Natural polysaccharides as promising reno-protective agents for the treatment of various kidney injury.

Renal injury, a prevalent clinical outcome with multifactorial etiology, imposes a substantial burden on society. Currently, there remains a lack of effective management and treatments. Extensive research has emphasized the diverse biological effects of natural polysaccharides, which exhibit promising potential for mitigating renal damage. This review commences with the pathogenesis of four common renal diseases and the shared mechanisms underlying renal injury. The renoprotective roles of polysaccharides in vivo and in vitro are summarized in the following five aspects: anti-oxidative stress effects, anti-apoptotic effects, anti-inflammatory effects, anti-fibrotic effects, and gut modulatory effects. Furthermore, we explore the structure-activity relationship and bioavailability of polysaccharides in relation to renal injury, as well as investigate their utility as biomaterials for alleviating renal injury. The clinical experiments of polysaccharides applied to patients with chronic kidney disease are also reviewed. Broadly, this review provides a comprehensive perspective on the research direction of natural polysaccharides in the context of renal injury, with the primary aim to serve as a reference for the clinical development of polysaccharides as pharmaceuticals and prebiotics for the treatment of kidney diseases.

Bone marrow-derived mesenchymal stem cells transplantation attenuates renal fibrosis following acute kidney injury by repairing the peritubular capillaries.

After the severe initial insults of acute kidney injury, progressive kidney tubulointerstitial fibrosis may occur, the peritubular capillary (PTC) rarefaction plays a key role in the disease progression. However, the mechanisms of PTC damage were not fully understood and potential therapeutic interventions were not explored. Previous studies of our research team and others in this field suggested that bone marrow-derived mesenchymal stem cells (BMSCs) transplanted into the AKI rat model may preserve the kidney function and pathological changes. In the current study, with the ischemia/reperfusion AKI rat model, we revealed that BMSCs transplantation attenuated the renal function decrease in the AKI model through preserving the peritubular capillaries (PTCs) function. The density of PTCs is maintained by BMSCs transplantation in the AKI model, detachment and relocation of pericytes in the PTCs diminished. Then we established that BMSCs transplantation may attenuate the renal fibrosis and preserve the kidney function after AKI by repairing the PTCs. Improving the vitality of pericytes, suppressing the detachment and trans-differentiation of pericytes, directly differentiation of BMSCs into pericytes by BMSCs transplantation all participate in the PTC repair. Through these processes, BMSCs rescued the microvascular damage and improved the density of PTCs. As a result, a preliminary conclusion can be reached that BMSCs transplantation can be an effective therapy for delaying renal fibrosis after AKI.

Nephropreventing effect of hypoxia-inducible factor 1α in a rat model of ischaemic/reperfusion acute kidney injury.

Acute kidney injury (AKI) occurs in 5% of hospitalized patients and in 50% of sepsis patients with acute renal dysfunction. However, there have been no safe and effective therapeutic strategies. The hypoxia condition is closely related to renal injury and function under AKI. As hypoxia-inducible factor 1α (HIF-1α) is critical for the cellular response to hypoxia, we investigated the protective effect of HIF-1α in a rat AKI model. We found that HIF-1α injection improved the survival of rat with AKI, and the level of creatinine and blood urea nitrogen (BUN) was also increased. Our data showed that HIF-1α treatment significantly alleviated ischaemic/reperfusion injury to kidney tubules and nephrocytes. We also found the downstream factors, such as EPOR, VEGF, and PHD3, were also upregulated by HIF-1α. Finally, it was observed that HIF-1α treatment also increased the percentage of adult resident progenitor cells (ARPC) in vitro and in vivo. In conclusion, HIF-1α plays a protective role in the ischaemic AKI model through stimulating the proliferation of ARPC, and our study provided a potential therapeutic strategy for AKI.

Effect of erythropoietin on the migration of bone marrow-derived mesenchymal stem cells to the acute kidney injury microenvironment.

