Hepatocyte growth factor modification promotes the amelioration effects of human umbilical cord mesenchymal stem cells on rat acute kidney injury

Human umbilical cord mesenchymal stem cells promote steroid-induced osteonecrosis of the femoral head repair by improving microvascular endothelial cell function

Recently, there has been growing interest in using cell therapy through core decompression (CD) to treat osteonecrosis of the femoral head (ONFH). Our study aimed to investigate the effectiveness and mechanism of human umbilical cord mesenchymal stem cells (hUCMSCs) in treating steroid-induced ONFH. We constructed a steroid-induced ONFH rabbit model as well as dexamethasone (Dex)-treated bone microvascular endothelial cells (BMECs) model of human femoral head. We injected hUCMSCs into the rabbit femoral head via CD. The effects of hUCMSCs on steroid-induced ONFH rabbit model and Dex-treated BMECs were evaluated via micro-CT, microangiography, histology, immunohistochemistry, wound healing, tube formation, and western blotting assay. Furthermore, we conducted single-cell RNA sequencing (scRNA-seq) to examine the characteristics of endothelial cells, the activation of signaling pathways, and inter-cellular communication in ONFH. Our data reveal that hUCMSCs improved the femoral head microstructure and bone repair and promoted angiogenesis in the steroid-induced ONFH rabbit model. Importantly, hUCMSCs improved the migration ability and angioplasty of Dex-treated BMECs by secreting COL6A2 to activate FAK/PI3K/AKT signaling pathway via integrin α1β1.

The Beneficial Effects of Mesenchymal Stem Cells in Acute Kidney Injury: A Narrative Review

BACKGROUND

Acute kidney injury (AKI) is a multifaced disease characterized by a rapid decline in renal function. However, with growing insight into the pathophysiologic mechanisms of AKI, currently available interventions for AKI are merely supportive. Thus, novel therapies are urgently needed to improve the outcomes of patients with AKI. This narrative review aims to explore enhancing the beneficial effects of Mesenchymal Stem Cells(MSCs) in AKI.

METHODS

The authors examined all studies regarding the role of MSCs in AKI. And the authors undertook a structured search of bibliographic databases for peer-reviewed research literature using a focused review question. The most relevant and up-to-date research was included.

RESULTS AND DISCUSSION

Based on encouraging preclinical results, stem cell therapy has been widely explored over the last decade. Among the various stem cell types investigated, mesenchymal stem cells are being intensely investigated by virtue of their numerous strengths, such as easy derivation, undemanding cell culture conditions, anti-apoptosis, immunomodulation, and anti-inflammation effects. Mounting evidence suggests that MSCs hold great potential in accelerating kidney repair following AKI in various preclinical models. Unfortunately, low engrafting efficiency and poor survival rate of injected MSCs in the injured renal tissue are major obstacles MSCs clinical application faces.

CONCLUSION

Various strategies, including genetic manipulation, mimicking the cellular microenvironment with different culture conditions, optimizing MSCs preparation and administration schedule, and screening patients who may more like benefit from MSCs therapy, have been developed to enhance the therapeutic potential of MSCs in AKI.

Optimization strategies of mesenchymal stem cell-based therapy for acute kidney injury

Considering the high prevalence and the lack of targeted pharmacological management of acute kidney injury (AKI), the search for new therapeutic approaches for it is in urgent demand. Mesenchymal stem cells (MSCs) have been increasingly recognized as a promising candidate for the treatment of AKI. However, clinical translation of MSCs-based therapies is hindered due to the poor retention and survival rates as well as the impaired paracrine ability of MSCs post-delivery. To address these issues, a series of strategies including local administration, three-dimensional culture, and preconditioning have been applied. Owing to the emergence and development of these novel biotechnologies, the effectiveness of MSCs in experimental AKI models is greatly improved. Here, we summarize the different approaches suggested to optimize the efficacy of MSCs therapy, aiming at promoting the therapeutic effects of MSCs on AKI patients.

Enhanced secretion of hepatocyte growth factor in human umbilical cord mesenchymal stem cells ameliorates pulmonary fibrosis induced by bleomycin in rats

Umbilical cord mesenchymal stem cells (UCMSCs) are a reportedly promising choice in the treatment of irreversible pulmonary fibrosis and lethal interstitial lung disease with limited drug treatment options. In this study, we investigated the therapeutic efficacy of UCMSCs overexpressing hepatocyte growth factor (HGF), which is considered one of the main anti-fibrotic factors secreted by MSCs. Adenovirus vector carrying the HGF gene was transfected into UCMSCs to produce HGF-modified UCMSCs (HGF-UCMSCs). Transfection promoted the proliferation of UCMSCs and did not change the morphology, and differentiation ability, or biomarkers. Rats were injected with HGF-UCMSCs on days 7 and 11 after intratracheal administration of bleomycin (10 mg/kg). We performed an analysis of histopathology and lung function to evaluate the anti-fibrotic effect. The results showed that HGF-UCMSCs decreased the Ashcroft scores in hematoxylin and eosin-stained sections, the percentage positive area in Masson trichrome-stained sections, and the hydroxyproline level in lungs. Forced expiratory volume in the first 300 m/forced vital capacity was also improved by HGF-UCMSCs. To explore the possible therapeutic mechanism of HGF-UCMSCs, we detected inflammatory factors in the lungs and performed mRNA sequencing in UCMSCs and HGF-UCMSCs. The data indicated that inhibition of interleukin-17 in the lung may be related to the anti-fibrosis of HGF-UCMSCs, and overexpressed HGF probably played a primary role in the treatment. Collectively, our study findings suggested that the overexpression of HGF may improve the anti-fibrotic effect of UCMSCs through directly or indirectly interacting with interleukin-17-producing cells in fibrotic lungs.

Long-Term Effects of Severe Burns on the Kidneys: Research Advances and Potential Therapeutic Approaches

Burns are a seriously underestimated form of trauma that not only damage the skin system but also cause various complications, such as acute kidney injury (AKI). Recent clinical studies have shown that the proportion of chronic kidney diseases (CKD) in burn patients after discharge is significantly higher than that in the general population, but the mechanism behind this is controversial. The traditional view is that CKD is associated with hypoperfusion, AKI, sepsis, and drugs administered in the early stages of burns. However, recent studies have shown that burns can cause long-term immune dysfunction, which is a high-risk factor for CKD. This suggests that burns affect the kidneys more than previously recognized. In other words, severe burns are not only an acute injury but also a chronic disease. Neglecting to study long-term kidney function in burn patients also results in a lack of preventive and therapeutic methods being developed. Furthermore, stem cells and their exosomes have shown excellent comprehensive therapeutic properties in the prevention and treatment of CKD, making them increasingly the focus of research attention. Their engineering strategy further improved the therapeutic performance. This review will focus on the research advances in burns on the development of CKD, illustrating the possible mechanism of burn-induced CKD and introducing potential biological treatment options and their engineering strategies.

Recent advances in the therapeutic efficacy of hepatocyte growth factor gene-modified mesenchymal stem cells in multiple disease settings

Mesenchymal stem cell (MSC) therapy is considered a new treatment for a wide range of diseases and injuries, but challenges remain, such as poor survival, homing and engraftment rates, thus limiting the therapeutic efficacy of the transplanted MSCs. Many strategies have been developed to enhance the therapeutic efficacy of MSCs, such as preconditioning, co-transplantation with graft materials and gene modification. Hepatocyte growth factor (HGF) is secreted by MSCs, which plays an important role in MSC therapy. It has been reported that the modification of the HGF gene is beneficial to the therapeutic efficacy of MSCs, including diseases of the heart, lung, liver, urinary system, bone and skin, lower limb ischaemia and immune-related diseases. This review focused on studies involving HGF/MSCs both in vitro and in vivo. The characteristics of HGF/MSCs were summarized, and the mechanisms of their improved therapeutic efficacy were analysed. Furthermore, some insights are provided for HGF/MSCs' clinical application based on our understanding of the HGF gene and MSC therapy.

