Cell-based therapies for experimental chronic kidney disease: a systematic review and meta-analysis

Safety and Biodistribution of an Autologous Bone Marrow-Derived Mononuclear Cell Infusion into Renal Arteries in Patients with Focal Segmental Glomerulosclerosis: A Phase 1 Study

Patients with focal segmental glomerulosclerosis (FSGS) who are refractory to drug treatment may present progressive loss of kidney function, leading to chronic kidney disease stage 5 under dialysis treatment. The safety of systemic administration of bone marrow-derived mononuclear cells (BMDMCs) has been shown in different preclinical models of kidney diseases. However, to date, no study has evaluated the safety and biodistribution of BMDMCs after infusion in renal arteries in patients with FSGS. We used a prospective, non-randomized, single-center longitudinal design to investigate this approach. Five patients with refractory FSGS and an estimated glomerular filtration rate (eGFR) between 20 and 40 ml/min/1.73 m2 underwent bone marrow aspiration and received an arterial infusion of autologous BMDMCs (5 × 107) for each kidney. In addition, BMDMCs labeled with technetium-99m (99mTc-BMDMCs) were used to assess the biodistribution by scintigraphy. All patients completed the 270-day follow-up protocol with no serious adverse events. A transient increase in creatinine was observed after the cell therapy, with improvement on day 30. 99mTc-BMDMCs were detected in both kidneys and counts were higher after 2 hr compared with 24 hr. The arterial infusion of BMDMCs in both kidneys of patients with FSGS was considered safe with stable eGFR at the end of follow-up. This trial is registered with NCT02693366.

Advances in the Treatment of Kidney Disorders using Mesenchymal Stem Cells

Renal disease is a medical condition that poses a potential threat to the life of an individual and is related to substantial morbidity and mortality rates in clinical environments. The aetiology of this condition is influenced by multiple factors, and its incidence tends to increase with progressive aging. Although supportive therapy and kidney transplantation have potential advantages, they also have limitations in terms of mitigating the progression of KD. Despite significant advancements in the domain of supportive therapy, mortality rates in patients continue to increase. Due to their ability to self-renew and multidirectionally differentiate, stem cell therapy has been shown to have tremendous potential in the repair of the diseased kidney. MSCs (Mesenchymal stem cells) are a cell population that is extensively distributed and can be located in various niches throughout an individual's lifespan. The cells in question are characterised by their potential for indefinite replication and their aptitude for undergoing differentiation into fully developed cells of mesodermal origin under laboratory conditions. It is essential to emphasize that MSCs have demonstrated a favorable safety profile and efficacy as a therapeutic intervention for renal diseases in both preclinical as well as clinical investigations. MSCs have been found to slow the advancement of kidney disease, and this impact is thought to be due to their control over a number of physiological processes, including immunological response, tubular epithelial- mesenchymal transition, oxidative stress, renal tubular cell death, and angiogenesis. In addition, MSCs demonstrate recognised effectiveness in managing both acute and chronic kidney diseases via paracrine pathways. The proposal to utilise a therapy that is based on stem-cells as an effective treatment has been put forward in search of discovering novel therapies to promote renal regeneration. Preclinical researchers have demonstrated that various types of stem cells can provide advantages in acute and chronic kidney disease. Moreover, preliminary results from clinical trials have suggested that these interventions are both safe and well-tolerated. This manuscript provides a brief overview of the potential renoprotective effects of stem cell-based treatments in acute as well as chronic renal dysfunction. Furthermore, the mechanisms that govern the process of kidney regeneration induced by stem cells are investigated. This article will examine the therapeutic approaches that make use of stem cells for the treatment of kidney disorders. The analysis will cover various cellular sources that have been utilised, potential mechanisms involved, and the outcomes that have been achieved so far.

Repetitive administration of cultured human CD34+ cells improve adenine-induced kidney injury in mice

BACKGROUND

There is no established treatment to impede the progression or restore kidney function in human chronic kidney disease (CKD).

