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

Placenta-derived mesenchymal stem cells protect against diabetic kidney disease by upregulating autophagy-mediated SIRT1/FOXO1 pathway

Diabetic kidney disease (DKD) is a common chronic microvascular complication of diabetes mellitus. Although studies have indicated the therapeutic potential of mesenchymal stem cells (MSCs) for DKD, the underlying molecular mechanisms remain unclear. Herein, we explored the renoprotective effect of placenta-derived MSCs (P-MSCs) and the potential mechanism of SIRT1/FOXO1 pathway-mediated autophagy in DKD. The urine microalbumin/creatinine ratio was determined using ELISA, and renal pathological changes were detected by special staining techniques. Immunofluorescence was used for detecting the renal tissue expression of podocin and nephrin; immunohistochemistry for the renal expression of autophagy-related proteins (LC3, Beclin-1, SIRT1, and FOXO1); and western blotting and PCR for the expression of podocyte autophagy- and pathway-related indicators. We found that P-MSCs ameliorated renal tubular injury and glomerular mesangial matrix deposition and alleviated podocyte damage in DKD rats. PMSCs enhanced autophagy levels and increased SIRT1 and FOXO1 expression in DKD rat renal tissue, whereas the autophagy inhibitor 3-methyladenine significantly attenuated the renoprotective effect of P-MSCs. P-MSCs improved HG-induced Mouse podocyte clone5(MPC5)injury, increased podocyte autophagy, and upregulated SIRT1 and FOXO1 expression. Moreover, downregulation of SIRT1 expression blocked the P-MSC-mediated enhancement of podocyte autophagy and improvement of podocyte injury. Thus, P-MSCs can significantly improve renal damage and reduce podocyte injury in DKD rats by modulating the SIRT1/FOXO1 pathway and enhancing podocyte autophagy.

Exploring the role of mesenchymal stem cells in modulating immune responses via Treg and Th2 cell activation: insights from mouse model of multiple sclerosis

Multiple sclerosis is a demyelinating neurodegenerative disease, and its animal model, experimental autoimmune encephalomyelitis (EAE), exhibits immunological and clinical similarities. The study aimed to examine mechanisms underlying therapeutic effects of mesenchymal stem cell administration in EAE. C57BL/6 mice were separated into control and treatment groups (T1, T2, and T3); EAE was induced in all animals. Clinical examinations were conducted daily, and on 25th day, animals were sacrificed, and spinal cord was stained for histological analysis. Additionally, spleen cell proliferation assay, assessments of cytokine, and gene expression in both spinal cord and spleen cells were performed. The results indicated a significant reduction in clinical symptoms among treatment groups compared to control group. Histological analyses revealed decreased infiltration of lymphocytes into the spinal cord and reduced demyelinated areas in treatment groups compared to control group. Cytokine production of IL-10, TGF-β, and IL-4 were significantly enhanced and IFN-γ and TNF-α in treatment groups were decreased relative to control group. Also, gene expression of CTLA-4, PD-1, IL-27, and IL-33 indicated a significant increase in treatment groups. The administration of MSCs significantly improved clinical symptoms, attenuated inflammation, and reduced spinal cord demyelination in EAE, suggesting a potential protective effect on disease progression.

Allogenic MSC infusion in kidney transplantation recipients promotes within 4 hours distinct B cell and T cell phenotypes

Background

Infusion of mesenchymal stromal cells (MSCs) has been proposed as immune-modulatory therapy in solid organ transplantation. The use of allogenic MSCs could improve standardization and allow for direct availability of the product.

Method

The nonrandomized phase Ib Neptune clinical trial provided safety and feasibility data on the use of allogenic bone-marrow-derived MSCs, infused in 10 patients at week 25 and 26 post kidney transplantation. Here, we performed detailed analysis on the peripheral blood immune cell composition of these patients up to 52 weeks post transplantation. We used a 40 marker antibody panel with mass cytometry to assess potential effects of MSC therapy on the immune system.

Results

We showed minor changes in major immune lineages at week 27, 34 and 52 post kidney transplantation after MSC infusion at week 25 and week 26, confirming previous data with regular flow cytometry. However, in a direct comparison between pre- and post MSC infusion, as soon as 4 hours after MSC infusion, we observed a significant increase in cell numbers of B cell and T cell subsets that shared a unique expression of CD11b, CD11c, CD38, CD39, and Ki-67.

Conclusion

Exploring these CD11b+CD11c+CD38+CD39+Ki-67+ B cells and T cells in the context of MSC infusion after kidney transplantation may be a promising avenue to better understand the immunological effects of MSC therapy.

Mesenchymal Stem Cell Therapy: Therapeutic Opportunities and Challenges for Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD), which severely affects the quality of patients' lives. However, the current therapeutic approaches can only postpone its progression to ESRD. It is therefore imperative to develop a novel therapeutic strategy for renal injury in DKD, with the objective of restoring renal function and reversing the process of ESRD. In recent years, the potential of mesenchymal stem cell (MSC) therapy for DKD has garnered increasing attention within the scientific community. Preclinical research on MSC therapy has yielded promising results, and the safety of MSC treatment in vivo has been substantiated in clinical studies. An increasing body of evidence suggests that MSC therapy has significant potential for the treatment of DKD. This article reviews the existing research on MSCs and their derived exosomes in treating DKD and analyzes the underlying mechanism of MSC-based therapy for DKD. Additionally, we discuss the potential of combining MSC therapy with conventional pharmacological treatments, along with the constraints and prospects of MSC therapy for DKD. We hope this review can provide a precise and comprehensive understanding of MSCs for the treatment of DKD.

Mesenchymal stem cell therapy in diabetic foot ulcer: An updated comprehensive review

Background

Diabetes has evolved into a worldwide public health issue. One of the most serious complications of diabetes is diabetic foot ulcer (DFU), which frequently creates a significant financial strain on patients and lowers their quality of life. Up until now, there has been no curative therapy for DFU, only symptomatic relief or an interruption in the disease's progression. Recent studies have focused attention on mesenchymal stem cells (MSCs), which provide innovative and potential treatment candidates for several illnesses as they can differentiate into various cell types. They are mostly extracted from the placenta, adipose tissue, umbilical cord (UC), and bone marrow (BM). Regardless of their origin, they show comparable features and small deviations. Our goal is to investigate MSCs' therapeutic effects, application obstacles, and patient benefit strategies for DFU therapy.

Methodology

A comprehensive search was conducted using specific keywords relating to DFU, MSCs, and connected topics in the databases of Medline, Scopus, Web of Science, and PubMed. The main focus of the selection criteria was on English-language literature that explored the relationship between DFU, MSCs, and related factors.