Stem cell-based therapy for ameliorating intrauterine adhesion and endometrium injury

Intrauterine adhesion refers to endometrial repair disorders which are usually caused by uterine injury and may lead to a series of complications such as abnormal menstrual bleeding, recurrent abortion and secondary infertility. At present, therapeutic approaches to intrauterine adhesion are limited due to the lack of effective methods to promote regeneration following severe endometrial injury. Therefore, to develop new methods to prevent endometrial injury and intrauterine adhesion has become an urgent need. For severely damaged endometrium, the loss of stem cells in the endometrium may affect its regeneration. This article aimed to discuss the characteristics of various stem cells and their applications for uterine tissue regeneration.

The protective mechanism of Klotho gene-modified bone marrow mesenchymal stem cells on acute kidney injury induced by rhabdomyolysis

Background

Studies have shown that the Klotho gene has tremendous potential for future therapeutic purposes in both acute and chronic kidney diseases (CKD). This study aimed to investigate the possible protective mechanisms of the Klotho gene against acute kidney injury (AKI) induced by rhabdomyolysis (RM).

Methods

In this study, bone marrow mesenchymal stem cells (BMSCs) were transfected with recombinant adenoviruses expressing the Klotho gene (BMSCs-Klotho) and by those expressing empty vector (BMSCs-EV). After successful transfection, we tested the proliferation, secretion and migration abilities of the BMSCs-Klotho compared with those of the BMSCs-EV and BMSCs. Then, 30 male C57BL/6 mice were examined, with 6 mice randomly assigned to the control group (PBS injected into the tail vein, CON) or one of the four treatment groups treated with either BMSCs-Klotho (AKI+BMSCs-Klotho), BMSCs-EV (AKI+BMSCs-EV), BMSCs (AKI+BMSCs) or PBS (AKI+PBS) after induction of RM. Seventy-two h after treatment, serum creatinine (SCr) and blood urea nitrogen (BUN) levels were obtained to assess renal function, and renal tissue was obtained to measure kidney tissue damage. Additionally, kidney protective mechanism-related indexes, such as EPO, IGF-1, KIM-1 and HIF-1, were analysed using Western blot analysis and immunohistochemistry.

Results

The results obtained showed that the proliferation, secretory and migration abilities of the BMSCs were significantly increased after transfection with the Klotho gene. Treatment with BMSCs-Klotho, BMSCs-EV or BMSCs improved renal function compared to treatment with PBS. However, the improvement observed in renal function in the BMSCs-Klotho group was better than that of the other groups. Histological analysis demonstrated that tissue damage was significantly decreased in the mice in the AKI+BMSCs-Klotho, AKI+BMSCs-EV or AKI+BMSCs groups compared to that in the mice in the AKI+PBS group. However, the best recovery was observed in the mice treated with BMSCs-Klotho concomitantly. Furthermore, the expression of protective factors erythropoietin (EPO) and insulin-like growth factor 1 (IGF-1) increased obviously, and the injury biomarkers kidney injury molecule 1 (KIM-1) and hypoxia inducible factor 1 (HIF-1) decreased notably in the group of BMSCs-Klotho, BMSCs-EV and BMSCs. Additionally, the levels of the aforementioned protein indicators in the AKI+BMSCs-Klotho group were not different from those in the CON group.

Conclusion

Klotho overexpression exerted positive effects on BMSCs and markedly promoted recovery from RM-induced AKI. These findings suggest that the overexpression of the Klotho gene might be a good candidate for further therapy for AKI in clinical trials.

Activation of aryl hydrocarbon receptor (AhR) in mesenchymal stem cells modulates macrophage polarization in asthma

Macrophage polarization has been demonstrated to exert a vital role on asthma pathogenesis. Mesenchymal stem cells (MSC) have the capacity to modulate macrophage differentiation from a pro-inflammatory M1 phenotype toward an anti-inflammatory M2 phenotype. However, the impact of MSC-macrophage interactions on asthma development and underlying mechanisms responsible for this interaction remain largely unknown. The aim of this study was to investigate the role of AhR expressed on MSC in macrophage polarization in a cockroach extract (CRE)-induced asthma mouse model. The studies here revealed that MSC polarized macrophages from a pro-inflammatory M1 phenotype toward an anti-inflammatory M2 phenotype in this model. The mRNA levels of interleukin (IL)-6, IL-1β, and NOS2 as M1 markers were significantly decreased while those of select M2 markers such as Arg-1, FIZZ1, and YM-1 were significantly enhanced. It was also observed that aryl hydrocarbon receptor (AhR) signaling was significantly increased during asthma pathogenesis as demonstrated by enhanced mRNA expression of AhR, CYP1a1, and CYP1b1. It was also seen that the elevated AhR signaling was able to attenuate the onset of asthma. Use of an AhR antagonist (CH223191) resulted in significant inhibition of the AhR signaling and increases in M2 marker expression, but led to elevation of expression of M1 markers in the CRE-induced asthma model. Taken together, the current study showed that MSC can modulate macrophage polarization, in part, via activation of AhR signaling during CRE-induced asthma.

Stem Cell-Based Therapy for Asherman Syndrome: Promises and Challenges

Asherman syndrome (AS) has an adverse effect on reproductive health and fertility by affecting endometrial regeneration. Stem cell-based therapies hold promise for future use in activating non-functional endometrium and reconstructing the endometrium in vivo. It has been postulated that various endometrial stem cells (EnSCs) are responsible for endometrial regeneration. Numerous studies have focused on bone marrow-derived stem cells (BMDSCs), which may provide new ideas for repairing endometrial lesions and reconstructing the endometrium. Other sources of stem cells, such as menstrual blood, umbilical cord, and amniotic membrane, have also attracted much attention as candidates for transplantation in AS. This review discusses the features and specific biomarkers among four types of resident endometrial stem cells, applications of four different sources of exogenous stem cells in AS, and development of stem cell therapy using biomaterials and exosomes.

Mesenchymal Stem Cells as Therapeutic Agents and Novel Carriers for the Delivery of Candidate Genes in Acute Kidney Injury

Acute kidney injury (AKI) is a heterogeneous syndrome characterized by a dramatic increase in serum creatinine. Mild AKI may merely be confined to kidney damage and resolve within days; however, severe AKI commonly involves extrarenal organ dysfunction and is associated with high mortality. There is no specific pharmaceutical treatment currently available that can reverse the course of this disease. Notably, mesenchymal stem cells (MSCs) show great promise for the management of AKI by targeting multiple pathophysiological pathways to facilitate tubular epithelial cell repair. It has been well established that the unique characteristics of MSCs make them ideal vectors for gene therapy. Thus, genetic modification has been attempted to achieve improved therapeutic outcomes in the management of AKI by overexpressing trophic cytokines or facilitating MSC delivery to renal tissues. The present article provides a comprehensive review of genetic modification strategies targeted at optimizing the therapeutic potential of MSCs in AKI.

Role and effect of vein-transplanted human umbilical cord mesenchymal stem cells in the repair of diabetic foot ulcers in rats

Diabetic foot ulcer (DFU) is one of diabetic complications, which is frequently present and tormented in diabetes mellitus. Most multipotent mesenchymal stromal cells (MSCs) are capable of immune evasion, providing an allogeneic, ready-to-use, cell product option for therapeutic applications. The beneficial effect of MSCs for the treatment of a variety of traumatic injuries, such as open wounds, has been extensively explored. In this study, a rat DFU model was used to simulate the pathophysiology of clinical patients and to investigate the localization of human umbilical cord mesenchymal stem cells (hUC-MSCs) after intravenous transplantation and its role in DFU healing, so as to evaluate the potential of hUC-MSCs in the treatment of DFU. The diabetic rat model was established by streptozotocin injection, which was used to create full-thickness foot dorsal skin wounds to mimic DFU by a 6-mm skin biopsy punch and a Westcott scissor. The hUC-MSCs were transplanted through femoral vein, and the ulcer cicatrization situation and the fate of hUC-MSCs were evaluated. Our data suggest that intravenously transplantated hUC-MSCs have the ability to migrate and locate to the wound tissue and are helpful to wound healing in DFU rats, partly by regulating inflammation, trans-differentiation and providing growth factors that promote angiogenesis, cell proliferation and collagen deposition. Herein, we demonstrate that hUC-MSC transplantation is able to accelerate DFU healing in rats and transplantation of exogenous stem cells may be a potential strategy for clinical application in DFUs.