AIM

To examine the efficacy of cultured human CD34+ cells with enhanced proliferating potential in kidney injury in mice.

METHODS

Human umbilical cord blood (UCB)-derived CD34+ cells were incubated for one week in vasculogenic conditioning medium. Vasculogenic culture significantly increased the number of CD34+ cells and their ability to form endothelial progenitor cell colony-forming units. Adenine-induced tubulointerstitial injury of the kidney was induced in immunodeficient non-obese diabetic/severe combined immunodeficiency mice, and cultured human UCB-CD34+ cells were administered at a dose of 1 × 10⁶/mouse on days 7, 14, and 21 after the start of adenine diet.

RESULTS

Repetitive administration of cultured UCB-CD34+ cells significantly improved the time-course of kidney dysfunction in the cell therapy group compared with that in the control group. Both interstitial fibrosis and tubular damage were significantly reduced in the cell therapy group compared with those in the control group (P < 0.01). Microvasculature integrity was significantly preserved (P < 0.01) and macrophage infiltration into kidney tissue was dramatically decreased in the cell therapy group compared with those in the control group (P < 0.001).

CONCLUSION

Early intervention using human cultured CD34+ cells significantly improved the progression of tubulointerstitial kidney injury. Repetitive administration of cultured human UCB-CD34+ cells significantly improved tubulointerstitial damage in adenine-induced kidney injury in mice via vasculoprotective and anti-inflammatory effects.

Renal Autologous Cell Therapy in Type 2 Diabetes with Late Stage 4 Diabetes-Related Chronic Kidney Disease: Trial Design and Early Analysis

INTRODUCTION

Cell-based therapies potentially delay the trajectory toward end-stage kidney disease (ESKD) in late stage 4 diabetic chronic kidney disease (DKD). We describe the trial design, baseline patient characteristics, and early results of an IRB-approved phase II multicenter clinical trial, utilizing Renal Autologous Cell Therapy (REACT) in adults with pre-ESKD due to type 2 DKD. The trial objectives were safety and tolerability of REACT by assessment of the procedure, product administration, and renal-specific adverse events in addition to evaluate the impact on renal function following injection.

METHODS

Ten adults with an eGFR of 14-20 mL/min/1.73 m2 were enrolled in a single-arm open-label trial. Following a percutaneous kidney biopsy, an ex vivo expansion of selected renal cells that form the REACT was injected into the cortex of the biopsied kidney with CT image guidance. Each participant received two doses of the REACT product at 6-month intervals. A 6-month observation pre-trial was required to establish patients' "own" baseline and rate of DKD progression.

RESULTS

Five men and 5 women underwent 19 REACT injections (1 participant received only one injection). Their baseline characteristics were as follows: 3 Hispanic/Latino, 7 non-Hispanic, 7 white; mean (SD) age: 58.9 years (5.22), BMI 35.8 (8.2), eGFR (sCR) 15.5 (2.72), eGFR (sCR + Cys-C) 17.7 (3.67) mL/min/1.73 m2, sCr 3.6 mg/mL (0.73), Cys-C 2.6 mg/mL (0.52), and log random UACR 7.9 mg/g (1.01). The pre- and post-injection eGFR slope was -6.5 mL/min/1.73 m2 and -3.9 mL/min/1.73 m2. No cell-related adverse events occurred, and two procedure-related hematomas required observation without transfusion or angiographic interventions. Dialysis was delayed a mean of 16 months (range 6-28 months). At 15 months, 2 patients (20%) have eGFR slope stability and have not commenced renal replacement therapy.

CONCLUSION

Trials that include patients with an eGFR of <20 mL/min/1.73 m2 are uncommon, and none to date involve autologous homologous cell-based treatments. REACT has the potential to stabilize or delay dialysis in high-risk late stage 4 DKD.