Bone marrow-derived mesenchymal stem cells (BMSCs) preferentially migrate to the injured tissue but with limited efficiency. Here we investigated the effect of erythropoietin (EPO) treatment on the BMSC migration to the acute kidney injury (AKI) microenvironment. The possible mechanisms were also discussed. A hypoxia/re-oxygenation (HR) model of renal tubular epithelial cells (RTECs) was established to generate AKI in vitro, and a chemotaxis experiment was conducted using the transwell chamber. EPO treatment enhanced the BMSC migration to the HR-RTEC culturing chamber in a SDF-1 level-dependent manner, which was fully inhibited by the treatment of anti-SDF-1 antibody. The BMSC migration could also be partly blocked by LY294002 (phosphoinositide 3-kinase (PI3K) inhibitor) and PD98059 (MAPK inhibitor). Western blot analysis showed that phosphorylated Akt and phosphorylated MAPK in BMSCs were enhanced by EPO treatment. In the in vivo experiment, BMSCs were transplanted into the AKI mice and EPO was subcutaneously injected. The results showed that EPO injection increased the SDF-1 protein expression and BMSC accumulation in the renal tissue, which was consistent with a decent improvement of renal function. In addition, the BMSC accumulation in the renal tissue was blocked by anti-SDF-1 antibody, LY294002 or PD98059. Our data suggest that AKI microenvironment had a directional chemotactic effect on BMSCs, which could be further enhanced by the EPO treatment. The increased SDF-1 level in the AKI microenvironment and the activations of PI3K/AKT and MAPK in BMSCs were the possible mechanisms for the effect of EPO. Therefore, BMSC transplantation combined with EPO injection can be a novel and effective approach for AKI repair.

Human adipose-derived stem cells modified by HIF-1α accelerate the recovery of cisplatin-induced acute renal injury in vitro.

Human adipose-derived stem cells (hASCs) improve renal function in acute kidney injury. Hypoxia-inducible factor-1α (HIF-1α) was transfected into hASCs. hASCs modified by lentivirus-mediated empty-vector and HIF-1α maintained their stem cell characteristics. The expression of the renal-protective gene, heme oxygenase-1 and vascular endothelial growth factor were significantly increased in hASCs modified by HIF-1α, compared to hASCs modified by empty-vector. Cellular ultra-structure and TUNEL staining revealed that hASCs modified by HIF-1α promoted the recovery of apoptotic morphology in cisplatin-treated human kidney-2 cells (HK-2 cells) when compared to hASCs modified by empty-vector. Additionally, hASCs modified by empty-vector inhibited caspase-3 expression and up-regulated Bcl-2 expression in cisplatin-treated HK-2 cells, an effect even more pronounced with hASCs modified by HIF-1α. Thus, HIF-1α gene-modified ASCs could be an effective way to enhance the renal-protective effect.

Tislelizumab induced dual organs dysfunction in a patient with advanced esophageal squamous cell carcinoma: a case report.

Background: Tislelizumab, a humanized IgG4 anti-PD-1 monoclonal antibody has been approved in China and Europe. According to the published clinical research, tislelizumab shows satisfactory safety profile. No severe hepatotoxicity or acute kidney injury were reported. Case presentation: We presented a case study of a 74-year-old man who developed acute kidney injury (grade 3) and acute liver injury (grade 4) after being administered tislelizumab for the treatment of esophageal squamous cell carcinoma. We reviewed the patient's history, physical examination, and laboratory findings and provided comprehensive differentials of the possible causes of the toxicities. Immune Checkpoint Inhibitors (ICI) hepatotoxicity and nephrotoxicity were confirmed clinically. We also discussed the management of toxicities associated with ICIs and the need for a multidisciplinary approach to care. Conclusions: The case highlights the importance of close monitoring and prompt management of toxicities associated with ICIs and the need for further research to better understand the risk factors for these toxicities and to identify effective treatments for them.

Study on Fu-Fang-Jin-Qian-Cao Inhibiting Autophagy in Calcium Oxalate-induced Renal Injury by UHPLC/Q-TOF-MS-based Metabonomics and Network Pharmacology Approaches.

