Injured Kidney Tissues Research Articles

Therapeutic potential of mesenchymal stem cells in acute kidney injury is affected by administration timing.

Mesenchymal stem cell (MSC) transplantation is a promising therapy for acute kidney injury; however, the efficacy is limited due to poor survival after transplantation. In this study, we investigated how MSC transplantation timing affected the survival and therapeutic potential of MSCs in the kidney ischemia-reperfusion (I/R) injury model. After kidney I/R injury, the inflammatory process and tissue damage were characterized over 1 week post-I/R, we found that inflammation peaked at 12-24 h post-I/R (h.p.i.), and urine neutrophil gelatinase-associated lipocalin (NGAL) measurements correlated highly with measures of inflammation. We cultured MSCs with supernatants from I/R injured kidney tissue homogenates collected at different time points and found that kidney homogenates from 12 and 24 h.p.i. were most toxic to MSCs, whereas homogenates from 1 h.p.i. were not as cytotoxic as those from 12 and 24 h.p.i. Compared with MSCs administered at 12, or 24 h.p.i., cells administered immediately after ischemia or 1 h.p.i. yielded the highest renoprotective and anti-inflammatory effects. Our findings indicate that MSC treatment for acute kidney injury is most effective when applied prior to the development of a potent inflammatory microenvironment, and urine NGAL may be helpful for detecting inflammation and selecting MSC transplantation timing in I/R kidney injury.

Increased Expression of Clusterin in Kidney of a Fatal Nephropathia Epidemica Case

Nephropathia epidemica (NE), a mild form of hemorrhagic fever with renal syndrome (HFRS), is endemic in the European part of Russia. This disease is characterized by an acute onset followed by symptoms related to kidney impairment. Histologically, NE is defined as a tubulointerstitial nephritis with the prominent leukocyte infiltration and interstitial hemorrhages. Also, the presence of IgM, complement component C3, and fibrin deposits along the basal surface of the tubular epithelial cells has been reported. The pathogenesis of immunoglobulin and complement deposition in the kidney tubules remains unknown. We found clusterin deposits in the kidney tissue from fatal NE. Clusterin was co-localized with hantavirus antigens and C3 complement on the basal side of the kidney tubules. Additionally, kidney infiltrating leukocytes were positive for clusterin. It has previously been documented that the expression of clusterin is restricted to epithelial cells and is often found on tubular cells of the injured kidney tissue. Additionally, clusterin can bind to immunoglobulins and complement components. We propose that upregulation of clusterin expression in the NE kidney is associated with damage to the tissue and may cause deposition of immunoglobulins and complement.

Dysregulation of renal microRNA expression after deep hypothermic circulatory arrest in rats.

Acute kidney injury (AKI) is a severe complication of cardiopulmonary bypass-deep hypothermic circulatory arrest (DHCA) surgery. Non-coding microRNAs (miRNAs) are considered as key players in kidney physiology and pathology. However, whether they are implicated in DHCA-induced AKI at the early stage post-surgery is less studied, and requires for further investigation. In this study, kidney tissues were removed at 2 h post-surgery from Sprague-Dawley rats that underwent a 60-min DHCA (18°C), with samples from sham-operated rats as control. Renal RNA isolates were analysed with Affymetrix miRNA microarray 4.0 containing 728 mature rat miRNA probes. Seventy-one miRNAs were down-regulated and 4 were up-regulated in the kidneys of DHCA rats [log2 (fold change, FC) > 1, P < 0.05]. Novel differentially expressed miRNAs, such as miRNA-3068, miR-1949 and miR-3473, were identified in the injured kidney tissues. Putative target genes of the down-regulated miR-30b-5p, miR-199a-5p, miR-148b-3p and miR-10a-3p were subjected to analyses of gene ontology (GO) categories and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The results indicated that these miRNAs targeted a large set of genes involved in essential biological processes related to AKI pathogenesis, such as apoptotic process and response to hypoxia, as well as genes implicated in critical signalling pathways, such as chemokine, lysosome and FoxO signalling pathways (false discovery rate-corrected, P < 0.05). The identified 75 differentially expressed miRNAs hold the potential to serve as novel early markers and novel therapeutic targets for DHCA-AKI.