Mesenchymal stem cells modified with angiotensin-converting enzyme 2 are superior for amelioration of glomerular fibrosis in diabetic nephropathy

AIMS

This study aimed to detect the effect of angiotensin-converting enzyme (ACE) 2-modified mesenchymal stem cells (MSCs) on glomerular fibrosis in vitro and in vivo and investigate the underlying molecular mechanism.

METHODS

MSCs transduced with the ACE2 gene (MSCs-ACE2) were cocultured with glomerular mesangial cells (GMCs) following Ang II stimulation. MSCs-ACE2 were transplanted into streptozotocin-induced diabetic rats. Physical, biochemical and morphological parameters were measured, and fibrotic indicators and renin-angiotensin system (RAS) components in GMCs and kidney tissues were assessed.

RESULTS

The transduction efficiency of MSCs was as high as 85%. The modified MSCs secreted soluble ACE2 protein into the culture medium. After transplantation into rats with diabetes, MSCs-ACE2 targeted injured kidneys and enhanced local expression of ACE2. Compared with MSC treatment alone, MSC-ACE2 treatment was superior in reducing albuminuria and improving glomerulosclerosis. In vitro and in vivo, MSCs-ACE2 were more beneficial than MSCs alone in decreasing Ang II and increasing Ang1-7, thereby inhibiting the detrimental effects of Ang II accumulation by downregulating collagen I and fibronectin (FN) expression and inhibiting the transforming growth factor (TGF-β)/Smad pathway.

CONCLUSIONS

MSCs modified with ACE2 therapy have additional benefits to the progression of diabetic nephropathy (DN) by inhibiting renal RAS activation and reducing glomerular fibrosis.

Growth Factor Gene-Modified Mesenchymal Stem Cells in Tissue Regeneration

There have been marked changes in the field of stem cell therapeutics in recent years, with many clinical trials having been conducted to date in an effort to treat myriad diseases. Mesenchymal stem cells (MSCs) are the cell type most frequently utilized in stem cell therapeutic and tissue regenerative strategies, and have been used with excellent safety to date. Unfortunately, these MSCs have limited ability to engraft and survive, reducing their clinical utility. MSCs are able to secrete growth factors that can support the regeneration of tissues, and engineering MSCs to express such growth factors can improve their survival, proliferation, differentiation, and tissue reconstructing abilities. As such, it is likely that such genetically modified MSCs may represent the next stage of regenerative therapy. Indeed, increasing volumes of preclinical research suggests that such modified MSCs expressing growth factors can effectively treat many forms of tissue damage. In the present review, we survey recent approaches to producing and utilizing growth factor gene-modified MSCs in the context of tissue repair and discuss its prospects for clinical application.

Potential targeted therapy and diagnosis based on novel insight into growth factors, receptors, and downstream effectors in acute kidney injury and acute kidney injury-chronic kidney disease progression

Acute kidney injury (AKI) is defined as a rapid decline in renal function and is characterized by excessive renal inflammation and programmed death of resident cells. AKI shows high morbidity and mortality, and severe or repeated AKI can transition to chronic kidney disease (CKD) or even end-stage renal disease (ESRD); however, very few effective and specific therapies are available, except for supportive treatment. Growth factors, such as epidermal growth factor (EGF), insulin-like growth factor (IGF), and transforming growth factor-β (TGF-β), are significantly altered in AKI models and have been suggested to play critical roles in the repair process of AKI because of their roles in cell regeneration and renal repair. In recent years, a series of studies have shown evidence that growth factors, receptors, and downstream effectors may be highly involved in the mechanism of AKI and may function in the early stage of AKI in response to stimuli by regulating inflammation and programmed cell death. Moreover, certain growth factors or correlated proteins act as biomarkers for AKI due to their sensitivity and specificity. Furthermore, growth factors originating from mesenchymal stem cells (MSCs) via paracrine signaling or extracellular vesicles recruit leukocytes or repair intrinsic cells and may participate in AKI repair or the AKI-CKD transition. In addition, growth factor-modified MSCs show superior therapeutic potential compared to that of unmodified controls. In this review, we summarized the current therapeutic and diagnostic strategies targeting growth factors to treat AKI in clinical trials. We also evaluated the possibilities of other growth factor-correlated molecules as therapeutic targets in the treatment of AKI and the AKI-CKD transition.

Umbilical Cord-Derived Mesenchymal Stem Cells Ameliorate Nephrocyte Injury and Proteinuria in a Diabetic Nephropathy Rat Model

Mesenchymal stem cells (MSCs) are shown to alleviate renal injury of diabetic nephropathy (DN) in rats. However, the underlying mechanism of this beneficial effect is not fully understood. The aims of this study are to evaluate effects of umbilical cord-derived mesenchymal stem cells (UC-MSCs) on renal cell apoptosis in streptozotocin- (STZ-) induced diabetic rats and explore the underlying mechanisms. Characteristics of UC-MSCs were identified by flow cytometry and differentiation capability. Six weeks after DN induction by STZ injection in Sprague-Dawley rats, the DN rats received UC-MSCs once a week for consecutive two weeks. DN-related physical and biochemical parameters were measured at 2 weeks after UC-MSC infusion. Renal histological changes were also assessed. Moreover, the apoptosis of renal cells and expression of apoptosis-related proteins were evaluated. Compared with DN rats, rats treated with UC-MSCs showed suppressed increase in 24-hour urinary total protein, urinary albumin to creatinine ratio, serum creatinine, and blood urea nitrogen. UC-MSC treatment ameliorated pathological abnormalities in the kidney of DN rats as evidenced by H&E, PAS, and Masson Trichrome staining. Furthermore, UC-MSC treatment reduced apoptosis of renal cells in DN rats. UC-MSCs promoted expression of antiapoptosis protein Bcl-xl and suppressed expression of high mobility group protein B1 (HMGB1) in the kidney of DN rats. Most importantly, UC-MSCs suppressed upregulation of thioredoxin-interacting protein (TXNIP), downregulation of thioredoxin 1 (TRX1), and activation of apoptosis signal-regulating kinase 1 (ASK1) and P38 MAPK in the kidney of DN rats. Our results suggest that UC-MSCs could alleviate nephrocyte injury and albuminuria of DN rats through their antiapoptotic property. The protective effects of UC-MSCs may be mediated by inhibiting TXNIP upregulation in part.

Effect of Human Amniotic Fluid Stem Cells on Kidney Function in a Model of Chronic Kidney Disease

Kidney disease is a major medical problem globally. Chronic kidney disease (CKD) is a progressive loss of kidney function. It causes accumulation of waste and fluid in the body, eventually resulting in kidney failure as well as damaging other organs. Although dialysis and kidney transplantation have been used as primary treatments for renal disease, dialysis does not restore full renal function, and there is a shortage of donor kidneys for transplantation. Recent advances in cell-based therapies have offered a means to augment and restore renal function. Various types of cells have been tested to evaluate their therapeutic effects on injured kidneys. Among various types of cells, amniotic fluid stem cells (AFSCs) share advantages of both embryonic and adult stem cells, such as pluripotent activity, remarkable plasticity, and immunomodulatory effects, which may allow their future therapeutic use as an "off-the-shelf" cell source. AFSC presents advantages of both conventional pluripotent and adult stem cells, such as pluripotent activity, remarkable plasticity, and immunomodulatory effects. This study demonstrates that administration of human-derived AFSC facilitates functional and structural improvement in a rat model of CKD, and suggests that cell therapy with AFSC has potential as a therapeutic strategy to recover renal function in patients with CKD. Impact Statement Patients with chronic kidney disease (CKD) have limited treatment options, and renal transplantation is the only definitive treatment method that restores kidney function. However, challenges associated with transplantation, including donor organ shortage, rejection, and life-long immunosuppression, remain a problem. Recently, stem cell-based therapies have been proposed as an alternative approach to augment and restore renal function. In this study, we used human-derived amniotic fluid stem cells (AFSCs) to treat CKD in a rat model and demonstrated that AFSC treatment facilitated positive effects in terms of improvements of renal function.