INTRODUCTION: Fu-Fang-Jin-Qian-Cao is a Chinese herbal preparation used to treat urinary calculi. Fu-Fang-Jin-Qian-Cao can protect renal tubular epithelial cells from calcium oxalateinduced renal injury by inhibiting ROS-mediated autopathy. The mechanism still needs further exploration. Metabonomics is a new subject; the combination of metabolomics and network pharmacology can find pathways for drugs to act on targets more efficiently. METHODS: Comprehensive metabolomics and network pharmacology to study the mechanism of Fu-Fang-Jin-Qian-Cao inhibiting autophagy in calcium oxalate-induced renal injury. Based on UHPLC-Q-TOF-MS, combined with biochemical analysis, a mice model of Calcium oxalateinduced renal injury was established to study the therapeutic effect of Fu-Fang-Jin-Qian-Cao. Based on the network pharmacology, the target signaling pathway and the protective effect of Fu- Fang-Jin-Qian-Cao on Calcium oxalate-induced renal injury by inhibiting autophagy were explored. Autophagy-related proteins LC3-II, BECN1, ATG5, and ATG7 were studied by immunohistochemistry. RESULTS: Combining network pharmacology and metabolomics, 50 differential metabolites and 2482 targets related to these metabolites were found. Subsequently, the targets enriched in PI3KAkt, MAPK and Ras signaling pathways. LC3-II, BECN1, ATG5 and ATG7 were up-regulated in Calcium oxalate-induced renal injury. All of them could be reversed after the Fu-Fang-Jin-Qian- Cao treatment. CONCLUSIONS: Fu-Fang-Jin-Qian-Cao can reverse ROS-induced activation of the MAPK signaling pathway and inhibition of the PI3K-Akt signaling pathway, thereby reducing autophagy damage of renal tubular epithelial cells in Calcium oxalate-induced renal injury.

Migration of CXCR4 gene-modified bone marrow-derived mesenchymal stem cells to the acute injured kidney.

Bone marrow-derived mesenchymal stem cells (BMSCs) can migrate to the injured kidney after acute kidney injury (AKI) with limited efficiency. This study investigated the effect of CXCR4 overexpression on BMSC migration to the AKI kidney and the possible mechanisms. CXCR4 gene-modified BMSCs (CXCR4-BMSCs) and null-BMSCs were prepared and transplanted into the AKI mice. Blood indicators, histology, expression of stromal cell-derived factor 1 (SDF-1), and BMSC migration were investigated. Hypoxia/re-oxygenation-pretreated renal tubular epithelial cells (HR-RTECs) were prepared to generate AKI in vitro. The chemotaxis experiment was performed using the transwell chamber. The phosphorylation of AKT and MAPK in the BMSCs was also investigated. The CXCR4-BMSCs showed a remarkable expression of CXCR4. The SDF-1 expression in the AKI renal tissue was increased. CXCR4-BMSCs transplantation sharply increased the accumulation of BMSCs in the renal tissue, which was consistent with a greater improvement of renal function. The in vitro experiments showed that the migration of BMSCs to the HR-RTEC culturing chamber was CXCR4-dependent, and could be fully inhibited by AMD3100, a CXCR4-specific antagonist. The migration could also be partly blocked by either LY294002 (PI3K inhibitor) or PD98059 (MAPK inhibitor). Phosphorylated Akt and MAPK were increased in the BMSCs co-cultured with HR-RTECs and their expression was the highest in the CXCR4-BMSCs, which could be recovered by AMD3100. Overexpression of CXCR4 gene could enhance BMSC migration to the kidney area after AKI. The SDF-1/CXCR4 axis via its activation of PI3K/AKT and MAPK in BMSCs could be the possible mechanisms underlying this function.

CXCR4-overexpressing bone marrow-derived mesenchymal stem cells improve repair of acute kidney injury.

Transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) can repair acute kidney injury (AKI), but with limited effect. We test the hypothesis that CXCR4 overexpression improves the repair ability of BMSCs and that this is related to increased homing of BMSCs and increased release of cytokines. Hypoxia/reoxygenation-pretreated renal tubular epithelial cells (HR-RTECs) were used. BMSCs, null-BMSCs, and CXCR4-BMSCs were cocultured with HR-RTECs. The number of migrating BMSCs was counted. Proliferating cell nuclear antigen (PCNA) expression, cell death, and expressions of cleaved caspase-3 and Bcl-2 in cocultured HR-RTECs were measured. Cytokeratin 18 (CK18) expression and cytokine secretions of the BMSCs cultured with HR-RTEC supernatant were detected. BMSC homing, renal function, proliferation, and cell death of tubular cells were assayed in the AKI mouse model. CXCR4-BMSCs showed a remarkable expression of CXCR4. Stromal cell-derived factor-1 in the HR-RTEC supernatant was increased. Migration of BMSCs was CXCR4-dependent. Proportions of CK18(+) cells in BMSCs, null-BMSCs, and CXCR4-BMSCs showed no difference. However, CXCR4 overexpression in BMSCs stimulated secretion of bone morphogenetic protein-7, hepatocyte growth factor, and interleukin 10. The neutralizing anti-CXCR4 antibody AMD3100 abolished this. In cocultured HR-RTECs the proportions of PCNA(+) cells and Bcl-2 expression were enhanced; however, the proportion of annexin V(+) cells and expression of cleaved caspase-3 were reduced. The in vivo study showed increased homing of CXCR4-BMSCs in kidneys, which was associated with improved renal function, reduced acute tubular necrosis scoring, accelerated mitogenic response of tubular cells, and reduced tubular cell death. The enhanced homing and paracrine actions of BMSCs with CXCR4 overexpression suggest beneficial effects of such cells in BMSC-based therapy for AKI.

Bone Marrow-Derived Mesenchymal Stem Cells Transplantation Attenuates Renal Fibrosis Following Acute Kidney Injury in Rats by Diminishing Pericyte-Myofibroblast Transition and Extracellular Matrix Augment.

BACKGROUND: Renal fibrosis is a common chronic outcome of acute kidney injury (AKI). Pericyte-myofibroblasts transition and production of abundant extracellular matrix are the important pathologic basis. This study investigated the effect of bone marrow-derived mesenchymal stem cells (BMSCs) transplantation on the AKI kidney fibrosis and the possible mechanisms. METHODS: By constructing the animal and cell model of AKI pericyte injury, the therapeutic effect of BMSCs on pericyte-myofibroblasts transition was detected. The production and accumulation of extracellular matrix, including collagen I, collagen III, and fibronectin were also tested. The mechanism was revealed by means of analysis of signal pathway. RESULTS: After AKI insult, many myofibroblasts emerged in the renal interstitium together with a large amount of extracellular matrix components. The BMSCs transplantation significantly decreased the number of myofibroblasts trans-differentiated from pericytes in the AKI model. The changes of vascular endothelial growth factor subtypes and Ang-I/AngII secreted by pericytes were also significantly reduced after BMSCs co-culture. At the same time, extracellular matrix components, including collagen I, collagen III, and fibronectin, decreased significantly. Transplantation treatment alleviated the fibrosis score. The transforming growth factor ß (TGF-ß) concentration decreased as well as the levels of Smad2/3 and p-Smad2/3 with the presence of BMSCs therapy. CONCLUSIONS: Bone marrow-derived mesenchymal stem cells transplantation diminished pericyte-myofibroblast transition and extracellular matrix augment after AKI by regulating the TGF-ß/Smad2/3 signaling pathway. It may be used as a novel therapeutic method for retarding renal fibrosis, which is worthy of further study.

[Effects of erythropoietin on mesenchymal stem cells' function of differentiation and secretion cultured under acute kidney injury microenvironment].

OBJECTIVE: To explore the effects of erythropoietin (EPO) on the differentiation and secretion of cultured bone marrow-derived mesenchymal stem cells (BM-MSC) in the microenvironment of acute kidney injury (AKI). METHODS: C57BL/6 murine BM-MSC (mBM-MSC) were successfully isolated by the methods of Percoll density gradient centrifugation and adherence cultivation. The AKI murine model was induced by ischemia/reperfusion (I/R). The homogenate supernatants were prepared for normal and I/R murine kidney. P3-mBM-MSC were treated differently: Group A: low glucose DMEM medium with 10% fetal bovine serum, Group B: normal murine kidney homogenate supernatant intervention, Group C: I/R kidney homogenate supernatant intervention, Group D: I/R kidney homogenate supernatant plus different concentrations of EPO (1, 5, 10, 50 U/ml). Each group was incubated for 1, 3, 5 and 7 days. Inverted microscope was used to observe the morphological changes of these cells and their ultrastructural changes were observed by transmission electron microscope. Cytokeratin-18 was detected by flow cytometry. The levels of bone morphogenetic protein-7 (BMP-7), hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) were detected by ELISA in culture medium. RESULTS: The cells yielded a high expression of CD29 and CD44 and a low expression of CD34 and CD45. Compared with Groups A and B, the cells of Group C presented oval and short fusiform shapes. After the intervention of EPO, Group D showed a cobble appearance. More organelles were also found. A trace expression of CK18 was found in Groups A and B. A positive expression of CK18 was significantly higher in Groups C and D than Groups A and B (P < 0.01). The expression of EPO 50 U/ml at Day 5 and 7 was higher than Group C of the same time (5 d: 35.22 ± 4.04 vs 8.72 ± 0.38, 7 d: 42.00 ± 5.39 vs 13.20 ± 1.14, both P < 0.01). The results of ELISA showed that the levels of BMP-7, HGF and VEGF in Group C decreased significantly (P < 0.01 or P < 0.05). CONCLUSION: The intervention of EPO may boost the differentiation of mBM-MSC but reverse its low secretion.

