Transplantation of human fetal pancreatic progenitor cells ameliorates renal injury in streptozotocin-induced diabetic nephropathy

Artemisinin attenuates early renal damage on diabetic nephropathy rats through suppressing TGF-β1 regulator and activating the Nrf2 signaling pathway

AIM

The present study aims to investigate the protective effects of artemisinin (ATZ) on early renal damage in experimental diabetic rats and its probable mechanism.

METHODS

Models of diabetic nephropathy (DN) rats was established utilizing streptozotocin (STZ)-injection intraperitoneally (55 mg/kg) method. All rats were subsequently divided into normal control group, model group and ATZ (25, 50, 75 mg/kg) group randomly. Biochemical parameters including body weight, kidney index, blood glucose, 24 h UAER, Scr, BUN, T-SOD, GSH-Px and MDA were comprehensively determined after 8-week consecutive administrations. HE and PAS stainings were performed to observe the histopathological alterations of kidney. Western blot was conducted to detect the expressions of TGF-β1, Nrf2, HQ-1 and NQO1.

KEY FINDINGS

ATZ at three concentrations in ATZ group significantly increased the body weight. Biochemical parameters altered significantly between model group and ATZ group. Moreover, ATZ inhibited TGF-β1 protein expression and activated the Nrf2 signaling pathway. Pathological histology results revealed the alterations including mesangial cells proliferation, thickness of glomerular capillary basement membrane, extracellular matrix (ECM) and the 24 h UAER. Western blot analysis demonstrated the increase of antioxidant proteins HO-1 and NQO1 and Nrf2-related proteins.

SIGNIFICANCE

ATZ could reduce early renal oxidative stress damage in DN rats by inhibiting TGF-β1 protein expression in kidney tissues as well as activating the Nrf2 signaling pathway and enhancing the expression of antioxidant proteins, thereby exerting the protective effects on DN kidney. The current study is the first report of ATZ on attenuating effects on kidney of DN rats, which could lay solid theoretical foundations on clinical application of ATZ to treat DN.

Mouse Umbilical Cord Mesenchymal Stem Cell Paracrine Alleviates Renal Fibrosis in Diabetic Nephropathy by Reducing Myofibroblast Transdifferentiation and Cell Proliferation and Upregulating MMPs in Mesangial Cells

Transplantation of umbilical cord mesenchymal stem cells (UC-MSCs) is currently considered a novel therapeutic strategy for diabetic nephropathy (DN). However, the mechanisms by which UC-MSCs ameliorate renal fibrosis in DN are not well understood. Herein, we firstly investigated the therapeutic effects of mouse UC-MSC infusion on kidney structural and functional impairment in streptozotocin- (STZ-) induced diabetic mice. We found that the repeated injection with mUC-MSCs alleviates albuminuria, glomerulus injury, and fibrosis in DN mouse models. Next, mesangial cells were exposed to 5.6 mM glucose, 30 mM glucose, or mUC-MSC-conditioned medium, and then we performed western blotting, immunofluorescence, wound healing assay, and cell proliferation assay to measure extracellular matrix (ECM) proteins and matrix metalloproteinases (MMPs), myofibroblast transdifferentiation (MFT), and cell proliferation. We demonstrated that mUC-MSC paracrine decreased the deposition of fibronectin and collagen I by inhibiting TGF-β1-triggered MFT and cell proliferation mediated by PI3K/Akt and MAPK signaling pathways, and elevating the levels of MMP2 and MMP9. Importantly, we provided evidence that the antifibrosis role of mUC-MSC paracrine in DN might be determined by exosomes shed by MSCs. Together, these findings reveal the mechanisms underlying the therapeutic effects of UC-MSCs on renal fibrosis in DN and provide the evidence for DN cell-free therapy based on UC-MSCs in the future.

Transplantation of Mouse Induced Pluripotent Stem Cell-Derived Podocytes in a Mouse Model of Membranous Nephropathy Attenuates Proteinuria

Injury to podocytes is a principle cause of initiation and progression of both immune and non-immune mediated glomerular diseases that result in proteinuria and decreased function of the kidney. Current advances in regenerative medicine shed light on the therapeutic potential of cell-based strategies for treatment of such disorders. Thus, there is hope that generation and transplantation of podocytes from induced pluripotent stem cells (iPSCs), could potentially be used as a curative treatment for glomerulonephritis caused by podocytes injury and loss. Despite several reports on the generation of iPSC-derived podocytes, there are rare reports about successful use of these cells in animal models. In this study, we first generated a model of anti-podocyte antibody-induced heavy proteinuria that resembled human membranous nephropathy and was characterized by the presence of sub-epithelial immune deposits and podocytes loss. Thereafter, we showed that transplantation of functional iPSC-derived podocytes following podocytes depletion results in recruitment of iPSC-derived podocytes within the damaged glomerulus, and leads to attenuation of proteinuria and histological alterations. These results provided evidence that application of iPSCs-derived renal cells could be a possible therapeutic strategy to favorably influence glomerular diseases outcomes.