Protective effect of bone marrow mesenchymal stem cells modified with klotho on renal ischemia-reperfusion injury

Objective: To detect the combination protective effect of bone marrow mesenchymal stem cells (BMSCs) and Klotho gene on the renal ischemia-reperfusion injury (RIRI).

Methods: BMSCs isolated from rats were transfected with Klotho gene to form BMSC^Kl. We injected BMSC^Kl to allogenic rat RIRI model. After 24 h and 72 h, we detected the serum creatinine (SCr), malondialdehyde (MDA), and superoxide dismutase (SOD) in renal tissue, Hematoxylin-eosin (HE) staining, and TUNEL of renal pathology. The expression of FoxO1 and p-FoxO1 in post-hypoxia tubular epithelial cells of normal rat kidney (NRK-52E) were detected by Western blot after cocultured with BMSC^Kl.

Results: Comparing with BMSC^Con group, Rats in BMSC^Kl group had lower SCr and MDA but higher SOD. Both HE and TUNEL score of renal tissue in BMSC^Kl group were lower than that of BMSC^Con group. Western blot indicated that FoxO1 was upregulated, while p-FoxO1 was downregulated in post-hypoxia NRK-52E cells.

Conclusions: BMSCs transfected with Klotho gene can further ameliorate RIRI. The possible mechanism may be attributed to the upregulation of SOD in NRK-52E caused by Klotho-FoxO1 axis.

Are cell-based therapies for kidney disease safe? A systematic review of preclinical evidence

The number of individuals affected by acute kidney injury (AKI) and chronic kidney disease (CKD) is constantly rising. In light of the limited availability of treatment options and their relative inefficacy, cell based therapeutic modalities have been studied. However, not many efforts are put into safety evaluation of such applications. The aim of this study was to review the existing published literature on adverse events reported in studies with genetically modified cells for treatment of kidney disease. A systematic review was conducted by searching PubMed and EMBASE for relevant articles published until June 2018. The search results were screened and relevant articles selected using pre-defined criteria, by two researchers independently. After initial screening of 6894 abstracts, a total number of 97 preclinical studies was finally included for full assessment. Of these, 61 (63%) presented an inappropriate study design for the evaluation of safety parameters. Only 4 studies (4%) had the optimal study design, while 32 (33%) showed sub-optimal study design with either direct or indirect evidence of adverse events. The high heterogeneity of studies included regarding cell type and number, genetic modification, administration route, and kidney disease model applied, combined with the consistent lack of appropriate control groups, makes a reliable safety evaluation of kidney cell-based therapies impossible. Only a limited number of relevant studies included looked into essential safety-related outcomes, such as inflammatory (48%), tumorigenic and teratogenic potential (12%), cell biodistribution (82%), microbiological safety with respect to microorganism contamination and latent viruses' reactivation (1%), as well as overall well-being and animal survival (19%). In conclusion, for benign cell-based therapies, well-designed pre-clinical studies, including all control groups required and good manufacturing processes securing safety, need to be done early in development. Preferably, this should be performed side by side with efficacy evaluation and according to the official guidelines of leading health organizations.

Mesenchymal Stem Cell-Derived Exosomes Ameliorated Diabetic Nephropathy by Autophagy Induction through the mTOR Signaling Pathway

BACKGROUND

Diabetic nephropathy (DN) is a serious complication of diabetes mellitus and a common cause of end-stage renal disease. Autophagy has a defensive role against kidney damage caused by hyperglycemia. Mesenchymal stem cell (MSC)-derived exosomes are currently considered as a new promising therapy for chronic renal injury. However, the renal-protective mechanism of exosomes on DN is not completely understood. We examined the potential role of MSC-derived exosomes for enhancement of autophagy activity and their effect on DN. In our study, we used five groups of rats: control; DN; DN treated with exosomes; DN treated with 3-methyladenine (3-MA) and chloroquine (inhibitors of autophagy); and DN treated with 3-methyladenine (3-MA), chloroquine, and exosome groups. We assessed renal function, morphology, and fibrosis. Moreover, ratios of the autophagy markers mechanistic target of rapamycin (mTOR), Beclin-1, light chain-3 (LC3-II), and LC3-II/LC3-I were detected. Additionally, electron microscopy was used for detection of autophagosomes.

RESULTS

Exosomes markedly improved renal function and showed histological restoration of renal tissues, with significant increase of LC3 and Beclin-1, and significant decrease of mTOR and fibrotic marker expression in renal tissue. All previous effects were partially abolished by the autophagy inhibitors chloroquine and 3-MA.

CONCLUSION

We conclude that autophagy induction by exosomes could attenuate DN in a rat model of streptozotocin-induced diabetes mellitus.

Stem cells for lupus nephritis: a concise review of current knowledge

Lupus nephritis (LN), a common manifestation of systemic lupus erythematosus (SLE), accounts for significant morbidity and mortality in SLE patients. Since the available standard therapies and biologic agents for LN are yet to achieve the desired response and have considerable secondary effects, stem cell therapy has now emerged as a new approach. This therapy involves the transplantation of hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs). Our current review will highlight the progress of stem cell therapy for LN, along with the challenges encountered and the future direction of this approach.

Human mesenchymal stem cell-derived extracellular vesicles/estrogen combined therapy safely ameliorates experimentally induced intrauterine adhesions in a female rat model

BACKGROUND

Mesenchymal stem cells (MSCs) have diverse functions in regulating injury and inflammation through the secretion of extracellular vesicles (EVs).

METHODS

In this study, we investigated the systemic administration of extracellular vesicles derived from human umbilical cord mesenchymal stem cells (UCMSCs-EVs) as a therapeutic agent for intrauterine adhesions (IUAs) caused by endometrial injury. Additionally, we investigated the therapeutic impact of both UCMSCs-EVs and estrogen either separately or in combination in a rat model. The inflammation, vascularization, proliferation, and extent of fibrosis were assessed by a histopathological and immunohistochemical assessment using transforming growth factor (TGF)-β as a fibrotic marker and vascular endothelial growth factor (VEGF) as a vascular marker. Additionally, quantitative real-time polymerase chain reaction (qRT-PCR) was used to analyze the expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-6 (inflammatory cytokines), CD140b (a marker of endometrial stem cells), and RUNX2 (an antifibrotic factor). Finally, Western blotting was used to evaluate collagen I and β-actin expression.

RESULTS

The therapeutic groups treated with either UCMSCs-EVs alone or combined with estrogen exhibited a significant decrease in inflammation and fibrosis (TNF-α, TGF-β, IL-1, IL-6, RUNX2, and collagen-I) as well as a significant decrease in vascularization (VEGF) compared with the untreated rats with IUAs. The most significant results were obtained in animals with IUAs that received a combined therapy of UCMSCs-EVs and estrogen.

CONCLUSIONS

We conclude that the synergistic action of human UCMSCs-EVs combined with estrogen provides a highly effective alternative regenerative agent in IUA treatment.

Stem/Stromal Cells for Treatment of Kidney Injuries With Focus on Preclinical Models

Within the last years, the use of stem cells (embryonic, induced pluripotent stem cells, or hematopoietic stem cells), Progenitor cells (e.g., endothelial progenitor cells), and most intensely mesenchymal stromal cells (MSC) has emerged as a promising cell-based therapy for several diseases including nephropathy. For patients with end-stage renal disease (ESRD), dialysis or finally organ transplantation are the only therapeutic modalities available. Since ESRD is associated with a high healthcare expenditure, MSC therapy represents an innovative approach. In a variety of preclinical and clinical studies, MSC have shown to exert renoprotective properties, mediated mainly by paracrine effects, immunomodulation, regulation of inflammation, secretion of several trophic factors, and possibly differentiation to renal precursors. However, studies are highly diverse; thus, knowledge is still limited regarding the exact mode of action, source of MSC in comparison to other stem cell types, administration route and dose, tracking of cells and documentation of therapeutic efficacy by new imaging techniques and tissue visualization. The aim of this review is to provide a summary of published studies of stem cell therapy in acute and chronic kidney injury, diabetic nephropathy, polycystic kidney disease, and kidney transplantation. Preclinical studies with allogeneic or xenogeneic cell therapy were first addressed, followed by a summary of clinical trials carried out with autologous or allogeneic hMSC. Studies were analyzed with respect to source of cell type, mechanism of action etc.