Inflammatory cytokine depletion in severe coronavirus disease 2019 infectious pneumonia: A case report.

RATIONALE: Multiorgan/system injury was observed in severely infected coronavirus disease 2019 (COVID-19) patients, in addition to viral pneumonia. Recognizing and correcting the key and immediate dysfunctions may reduce mortality. PATIENT CONCERNS: A 66-year-old previously healthy male patient was referred to the isolation ward in Guanggu Branch of Hubei Province Maternity and Childcare Hospital with a high fever and nonproductive cough for twenty days. DIAGNOSES: Diagnosis of severe COVID-19 infectious pneumonia was established by travel history, clinical features, chest imaging, and a positive oropharyngeal swab specimen result for the severe acute respiratory syndrome coronavirus 2 RT-PCR assay. INTERVENTIONS: In addition to standard supportive care, combined inflammatory cytokine depletion therapy (double filtration plasma pheresis and tocilizumab) and convalescent plasma were administered. OUTCOMES: The patient's homeostatic parameters (blood pressure, heart rate, spontaneous respiration, SPO2, and blood gas) recovered, along with the recovery on chest imaging. All the intravenous catheters were removed. Supportive care continued for several days, and the patient was transferred to a non-ICU isolation ward. LESSONS: It is not safe to draw causal conclusions between cytokine depletion and clinical manifestation improvement with only 1 case, but this is a potential research direction in facing the COVID-19 crisis.

Clinical course and risk factors for recurrence of positive SARS-CoV-2 RNA: a retrospective cohort study from Wuhan, China.

The coronavirus disease 2019 (COVID-19) pandemic is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The objective of this study was to determine the clinical course and risk factors for patients showing recurrent SARS-CoV-2 RNA positivity. A total of 1087 COVID-19 patients confirmed by RT-PCR from February 24, 2020 to March 31, 2020 were retrospectively enrolled. Advanced age was significantly associated with mortality. In addition, 81 (7.6%) of the discharged patients tested positive for SARS-CoV-2 RNA during the isolation period. For patients with recurrent RT-PCR positivity, the median duration from illness onset to recurrence was 50 days. Multivariate regression analysis identified elevated serum IL-6, increased lymphocyte counts and CT imaging features of lung consolidation during hospitalization as the independent risk factors of recurrence. We hypothesized that the balance between immune response and virus toxicity may be the underlying mechanism of this phenomenon. For patients with a high risk of recurrence, a prolonged observation and additional preventative measures should be implemented for at least 50 days after illness onset to prevent future outbreaks.

Enhanced proliferation and differentiation of HO-1 gene-modified bone marrow-derived mesenchymal stem cells in the acute injured kidney.