Chronic Kidney Disease: Challenges in Translational Medicine

Chronic kidney disease (CKD) has long been recognized as a state of progressive decline in renal function. Morbidity and mortality are well correlated to the stage of renal function decline. Approximately one million deaths are estimated to be related to CKD worldwide. They are mostly associated with cardiovascular disease as a result of concurrent hypertension, accelerated atherosclerosis, and volume overload. Even with the best current treatment, disease progression is the general rule with a small fraction who reach CKD stage 5 requiring kidney transplantation or dialysis. Transplant patients show substantial reductions in mortality and cardiovascular events, as well as improvements in quality of life. However, the capacity of health systems to deliver kidney transplantation varies worldwide with worse indicators in low-income countries. Consequently, exploring novel and better therapeutic options for CKD is mandatory. Cell-based therapy is a promising strategy for treating CKD in preclinical models, and several clinical trials involving kidney disease exhibit a favorable safety profile. This chapter aims to provide an overview of CKD and the recent results of clinical trials of cell therapy in kidney diseases.

Still finding ways to augment the existing management of acute and chronic kidney diseases with targeted gene and cell therapies: Opportunities and hurdles

The rising global incidence of acute and chronic kidney diseases has increased the demand for renal replacement therapy. This issue, compounded with the limited availability of viable kidneys for transplantation, has propelled the search for alternative strategies to address the growing health and economic burdens associated with these conditions. In the search for such alternatives, significant efforts have been devised to augment the current and primarily supportive management of renal injury with novel regenerative strategies. For example, gene- and cell-based approaches that utilize recombinant peptides/proteins, gene, cell, organoid, and RNAi technologies have shown promising outcomes primarily in experimental models. Supporting research has also been conducted to improve our understanding of the critical aspects that facilitate the development of efficient gene- and cell-based techniques that the complex structure of the kidney has traditionally limited. This manuscript is intended to communicate efforts that have driven the development of such therapies by identifying the vectors and delivery routes needed to drive exogenous transgene incorporation that may support the treatment of acute and chronic kidney diseases.

The therapeutic potential of Camel Wharton jelly mesenchymal stem cells (CWJ-MSCs) in canine chronic kidney disease model

Background

Chronic kidney disease (CKD) is a worldwide health problem that its incidence increases nowadays with the increase in the risk of environmental pollution. CKD can progress to end-stage renal disease (ESRD) which usually ends fatally. This study aimed to examine the therapeutic potential of Camel Wharton jelly-mesenchymal stem cells (CWJ-MSCs) in chronic kidney disease model induced in dogs.

Methods

CWJ-MSCs were injected directed to the kidney with ultrasonographic guidance in dogs with 5/6 nephrectomy to evaluate its therapeutic potency in such cases. Analysis of variance was applied in normally distributed quantitative variables while a non-parametric Mann–Whitney test was used for non-normally distributed quantitative variables.

Results

The serum urea and creatinine in the treated group were significantly decreased transferring dogs in the treated group from stage 3 to stage 2 CKD according to the IRIS staging system. Histopathology of renal tissue revealed improving CKD lesions by increasing regeneration of degenerated tubules, maintaining the integrity of glomeruli. New vascularization with blood vessels remodeling were common findings. Periodic acid Schiff stain of renal tissue showed the integrity of renal tubules and thickness of the glomerular basement membrane. Fibrosis of cortex and medulla was lower in the treated group than in the CKD model as monitored by Mallory’s trichrome stain (MTC). NGAL and KIM-1 genes expression were decreased while VEGF and EGF genes expression were increased indicating renal tissue repair.

Conclusions

CWJ-MSCs have a therapeutic potential in the CKD model induced in dogs.

Efficacy and Safety of Human Bone Marrow-Derived Mesenchymal Stem Cells according to Injection Route and Dose in a Chronic Kidney Disease Rat Model

Background and Objectives

We compared the efficacy and safety of human bone marrow-derived mesenchymal stem cells (hBMSC), delivered at different doses and via different injection routes in an animal model of chronic kidney disease.