Results and Discussion

Numerous studies are being conducted and have demonstrated that MSCs can induce re-epithelialization and angiogenesis, decrease inflammation, contribute to immunological modulation, and subsequently promote DFU healing, making them a promising approach to treating DFU. This review article provides a general snapshot of DFU (including clinical presentation, risk factors and etiopathogenesis, and conventional treatment) and discusses the clinical progress of MSCs in the management of DFU, taking into consideration the side effects and challenges during the application of MSCs and how to overcome these challenges to achieve maximum benefits.

Conclusion

The incorporation of MSCs in the management of DFU highlights their potential as a feasible therapeutic strategy. Establishing a comprehensive understanding of the complex relationship between DFU pathophysiology, MSC therapies, and related obstacles is essential for optimizing therapy outcomes and maximizing patient benefits.

Human umbilical cord mesenchymal stem cell therapy for renal dysfunction in Alport syndrome: protocol for an open-label, single-arm trial in China

INTRODUCTION

Alport syndrome (AS) is one of the most common fatal hereditary renal diseases in human, with a high risk of progressing to end-stage renal disease without effective treatments. Mesenchymal stem cells (MSCs) have recently emerged as a promising therapeutic strategy for chronic kidney disease. However, the safety and therapeutic potential of MSC transfusion for patients with AS are still need to be confirmed. Therefore, we have designed a clinical trial to evaluate the hypothesis that intravenous infusion of human umbilical cord-derived MSC (hUC-MSC) is safe, feasible, and well-tolerated in children with AS.

METHODS AND ANALYSIS

We report the protocol of the first prospective, open-label, single-arm clinical trial to evaluate the safety and preliminary efficacy of hUC-MSC transfusion in children with early-stage AS. Paediatric patients diagnosed with AS who have persistent albuminuria will be candidates for screening. Twelve eligible patients are planned to recruit and will receive hUC-MSC infusions under close safety monitoring, and complete the efficacy assessments at scheduled follow-up visits. The primary endpoints include the occurrence of adverse events to assess safety and the albuminuria level for efficacy evaluation. Secondary endpoint assessments are based on haematuria and glomerular filtration measurements. Each patient's efficacy endpoints will be evaluated against their baseline levels. Additionally, the underlying mechanism of hUC-MSC therapy will be explored through transcriptomic and proteomic analysis of blood and urine samples.

ETHICS AND DISSEMINATION

The protocol (V.1.0, date 17 January 2015) was approved by the institutional review board of the Affiliated Taihe Hospital of Hubei University of Medicine (ethical approval 03 March 2015). Written informed consent will be obtained from the patient and/or guardians before study specific process. In addition to publication in a peer-reviewed scientific journal, a lay summary of study will be available for participants and the public on the Chinese Organization for Rare Disorders website (http://www.cord.org.cn/).

TRIAL REGISTRATION NUMBER

ISRCTN62094626.

Therapeutic potential of mesenchymal stem cells from human iPSC-derived teratomas for osteochondral defect regeneration

Human induced pluripotent stem cells (iPSCs) hold great promise for personalized medicine, as they can be differentiated into specific cell types, especially mesenchymal stem cells (MSCs). Therefore, our study sought to assess the feasibility of deriving MSCs from teratomas generated from human iPSCs. Teratomas serve as a model to mimic multilineage human development, thus enriching specific somatic progenitors and stem cells. Here, we discovered a small, condensed mass of MSCs within iPSC-generated teratomas. Afterward, we successfully isolated MSCs from this condensed mass, which was a byproduct of teratoma development. To evaluate the characteristics and cell behaviors of iPSC-derived MSCs (iPSC-MSCs), we conducted comprehensive assessments using qPCR, immunophenotype analysis, and cell proliferation-related assays. Remarkably, iPSC-MSCs exhibited an immunophenotype resembling that of conventional MSCs, and they displayed robust proliferative capabilities, similar to those of higher pluripotent stem cell-derived MSCs. Furthermore, iPSC-MSCs demonstrated the ability to differentiate into multiple lineages in vitro. Finally, we evaluated the therapeutic potential of iPSC-MSCs using an osteochondral defect model. Our findings demonstrated that teratomas are a promising source for the isolation of condensed MSCs. More importantly, our results suggest that iPSC-MSCs derived from teratomas possess the capacity for tissue regeneration, highlighting their promise for future therapeutic applications.

Bone marrow-derived c-kit positive stem cell administration protects against diabetes-induced nephropathy in a rat model by reversing PI3K/AKT/GSK-3β pathway and inhibiting cell apoptosis

Stem cell-based therapy has been proposed as a novel therapeutic strategy for diabetic nephropathy. This study was designed to evaluate the effect of systemic administration of rat bone marrow-derived c-kit positive (c-kit+) cells on diabetic nephropathy in male rats, focusing on PI3K/AKT/GSK-3β pathway and apoptosis as a possible therapeutic mechanism. Twenty-eight animals were randomly classified into four groups: Control group (C), diabetic group (D), diabetic group, intravenously received 50 μl phosphate-buffered saline (PBS) containing 3 × 105 c-kit- cells (D + ckit-); and diabetic group, intravenously received 50 μl PBS containing 3 × 105 c-Kit positive cells (D + ckit+). Control and diabetic groups intravenously received 50 μl PBS. C-kit+ cell therapy could reduce renal fibrosis, which was associated with attenuation of inflammation as indicated by decreased TNF-α and IL-6 levels in the kidney tissue. In addition, c-kit+ cells restored the expression levels of PI3K, pAKT, and GSK-3β proteins. Furthermore, renal apoptosis was decreased following c-kit+ cell therapy, evidenced by the lower apoptotic index in parallel with the increased Bcl-2 and decreased Bax and Caspase-3 levels. Our results showed that in contrast to c-kit- cells, the administration of c-kit+ cells ameliorate diabetic nephropathy and suggested that c-kit+ cells could be an alternative cell source for attenuating diabetic nephropathy.

Stem cells as a regenerative medicine approach in treatment of microvascular diabetic complications

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by high blood glucose and is associated with high morbidity and mortality among the diabetic population. Uncontrolled chronic hyperglycaemia causes increased formation and accumulation of different oxidative and nitrosative stress markers, resulting in microvascular and macrovascular complications, which might seriously affect the quality of a patient's life. Conventional treatment strategies are confined to controlling blood glucose by regulating the insulin level and are not involved in attenuating the life-threatening complications of diabetes mellitus. Thus, there is an unmet need to develop a viable treatment strategy that could target the multi-etiological factors involved in the pathogenesis of diabetic complications. Stem cell therapy, a regenerative medicine approach, has been investigated in diabetic complications owing to their unique characteristic features of self-renewal, multilineage differentiation and regeneration potential. The present review is focused on potential therapeutic applications of stem cells in the treatment of microvascular diabetic complications such as nephropathy, retinopathy, and polyneuropathy.

