Bone marrow-derived cells contribute to glomerular cell turnover and repair, but the cell types involved are unknown. Whether rat mesenchymal stem cells (MSC) can accelerate recovery from damage in rat mesangioproliferative anti-Thy1.1 glomerulonephritis was studied. After injection into the left renal artery on day 2 after disease induction, fluorescently labeled MSC were detected in 20 to 50% of glomeruli and rare intrarenal vessels but not in the tubulointerstitium, in contralateral kidneys, or in medium controls. In control experiments, injected mesangial cells were detected less frequently in glomeruli in comparison with injected MSC. In nephritic outbred Wistar rats, MSC injection led to an approximately 50% reduction of mesangiolysis on days 4 and 6 after disease induction, accompanied by three-to four-fold higher intraglomerular cell proliferation on day 4 and more rapid mesangial reconstitution as detected by ␣-smooth muscle actin expression. Injection of MSC into tail veins or intra-arterial injection of mesangial cells instead of MSC failed to reproduce any of these findings. In inbred Lewis rats, anti-Thy1.1 nephritis followed an aggravated course with transient acute renal failure. Acute renal failure was ameliorated by MSC injection into the left renal artery on day 2 after disease induction. Again, MSC led to more rapid recovery from mesangiolysis, increased glomerular cell proliferation, and reduction of proteinuria by 28%. Double immunostaining of 5-bromo-2-deoxyuridine-labeled MSC for endothelial, mesangial, or monocyte/macrophage antigens showed that 85 to 95% of MSC that localized in glomeruli on day 6 failed to express these markers. In vitro, MSC secreted high amounts of vascular endothelial growth factor and TGF-␤1 but not PDGF-BB. In conclusion, even low numbers of MSC can markedly accelerate glomerular recovery from mesangiolytic damage possibly related to paracrine growth factor release and not to differentiation into resident glomerular cell types or monocytes/macrophages.

The mechanisms for vascular calcification and its associated cardiovascular mortality in patients with ESRD are not completely understood. Dialysis patients exhibit profound vitamin K deficiency, which may impair carboxylation of the calcification inhibitor matrix gla protein (MGP). Here, we tested whether distinct circulating inactive vitamin K-dependent proteins associate with all-cause or cardiovascular mortality. We observed higher levels of both desphospho-uncarboxylated MGP (dp-ucMGP) and desphospho-carboxylated MGP (dp-cMGP) among 188 hemodialysis patients compared with 98 agematched subjects with normal renal function. Levels of dp-ucMGP correlated with those of protein induced by vitamin K absence II (PIVKA-II; r ϭ 0.62, P Ͻ 0.0001). We found increased PIVKA-II levels in 121 (64%) dialysis patients, indicating pronounced vitamin K deficiency. Kaplan-Meier analysis showed that patients with low levels of dp-cMGP had an increased risk for all-cause and cardiovascular mortality. Multivariable Cox regression confirmed that low levels of dp-cMGP increase mortality risk (all-cause: HR, 2.2; 95% CI, 1.1 to 4.3; cardiovascular: HR, 2.7; 95% CI, 1.2 to 6.2). Furthermore, patients with higher vascular calcification scores showed lower levels of dp-cMGP. In 17 hemodialysis patients, daily supplementation with vitamin K2 for 6 weeks reduced dp-ucMGP levels by 27% (P ϭ 0.003) but did not affect dp-cMGP levels. In conclusion, the majority of dialysis patients exhibit pronounced vitamin K deficiency. Lower levels of circulating dp-cMGP may serve as a predictor of mortality in dialysis patients. Whether vitamin K supplementation improves outcomes requires further study. 22: 387-395, 201122: 387-395, . doi: 10.1681 Dialysis patients show an increased total and cardiovascular mortality. 1 Cardiovascular calcifications are well-established mortality predictors in ESRD patients. 2 Calcification is not only a passive but an actively regulated process dependent on calcification inhibitors. 3 Fetuin-A, a liver-derived protein, acts as a systemic calcification inhibitor, 4 and low serum levels have been shown to predict mortality in dialysis patients. 5 Matrix gla protein (MGP) is produced by vascular smooth muscle cells and acts locally in the vascular wall. 6 MGP can be modified by ␥-glutamate carboxylation and serine phosphorylation. The function of phosphorylation is not yet known, but recent data suggest that it plays a role in regulating the secretion of proteins into the extracellular environ- J Am Soc Nephrol