Methods and Results

A total of ninety 12-week-old rats underwent 5/6 nephrectomy and randomized among nine groups: sham, renal artery control (RA-C), tail vein control (TV-C), renal artery low dose (RA-LD) (0.5×10⁶ cells), renal artery moderate dose (RA-MD) (1.0×10⁶ cells), renal artery high dose (RA-HD) (2.0×10⁶ cells), tail vein low dose (TV-LD) (0.5×10⁶ cells), tail vein moderate dose (TV-MD) (1.0×10⁶ cells), and tail vein high dose (TV-HD) (2.0×10⁶ cells). Renal function and mortality of rats were evaluated after hBMSC injection. Serum blood urea nitrogen was significantly lower in the TV-HD group at 2 weeks (p<0.01), 16 weeks (p<0.05), and 24 weeks (p<0.01) than in the TV-C group, as determined by one-way ANOVA. Serum creatinine was significantly lower in the TV-HD group at 24 weeks (p<0.05). At 8 weeks, creatinine clearance was significantly higher in the TV-MD and TV-HD groups (p<0.01, p<0.05) than in the TV-C group. In the safety evaluation, we observed no significant difference among the groups.

Conclusions

Our findings confirm the efficacy and safety of high dose (2×10⁶ cells) injection of hBMSC via the tail vein.

A Novel Approach to Enhance the Regenerative Potential of Circulating Endothelial Progenitor Cells in Patients with End-Stage Kidney Disease

Circulating bone marrow-derived endothelial progenitor cells (EPCs) facilitate vascular repair in several organs including the kidney but are progressively diminished in end-stage kidney disease (ESKD) patients, which correlates with cardiovascular outcomes and related mortality. We thus determined if enhancing the tissue-reparative effects of human bone marrow-derived mesenchymal stromal cells (BM-MSCs) with the vasculogenic effects of recombinant human relaxin (RLX) could promote EPC proliferation and function. CD34⁺ EPCs were isolated from the blood of healthy and ESKD patients, cultured until late EPCs had formed, then stimulated with BM-MSC-derived condition media (CM; 25%), RLX (1 or 10 ng/mL), or both treatments combined. Whilst RLX alone stimulated EPC proliferation, capillary tube formation and wound healing in vitro, these measures were more rapidly and markedly enhanced by the combined effects of BM-MSC-derived CM and RLX in EPCs derived from both healthy and ESKD patients. These findings have important clinical implications, having identified a novel combination therapy that can restore and enhance EPC number and function in ESKD patients.

Allogeneic adipose tissue-derived stem cells ELIXCYTE® in chronic kidney disease: A phase I study assessing safety and clinical feasibility

The purpose of this phase I clinical trial is to assess the safety and tolerability of allogeneic adipose tissue‐derived stem cells (ADSCs) among chronic kidney disease (CKD) patients. 12 eligible CKD patients with an estimated glomerular filtration rate (eGFR) of 15–44 ml/min/1.73 m² received one dose of intravenous allogeneic ADSCs (ELIXCYTE^®), as 3 groups: 3 low dose (6.4 × 10⁷ cells in total of 8 ml), 3 middle dose (19.2 × 10⁷ cells in total of 24 ml) and 6 high dose (32.0 × 10⁷ cells in total of 40 ml) of ELIXCYTE^® and evaluated after 48 weeks. Primary endpoint was the safety profiles in terms of incidence of adverse events (AEs) and serious adverse event (SAE). Two subjects in high dose group experienced a total of 2 treatment‐related AEs which are Grade 1 slow speech and Grade 1 bradyphrenia after the infusion. One subject in middle dose group experienced an SAE unlikely related to treatment, grade 2 proteinuria. No fatal AE was reported in this study. An increase in eGFR was observed in 7 out of 12 subjects (58%) at Week 24 and in 6 of 12 subjects (50%) by Week 48. By Week 24, an increase in eGFR by more than 20% among all CKD patients with baseline eGFR ≧ 30 ml/min/1.73 m² as compared to only 2 subjects in baseline eGFR < 30 ml/min/1.73 m² group. No significant reduction in proteinuria was noted among all subjects. This phase I trial demonstrated single‐dose intravenous ELIXCYTE was well tolerated in moderate‐to‐severe CKD patients and its preliminary efficacy warrants future studies.