The aim of the present study was to investigate the effect of heme oxygenase-1 (HO-1) overexpression on the survival and differentiation ability of bone marrow­derived mesenchymal stem cells (BMSCs) in the acute kidney injury (AKI) microenvironment. HO-1-BMSCs and enhanced green fluorescent protein (eGFP)-BMSCs were constructed. Rat ischemia/reperfusion (I/R)­AKI-kidney homogenate supernatant was prep-ared to treat the BMSCs, eGFP-BMSCs and HO-1-BMSCs in vitro. In the AKI microenvironment, the HO-1-BMSCs exhibited a smaller proportion of cells at the G0/G1 phase, and a larger proportion of cells expressing proliferating cell nuclear antigen (PCNA) and cytokeratin 18 (CK18). Phosphorylated protein kinase B (Akt) and extracellular signal­regulated kinase (ERK) protein levels were observed to be increased in the HO-1-BMSCs compared with the BMSCs. LY294002 and PD98059 each inhibited the above effects. BMSCs, eGFP-BMSCs and HO-1-BMSCs were implanted into an I/R-AKI rat model. The proportions of PCNA+ BMSCs and CK18+ BMSCs were higher in the HO-1-BMSCs group compared with the BMSCs group, which resulted in a decreased acute tubular necrosis score and improved renal function for the AKI rats. In conclusion, the enhanced proliferation and differentiation of HO-1-BMSCs suggest the beneficial effects of such cells in the BMSC-based therapy of AKI. The mechanism underlying these effects may involve the stimulation of Akt and ERK signaling.

Transcuprein is a macroglobulin regulated by copper and iron availability.

Transcuprein is a high-affinity copper carrier in the plasma that is involved in the initial distribution of copper entering the blood from the digestive tract. To identify and obtain cDNA for this protein, it was purified from rat plasma by size exclusion and copper-chelate affinity chromatography, and amino acid sequences were obtained. These revealed a 190-kDa glycosylated protein identified as the macroglobulin alpha(1)-inhibitor III, the main macroglobulin of rodent blood plasma. Albumin (65 kDa) copurified in variable amounts and was concluded to be a contaminant (although it can transiently bind the macroglobulin). The main macroglobulin in human blood plasma (alpha(2)-macroglobulin), which is homologous to alpha(1)-inhibitor III, also bound copper tightly. Expression of alpha(1)I3 (transcuprein) mRNA by the liver was examined in rats with and without copper deficiency, using quantitative polymerase chain reaction methodology and Northern blot analysis. Protein expression was examined by Western blotting. Deficient rats with 40% less ceruloplasmin oxidase activity and liver copper concentrations expressed about twice as much alpha(1)I3 mRNA, but circulating levels of transcuprein did not differ. Iron deficiency, which increased liver copper concentrations by threefold, reduced transcuprein mRNA expression and circulating levels of transcuprein relative to what occurred in rats with normal or excess iron. We conclude that transcupreins are specific macroglobulins that not only carry zinc but also carry transport copper in the blood, and that their expression can be modulated by copper and iron availability.

Alleviation of apoptosis of bone marrow-derived mesenchymal stem cells in the acute injured kidney by heme oxygenase-1 gene modification.

Bone marrow-derived mesenchymal stem cells (BMSCs) transplantation is beneficial for the treatment of acute kidney injury (AKI), but the poor survival of BMSCs limits the repair effect. The oxidative stress in the AKI microenvironment is regarded as the main reason. Considering the potent anti-oxidant ability of heme oxygenase-1 (HO-1), HO-1 overexpression in BMSCs can be expected to improve the survival of BMSCs and correspondingly enhance the AKI repair effect. Here, BMSCs are transfected with pLV-HO-1/eGFP and pLV-eGFP by the lentivirus vector to get HO-1-BMSCs and eGFP-BMSCs, respectively. Ischemia/reperfusion-AKI kidney homogenate supernatant (KHS) is prepared for treating BMSCs, eGFP-BMSCs and HO-1-BMSCs. AKI-KHS results in a high inhibitory rate of BMSCs growth and a high proportion of TUNEL positive BMSCs, while HO-1 overexpression inverses this phenomenon and re-establishes the antioxidant and oxidant balance in HO-1-BMSCs. Phosphorylations of p53 and p38 mitogen-activated protein kinases (p38 MAPK) in HO-1-BMSCs decrease. Lower levels of monocyte chemotactic protein 1, tumor necrosis factor-α and interleukin 1ß are also observed in supernatant of HO-1-BMSCs. The in vivo study shows that HO-1 overexpression sharply decreases the apoptosis of BMSCs in the injured kidney, and correspondingly the renal function of the AKI rats improves significantly. In conclusion, BMSCs with HO-1 overexpression suggests a better survival in the I/R-AKI microenvironment and a better kidney repair effect. The anti-oxidant effect via the inactivations of the downstream p53 and p38MAPK in BMSCs and the anti-inflammation could be the mechanisms. It provides a novel approach for the cell-based AKI-therapy.