Upscaling human mesenchymal stromal cell production in a novel vertical-wheel bioreactor enhances extracellular vesicle secretion and cargo profile

Human mesenchymal stromal cells (hMSCs) are mechanically sensitive undergoing phenotypic alterations when subjected to shear stress, cell aggregation, and substrate changes encountered in 3D dynamic bioreactor cultures. However, little is known about how bioreactor microenvironment affects the secretion and cargo profiles of hMSC-derived extracellular vesicles (EVs) including the subset, "exosomes", which contain therapeutic proteins, nucleic acids, and lipids from the parent cells. In this study, bone marrow-derived hMSCs were expanded on 3D Synthemax II microcarriers in the PBS mini 0.1L Vertical-Wheel bioreactor system under variable shear stress levels at 25, 40, and 64 RPM (0.1-0.3 dyn/cm²). The bioreactor system promotes EV secretion from hMSCs by 2.5-fold and upregulates the expression of EV biogenesis markers and glycolysis genes compared to the static 2D culture. The microRNA cargo was also altered in the EVs from bioreactor culture including the upregulation of miR-10, 19a, 19b, 21, 132, and 377. EV protein cargo was characterized by proteomics analysis, showing upregulation of metabolic, autophagy and ROS-related proteins comparing with 2D cultured EVs. In addition, the scalability of the Vertical-Wheel bioreactor system was demonstrated in a 0.5L bioreactor, showing similar or better hMSC-EV secretion and cargo content compared to the 0.1L bioreactor. This study advances our understanding of bio-manufacturing of stem cell-derived EVs for applications in cell-free therapy towards treating neurological disorders such as ischemic stroke, Alzheimer's disease, and multiple sclerosis.

Clinical Trials Using Mesenchymal Stem Cells for Spinal Cord Injury: Challenges in Generating Evidence

Spinal cord injury (SCI) remains an important public health problem which often causes permanent loss of muscle strength, sensation, and function below the site of the injury, generating physical, psychological, and social impacts throughout the lives of the affected individuals, since there are no effective treatments available. The use of stem cells has been investigated as a therapeutic approach for the treatment of SCI. Although a significant number of studies have been conducted in pre-clinical and clinical settings, so far there is no established cell therapy for the treatment of SCI. One aspect that makes it difficult to evaluate the efficacy is the heterogeneity of experimental designs in the clinical trials that have been published. Cell transplantation methods vary widely among the trials, and there are still no standardized protocols or recommendations for the therapeutic use of stem cells in SCI. Among the different cell types, mesenchymal stem/stromal cells (MSCs) are the most frequently tested in clinical trials for SCI treatment. This study reviews the clinical applications of MSCs for SCI, focusing on the critical analysis of 17 clinical trials published thus far, with emphasis on their design and quality. Moreover, it highlights the need for more evidence-based studies designed as randomized controlled trials and potential challenges to be addressed in context of stem cell therapies for SCI.

Extracellular Vesicles in Type 1 Diabetes: A Versatile Tool

Type 1 diabetes is a chronic autoimmune disease affecting nearly 35 million people. This disease develops as T-cells continually attack the β-cells of the islets of Langerhans in the pancreas, which leads to β-cell death, and steadily decreasing secretion of insulin. Lowered levels of insulin minimize the uptake of glucose into cells, thus putting the body in a hyperglycemic state. Despite significant progress in the understanding of the pathophysiology of this disease, there is a need for novel developments in the diagnostics and management of type 1 diabetes. Extracellular vesicles (EVs) are lipid-bound nanoparticles that contain diverse content from their cell of origin and can be used as a biomarker for both the onset of diabetes and transplantation rejection. Furthermore, vesicles can be loaded with therapeutic cargo and delivered in conjunction with a transplant to increase cell survival and long-term outcomes. Crucially, several studies have linked EVs and their cargos to the progression of type 1 diabetes. As a result, gaining a better understanding of EVs would help researchers better comprehend the utility of EVs in regulating and understanding type 1 diabetes. EVs are a composition of biologically active components such as nucleic acids, proteins, metabolites, and lipids that can be transported to particular cells/tissues through the blood system. Through their varied content, EVs can serve as a flexible aid in the diagnosis and management of type 1 diabetes. In this review, we provide an overview of existing knowledge about EVs. We also cover the role of EVs in the pathogenesis, detection, and treatment of type 1 diabetes and the function of EVs in pancreas and islet β-cell transplantation.

Hypoxia preconditioning increases the ability of healthy but not diabetic rat-derived adipose stromal/stem cells (ASC) to improve histological lesions of streptozotocin-induced diabetic nephropathy

BACKGROUND

Mesenchymal stromal cells (MSC) have demonstrated ability to improve diabetic nephropathy (DN) in experimental models, as well as by improving kidney endogenous progenitor cells proliferation and differentiation. Many studies have demonstrated the effect of hypoxia on MSC improving their functionality but the potential enhancement of the nephroprotective properties of MSC cultured under low oxygen concentration has been explored in few studies, none of them in the context of DN. On the other hand, diabetes is associated with abnormalities in MSCs functionality. These findings related to the hypoxia preconditioning ability to enhance adipose-tissue derived-MSC (ASC) performance have led us to wonder if hypoxia could increase the known beneficial effect of normal ASC in DN and if it could correct the expected inability of diabetic rat-derived ASC to exert this effect in vivo. To answer these questions, in the present study we have used ASC from healthy and diabetic-induced rats, cultured under standard conditions or hypoxia preconditioned, in a DN rat model induced by streptozotocin (STZ).

METHODS

Diabetes was induced in Wistar-rats by 60 mg/kg streptozotocin (STZ) intraperitoneal injection. Fifteen days thereafter, five diabetic-induced rats and five healthy, previously injected with saline, were sacrificed and used as ASC donors . Both healthy and diabetic rat-derived ASC (cASC and dASC, respectively) were cultured under standard conditions (21%O2)(N) or were subjected to a 48 h conditioning period in hypoxia (3%O2)(H). Thus, four types of cells were generated depending on their origin (healthy or diabetic-induced rats) and the culture conditions(N or H):cASC-N, cASC-H, dASC-N and dASC-H. DN experimental study were carried out fifteen days after STZ induction of diabetes in fifty-two healthy rats. DN-induced-animals were randomly assigned to be injected with 200 µL saline as placebo or with 3 × 106 cASC-N, cASC-H, dASC-N or dASC-H, according to the study group. Serum glucose, urea and creatinine, and urine albumin levels were measured at 2-weeks intervals until day+ 45 after ND-induction.Animals were sacrificed and kidneys extracted for histopathological and transmission electron microcopy analysis RESULTS: None of the four study groups that received cell treatment showed significant changes in serum glucose, urea and creatinine levels, urine albumin concentration and body weight compared to placebo ND-induced group. Interestingly, only the group that received cASC-H showed a reduction in glucose and creatinine levels although it did not reach statistical significance.All DN-induced groups treated with ASC reduced significantly renal lesions such as mesangial expansion, mesangiolysis, microaneurysms and acute tubular necrosis compared to ND-induced placebo group (p ≤ 0.05). Renal injuries such as clear tubular cell changes, thickening of tubular basement membrane, tubular cysts and interstitial fibrosis significantly showed reduction in ND-induced rats treated with cASC-H regarding to their received cASCN (p ≤ 0.05). Non statistical differences were observed in the improvement capacity of cASC and dASC culture under standard condition.However, hypoxia preconditioning reduces the presence of tubular cysts (p ≤ 0.01).