Effects of obesity on reparative function of human adipose tissue-derived mesenchymal stem cells on ischemic murine kidneys

Introduction:

Obesity is a health burden that impairs cellular processes. Mesenchymal stem/stromal cells (MSCs) are endowed with reparative properties and can ameliorate renal injury. Obesity impairs human MSC function in-vitro, but its effect on their in-vivo reparative potency remains unknown.

Subjects and Methods:

Abdominal adipose tissue-derived MSC were harvested from patients without (‘lean’) or with obesity (‘obese’) (body mass index<30 or ≥30kg/m², respectively) during kidney donation or bariatric surgery, respectively. MSC (5x10⁵/200μL) or vehicle were then injected into 129S1 mice 2 weeks after renal artery stenosis (RAS) or sham surgery (n=8/group). Two weeks later, mice underwent magnetic resonance imaging to assess renal perfusion and oxygenation in-vivo, and kidneys then harvested for ex-vivo studies.

Results:

Similar numbers of lean and obese-MSCs engrafted in stenotic mouse kidneys. Vehicle-treated RAS mice had reduced stenotic-kidney cortical and medullary perfusion and oxygenation. Lean (but not obese) MSC normalized ischemic kidney cortical perfusion, whereas both effectively mitigated renal hypoxia. Serum creatinine and blood pressure were elevated in RAS mice and lowered only by lean-MSC. Both types of MSCs alleviated stenotic-kidney fibrosis, but lean-MSC more effectively than obese-MSC. MSC senescence-associated beta-gal activity, and gene expression of p16, p21, and vascular endothelial growth factor correlated with recipient kidney perfusion and tissue injury, linking MSC characteristics with their in-vivo reparative capacity.

Discussion:

Human obesity impairs the reparative properties of adipose-tissue-derived MSCs, possibly by inducing cellular senescence. Dysfunction and senescence of the endogenous MSC repair system in patients with obesity may warrant targeting interventions to restore MSC vitality.

Combined meta-analysis of preclinical cell therapy studies shows overlapping effect modifiers for multiple diseases

Introduction

Cell therapy has been studied in many different research domains. Cellular replacement of damaged solid tissues is at an early stage of development, with much still to be understood. Systematic reviews and meta-analyses are widely used to aggregate data and find important patterns of results within research domains.

We set out to find common biological denominators affecting efficacy in preclinical cell therapy studies for renal, neurological and cardiac disease.

Methods

We used datasets of five previously published meta-analyses investigating cell therapy in preclinical models of chronic kidney disease, spinal cord injury, stroke and ischaemic heart disease. We transformed primary outcomes to ratios of means to permit direct comparison across disease areas. Prespecified variables of interest were species, immunosuppression, cell type, cell origin, dose, delivery and timing of the cell therapy.

Results

The five datasets from 506 publications yielded data from 13 638 animals. Animal size affects therapeutic efficacy in an inverse manner. Cell type influenced efficacy in multiple datasets differently, with no clear trend for specific cell types being superior. Immunosuppression showed a negative effect in spinal cord injury and a positive effect in cardiac ischaemic models. There was a dose–dependent relationship across the different models. Pretreatment seems to be superior compared with administration after the onset of disease.

Conclusions

Preclinical cell therapy studies are affected by multiple variables, including species, immunosuppression, dose and treatment timing. These data are important when designing preclinical studies before commencing clinical trials.

Mesenchymal stromal cells: what have we learned so far about their therapeutic potential and mechanisms of action?