Glomerulonephritis (GN) isM esenchymal stem cells (MSC) hold special promise for renal repair, because nephrons are largely of mesenchymal origin (1). The potential of MSC for renal repair has been shown in rodent models of acute renal failure (ARF), where the course of glycerol, cisplatin, or ischemia-reperfusion induced ARF was improved by MSC injection shortly after disease induction (2-5). In addition, we recently reported that injection of rat MSC into a renal artery can accelerate recovery from mesangiolytic damage and prevent transient ARF in rat anti-Thy1.1 glomerulonephritis (GN) (6). AntiThy1.1 nephritis is a model of acute mesangioproliferative glomerulonephritis and is characterized by initial mesangiolysis followed within a few days by glomerular repair via endothelial and mesangial cell proliferation and accumulation of mesangial matrix. We have also provided evidence that MSC likely exerted these effects in glomeruli by paracrine effects, such as the release of high amounts of vascular endothelial growth factor (VEGF) and TGF-␤1 rather than by differentiation into resident glomerular cell types or monocytes/macrophages (6).In this study, we investigated the long-term effects of MSC administration in early anti-Thy1.1 nephritis. Normally, antiThy1.1 nephritis in rats follows a self-limited course, and spontaneous restitution of the glomerular architecture can be observed within approximately 4 wk. For enhancement of the relevance of the model for progressive renal disease in humans, the model in this study was aggravated and transformed into a course of progressive renal failure by previous uninephrectomy of the rats (7,8). Materials and MethodsRats were housed under standard conditions in a light-, temperature-, and humidity-controlled environment with free access to tap water and standard rat diet. All animal protocols were approved by the local government authorities. Harvest and Culture of MSCInbred male Lewis rats that weighed 180 to 210 g (Harlan, Horst, Netherlands) served as bone marrow donors; MSC were prepared as described previously (6). Cells were seeded onto six-well plates (nine

Vascular calcification is a recognized risk factor for cardiovascular mortality in patients with end-stage renal disease. The aim of this study was to identify risk factors for vascular access calcification and to determine if patients with this disorder are at increased risk of death. Vascular access calcification was found in 49 of 212 hemodialysis patients as measured by plain X-ray (arteriovenous fistula or synthetic graft) in two dimensions. Male gender, diabetes mellitus, and length of time on dialysis were independent predictors for access calcification determined by logistic regression multivariate analysis. Serum parameters were not independently related to access calcification. Kaplan-Meier analysis showed an increased mortality risk, and Cox regression analysis confirmed that vascular access calcification was an independent mortality predictor. Our study suggests that detection of vascular access calcification is a cost-effective method to identify patients at increased mortality risk.

Background/Aims: Dialysis patients display an increased mortality which is associated with cardiovascular calcifications. Diabetes mellitus and ethnicity are known factors that affect the extent of cardiovascular calcifications. However, most studies have investigated mixed cohorts with diabetics and/or mixed ethnicity. Methods: Cardiovascular calcifications were assessed in non-diabetic Caucasian haemodialysis patients by the semiquantitative Adragao calcification score (X-ray pelvis and hands) and a novel composite calcification score encompassing the Adragao score as well as calcifications detected by X-ray of the fistula arm, echocardiography of heart valves and carotid ultrasound. Results: Using multivariate analysis, age, male gender, dialysis vintage, lower Kt/V, calcium-phosphate product, smoking and high-sensitivity CRP were independent risk factors for cardiovascular calcifications as assessed by the Adragao or the composite score. Pulse wave velocity was independently related to both calcification scores. Body mass index, cholesterol, triglycerides, iPTH and serum levels of fetuin-A and uncarboxylated matrix Gla protein were not associated with cardiovascular calcifications. Conclusions: In our cohort of non-diabetic Caucasian haemodialysis patients, age, male gender, dialysis vintage, smoking, calcium-phosphate product, high-sensitivity CRP and lower Kt/V were independent risk factors for cardiovascular calcifications. Whether lowering the calcium-phosphate product and increasing dialysis efficiency can reduce cardiovascular calcifications in dialysis patients remains to be determined.