CONCLUSIONS

Hypoxia preconditioning enhances the ability of healthy rat-derived ASC to improve kidney injury in a rat model of DN. Moreover, diabetic-derived ASC exhibits a similar ability to healthy ASC which is clearly more than expected, but it is not significantly modified by hypoxia preconditioning.

AD-MSCs and BM-MSCs Ameliorating Effects on The Metabolic and Hepato-renal Abnormalities in Type 1 Diabetic Rats

Diabetes mellitus (DM) is one of the most serious threats in the 21th century throughout the human population that needs to be addressed cautiously. Nowadays, stem cell injection is considered among the most promising protocols for DM therapy; owing to its marked tissues and organs repair capability. Therefore, our 4 weeks study was undertaken to elucidate the probable beneficial effects of two types of adult mesenchymal stem cells (MSCs) on metabolism disturbance and some tissue function defects in diabetic rats. Animals were classified into 4 groups; the control group, the diabetic group, the diabetic group received a single dose of adipose tissue-derived MSCs and the diabetic group received a single dose of bone marrow-derived MSCs. Herein, both MSCs treated groups markedly reduced hyperglycemia resulting from diabetes induction via lowering serum glucose and rising insulin and C-peptide levels, compared to the diabetic group. Moreover, the increased lipid fractions levels were reverted back to near normal values as a consequence to MSCs injection compared to the diabetic untreated rats. Furthermore, both MSCs types were found to have hepato-renal protective effects indicated through the decreased serum levels of both liver and kidney functions markers in the treated diabetic rats. Taken together, our results highlighted the therapeutic benefits of both MSCs types in alleviating metabolic anomalies and hepato-renal diabetic complications.

Mesenchymal Stem Cell-Based Therapy as a New Approach for the Treatment of Systemic Sclerosis

Systemic sclerosis (SSc) is an intractable autoimmune disease with unmet medical needs. Conventional immunosuppressive therapies have modest efficacy and obvious side effects. Targeted therapies with small molecules and antibodies remain under investigation in small pilot studies. The major breakthrough was the development of autologous haematopoietic stem cell transplantation (AHSCT) to treat refractory SSc with rapidly progressive internal organ involvement. However, AHSCT is contraindicated in patients with advanced visceral involvement. Mesenchymal stem cells (MSCs) which are characterized by immunosuppressive, antifibrotic and proangiogenic capabilities may be a promising alternative option for the treatment of SSc. Multiple preclinical and clinical studies on the use of MSCs to treat SSc are underway. However, there are several unresolved limitations and safety concerns of MSC transplantation, such as immune rejections and risks of tumour formation, respectively. Since the major therapeutic potential of MSCs has been ascribed to their paracrine signalling, the use of MSC-derived extracellular vesicles (EVs)/secretomes/exosomes as a "cell-free" therapy might be an alternative option to circumvent the limitations of MSC-based therapies. In the present review, we overview the current knowledge regarding the therapeutic efficacy of MSCs in SSc, focusing on progresses reported in preclinical and clinical studies using MSCs, as well as challenges and future directions of MSC transplantation as a treatment option for patients with SSc.

Mechanism of Action of Mesenchymal Stem Cells (MSCs): impact of delivery method

INTRODUCTION

Mesenchymal stromal cells (MSCs; AKA mesenchymal stem cells) stimulate healing and reduce inflammation. Promising therapeutic responses are seen in many late-phase clinical trials, but others have not satisfied their primary endpoints, making translation of MSCs into clinical practice difficult. These inconsistencies may be related to the route of MSC delivery, lack of product optimization, or varying background therapies received in clinical trials over time.

AREAS COVERED

Here we discuss the different routes of MSC delivery, highlighting the proposed mechanism(s) of therapeutic action as well as potential safety concerns. PubMed search criteria used: MSC plus: local administration; routes of administration; delivery methods; mechanism of action; therapy in different diseases.

EXPERT OPINION

Direct injection of MSCs using a controlled local delivery approach appears to have benefits in certain disease states, but further studies are required to make definitive conclusions regarding the superiority of one delivery method over another.

The Exosomal lncRNA KLF3-AS1 From Ischemic Cardiomyocytes Mediates IGF-1 Secretion by MSCs to Rescue Myocardial Ischemia-Reperfusion Injury

The purpose of the study was to explore the mechanism by which myocardial ischemia-reperfusion (I/R) injury-induced exosomes modulate mesenchymal stem cells (MSCs) to regulate myocardial injury. In this study, we established an I/R injury model in vivo and a hypoxia-reoxygenation (H/R) model in vitro. Then, exosomes isolated from H/R-exposed H9c2 cells were characterized using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blot analysis. CCK-8 assays and flow cytometry were performed to assess cell injury. ELISA was applied to determine the level of insulin-like growth factor 1 (IGF-1). Echocardiography was used to assess cardiac function in vivo. HE staining and TUNEL assays were conducted to analyze myocardial injury in vivo. In the present study, H/R-exposed H9c2 cells induced IGF-1 secretion from MSCs to inhibit cell myocardial injury. Moreover, exosomes derived from H/R-exposed H9c2 cells were introduced to MSCs to increase IGF-1 levels. The lncRNA KLF3-AS1 was dramatically upregulated in exosomes derived from H/R-treated H9c2 cells. Functional experiments showed that the exosomal lncRNA KLF3-AS1 promoted IGF-1 secretion from MSCs and increased H9c2 cell viability. In addition, miR-23c contains potential binding sites for both KLF3-AS1 and STAT5B, and miR-23c directly bound to the 3'-UTRs of KLF3-AS1 and STAT5B. Furthermore, the lncRNA KLF3-AS1 promoted IGF-1 secretion from MSCs and rescued myocardial cell injury in vivo and in vitro by upregulating STAT5B expression. The lncRNA KLF3-AS1 may serve as a new direction for the treatment of myocardial I/R injury.

An overview of mesenchymal stem cells and their potential therapeutic benefits in cancer therapy

There has been increased interest in using stem cells for regenerative medicine and cancer therapy in the past decade. Mesenchymal stem cells (MSCs) are among the most studied stem cells due to their unique characteristics, such as self-renewal and developmental potency to differentiate into numerous cell types. MSC use has fewer ethical challenges compared with other types of stem cells. Although a number of studies have reported the beneficial effects of MSC-based therapies in treating various diseases, their contribution to cancer therapy remains controversial. The behaviour of MSCs is determined by the interaction between intrinsic transcriptional genes and extrinsic environmental factors. Numerous studies continue to emerge, as there is no denying the potential of MSCs to treat a wide variety of human afflictions. Therefore, the present review article provided an overview of MSCs and their differences compared with embryonic stem cells, and described the molecular mechanisms involved in maintaining their stemness. In addition, the article examined the therapeutic application of stem cells in the field of cancer. The present article also discussed the current divergent roles of MSCs in cancer therapy and the future potential in this field.