Mesenchymal Stromal Cells Derived Extracellular Vesicles Ameliorate Acute Renal Ischemia Reperfusion Injury by Inhibition of Mitochondrial Fission through miR-30.

Background. The immoderation of mitochondrial fission is one of the main contributors in ischemia reperfusion injury (IRI) and mesenchymal stromal cells (MSCs) derived extracellular vesicles have been regarded as a potential therapy method. Here, we hypothesized that extracellular vesicles (EVs) derived from human Wharton Jelly mesenchymal stromal cells (hWJMSCs) ameliorate acute renal IRI by inhibiting mitochondrial fission through miR-30b/c/d. Methods. EVs isolated from the condition medium of MCS were injected intravenously in rats immediately after monolateral nephrectomy and renal pedicle occlusion for 45 minutes. Animals were sacrificed at 24 h after reperfusion and samples were collected. MitoTracker Red staining was used to see the morphology of the mitochondria. The expression of DRP1 was measured by western blot. miR-30 in EVs and rat tubular epithelial cells was assessed by qRT-PCR. Apoptosis pathway was identified by immunostaining. Results. We found that the expression of miR-30 in injured kidney tissues was declined and mitochondrial dynamics turned to fission. But they were both restored in EVs group in parallel with reduced cell apoptosis. What is more, when the miR-30 antagomirs were used to reduce the miRNA levels, all the related effects of EVs reduced remarkably. Conclusion. A single administration of hWJMSC-EVs could protect the kidney from IRI by inhibition of mitochondrial fission via miR-30.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles Protect Against Acute Kidney Injury Through Anti-Oxidation by Enhancing Nrf2/ARE Activation in Rats

Background/Aims: Anti-oxidation is an effective strategy for curing acute kidney injury (AKI). Herein, we suggest that extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) might play an anti-oxidative role by enhancing Nrf2/ARE activation in AKI. Methods: EVs isolated from the conditioned medium of human Wharton's Jelly mesenchymal stromal cells and human foreskin fibroblast were intravenously injected in rats immediately after 45 min of unilateral kidney ischemia. Animals were sacrificed 24 h after injury. Results: Results showed that renal tubular injury was alleviated and renal function was improved by MSC-EVs. Cell apoptosis and sNGAL levels, which reflect kidney cell injury, were reduced. Moreover, MSC-EVs decreased oxidative stress in injured kidney tissues and NRK-52E cells under hypoxia injury. Nrf2/antioxidant response element (ARE) enhancement and HO-1 up-regulation were further observed after MSC-EV treatment both in vivo and in vitro. Conclusions: MSC-EVs may protect against AKI possibly through anti-oxidation by enhancing Nrf2/ARE activation.

The Anti-Oxidative Role of Micro-Vesicles Derived from Human Wharton-Jelly Mesenchymal Stromal Cells through NOX2/gp91(phox) Suppression in Alleviating Renal Ischemia-Reperfusion Injury in Rats

Oxidative stress is known as one of the main contributors in renal ischemia/reperfusion injury (IRI). Here we hypothesized that Micro-vesicles (MVs) derived from human Wharton Jelly mesenchymal stromal cells (hWJMSCs) could protect kidney against IRI through mitigating oxidative stress. MVs isolated from hWJMSCs conditioned medium were injected intravenously in rats immediately after unilateral kidney ischemia for 60 min. The animals were sacrificed at 24h, 48h and 2 weeks respectively after reperfusion. Our results show that the expression of NOX2 and reactive oxygen species (ROS) in injured kidney tissues was declined and the oxidative stress was alleviated in MVs group at 24h and 48h in parallel with the reduced apoptosis and enhanced proliferation of cells. IRI-initiated fibrosis was abrogated by MVs coincident with renal function amelioration at 2 weeks. NOX2 was also found down-regulated by MVs both in human umbilical vein endothelial cells (HUVEC) and NRK-52E cell line under hypoxia injury model in vitro. In conclusion, a single administration of hWJMSC-MVs might protect the kidney by alleviation of the oxidative stress in the early stage of kidney IRI through suppressing NOX2 expression. Moreover, it could reduce the fibrosis and improved renal function.