Role of adult resident renal progenitor cells in tubular repair after acute kidney injury.

Acute kidney injury is a serious global health problem and determinant of morbidity and mortality. Recent advancements in the field of stem cell research raise hopes for stem cell-based regenerative approaches to treat acute kidney diseases. In this review, the authors summarized the latest research advances of the adult resident renal progenitor cells (ARPCs) on kidney repair, the role of ARPCs on tubular regeneration after acute kidney injury, the current understanding of the mechanisms related to ARPC activation and modulation, as well as the challenges that remain to be faced.

Erythropoietin promotes the repair effect of acute kidney injury by bone-marrow mesenchymal stem cells transplantation.

Bone-marrow mesenchymal stem cells (BMSCs) transplantation is effective for acute kidney injury (AKI) repair but with limited efficiency. In the present study, BMSCs marked by bromodeoxyuridine (BrdU) were transplanted to the AKI mouse model with erythropoietin (EPO) being subcutaneously injected. The blood urea nitrogen (BUN) and serum creatinine (Scr) levels, pathological changes, distribution of BMSCs, expressions of the cytokeratin 18 (CK18) and the stromal cell-derived factor 1 (SDF-1) in the nephridial tissues were measured. The directional migration of BMSCs to the AKI microenvironment in vitro was also tested. The results showed that BMSCs transplantation or EPO injection alone decreased the BUN and Scr levels and the acute tubular necrosis (ATN) scoring in varied degrees. The combination of these decreased the above indicators' levels significantly. BrdU(+) cells (BMSCs) were observed in the AKI nephridial tissues, and CK18 expressed in the cytoplasm of these cells. EPO injection increased the proportion of BrdU(+) cells with the enhanced expression of SDF-1 in the AKI nephridial tissues. EPO increased the migrating number of BMSCs to the AKI microenvironment in vitro, and additional anti-SDF-1 treatment with SDF-1 antibody neutralized this effect. Our results showed that EPO increased the number of the transplanted BMSCs in the injured nephridial tissues and enhanced the AKI repair effect of BMSCs transplantation. The enhanced kidney-homing efficiency for BMSCs mediated by the SDF-1/CXCR4 pathway is one of the possible mechanisms for EPO performance.

Effect and mechanism of erythropoietin on mesenchymal stem cell proliferation in vitro under the acute kidney injury microenvironment.

Erythropoietin (EPO) can stimulate the proliferation and protraction of endothelial progenitor cells, and plays an important role in the proliferation and differentiation of marrow-derived mesenchymal stem cells (mMSCs) under the acute kidney injury (AKI) microenvironment. In the present study, C57BL/6 mice mMSCs were isolated, and AKI mice models were prepared. The renal cortex was obtained to prepare the ischemia/reperfusion (I/R) kidney homogenate supernatant. P3-mMSCs were treated by different methods: one group was added only I/R kidney homogenate supernatant, and another contained different concentrations of EPO (1, 5, 10, 50 IU/mL) in I/R kidney homogenate supernatant. The proliferation and apoptosis of mMSCs were detected by CCK-8 and TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling), respectively. Expression of erythropoietin receptor (EPOR) and protein of the signal pathway related to proliferation/apoptosis were also examined. The results showed that the proliferation ability of mMSCs treated with I/R kidney homogenate supernatant decreased significantly, while the apoptosis percentage was significantly higher than that of the control. After intervention of EPO, their proliferation enhanced and the apoptosis percentage decreased. EPOR expression was positive in P3-mMSCs. EPO decreased the expression of caspase-3 of mMSCs under the AKI microenvironment in a dose- and time-dependent manner, but increased the Bcl-2 expression. The expression of phosphor-Janus kinase 2, phosphor-signal transducer and activator of transcription (pSTAT-5) increased significantly in 10 IU/mL EPO cultured for five days. Our results show that EPO can promote proliferation of mMSCs in vitro under the AKI microenvironment, which is mediated by EPOR and related with the proliferation/apoptosis signal pathway.