Amniotic fluid cells: current progress and emerging challenges in renal regeneration

Amniotic fluid (AF) contains a heterogeneous population of cells that have been identified to possess pluripotent and progenitor-like characteristics. These cells have been applied in various regenerative medicine applications ranging from in vitro cell differentiation to tissue engineering to cellular therapies for different organs including the heart, the liver, the lung, and the kidneys. In this review, we examine the different methodologies used for the derivation of amniotic fluid stem cells and renal progenitors, and their application in renal repair and regeneration. Moreover, we discuss the recent achievements and newly emerging challenges in our understanding of their biology, their immunoregulatory characteristics, and their paracrine-mediated therapeutic potential for the treatment of acute and chronic kidney diseases.

Cell-Based Therapies in Acute Kidney Injury (AKI)

Acute kidney injury frequently occurs in hospitalized patients all over the world. The prognosis remains poor since specific therapies for promoting kidney regeneration/repair are still missing. In recent years cell-based strategies have improved AKI outcomes under experimental circumstances. Four groups of cells, each of them displaying certain biological and functional characteristics have been evaluated in AKI, induced Pluripotent Stem Cells (iPSCs), Spermatagonial Stem Cells (SSCs), Proangiogenic Cells (PACs) and Endothelial Colony Forming Cells (ECFCs), and Mesenchymal Stem Cells (MSCs). All of these have been documented to stabilize either parameters of kidney excretory dysfunction and/or certain morphological parameters. The mechanisms responsible for AKI protection include direct (cell incorporation) and indirect processes, the latter being mediated by humoral factors and particularly by the production of so-called extracellular vesicles. Cell-derived vesicular organelles have been shown to carry pro-regenerative micro-RNA molecules which stabilize the vascular and tubular function. The first trials in humans have been initiated, the majority of such trials employs MSCs. However, any transfer of cell-based strategies in the clinical practice is potentially associated with significant difficulties. These include cell availability, tolerance and competence. The article intends to summarize essential informations about all of the four populations mentioned above and to discuss implications for the management of human AKI.

Ischemia-Reperfusion Injury Reduces Long Term Renal Graft Survival: Mechanism and Beyond

Ischemia-reperfusion injury (IRI) during renal transplantation often initiates non-specific inflammatory responses that can result in the loss of kidney graft viability. However, the long-term consequence of IRI on renal grafts survival is uncertain. Here we review clinical evidence and laboratory studies, and elucidate the association between early IRI and later graft loss. Our critical analysis of previous publications indicates that early IRI does contribute to later graft loss through reduction of renal functional mass, graft vascular injury, and chronic hypoxia, as well as subsequent fibrosis. IRI is also known to induce kidney allograft dysfunction and acute rejection, reducing graft survival. Therefore, attempts have been made to substitute traditional preserving solutions with novel agents, yielding promising results.

•

Ischaemia reperfusion injury (IRI) potentiates delayed renal graft function and causes reduction in renal graft survival

•

IRI causes innate immune system activation, hypoxic injury, inflammation and graft vascular disease

•

Reducing prolonged cold ischaemic time improves graft survival

•

Novel protective strategies include mesenchymal stem cells, machine perfusion, and ex vivo preservation solution saturated with gas.

•

Further studies are needed to investigate the long-term effects of novel ex vivo preservation agents

Blocking of autocrine IGF-1 reduces viability of human umbilical cord mesenchymal stem cells via inhibition of the Akt/Gsk-3β signaling pathway

Human umbilical cord mesenchymal stem cells (hUCMSCs) are able to secrete growth factors, such as hepatocyte growth factor, vascular endothelial growth factor and insulin‑like growth factor‑1 (IGF‑1). The secretion of these growth factors by transplanted hUCMSCs have been identified to stimulate the growth of the host cells in the target organs or tissues. The aim of the present study was to investigate the effect of autocrine IGF‑1 on cell viability of hUCMSCs. The expression levels of IGF‑1 and the IGF‑1 receptor (IGF‑1R) in hUCMSCs were identified using immunocytochemistry staining. In order to block autocrine IGF‑1, hUCMSCs were treated with 5 µg/ml αIR‑3, a specific IGF‑1R antibody, for 24 h. The cells cultured in medium without αIR‑3 were used as the control group. Cell viability, apoptosis, cell cycle and the proliferation‑associated proteins were quantified using an MTT assay, flow cytometry and western blotting. The findings of the present study revealed that IGF‑1 and IGF‑1R were positively expressed in hUCMSCs. Treatment with αIR‑3 significantly reduced cell viability and increased apoptosis of hUCMSCs (P<0.01). Cell cycle analysis indicated that the number of cells in the G2/M phase was reduced in the αIR‑3‑treated group compared with the control group. Western blotting revealed that the expression levels of phosphorylated (p)‑protein kinase B (Akt), p‑glycogen synthase kinase 3β (GSK‑3β), p‑p70 S6 kinase and cyclin D1 were markedly reduced and p21 expression was markedly increased in the αIR‑3‑treated group as compared with the control group (P<0.05). However, no significant difference was identified in the p‑extracellular‑signal regulated kinase 1/2 expression when the αIR‑3 treatment group was compared with the control group. (P>0.05). The findings of the present study suggested that the autocrine IGF‑1 from hUCMSCs may be capable of influencing cell viability of hUCMSCs, which may be associated with activation of Akt/GSK‑3β signaling pathway.

Genetically‑modified stem cells in treatment of human diseases: Tissue kallikrein (KLK1)‑based targeted therapy (Review)

The tissue kallikrein-kinin system (KKS) is an endogenous multiprotein metabolic cascade which is implicated in the homeostasis of the cardiovascular, renal and central nervous system. Human tissue kallikrein (KLK1) is a serine protease, component of the KKS that has been demonstrated to exert pleiotropic beneficial effects in protection from tissue injury through its anti-inflammatory, anti-apoptotic, anti-fibrotic and anti-oxidative actions. Mesenchymal stem cells (MSCs) or endothelial progenitor cells (EPCs) constitute populations of well-characterized, readily obtainable multipotent cells with special immunomodulatory, migratory and paracrine properties rendering them appealing potential therapeutics in experimental animal models of various diseases. Genetic modification enhances their inherent properties. MSCs or EPCs are competent cellular vehicles for drug and/or gene delivery in the targeted treatment of diseases. KLK1 gene delivery using adenoviral vectors or KLK1 protein infusion into injured tissues of animal models has provided particularly encouraging results in attenuating or reversing myocardial, renal and cerebrovascular ischemic phenotype and tissue damage, thus paving the way for the administration of genetically modified MSCs or EPCs with the human tissue KLK1 gene. Engraftment of KLK1-modified MSCs and/or KLK1-modified EPCs resulted in advanced beneficial outcome regarding heart and kidney protection and recovery from ischemic insults. Collectively, findings from pre-clinical studies raise the possibility that tissue KLK1 may be a novel future therapeutic target in the treatment of a wide range of cardiovascular, cerebrovascular and renal disorders.