Autologous bone marrow-derived mesenchymal stem cells for interstitial fibrosis and tubular atrophy: a pilot study

Background

Mesenchymal stem cells (MSCs)-based therapy has shown promising results for renal injury. In this study, the efficacy and safety of autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) in treating nonspecific interstitial fibrosis and tubular atrophy (IFTA) were evaluated.

Methods

From March 2011 to January 2013, 11 renal transplanted patients with IFTA were recruited. At baseline, patients were given one intra-arterial infusion of BM-MSCs; 7 days and 1 month later, another two intravenous infusions of cells were followed. Serum creatinine, creatinine clearance rate, and serum cystatin-C at baseline and 7 days, 1 month, 3 months, 6 months, and 12 months after the intra-arterial infusion of BM-MSCs were used to assess renal function. At baseline and 6 months, histological examination based on hematoxylin-eosin, Masson’s trichrome and periodic acid-Schiff staining and immunohistochemistry for transforming growth factor β1 (TGF-β1) and connective tissue growth factor (CTGF) was performed. Adverse events were recorded to evaluate the safety of BM-MSCs treatment.

Results

At 12 months, the renal function of 6 patients (54.5%) was improved, 3 (27.3%) were stable and 2 (18.2%) were worsened. At 6 months, the mean IFTA scores of all participators were similar with the baseline (1.73 ± 0.41 vs.1.50 ± 0.0.77, p = 0.242); however, it was significantly decreased when only 6 patients with improved renal function were analyzed (1.67 ± 0.41 vs. 1.08 ± 0.20, p = 0.013). Besides, decreased expression of TGF-β1 and CTGF were also observed at 6 months. During 1 year follow-up period, only two minor complications including infection and allergy were observed.

Conclusion

Our results demonstrated that autologous BM-MSCs are safe and beneficial for IFTA patients. Abbreviations: MSCs: mesenchymal stem cells; BM-MSCs: marrow-derived mesenchymal stem cells; IFTA: interstitial fibrosis and tubular atrophy; CAN: chronic allograft nephropathy; CNIs: calcineurin inhibitors; Scr: serum creatinine; CCr: creatinine clearance rate; Cys-C: cystatin-C; TGF-β1: transforming growth factor β1; CTGF: connective tissue growth factor

A systematic review and meta-analysis of cell-based interventions in experimental diabetic kidney disease

Regenerative, cell‐based therapy is a promising treatment option for diabetic kidney disease (DKD), which has no cure. To prepare for clinical translation, this systematic review and meta‐analysis summarized the effect of cell‐based interventions in DKD animal models and treatment‐related factors modifying outcomes. Electronic databases were searched for original investigations applying cell‐based therapy in diabetic animals with kidney endpoints (January 1998‐May 2019). Weighted or standardized mean differences were estimated for kidney outcomes and pooled using random‐effects models. Subgroup analyses tested treatment‐related factor effects for outcomes (creatinine, urea, urine protein, fibrosis, and inflammation). In 40 studies (992 diabetic rodents), therapy included mesenchymal stem/stromal cells (MSC; 61%), umbilical cord/amniotic fluid cells (UC/AF; 15%), non‐MSC (15%), and cell‐derived products (13%). Tissue sources included bone marrow (BM; 65%), UC/AF (15%), adipose (9%), and others (11%). Cell‐based therapy significantly improved kidney function while reducing injury markers (proteinuria, histology, fibrosis, inflammation, apoptosis, epithelial‐mesenchymal‐transition, oxidative stress). Preconditioning, xenotransplantation, and disease‐source approaches were effective. MSC and UC/AF cells had greater effect on kidney function while cell products improved fibrosis. BM and UC/AF tissue sources more effectively improved kidney function and proteinuria vs adipose or other tissues. Cell dose, frequency, and administration route also imparted different benefits. In conclusion, cell‐based interventions in diabetic animals improved kidney function and reduced injury with treatment‐related factors modifying these effects. These findings may aid in development of optimal repair strategies through selective use of cells/products, tissue sources, and dose administrations to allow for successful adaptation of this novel therapeutic in human DKD.

Resveratrol Pretreatment Improved Heart Recovery Ability of Hyperglycemic Bone Marrow Stem Cells Transplantation in Diabetic Myocardial Infarction by Down-Regulating MicroRNA-34a

AIM: To examine the effect of resveratrol (RSV) on bone marrow mesenchymal stem cells (BMSCs) under hyperglycemic conditions and on BMSCs transplantation in diabetic rats with myocardial infarction (MI).

METHODS:In vitro, BMSCs were isolated from 3-week-old male Sprague Dawley (SD) rats and cultured under hyperglycemic conditions for up to 28 days. Cell viability was analyzed by cell counting kit-8 (CCK-8) assays. The expression of miR-34a was measured by RT-qPCR. Western blotting was used to examine the protein expression of SIRT1, P21, P16, VEGF and HIF-1α. A senescence-associated β-galactosidase assay was used to examine the senescence level of each group. In vivo, a diabetes model was established by feeding rats a high-sugar and high-fat diet for 8 weeks, injecting the animals with streptozotocin (STZ) and continuing high-sugar and high-fat feeding for 4 additional weeks. Then, left anterior descending coronary artery (LAD) cessation was used to established the myocardial infarction (MI) models. Each group of rats was transplanted with differentially preconditioned BMSCs after myocardial infarction. Ultrasound was used to analyze cardiac function 1 and 3 weeks after the operation, and frozen heart sections were used for immunohistochemical analysis, Masson staining and CD31 measurement. In addition, ELISA analysis of serum cytokine levels was performed.

RESULTS: This study showed that the viability of BMSCs cultured under hyperglycemic conditions was decreased, the cells became senescent. Besides, an obviously increased in the expression of miR-34a was detected. Moreover, RSV preconditioning reduced the expression of miR-34a in BMSCs after high glucose stimulation and rejuvenated BMSCs under hyperglycemic conditions. Further analysis showed that the transplantation of RSV-BMSCs were benefit to heart recovery following infarction in diabetic rats, promoted proangiogenic factor release and increased arteriole and capillary densities.

CONCLUSION: RSV rejuvenated BMSCs after chronic hyperglycemia-induced senescence by interacting with miR-34a and optimized the therapeutic effect of BMSCs on diabetes with myocardial infarction.