Mesenchymal stromal cells (MSCs) have been found to be safe and effective in a wide range of animal models of human disease. MSCs have been tested in thousands of clinical trials, but results show that while these cells appear to be safe, they tend to lack efficacy. This has raised questions about whether animal models are useful for predicting efficacy in patients. However, a problem with animal studies is that there is a lack of standardisation in the models and MSC therapy regimes used; there appears to be publication bias towards studies reporting positive outcomes; and the reproducibility of results from animal experiments tends not to be confirmed prior to clinical translation. A further problem is that while some progress has been made towards investigating the mechanisms of action (MoA) of MSCs, we still fail to understand how they work. To make progress, it is important to ensure that prior to clinical translation, the beneficial effects of MSCs in animal studies are real and can be repeated by independent research groups. We also need to understand the MoA of MSCs to assess whether their effects are likely to be beneficial across different species. In this review, we give an overview of the current clinical picture of MSC therapies and discuss what we have learned from animal studies. We also give a comprehensive update of what we know about the MoA of MSCs, particularly in relation to their role in immunomodulation.

When Origin Matters: Properties of Mesenchymal Stromal Cells From Different Sources for Clinical Translation in Kidney Disease

Advanced therapy medicinal products (ATMPs) offer new prospects to improve the treatment of conditions with unmet medical needs. Kidney diseases are a current major health concern with an increasing global prevalence. Chronic renal failure appears after many years of impairment, which opens a temporary window to apply novel therapeutic approaches to delay or halt disease progression. The immunomodulatory, anti-inflammatory, and pro-regenerative properties of mesenchymal stromal cells (MSCs) have sparked interest for their use in cell-based regenerative therapies. Currently, several early-phase clinical trials have been completed and many are ongoing to explore MSC safety and efficacy in a wide range of nephropathies. However, one of the current roadblocks to the clinical translation of MSC therapies relates to the lack of standardization and harmonization of MSC manufacturing protocols, which currently hinders inter-study comparability. Studies have shown that cell culture processing variables can have significant effects on MSC phenotype and functionality, and these are highly variable across laboratories. In addition, heterogeneity within MSC populations is another obstacle. Furthermore, MSCs may be isolated from several sources which adds another variable to the comparative assessment of outcomes. There is now a growing body of literature highlighting unique and distinctive properties of MSCs according to the tissue origin, and that characteristics such as donor, age, sex and underlying medical conditions may alter the therapeutic effect of MSCs. These variables must be taken into consideration when developing a cell therapy product. Having an optimal scale-up strategy for MSC manufacturing is critical for ensuring product quality while minimizing costs and time of production, as well as avoiding potential risks. Ideally, optimal scale-up strategies must be carefully considered and identified during the early stages of development, as making changes later in the bioprocess workflow will require re-optimization and validation, which may have a significant long-term impact on the cost of the therapy. This article provides a summary of important cell culture processing variables to consider in the scale-up of MSC manufacturing as well as giving a comprehensive review of tissue of origin-specific biological characteristics of MSCs and their use in current clinical trials in a range of renal pathologies.

Current advances of stem cell-based therapy for kidney diseases

Kidney diseases are a prevalent health problem around the world. Multidrug therapy used in the current routine treatment for kidney diseases can only delay disease progression. None of these drugs or treatments can reverse the progression to an end-stage of the disease. Therefore, it is crucial to explore novel therapeutics to improve patients’ quality of life and possibly cure, reverse, or alleviate the kidney disease. Stem cells have promising potentials as a form of regenerative medicine for kidney diseases due to their unlimited replication and their ability to differentiate into kidney cells in vitro. Mounting evidences from the administration of stem cells in an experimental kidney disease model suggested that stem cell-based therapy has therapeutic or renoprotective effects to attenuate kidney damage while improving the function and structure of both glomerular and tubular compartments. This review summarises the current stem cell-based therapeutic approaches to treat kidney diseases, including the various cell sources, animal models or in vitro studies. The challenges of progressing from proof-of-principle in the laboratory to widespread clinical application and the human clinical trial outcomes reported to date are also highlighted. The success of cell-based therapy could widen the scope of regenerative medicine in the future.