Strategies to enhance paracrine potency of transplanted mesenchymal stem cells in intractable neonatal disorders

Mesenchymal stem cell (MSC) transplantation represents the next breakthrough in the treatment of currently intractable and devastating neonatal disorders with complex multifactorial etiologies, including bronchopulmonary dysplasia, hypoxic ischemic encephalopathy, and intraventricular hemorrhage. Absent engraftment and direct differentiation of transplanted MSCs, and the "hit-and-run" therapeutic effects of these MSCs suggest that their pleiotropic protection might be attributable to paracrine activity via the secretion of various biologic factors rather than to regenerative activity. The transplanted MSCs, therefore, exert their therapeutic effects not by acting as "stem cells," but rather by acting as "paracrine factors factory." The MSCs sense the microenvironment of the injury site and secrete various paracrine factors that serve several reparative functions, including antiapoptotic, anti-inflammatory, antioxidative, antifibrotic, and/or antibacterial effects in response to environmental cues to enhance regeneration of the damaged tissue. Therefore, the therapeutic efficacy of MSCs might be dependent on their paracrine potency. In this review, we focus on recent investigations that elucidate the specifically regulated paracrine mechanisms of MSCs by injury type and discuss potential strategies to enhance paracrine potency, and thus therapeutic efficacy, of transplanted MSCs, including determining the appropriate source and preconditioning strategy for MSCs and the route and timing of their administration.

Tissue engineering for urinary tract reconstruction and repair: Progress and prospect in China

Several urinary tract pathologic conditions, such as strictures, cancer, and obliterations, require reconstructive plastic surgery. Reconstruction of the urinary tract is an intractable task for urologists due to insufficient autologous tissue. Limitations of autologous tissue application prompted urologists to investigate ideal substitutes. Tissue engineering is a new direction in these cases. Advances in tissue engineering over the last 2 decades may offer alternative approaches for the urinary tract reconstruction. The main components of tissue engineering include biomaterials and cells. Biomaterials can be used with or without cultured cells. This paper focuses on cell sources, biomaterials, and existing methods of tissue engineering for urinary tract reconstruction in China. The paper also details challenges and perspectives involved in urinary tract reconstruction.

3,3'-Diindolylmethane stimulates exosomal Wnt11 autocrine signaling in human umbilical cord mesenchymal stem cells to enhance wound healing

Human umbilical cord-derived mesenchymal stem cells (hucMSCs) are suggested as a promising therapeutic tool in regenerative medicine, however, their efficacy requires improvement. Small molecules and drugs come up to be a convenient strategy in regulating stem cells fate and function. Here, we evaluated 3,3'-diindolylmethane (DIM), a natural small-molecule compound involved in the repairing effects of hucMSCs on a deep second-degree burn injury rat model. HucMSCs primed with 50 μM of DIM exhibited desirable repairing effects compared with untreated hucMSCs. DIM enhanced the stemness of hucMSCs, which was related to the activation of Wnt/β-catenin signaling. β-catenin inhibition impaired the healing effects of DIM-primed hucMSCs (DIM-hucMSCs) in vivo. Moreover, we demonstrated that DIM upregulated Wnt11 expression in hucMSC-derived exosomes. Wnt11 knockdown inhibited β-catenin activation and stemness induction in DIM-hucMSCs and abrogated their therapeutic effects in vivo. Thus, our findings indicate that DIM promotes the stemness of hucMSCs through increased exosomal Wnt11 autocrine signaling, which provides a novel strategy for improving the therapeutic effects of hucMSCs on wound healing.

Pre-incubation with hucMSC-exosomes prevents cisplatin-induced nephrotoxicity by activating autophagy

Background

The administration of cisplatin is limited due to its nephrotoxic side effects, and prevention of this nephrotoxicity of cisplatin is difficult. Mesenchymal stem cell (MSC)-derived exosomes have been implicated as a novel therapeutic approach for tissue injury. In this study, we demonstrated that the pretreatment of human umbilical cord MSC-derived exosomes (hucMSC-Ex) can prevent the development of cisplatin-induced renal toxicity by activation of autophagy in vitro and in vivo.

Methods

In vitro, rat renal tubular epithelial (NRK-52E) cells were pre-incubated with exosomes from hucMSC or HFL1 (human lung fibroblast cells; as control) for 30 min, and 3-methyladenine (an autophagic inhibitor) and rapamycin (an autophagic inducer) for 1 h before cisplatin treatment for 8 h, respectively. Cells were harvested for apoptosis assay, enzyme-linked immunosorbent assay (ELISA), Western blot, and quantitative real-time polymerase chain reaction (qRT-PCR). In vivo, we constructed cisplatin-induced acute kidney injury rat models. Prior to treatment with cisplatin for 0.5 h, hucMSC-Ex or HFL1-Ex were injected into the kidneys via the renal capsule. 3-methyladenine and rapamycin were injected under the kidney capsule before hucMSC-Ex. All animals were sacrificed at 3 days after cisplatin injection. Renal function, Luminex assay, tubular apoptosis and proliferation, and autophagy response were evaluated.

Results

hucMSC-Ex inhibited cisplatin-induced mitochondrial apoptosis and secretion of inflammatory cytokines in renal tubular epithelial cells in vitro. hucMSC-Ex increased the expression of the autophagic marker protein LC3B and the autophagy-related genes ATG5 and ATG7 in NRK-52E cells. Rapamycin mimicked the effects of hucMSC-Ex in protecting against cisplatin-induced renal injury, while the effects were abrogated by the autophagy inhibitor 3-methyladenine in the animals.

Conclusions

Our findings indicate that the activation of autophagy induced by hucMSC-Ex can effectively relieve the nephrotoxicity of cisplatin. Therefore, pre-treatment of hucMSC-Ex may be a new method to improve the therapeutic effect of cisplatin.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0463-4) contains supplementary material, which is available to authorized users.

Concise Review: Mesenchymal Stem (Stromal) Cells: Biology and Preclinical Evidence for Therapeutic Potential for Organ Dysfunction Following Trauma or Sepsis

Several experimental studies have provided evidence that bone-marrow derived mesenchymal stem (stromal) cells (MSC) may be effective in treating critically ill surgical patients who develop traumatic brain injury, acute renal failure, or the acute respiratory distress syndrome. There is also preclinical evidence that MSC may be effective in treating sepsis-induced organ failure, including evidence that MSC have antimicrobial properties. This review considers preclinical studies with direct relevance to organ failure following trauma, sepsis or major infections that apply to critically ill patients. Progress has been made in understanding the mechanisms of benefit, including MSC release of paracrine factors, transfer of mitochondria, and elaboration of exosomes and microvesicles. Regardless of how well they are designed, preclinical studies have limitations in modeling the complexity of clinical syndromes, especially in patients who are critically ill. In order to facilitate translation of the preclinical studies of MSC to critically ill patients, there will need to be more standardization regarding MSC production with a focus on culture methods and cell characterization. Finally, well designed clinical trials will be needed in critically ill patient to assess safety and efficacy. Stem Cells 2017;35:316-324.

Human vascular progenitor cells derived from renal arteries are endothelial-like and assist in the repair of injured renal capillary networks

Vascular progenitor cells show promise for the treatment of microvasculature endothelial injury. We investigated the function of renal artery progenitor cells derived from radical nephrectomy patients, in animal models of acute ischemic and hyperperfusion injuries. Present in human adventitia, CD34positive/CD105negative cells were clonal and expressed transcription factors Sox2/Oct4 as well as surface markers CXCR4 (CD184)/KDR(CD309) consistent with endothelial progenitor cells. Termed renal artery-derived vascular progenitor cells (RAPC), injected cells were associated with decreased serum creatinine after ischemia/reperfusion, reduced albuminuria after hyperperfusion, and improved blood flow in both models. A small population of RAPC integrated with the renal microvasculature following either experimental injury. At a cellular level, RAPC promoted local endothelial migration in co-culture. Profiling of RAPC microRNA identified high levels of miRNA 218; also found at high levels in exosomes isolated from RAPC conditioned media after cell contact for 24 hours. After hydrogen peroxide-induced endothelial injury, RAPC exosomes harbored Robo-1 transcript; a gene known to be regulated by mir218. Such exosomes enhanced endothelial cell migration in culture in the absence of RAPC. Thus, our work shows the feasibility of pre-emptive pro-angiogenic progenitor cell procurement from a targeted patient population and potential therapeutic use in the form of autologous cell transplantation.