Sleeve Gastrectomy Attenuates Diabetic Nephropathy by Upregulating Nephrin Expressions in Diabetic Obese Rats

PURPOSE

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease, and sleeve gastrectomy (SG) is considered to be an effective strategy to improve pre-existing DN. However, the mechanism remains unknown.

MATERIALS AND METHODS

Animal model of DN was induced by high-fat diet (HFD) and streptozotocin (STZ). SG or sham surgery was performed and rats were sacrificed at 4, 8, and 12 weeks after surgery. The basic parameters (blood glucose, body weight, kidney weight), indicators of renal function including serum creatinine (Scr), blood urea nitrogen (BUN), urine microalbumin, urine creatinine (Ucr), microalbumin creatinine ratio (UACR), ultrastructural changes of glomerulus, and the expression of nephrin gene and protein in glomerular podocytes were compared among groups.

RESULTS

Blood glucose and body weight of SG rats were significantly lower than those of the sham-operated rats, and renal function of SG groups were also significantly improved within the postoperative period of 12 weeks. The results of periodic acid-Schiff staining (PAS) and transmission electron microscopy (TEM) showed that glomerular hypertrophy and accumulation of extracellular matrix proteins were significantly alleviated after SG, and the thickness of basement membrane and the fusion or effacement of foot processes were also significantly improved. The mRNA and protein expression of nephrin in SG groups was significantly higher than that in the sham group.

CONCLUSION

These results suggest that SG attenuates DN by upregulating the expression of nephrin and improving the ultrastructure of glomerular filtration membrane. This study indicates that SG can be used as an available therapeutic intervention for DN.

Human umbilical cord mesenchymal stem cells attenuate podocyte injury under high glucose via TLR2 and TLR4 signaling

AIMS

This research aimed to investigate the effects of high glucose (HG) on the innate immunity of podocytes and diabetic nephropathy (DN) mice via Toll like receptor (TLR) signaling, and explore the protective effectsof human umbilical cord mesenchymal stem cells (HUC-MSCs) on this process.

METHODS

HUC-MSCs obtained from human umbilical cord were cocultured with podocytes and transplanted into DN mice. Flow cytometry, CCK-8assay, ELISA, western blot analysis, periodicacid-schiff, masson, immunohistochemistry and immunofluorescence staining was used to detect the inflammation, TLR signaling, physical, biochemical and morphological parameters in podocytes and DN mice.

RESULTS

HG reduced the viability of podocytes, activated TLR2 and TLR4 signaling pathway and increased the expression of inflammatory cytokines such as IL-6, IL-1β, TNF-α, and MCP-1 in podocytes and DN mice. However, HUC-MSCs decreased the inflammation and restrained the TLR signaling pathway caused by HG in vitro and in vivo. Furthermore the rhHGF decreased the expression of TLR2 and TLR4 while the blockade of HGF increased the expression of TLR2 and TLR4 in podocytes.

CONCLUSIONS

HUC-MSCs have benefits to the podocytes under HG and the progression of DN by inhibiting TLR signaling pathway and depressing the inflammation. HUC-MSCs may be a therapeutic strategy for treating patients with DN.

MiR-34a inhibitor protects mesenchymal stem cells from hyperglycaemic injury through the activation of the SIRT1/FoxO3a autophagy pathway

BACKGROUND

Mesenchymal stem cells (MSCs) are favourable treatments for ischaemic diseases; however, MSCs from diabetic patients are not useful for this purpose. Recent studies have shown that the expression of miR-34a is significantly increased in patients with hyperglycaemia; the precise role of miR-34a in MSCs in diabetes needs to be clarified.

OBJECTIVE

The aim of this study is to determine the precise role of miR-34a in MSCs exposed to hyperglycaemia and in recovery heart function after myocardial infarction (MI) in diabetes mellitus (DM) rats.

METHODS

DM rat models were established by high-fat diet combined with streptozotocin (STZ) injection. MSCs were isolated from the bone marrow of donor rats. Chronic culture of MSCs under high glucose was used to mimic the DM micro-environment. The role of miR-34a in regulating cell viability, senescence and paracrine effects were investigated using a cell counting kit-8 (CCK-8) assay, senescence-associated β-galactosidase (SA-β-gal) staining and vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) ELISA, respectively. The expression of autophagy- and senescence-associated proteins in MSCs and silent information regulator 1 (SIRT1) and forkhead box class O 3a (FoxO3a) were analysed by western blotting. Autophagic bodies were analysed by transmission electron microscopy (TEM). The MI model was established by left anterior descending coronary artery (LAD) ligation, and then, the rats were transplanted with differentially treated MSCs intramuscularly at sites around the border zone of the infarcted heart. Thereafter, cardiac function in rats in each group was detected via cardiac ultrasonography at 1 week and 3 weeks after surgery. The infarct size was determined through a 2,3,5-triphenyltetrazolium chloride (TTC) staining assay, while myocardial fibrosis was assessed by Masson staining.

RESULTS

The results of the current study showed that miR-34a was significantly increased under chronic hyperglycaemia exposure. Overexpression of miR-34a was significantly associated with impaired cell viability, exacerbated senescence and disrupted cell paracrine capacity. Moreover, we found that the mechanism underlying miR-34a-mediated deterioration of MSCs exposed to high glucose involved the activation of the SIRT1/FoxO3a autophagy pathway. Further analysis showed that miR-34a inhibitor-treated MSC transplantation could improve cardiac function and decrease the scar area in DM rats.

CONCLUSIONS

Our study demonstrates for the first time that miR-34a mediates the deterioration of MSCs' functions under hyperglycaemia. The underlying mechanism may involve the SIRT1/FoxO3a autophagy signalling pathway. Thus, inhibition of miR-34a might have important therapeutic implications in MSC-based therapies for myocardial infarction in DM patients.

Time-sequential correlations between diabetic kidney disease and diabetic retinopathy in type 2 diabetes - an 8-year prospective cohort study

PURPOSE

To investigate the time-sequential correlations between progression/remission of diabetic kidney disease (DKD) and development of diabetic retinopathy (DR) or diabetic macular oedema (DME) in type 2 diabetes (T2D).

METHODS

This was an 8-year prospective cohort study in which 576 patients with T2D and microalbuminuria from one medical centre in Taiwan were recruited. Progression of microalbuminuria was defined as shift of urinary albumin/creatinine ratio (ACR) into 300 mg/g or more; remission of microalbuminuria was defined as having a urinary ACR less than 30 mg/g in at least two of three tests over a period of 6 months. Cox regression analysis was used to evaluate the hazard ratios (HRs) for progression or remission of microalbuminuria on development of any DR, proliferative DR (PDR) and DME.