Infusion of IL-10–expressing cells protects against renal ischemia through induction of lipocalin-2

Ischemia/reperfusion injury is a leading cause of acute renal failure triggering an inflammatory response associated with infiltrating macrophages, which determine disease outcome. To repair the inflammation we designed a procedure whereby macrophages that overexpress the anti-inflammatory agent interleukin (IL)-10 were adoptively transferred. These bone marrow-derived macrophages were able to increase their intracellular iron pool that, in turn, augmented the expression of lipocalin-2 and its receptors. Infusion of these macrophages into rats after 1 h of reperfusion resulted in localization of the cells to injured kidney tissue, caused increases in regenerative markers, and a notable reduction in both blood urea nitrogen and creatinine. Furthermore, IL-10 therapy decreased the local inflammatory profile and upregulated the expression of pro-regenerative lipocalin-2 and its receptors. IL-10-mediated protection and subsequent renal repair were dependent on the presence of iron and lipocalin-2, since the administration of a neutralizing antibody for lipocalin-2 or administration of IL-10 macrophages pretreated with the iron chelating agent deferoxamine abrogated IL-10-mediated protective effects. Thus, adoptive transfer of IL-10 macrophages to ischemic kidneys blunts acute kidney injury. These effects are mediated through the action of intracellular iron to induce lipocalin-2.

CD248+ stromal cells are associated with progressive chronic kidney disease

Stromal fibroblasts are the primary cells of the kidney that produce fibrotic matrix. CD248 is a stromal marker expressed on fibroblasts and pericytes within the human kidney. Here, we tested whether CD248 expression in the kidney colocalizes with fibrosis and if it is associated with known determinants of chronic kidney disease (CKD). CD248 expression was located and quantified in situ by immunohistochemistry in kidney biopsies from 93 patients with IgA nephropathy and compared with 22 archived biopsies encompassing normal kidney tissue as control. In normal kidney tissue, CD248 was expressed by resident pericytes, stromal fibroblasts, and was upregulated in human CKD. The expression was linked to known determinants of renal progression. This relationship was maintained in a multivariate analysis with CD248 expression linked to renal survival. CD248 was expressed by a population of α-smooth muscle actin (SMA)(+) myofibroblasts and α-SMA(-) stromal cells but not expressed on CD45(+) leukocytes. Thus, CD248 defines a subset of stromal cells, including but not limited to some myofibroblasts, linked to albuminuria and tubulointerstitial damage during tissue remodeling in CKD.

Acute Kidney Injury: Current Perspectives

Acute kidney injury (AKI) increases morbidity and mortality, particularly for the critically ill. Recent definitions standardizing AKI to reflect graded changes in serum creatinine and urine output (per the Risk, Injury, Failure, Loss, and End-stage renal failure [RIFLE] and Acute Kidney Injury Network [AKIN] criteria) with severity of renal injury and developments in AKI pathobiology are being utilized to identify biomarkers of early kidney injury. These developments may be useful in the early intervention of preventing AKI. Although there has been progress in the management of AKI, therapeutic challenges include appropriate prophylaxis prior to contrast administration, use of diuretics, vasopressors, and the type and dose of renal replacement therapy. Future use of bioartificial dialyzers, plasma therapies, and the possibility of stem cell regeneration of injured kidney tissue are being actively investigated to provide alternative treatment options for AKI. This review aims to provide an overview of current practices, available therapies, and continued research in AKI therapy.

