF-1 expression profile, using extracellular and intracellular immunostaining procedures and flow cytometric analysis. We also evaluated 24 h SDF-1 yield in the cell culture supernatant, using a commercially available ELISA kit. SDF-1 levels were compared to those of two mature endothelial cell (EC) lines (HUVEC and HMVEC) and to the mononuclear (MN) population from which we isolated the early EPC. We also evaluated SDF expression under the influence of TNFα and VEGF, two relevant molecules for inflammatory conditions. We show here that early EPC express both surface and intracellular SDF-1. Intracellular expression was also identified in mature EC and MN cells, but only a small percent of mature EC expressed SDF-1 on their surface. In the MN fraction, only cells from the monocyte subpopulation show surface SDF-1 expression. Early EPC secreted two times more SDF-1 than mature EC and MN cells. Exposure to TNFa slightly increased intracellular SDF-1 level in all cell types, while surprisingly, VEGF165 induced a slight decrease in SDF-1 content in early EPC and MN cells and on the surface of monocytes. TNFα and VEGF165 didn't significantly modified SDF release. Several SDF-1 regulatory mechanisms can be involved in this modulation. Considering the dual capacity of EPC to secrete and express SDF-1 on their surface, we hypothesize that these cells might be able to create a local SDF-1 gradient to attract additional CXCR4+ stem/progenitor cells that might further increase neovasculogenesis at an ischemic site. Also, administration of a purified population of peripheral blood-derived early EPC might represent a more effective therapeutic strategy for triggering neovasculogenesis than the whole PBMC population. Source


Dumitrescu M.,N Simionescu Of The Romanian Academy | Costache G.,N Simionescu Of The Romanian Academy | Constantin A.,N Simionescu Of The Romanian Academy | Popov D.,N Simionescu Of The Romanian Academy
Annals of the Romanian Society for Cell Biology | Year: 2013

Hypertension (HT) is a major contributor to the development of renal failure, mainly due to increased oxidative stress. The causative relationship between raised blood pressure and overproduction of reactive oxygen species (ROS) is still controversial. Growing evidence attributes to NADP(H) oxidase the main role in ROS production in the renal cortex, while the angiotensin conversion enzyme (ACE) inhibitor, Zofenopril, is known to exert protective effects in kidney ischemia/reperfusion injury. In this study we approached understanding the biochemical background of imbalance between activation of pro-oxidant enzymes and decreased scavenging of ROS in HT, an issue with still many gaps in perception. With this goal we investigated the effects of Zofenopril on kidney cortex in an experimental model of Nω-Nitro-L-Arginine Methyl Ester (LNAME) induced HT in rats. Animals were divided in 3 groups: HT group (receiving orally 50mg/b.w./day L-NAME, for 6 weeks), HTZ group (HT, receiving orally 15 mg/b.w./day Zofenopril, for 4 weeks), and controls (age-matched C group). Compared to C group, the HT group shows increased blood pressure and serum ACE activity, modification of the kidney cortex normal structure (consisting in tubular atrophy, interstitial fibrosis, obstructive hyalinosis of the renal tubules, effacement of foot processes, mesangial matrix expansion, and reduced number of glomerular filtration slits), biochemical changes indicative for installment of oxidative stress (enhanced NADP(H) oxidase activity, augmented protein expression of p47phox, p67phox subunits of the NADP(H) oxidase, and of p50, and p65 NFkB subunits, and increased protein carbonylation), and reduced antioxidant defense (altered GSH to GSSG ratio and diminished GPx activity). Compared to HT group, the HTZ group shows improvement of structural modifications, along with biochemical changes that demonstrate Zofenopril antioxidant potential. These consist in decreased ROS production and protein expression of NADP(H) oxidase subunits, reduced concentration of protein carbonyls, and activation of the antioxidant defense (improved GSH to GSSG ratio and GPx activity). The original results here reported sustain the renoprotective, antioxidant effect of Zofenopril in the experimental model of L-NAME-induced HT. Source

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