RESULTS

After adjusting for baseline characteristics , remission of microalbuminuria was a significant protecting factor for development of PDR (HR = 0.290, 95% CI: 0.102-0.826, p = 0.020) and DME (HR = 0.404, 95% CI: 0.188-0.864, p = 0.020). After further adjustment for the mean follow-up HbA1c and systolic blood pressure, remission of microalbuminuria was still a significant protecting factor for development of PDR (HR = 0.348, 95% CI: 0.122-0.992, p = 0.048).

CONCLUSIONS

Remission of microalbuminuria was an independent protecting factor for development of PDR and DME. Aggressive treatment for DKD might help prevent the progression of DR.

Senescence-Associated Secretory Phenotype Suppression Mediated by Small-Sized Mesenchymal Stem Cells Delays Cellular Senescence through TLR2 and TLR5 Signaling

In order to provide a sufficient number of cells for clinical use, mesenchymal stem cells (MSCs) must be cultured for long-term expansion, which inevitably triggers cellular senescence. Although the small size of MSCs is known as a critical determinant of their fate, the main regulators of stem cell senescence and the underlying signaling have not been addressed. Umbilical cord blood-derived MSCs (UCB-MSCs) were obtained using size-isolation methods and then cultured with control or small cells to investigate the major factors that modulate MSC senescence. Cytokine array data suggested that the secretion of interukin-8 (IL-8) or growth-regulated oncogene-alpha (GROa) by senescent cells was markedly inhibited during incubation of small cells along with suppression of cognate receptor (C-X-C motif chemokine receptor2, CXCR2) via blockade of the autocrine/paracrine positive loop. Moreover, signaling via toll-like receptor 2 (TLR2) and TLR5, both pattern recognition receptors, drove cellular senescence of MSCs, but was inhibited in small cells. The activation of TLRs (2 and 5) through ligand treatment induced a senescent phenotype in small cells. Collectively, our data suggest that small cell from UCB-MSCs exhibit delayed cellular senescence by inhibiting the process of TLR signaling-mediated senescence-associated secretory phenotype (SASP) activation.

MYDGF attenuates podocyte injury and proteinuria by activating Akt/BAD signal pathway in mice with diabetic kidney disease

AIMS/HYPOTHESIS

Myeloid-derived growth factor (MYDGF), mainly secreted by bone marrow-derived cells, has been known to promote glucagon-like peptide-1 production and improve glucose/lipid metabolism in mouse models of diabetes, but little is known about the functions of MYDGF in diabetic kidney disease (DKD). Here, we investigated whether MYDGF can prevent the progression of DKD.

METHODS

In vivo experiments, both loss- and gain-of-function strategies were used to evaluate the effect of MYDGF on albuminuria and pathological glomerular lesions. We used streptozotocin-treated Mydgf knockout and wild-type mice on high fat diets to induce a model of DKD. Then, albuminuria, glomerular lesions and podocyte injury were evaluated in Mydgf knockout and wild-type DKD mice treated with adeno-associated virus-mediated Mydgf gene transfer. In vitro and ex vivo experiments, the expression of slit diaphragm protein nephrin and podocyte apoptosis were evaluated in conditionally immortalised mouse podocytes and isolated glomeruli from non-diabetic wild-type mice treated with recombinant MYDGF.

RESULTS

MYDGF deficiency caused more severe podocyte injury in DKD mice, including the disruption of slit diaphragm proteins (nephrin and podocin) and an increase in desmin expression and podocyte apoptosis, and subsequently caused more severe glomerular injury and increased albuminuria by 39.6% compared with those of wild-type DKD mice (p < 0.01). Inversely, MYDGF replenishment attenuated podocyte and glomerular injury in both wild-type and Mydgf knockout DKD mice and then decreased albuminuria by 36.7% in wild-type DKD mice (p < 0.01) and 34.9% in Mydgf knockout DKD mice (p < 0.01). Moreover, recombinant MYDGF preserved nephrin expression and inhibited podocyte apoptosis in vitro and ex vivo. Mechanistically, the renoprotection of MYDGF was attributed to the activation of the Akt/Bcl-2-associated death promoter (BAD) pathway.

CONCLUSIONS/INTERPRETATION

The study demonstrates that MYDGF protects podocytes from injury and prevents the progression of DKD, providing a novel strategy for the treatment of DKD. Graphical abstract.

Anti-Fibrotic Effect of Human Wharton's Jelly-Derived Mesenchymal Stem Cells on Skeletal Muscle Cells, Mediated by Secretion of MMP-1

Extracellular matrix (ECM) components play an important role in maintaining skeletal muscle function, but excessive accumulation of ECM components interferes with skeletal muscle regeneration after injury, eventually inducing fibrosis. Increased oxidative stress level caused by dystrophin deficiency is a key factor in fibrosis in Duchenne muscular dystrophy (DMD) patients. Mesenchymal stem cells (MSCs) are considered a promising therapeutic agent for various diseases involving fibrosis. In particular, the paracrine factors secreted by MSCs play an important role in the therapeutic effects of MSCs. In this study, we investigated the effects of MSCs on skeletal muscle fibrosis. In 2–5-month-old mdx mice intravenously injected with 1 × 10⁵ Wharton’s jelly (WJ)-derived MSCs (WJ-MSCs), fibrosis intensity and accumulation of calcium/necrotic fibers were significantly decreased. To elucidate the mechanism of this effect, we verified the effect of WJ-MSCs in a hydrogen peroxide-induced fibrosis myotubes model. In addition, we demonstrated that matrix metalloproteinase-1 (MMP-1), a paracrine factor, is critical for this anti-fibrotic effect of WJ-MSCs. These findings demonstrate that WJ-MSCs exert anti-fibrotic effects against skeletal muscle fibrosis, primarily via MMP-1, indicating a novel target for the treatment of muscle diseases, such as DMD.

Human umbilical cord-derived mesenchymal stem cells prevent the progression of early diabetic nephropathy through inhibiting inflammation and fibrosis

Background

Diabetic nephropathy (DN) is one of the most serious complications of diabetes and the leading cause of end-stage chronic kidney disease. Currently, there are no effective drugs for treating DN. Therefore, novel and effective strategies to ameliorate DN at the early stage should be identified. This study aimed to explore the effectiveness and underlying mechanisms of human umbilical cord mesenchymal stem cells (UC-MSCs) in DN.

Methods

We identified the basic biological properties and examined the multilineage differentiation potential of UC-MSCs. Streptozotocin (STZ)-induced DN rats were infused with 2 × 10⁶ UC-MSCs via the tail vein at week 6. After 2 weeks, we measured blood glucose level, levels of renal function parameters in the blood and urine, and cytokine levels in the kidney and blood, and analyzed renal pathological changes after UC-MSC treatment. We also determined the colonization of UC-MSCs in the kidney with or without STZ injection. Moreover, in vitro experiments were performed to analyze cytokine levels of renal tubular epithelial cell lines (NRK-52E, HK2) and human renal glomerular endothelial cell line (hrGECs).