Diabetic Kidney Disease Alters the Transcriptome and Function of Human Adipose-Derived Mesenchymal Stromal Cells but Maintains Immunomodulatory and Paracrine Activities Important for Renal Repair

Mesenchymal stem/stromal cells (MSCs) facilitate repair in experimental diabetic kidney disease (DKD). However, the hyperglycemic and uremic milieu may diminish regenerative capacity of patient-derived therapy. We hypothesized that DKD reduces human MSC paracrine function. Adipose-derived MSC from 38 participants with DKD and 16 control subjects were assessed for cell surface markers, trilineage differentiation, RNA sequencing (RNA-seq), in vitro function (coculture or conditioned medium experiments with T cells and human kidney cells [HK-2]), secretome profile, and cellular senescence abundance. The direction of association between MSC function and patient characteristics were also tested. RNA-seq analysis identified 353 differentially expressed genes and downregulation of several immunomodulatory genes/pathways in DKD-MSC versus Control-MSC. DKD-MSC phenotype, differentiation, and tube formation capacity were preserved, but migration was reduced. DKD-MSC with and without interferon-γ priming inhibited T-cell proliferation greater than Control-MSC. DKD-MSC medium contained higher levels of anti-inflammatory cytokines (indoleamine 2,3-deoxygenase 1 and prostaglandin-E2) and prorepair factors (hepatocyte growth factor and stromal cell-derived factor 1) but lower IL-6 versus control-MSC medium. DKD-MSC medium protected high glucose plus transforming growth factor-β-exposed HK-2 cells by reducing apoptotic, fibrotic, and inflammatory marker expression. Few DKD-MSC functions were affected by patient characteristics, including age, sex, BMI, hemoglobin A_1c, kidney function, and urine albumin excretion. However, senescence-associated β-galactosidase activity was lower in DKD-MSC from participants on metformin therapy. Therefore, while DKD altered the transcriptome and migratory function of culture-expanded MSCs, DKD-MSC functionality, trophic factor secretion, and immunomodulatory activities contributing to repair remained intact. These observations support testing of patient-derived MSC therapy and may inform preconditioning regimens in DKD clinical trials.

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.

Harnessing the Physiological Functions of Cellular Prion Protein in the Kidneys: Applications for Treating Renal Diseases

A cellular prion protein (PrP^C) is a ubiquitous cell surface glycoprotein, and its physiological functions have been receiving increased attention. Endogenous PrP^C is present in various kidney tissues and undergoes glomerular filtration. In prion diseases, abnormal prion proteins are found to accumulate in renal tissues and filtered into urine. Urinary prion protein could serve as a diagnostic biomarker. PrP^C plays a role in cellular signaling pathways, reno-protective effects, and kidney iron uptake. PrP^C signaling affects mitochondrial function via the ERK pathway and is affected by the regulatory influence of microRNAs, small molecules, and signaling proteins. Targeting PrP^C in acute and chronic kidney disease could help improve iron homeostasis, ameliorate damage from ischemia/reperfusion injury, and enhance the efficacy of mesenchymal stem/stromal cell or extracellular vesicle-based therapeutic strategies. PrP^C may also be under the influence of BMP/Smad signaling and affect the progression of TGF-β-related renal fibrosis. PrP^C conveys TNF-α resistance in some renal cancers, and therefore, the coadministration of anti-PrP^C antibodies improves chemotherapy. PrP^C can be used to design antibody-drug conjugates, aptamer-drug conjugates, and customized tissue inhibitors of metalloproteinases to suppress cancer. With preclinical studies demonstrating promising results, further research on PrP^C in the kidney may lead to innovative PrP^C-based therapeutic strategies for renal disease.