Exosomes from Human Umbilical Cord Mesenchymal Stem Cells: Identification, Purification, and Biological Characteristics

Our and other groups have discovered that mesenchymal stem cells (MSCs) derived exosomes are a novel therapeutical modality for many diseases. In this study, we summarized a method to extract and purify hucMSCs-exosomes using ultrafiltration and gradient centrifugation in our laboratory and proved that hucMSCs-exosomes prepared according to our procedure were stable and bioactive. Results showed that exosomes derived from hucMSC were 40~100 nm and CD9 and CD81 positive. Functionally, hucMSCs-exosomes promoted cell proliferation and protected against oxidative stress-induced cell apoptosis in vitro by activation of ERK1/2 and p38. Interestingly, UV exposure abrogated the regulatory roles of exosomes under oxidative stress, indicating that hucMSCs-exosomes may regulate cell growth and apoptosis by exosomal shuttle of RNA. Furthermore, cytokine profile analysis revealed that hucMSCs-exosomes contained high dose of IL-6, IL-8, and other cytokines. The established method is practical and efficient, which provides a basis for further evaluating the potential of hucMSCs-exosomes as therapeutic agents.

MicroRNA-146b, a Sensitive Indicator of Mesenchymal Stem Cell Repair of Acute Renal Injury

: The role of mesenchymal stem cells (MSCs) in kidney injury repair has been studied widely. However, the underlying molecular mechanism remains unclear. We profiled the altered microRNAs in renal tissues from cisplatin-induced acute kidney injury (AKI) rats treated with or without rat bone marrow MSCs (rMSCs). We observed that microRNA-146b (miR-146b) expression was considerably upregulated in renal tissues from AKI rats compared with that in healthy rats, and the expression decreased following MSC treatment after cisplatin administration. At the early stage of AKI, serum miR-146b levels exhibited a rapid increase that was even faster than that of two conventional renal function indexes: serum creatinine and blood urea nitrogen levels. Furthermore, the serum miR-146b levels in AKI patients were higher than those in healthy people. In vitro exposure to cisplatin also increased miR-146b expression in renal tubular epithelial cells (TECs). miR-146b knockdown protected renal TECs from cisplatin-induced apoptosis and promoted their proliferation. Moreover, ErbB4 was identified as a direct target of miR-146b, and miR-146b inhibition induced ErbB4 expression, resulting in enhanced proliferation of injured renal TECs. In addition, restoration by rMSCs could be controlled through ErbB4 downregulation. In conclusion, elevated miR-146b expression contributes to cisplatin-induced AKI, partly through ErbB4 downregulation. miR-146b might be an early biomarker for AKI, and miR-146b inhibition could be a novel strategy for AKI treatment.

SIGNIFICANCE

The present study found that microRNA-146b (miR-146b) might be a novel biomarker for acute kidney injury and an indicator for its recovery after treatment with mesenchymal stem cells (MSCs). The results showed that in acute kidney injury induced by cisplatin, miR-146b in serum increased more quickly than did the usual indexes of kidney injury and decreased with restoration of MSCs. In addition, inhibition of miR-146b could ameliorate the apoptosis induced by cisplatin and potentially improve the proliferation by freeing ErbB4 and its downstream proteins.

Mesenchymal Stem Cell-Based Therapy for Kidney Disease: A Review of Clinical Evidence

Mesenchymal stem cells form a population of self-renewing, multipotent cells that can be isolated from several tissues. Multiple preclinical studies have demonstrated that the administration of exogenous MSC could prevent renal injury and could promote renal recovery through a series of complex mechanisms, in particular via immunomodulation of the immune system and release of paracrine factors and microvesicles. Due to their therapeutic potentials, MSC are being evaluated as a possible player in treatment of human kidney disease, and an increasing number of clinical trials to assess the safety, feasibility, and efficacy of MSC-based therapy in various kidney diseases have been proposed. In the present review, we will summarize the current knowledge on MSC infusion to treat acute kidney injury, chronic kidney disease, diabetic nephropathy, focal segmental glomerulosclerosis, systemic lupus erythematosus, and kidney transplantation. The data obtained from these clinical trials will provide further insight into safety, feasibility, and efficacy of MSC-based therapy in renal pathologies and allow the design of consensus protocol for clinical purpose.

Tweaking Mesenchymal Stem/Progenitor Cell Immunomodulatory Properties with Viral Vectors Delivering Cytokines

Mesenchymal Stem Cells (MSCs) can be found in various body sites. Their main role is to differentiate into cartilage, bone, muscle, and fat cells to allow tissue maintenance and repair. During inflammation, MSCs exhibit important immunomodulatory properties that are not constitutive, but require activation, upon which they may exert immunosuppressive functions. MSCs are defined as "sensors of inflammation" since they modulate their ability of interfering with the immune system both in vitro and in vivo upon interaction with different factors. MSCs may influence immune responses through different mechanisms, such as direct cell-to-cell contact, release of soluble factors, and through the induction of anergy and apoptosis. Human MSCs are defined as plastic-adherent cells expressing specific surface molecules. Lack of MHC class II antigens makes them appealing as allogeneic tools for the therapy of both autoimmune diseases and cancer. MSC therapeutic potential could be highly enhanced by the expression of exogenous cytokines provided by transduction with viral vectors. In this review, we attempt to summarize the results of a great number of in vitro and in vivo studies aimed at improving the ability of MSCs as immunomodulators in the therapy of autoimmune, degenerative diseases and cancer. We will also compare results obtained with different vectors to deliver heterologous genes to these cells.

Could stem cells be the future therapy for sepsis?

The severity and threat of sepsis is well known, and despite several decades of research, the mortality continues to be high. Stem cells have great potential to be used in various clinical disorders. The innate ability of stem cells such as pluripotency, self-renewal makes them potential agents for therapeutic intervention. The pathophysiology of sepsis is a plethora of complex mechanisms which include the initial microbial infection, followed by "cytokine storm," endothelial dysfunction, coagulation cascade, and the late phase of apoptosis and immune paralysis which ultimately results in multiple organ dysfunction. Stem cells could potentially alter each step of this complex pathophysiology of sepsis. Multiple organ dysfunction associated with sepsis most often leads to death and stem cells have shown their ability to prevent the organ damage and improve the organ function. The possible mechanisms of therapeutic potential of stem cells in sepsis have been discussed in detail. The route of administration, dose level, and timing also play vital role in the overall effect of stem cells in sepsis.

Renoprotective approaches and strategies in acute kidney injury

Acute kidney injury (AKI) is a major renal disease associated with high mortality rate and increasing prevalence. Decades of research have suggested numerous chemical and biological agents with beneficial effects in AKI. In addition, cell therapy and molecular targeting have been explored for reducing kidney tissue damage and promoting kidney repair or recovery from AKI. Mechanistically, these approaches may mitigate oxidative stress, inflammation, cell death, and mitochondrial and other organellar damage, or activate cytoprotective mechanisms such as autophagy and pro-survival factors. However, none of these findings has been successfully translated into clinical treatment of AKI. In this review, we analyze these findings and propose experimental strategies for the identification of renoprotective agents or methods with clinical potential. Moreover, we propose the consideration of combination therapy by targeting multiple targets in AKI.

Enhanced renoprotective effect of IGF-1 modified human umbilical cord-derived mesenchymal stem cells on gentamicin-induced acute kidney injury

The therapeutic action of umbilical cord-derived mesenchymal stem cells (UC-MSCs) against acute kidney injury (AKI) has been demonstrated by several groups. However, how to further enhance the renoprotective effect of UC-MSCs and improve the therapy effect, are still unclear. In this study, we mainly investigated whether insulin-like growth factor-1 (IGF-1)-modified UC-MSCs hold an enhanced protective effect on gentamicin-induced AKI in vivo. Our results indicated that the IGF-1 overexpression could enhance the therapeutic action of human UC-MSCs, and the AKI rats treated with IGF-1-overexpressed UC-MSCs (UC-MSCs-IGF-1) showed better recovery of biochemical variables in serum or urine associated with renal function, histological injury and renal apoptosis, compared with AKI rats treated with normal UC-MSCs. RNA microarray analysis indicated that some key genes in the signal pathways associated with anti-oxidation, anti-inflammatory, and cell migratory capacity were up-regulated in UC-MSCs-IGF-1, and the results were further confirmed with qPCR. Furthermore, a series of detection in vitro and in vivo indicated that the UC-MSCs-IGF-1 hold better anti-oxidation, anti-inflammatory, and cell migratory capacity for IGF-1 overexpression. Thus, our study indicated that enhancement of UC-MSCs bioactivities with IGF-1 overexpression could increase the UC-MSCs therapeutic potential and further developed a new therapeutic strategy for the treatment of AKI.