Results

UC-MSCs significantly ameliorated functional parameters, such as 24-h urinary protein, creatinine clearance rate, serum creatinine, urea nitrogen, and renal hypertrophy index. Pathological changes in the kidney were manifested by significant reductions in renal vacuole degeneration, inflammatory cell infiltration, and renal interstitial fibrosis after UC-MSC treatment. We observed that the number of UC-MSCs recruited to the injured kidneys was increased compared with the controls. UC-MSCs apparently reduced the levels of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) and pro-fibrotic factor (TGF-β) in the kidney and blood of DN rats. In vitro experiments showed that UC-MSC conditioned medium and UC-MSC-derived exosomes decreased the production of these cytokines in high glucose-injured renal tubular epithelial cells, and renal glomerular endothelial cells. Moreover, UC-MSCs secreted large amounts of growth factors including epidermal growth factor, fibroblast growth factor, hepatocyte growth factor, and vascular endothelial growth factor.

Conclusion

UC-MSCs can effectively improve the renal function, inhibit inflammation and fibrosis, and prevent its progression in a model of diabetes-induced chronic renal injury, indicating that UC-MSCs could be a promising treatment strategy for DN.

The future of diabetic kidney disease management: what to expect from the experimental studies?

Diabetic kidney disease (DKD) is a major cause of end-stage renal disease. Intensive blood glucose and blood pressure control, particularly using inhibitors of the renin-angiotensin system, have long been mainstays of therapy in patients with DKD. Moreover, new anti-hyperglycemic drugs have recently shown renoprotective effects and this represents a major progress in the management of DKD. However, the risk of progression is still substantial and additional drugs are required. Recent preclinical studies have identified novel therapeutic targets that may optimize renoprotection in the near future. Besides strategies aimed to reduce oxidative stress and inflammation in the kidney, novel extra-renal approaches targeting stem cells, extracellular vesicles, and the microbiota are on the horizon with promising preclinical data. Herein, we will review these lines of research and discuss potential clinical applications. Given the poor yield of experimental studies in DKD in the past years, we will also discuss strategies to improve translation of preclinical research to humans.

Role of Mesenchymal Stromal Cells as Therapeutic Agents: Potential Mechanisms of Action and Implications in Their Clinical Use

Due to the great therapeutic interest that involves the translation of mesenchymal stromal cells (MSCs) into clinical practice, they have been widely studied as innovative drugs, in order to treat multiple pathologies. MSC-based cell therapy involves the administration of MSCs either locally or systemically into the receptor body where they can traffic and migrate towards the affected tissue and participate in the process of healing. The therapeutic effects of MSCs compromise of different mechanisms such as the functional integration of differentiated MSCs into diseased host tissue after transplantation, their paracrine support, and their impact on the regulation of both the innate and the acquired immune system. Here, we establish and provide recent advances about the principal mechanisms of action through which MSCs can perform their activity and effect as a therapeutic tool. The purpose of this review is to examine and discuss the MSCs capacity of migration, their paracrine effect, as well as MSC-mediated modifications on immune cell responses.

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

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

Mesenchymal Stem Cells Reduce Corneal Fibrosis and Inflammation via Extracellular Vesicle-Mediated Delivery of miRNA

Mesenchymal stem cells from corneal stromal stem cells (CSSC) prevent fibrotic scarring and stimulate regeneration of transparent stromal tissue after corneal wounding in mice. These effects rely on the ability of CSSC to block neutrophil infiltration into the damaged cornea. The current study investigated the hypothesis that tissue regeneration by CSSC is mediated by secreted extracellular vesicles (EVs). CSSC produced EVs 130-150 nm in diameter with surface proteins that include CD63, CD81, and CD9. EVs from CSSC reduced visual scarring in murine corneal wounds as effectively as did live cells, but EVs from human embryonic kidney (HEK)293T cells had no regenerative properties. CSSC EV treatment of wounds decreased expression of fibrotic genes Col3a1 and Acta2, blocked neutrophil infiltration, and restored normal tissue morphology. CSSC EVs labeled with carboxyfluorescein succinimidyl ester dye, rapidly fused with corneal epithelial and stromal cells in culture, transferring microRNA (miRNA) to the target cells. Knockdown of mRNA for Alix, a component of the endosomal sorting complex required for transport, using siRNA, resulted in an 85% reduction of miRNA in the secreted EVs. The EVs with reduced miRNA were ineffective at blocking corneal scarring. Furthermore, CSSC with reduced Alix expression also lost their regenerative function, suggesting EVs as an obligate component in the delivery of miRNA. The results of these studies support an essential role for extracellular vesicles in the process by which CSSC cells block scarring and initiate regeneration of transparent corneal tissue after wounding. EVs appear to serve as a delivery vehicle for miRNA, which affects the regenerative action. Stem Cells Translational Medicine 2019;8:1192-1201.

Stem Cell Therapies in Kidney Diseases: Progress and Challenges

The prevalence of renal diseases is emerging as a public health problem. Despite major progress in supportive therapy, mortality rates among patients remain high. In an attempt to find innovative treatments to stimulate kidney regeneration, stem cell-based technology has been proposed as a potentially promising strategy. Here, we summarise the renoprotective potential of pluripotent and adult stem cell therapy in experimental models of acute and chronic kidney injury and we explore the different mechanisms at the basis of stem cell-induced kidney regeneration. Specifically, cell engraftment, incorporation into renal structures, or paracrine activities of embryonic or induced pluripotent stem cells as well as mesenchymal stem cells and renal precursors are analysed. We also discuss the relevance of stem cell secretome-derived bioproducts, including soluble factors and extracellular vesicles, and the option of using them as cell-free therapy to induce reparative processes. The translation of the experimental results into clinical trials is also addressed, highlighting the safety and feasibility of stem cell treatments in patients with kidney injury.

Stem cells as a potential therapy for diabetes mellitus: a call-to-action in Latin America

Latin America is a fast-growing region that currently faces unique challenges in the treatment of all forms of diabetes mellitus. The burden of this disease will be even greater in the coming years due, in part, to the large proportion of young adults living in urban areas and engaging in unhealthy lifestyles. Unfortunately, the national health systems in Latin-American countries are unprepared and urgently need to reorganize their health care services to achieve diabetic therapeutic goals. Stem cell research is attracting increasing attention as a promising and fast-growing field in Latin America. As future healthcare systems will include the development of regenerative medicine through stem cell research, Latin America is urged to issue a call-to-action on stem cell research. Increased efforts are required in studies focused on stem cells for the treatment of diabetes. In this review, we aim to inform physicians, researchers, patients and funding sources about the advances in stem cell research for possible future applications in diabetes mellitus. Emerging studies are demonstrating the potential of stem cells for β cell differentiation and pancreatic regeneration. The major economic burden implicated in patients with diabetes complications suggests that stem cell research may relieve diabetic complications. Closer attention should be paid to stem cell research in the future as an alternative treatment for diabetes mellitus.