Allogenic fetal membrane-derived mesenchymal stem cells contribute to renal repair in experimental glomerulonephritis

Mesenchymal stem cells (MSC) have been reported to be an attractive therapeutic cell source for the treatment of renal diseases. Recently, we reported that transplantation of allogenic fetal membrane-derived MSC (FM-MSC), which are available noninvasively in large amounts, had a therapeutic effect on a hindlimb ischemia model (Ishikane S, Ohnishi S, Yamahara K, Sada M, Harada K, Mishima K, Iwasaki K, Fujiwara M, Kitamura S, Nagaya N, Ikeda T. Stem Cells 26: 2625-2633, 2008). Here, we investigated whether allogenic FM-MSC administration could ameliorate renal injury in experimental glomerulonephritis. Lewis rats with anti-Thy1 nephritis intravenously received FM-MSC obtained from major histocompatibility complex-mismatched ACI rats (FM-MSC group) or a PBS (PBS group). Nephritic rats exhibited an increased urinary protein excretion in the PBS group, whereas the FM-MSC group rats had a significantly lower level of increase (P < 0.05 vs. PBS group). FM-MSC transplantation significantly reduced activated mesangial cell (MC) proliferation, glomerular monocyte/macrophage infiltration, mesangial matrix accumulation, as well as the glomerular expression of inflammatory or extracellular matrix-related genes including TNF-α, monocyte chemoattractant protein 1 (MCP-1), type I collagen, TGF-β, type 1 plasminogen activator inhibitor (PAI-1) (P < 0.05 vs. PBS group). In vitro, FM-MSC-derived conditioned medium significantly attenuated the expression of TNF-α and MCP-1 in rat MC through a prostaglandin E(2)-dependent mechanism. These data suggest that transplanted FM-MSC contributed to the healing process in injured kidney tissue by producing paracrine factors. Our results indicate that allogenic FM-MSC transplantation is a potent therapeutic strategy for the treatment of acute glomerulonephritis.

Bone marrow mesenchymal stem cells ameliorate rat acute renal failure by differentiation into renal tubular epithelial-like cells

In the present study, we investigated the therapeutic potential of mesenchymal stem cells (MSCs) in a rat acute renal failure (ARF) model and explored the possible in vivo and in vitro mechanisms of action. Rat and human MSCs were isolated from bone marrow. After being co-cultured with injured kidney tissues in trans-well dishes in vitro, the rat MSCs became rounded renal tubular epithelial-like cells, and highly expressed renal markers such as cytokeratin 18 (CK18) and aquaporin-1 (AQP1). Human MSCs were infused into rats with ARF, and techniques of microscopy, histology, PCR, RT-PCR and fluorescence in situ hybridization were used to characterize the MSCs after transplantation. We found that there were more exogenous human MSCs localized to injured kidney tissues. The kidney recovery rate in the transplanted MSC group was higher than in the control group. Genes associated with human renal tubular epithelial cells such as AQP1 and parathyroid hormone receptor 1 were detected. These findings suggest that the injured kidney tissue induced rat and human MSCs to differentiate into renal tubular epithelial-like cells in vitro and in vivo, and exogenous human MSCs can home specifically to injured regions and efficiently cure rat ARF. These results demonstrate that cell therapy has potential as a novel intervention in ARF.

Intervention of crescentic glomerulonephritis by antibodies to monocyte chemotactic and activating factor (MCAF/MCP‐1)

We investigated the pathophysiological role of a potent macrophage (M(phi)) chemotactic cytokine (chemokine), monocyte chemotactic and activating factor/monocyte chemoattractant protein-1 (MCAF/MCP-1), in an animal model of crescentic glomerulonephritis. Administration of a small dose of nephrotoxic sera induced severe proliferative and necrotizing glomerulonephritis, with crescentic formation in the early phase and glomerulosclerosis in the later phase, in Wistar-Kyoto rats. MCAF/MCP-1 protein was detected immunohistochemically in glomeruli, vascular endothelial cells, and tubular epithelial cells in the early phase of injured kidney tissues but not in normal ones. Anti-MCAF/MCP-1 antibodies decreased the number of M(phi) in glomeruli, and prevented crescentic formation and the fusion of epithelial cell foot process in nephritic rats, thereby decreasing the excreted amounts of protein to normal levels on days 3 and 6. Furthermore, anti-MCAF/MCP-1 antibodies remarkably reduced glomerulosclerosis and improved renal dysfunction as well as proteinuria in the later phase (56 days). These results indicate that MCAF/MCP-1 essentially participates in the impairment of renal functions associated with crescentic glomerulonephritis by recruiting and activating M(phi).