Paracrine effect of mesenchymal stem cell as a novel therapeutic strategy for diabetic nephropathy

Diabetic nephropathy (DN) is a microvascular complication of diabetes mellitus (DM) and the main reason for end-stage renal diseases (ESRD). Based on the role of mesenchymal stem cells (MSCs) in regenerative medicine, the MSC therapy has been considered a promising strategy to ameliorate the progression of DN. In this article, we review the therapeutic potential of MSCs in DN, mainly involving MSC paracrine mechanism based on trophic factors and extracellular vesicles. Knowledge of mechanism underlying the therapeutic action of MSCs on DN can provide much needed new drug targets for this disease.

The receptor for advanced glycation endproducts is a mediator of toxicity by IAPP and other proteotoxic aggregates: Establishing and exploiting common ground for novel amyloidosis therapies

Proteotoxicity plays a key role in many devastating human disorders, including Alzheimer's, Huntington's and Parkinson's diseases; type 2 diabetes; systemic amyloidosis; and cardiac dysfunction, to name a few. The cellular mechanisms of proteotoxicity in these disorders have been the focus of considerable research, but their role in prevalent and morbid disorders, such as diabetes, is less appreciated. There is a large body of literature on the impact of glucotoxicity and lipotoxicity on insulin-producing pancreatic β-cells, and there is increasing recognition that proteotoxicty plays a key role. Pancreatic islet amyloidosis by the hormone IAPP, the production of advanced glycation endproducts (AGE), and insulin misprocessing into cytotoxic aggregates are all sources of β-cell proteotoxicity in diabetes. AGE, produced by the reaction of reducing sugars with proteins and lipids are ligands for the receptor for AGE (RAGE), as are the toxic pre-fibrillar aggregates of IAPP produced during amyloid formation. The mechanisms of amyloid formation by IAPP in vivo or in vitro are not well understood, and the cellular mechanisms of IAPP-induced β-cell death are not fully defined. Here, we review recent findings that illuminate the factors and mechanisms involved in β-cell proteotoxicity in diabetes. Together, these new insights have far-reaching implications for the establishment of unifying mechanisms by which pathological amyloidoses imbue their injurious effects in vivo.

HIF1α deletion facilitates adipose stem cells to repair renal fibrosis in diabetic mice

Adipose stem cell (ASC) transplantation is a promising therapeutic strategy for diabetic renal fibrosis. Hypoxia-inducible factor 1α (HIF1α) is a negative regulatory factor of mitochondrial function. In the current study, we aimed to explore if HIF1α deletion protects against hyperglycemia-induced ASC damage and enhances the therapeutic efficiency of ASCs in diabetic renal fibrosis. Our data indicated that HIF1α was upregulated in ASCs in response to high glucose stimulation. Higher HIF1α expression was associated with ASC apoptosis and proliferation arrest. Loss of HIF1α activated mitophagy protecting ASCs against high glucose-induced apoptosis via preserving mitochondrial function. Transplanting HIF1α-deleted ASCs in db/db mice improved the abnormalities in glucose metabolic parameters, including the levels of glucose, insulin, C-peptide, HbA1c, and inflammatory markers. In addition, the engraftment of HIF1α-modified ASCs also reversed renal function, decreased renal hypertrophy, and ameliorated renal histological changes in db/db mice. Functional studies confirmed that HIF1α-modified ASCs reduced renal fibrosis. Collectively, our results demonstrate that ASCs may be a promising therapeutic treatment for ameliorating diabetes and the development of renal fibrosis and that the loss of HIF1α in ASCs may further increase the efficiency of stem cell-based therapy. These findings provide a new understanding about the protective effects of HIF1α silencing on ASCs and offer a new strategy for promoting the therapeutic efficacy of ASCs in diabetic renal fibrosis.

Decreased serum extracellular superoxide dismutase activity is associated with albuminuria in Chinese patients with type 2 diabetes mellitus

AIMS

The aim of this study was to determine the activity of serum extracellular superoxide dismutase (ecSOD) in patients with type 2 diabetes mellitus (T2DM) and healthy subjects, and to determine the prospective association between baseline serum ecSOD activity and the subsequent risk of albuminuria progression in a cohort of Chinese T2DM patients.

METHODS

A total of 458 T2DM patients and 100 healthy subjects were assessed. After a median follow-up of 7.7 months, 319 patients with baseline normoalbuminuria (urinary albumin-to-creatinine ratio [UACR] <30 mg/g) and 77 patients with baseline microalbuminuria (UACR = 30-299 mg/g) were divided into progression and non-progression groups according to UACR changes. Serum ecSOD activity was determined by the autoxidation of pyrogallol method. Multivariate Cox regression analysis was used for investigating the predictors for albuminuria progression.

RESULTS

Compared with healthy controls (174.5 ± 25.1 U/mL), serum ecSOD activity significantly decreased in T2DM patients with normoalbuminuria (114.9 ± 13.2 U/mL), with microalbuminuria (106.6 ± 16.3 U/mL), and with macroalbuminuria (97.1 ± 18.2 U/mL) (all P < 0.001). Serum ecSOD activity was associated with albuminuria (odds ratio [OR] = 1.028, P = 0.004) in T2DM patients. Baseline serum ecSOD activity (hazard ratio [HR] = 0.902, 95% CI 0.877-0.928, P < 0.001) was an independent predictor for albuminuria progression.

CONCLUSION

Serum ecSOD activity may be useful for predicting the future risk of albuminuria progression in Chinese T2DM patients.