Three-Dimensional Aggregates Enhance the Therapeutic Effects of Adipose Mesenchymal Stem Cells for Ischemia-Reperfusion Induced Kidney Injury in Rats

It has been shown that administration of adipose derived mesenchymal stem cells (AdMSCs) enhanced structural and functional recovery of renal ischemia-reperfusion (IR) injury. Low engraftment of stem cells, however, limits the therapeutic effects of AdMSCs. The present study was designed to enhance the therapeutic effects of AdMSCs by delivering AdMSCs in a three-dimensional (3D) aggregates form. Microwell was used to produce 3D AdMSCs aggregates. In vitro data indicated that AdMSCs in 3D aggregates were less susceptible to oxidative and hypoxia stress induced by 200 μM peroxide and hypoxia/reoxygenation, respectively, compared with those cultured in two-dimensional (2D) monolayer. Furthermore, AdMSCs in 3D aggregates secreted more proangiogenic factors than those cultured in 2D monolayer. 2D AdMSCs or 3D AdMSCs aggregates were injected into renal cortex immediately after induction of renal IR injury. In vivo data revealed that 3D aggregates enhanced the effects of AdMSCs in recovering function and structure after renal IR injury. Improved grafted AdMSCs were observed in kidney injected with 3D aggregates compared with AdMSCs cultured in 2D monolayer. Our results demonstrated that 3D AdMSCs aggregated produced by microwell enhanced the retention and therapeutic effects of AdMSCs for renal IR injury.

Intra-arterial catheter system to repeatedly deliver mesenchymal stem cells in a rat renal failure model

BACKGROUND

Mesenchymal stem cell therapy in renal failure is rarely used because of low rates of cell engraftment after systemic delivery. Repeated intra-arterial cell administration may improve results; however, no current delivery method permits repeated intra-arterial infusions in a rat model. In this study, we developed an intra-arterial delivery system for repeated stem cell infusion via the aorta, catheterizing the left femoral artery to the suprarenal aorta under fluoroscopic guidance in rats with adenosine-induced renal failure.

METHODS

First, we compared our intra-arterial catheter system (C group, n = 3) with tail vein injection (V group, n = 3) for engraftment efficacy, using mesenchymal stem cells from luciferase transgenic rats. Rats were infused with the cells and euthanized the following day; we performed cell-tracking experiments using a bioluminescence imaging system to assess the distribution of the infused cells. Second, we assessed the safety of the system over a 30-day period in a second group of six rats receiving infusions every 7 days.

RESULTS

Cells infused through our delivery system efficiently engrafted into the kidney, compared with peripheral venous infusion. In five of the six rats in the safety study, the delivery system remained patent for at least 9 days (range, 9-24 days). Complications became evident only after 10 days.

CONCLUSION

Our intra-arterial catheter system was effective in delivering cells to the kidney and permitted repeated injection of cells.

Methylation status of the FHIT gene in the transformed human mesenchymal F6 stem cell line

The fragile histidine triad (FHIT) gene is known to be a tumor suppressor gene and the abnormal methylation of FHIT has been identified in leukemia and several solid tumors. The transformation of the tumor F6 cell line from human fetal mesenchymal stem cells (FMSCs) was first reported in a previous study that also identified the presence of a population of cancer stem cells in the F6 cell line. However, the existence of the epigenetic changes during the transformation process have yet to be elucidated. To confirm the role of the FHIT gene in the transformation process of FMSC, the expression level and methylation status of the FHIT gene was examined in F6 tumor cells and FMSCs. Additionally, the alteration in cell morphology, the cell cycle and apoptosis in F6 cells following 5-Aza-CdR treatment was assessed. It was found that the FHIT gene was expressed in FMSCs, but not in F6 cells. The methylation-specific PCR results demonstrated that the promoter methylation of FHIT genes existed in the F6 cell line. Subsequent to treatment with 5-Aza-CdR the expression of FHIT genes was restored in F6 cells. In addition, the morphology of F6 cells was altered, and the cell cycle was arrested in the G₂ phase, with the initiation of apoptosis. Overall, the present findings demonstrated that the FHIT gene was methylated in F6 cells and demethylation treatment lead to changes in the biological characteristics, thereby promoting the apoptosis of F6 cells. FHIT gene methylation may be one of the molecular events involved in the development and transformation of FMSCs into F6 tumor cells.

Combination of retinoic acid, dimethyl sulfoxide and 5-azacytidine promotes cardiac differentiation of human fetal liver-derived mesenchymal stem cells

There are controversial reports about cardiac differentiation potential of mesenchymal stem cells (MSCs), and there is still no well-defined protocol for the induction of cardiac differentiation. The effects of retinoic acid (RA) and dimethyl sulfoxide (DMSO) on the proliferation and differentiation of human fetal liver-derived MSCs (HFMSCs) as well as the pluripotent state induced by 5-azacytidine (5-aza) in vitro were investigated. MSCs were isolated from fetal livers and cultured in accordance with previous reports. Cells were plated and were treated for 24 h by the combination of 5-aza, RA and DMSO in different doses. Different culture conditions were tested in our study, including temperature, oxygen content and medium. Three weeks later, cells were harvested for the certification of cardiac differentiation as well as the pluripotency, which indicated by cardiac markers and Oct4. It was found that the cardiac differentiation was only induced when HFMSCs were treated in the following conditions: in high-dose combination (5-aza 50 μM + RA 10(-1) μM + DMSO 1 %) in cardiac differentiation medium at 37 °C and 20 % O2. The results of immunohistochemistry and quantitative RT-PCR showed that about 40 % of the cells positively expressed Nkx2.5, desmin and cardiac troponin I, as well as Oct4. No beating cells were observed during the period. The combined treatment with RA, DMSO and 5-aza in high-dose could promote HFMSCs to differentiate into cardiomyocyte-like cells and possibly through the change of their pluripotent state.

Exosomes Derived from Human Umbilical Cord Mesenchymal Stem Cells Relieve Acute Myocardial Ischemic Injury

This study is aimed at investigating whether human umbilical cord mesenchymal stem cell- (hucMSC-) derived exosomes (hucMSC-exosomes) have a protective effect on acute myocardial infarction (AMI). Exosomes were characterized under transmission electron microscopy and the particles of exosomes were further examined through nanoparticle tracking analysis. Exosomes (400 μg protein) were intravenously administrated immediately following ligation of the left anterior descending (LAD) coronary artery in rats. Cardiac function was evaluated by echocardiography and apoptotic cells were counted using TUNEL staining. The cardiac fibrosis was assessed using Masson's trichrome staining. The Ki67 positive cells in ischemic myocardium were determined using immunohistochemistry. The effect of hucMSC-exosomes on blood vessel formation was evaluated through tube formation and migration of human umbilical vein endothelial cells (EA.hy926 cells). The results indicated that ligation of the LAD coronary artery reduced cardiac function and induced cardiomyocyte apoptosis. Administration of hucMSC-exosomes significantly improved cardiac systolic function and reduced cardiac fibrosis. Moreover, hucMSC-exosomes protected myocardial cells from apoptosis and promoted the tube formation and migration of EA.hy926 cells. It is concluded that hucMSC-exosomes improved cardiac systolic function by protecting myocardial cells from apoptosis and promoting angiogenesis. These effects of hucMSC-exosomes might be associated with regulating the expression of Bcl-2 family.