Therapeutic Insights in Chronic Kidney Disease Progression

Chronic kidney disease (CKD) has been recognized as a leading public health problem worldwide. Through its effect on cardiovascular risk and end-stage kidney disease, CKD directly affects the global burden of morbidity and mortality. Classical optimal management of CKD includes blood pressure control, treatment of albuminuria with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, avoidance of potential nephrotoxins and obesity, drug dosing adjustments, and cardiovascular risk reduction. Diabetes might account for more than half of CKD burden, and obesity is the most important prompted factor for this disease. New antihyperglycemic drugs, such as sodium-glucose-cotransporter 2 inhibitors have shown to slow the decline of GFR, bringing additional benefit in weight reduction, cardiovascular, and other kidney outcomes. On the other hand, a new generation of non-steroidal mineralocorticoid receptor antagonist has recently been developed to obtain a selective receptor inhibition reducing side effects like hyperkalemia and thereby making the drugs suitable for administration to CKD patients. Moreover, two new potassium-lowering therapies have shown to improve tolerance, allowing for higher dosage of renin-angiotensin system inhibitors and therefore enhancing their nephroprotective effect. Regardless of its cause, CKD is characterized by reduced renal regeneration capacity, microvascular damage, oxidative stress and inflammation, resulting in fibrosis and progressive, and irreversible nephron loss. Therefore, a holistic approach should be taken targeting the diverse processes and biological contexts that are associated with CKD progression. To date, therapeutic interventions when tubulointerstitial fibrosis is already established have proved to be insufficient, thus research effort should focus on unraveling early disease mechanisms. An array of novel therapeutic approaches targeting epigenetic regulators are now undergoing phase II or phase III trials and might provide a simultaneous regulatory activity that coordinately regulate different aspects of CKD progression.

Administration of mesenchymal stem cells in diabetic kidney disease: a systematic review and meta-analysis

BACKGROUND

Mesenchymal stem cell (MSC) therapy shows great promise for diabetic kidney disease (DKD) patients. Research has been carried out on this topic in recent years. The main goals of this paper are to evaluate the therapeutic effects of MSCs on DKD through a meta-analysis and address the mechanism through a systematic review of the literature.

METHOD

An electronic search of the Embase, Cochrane Library, ISI Web of Science, PubMed, and US National Library of Medicine (NLM) databases was performed for all articles about MSC therapy for DKD, without species limitations, up to January 2020. Data were pooled for analysis with Stata SE 12.

RESULT

The MSC-treated group showed a large and statistically significant hypoglycemic effect at 1 week, 2 weeks, 3 weeks, 1 month, 2 months, 3 months, and 6 months. Total hypoglycemic effect was observed (SMD = - 1.954, 95%CI - 2.389 to - 1.519, p < 0.001; I² = 85.1%). The overall effects on serum creatinine (SCr) and blood urea nitrogen (BUN) were analyzed, suggesting that MSC decreased SCr and BUN and mitigated the impairment of renal function (SCr: SMD = - 4.838, 95%CI - 6.789 to - 2.887, p < 0.001; I² = 90.8%; BUN: SMD = - 4.912, 95%CI - 6.402 to - 3.422, p < 0.001; I² = 89.3%). Furthermore, MSC therapy decreased the excretion of urinary albumin. Fibrosis indicators were assessed, and the results showed that transforming growth factor-β, collagen I, fibronectin, and α-smooth muscle actin were significantly decreased in the MSC-treated group compared to the control group.

CONCLUSION

MSCs might improve glycemic control and reduce SCr, BUN, and urinary protein. MSCs can also alleviate renal fibrosis. MSC therapy might be a potential treatment for DKD.

Matrix Metalloproteinases and Tissue Inhibitors of Metalloproteinases in Extracellular Matrix Remodeling during Left Ventricular Diastolic Dysfunction and Heart Failure with Preserved Ejection Fraction: A Systematic Review and Meta-Analysis

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are pivotal regulators of extracellular matrix (ECM) composition and could, due to their dynamic activity, function as prognostic tools for fibrosis and cardiac function in left ventricular diastolic dysfunction (LVDD) and heart failure with preserved ejection fraction (HFpEF). We conducted a systematic review on experimental animal models of LVDD and HFpEF published in MEDLINE or Embase. Twenty-three studies were included with a total of 36 comparisons that reported established LVDD, quantification of cardiac fibrosis and cardiac MMP or TIMP expression or activity. LVDD/HFpEF models were divided based on underlying pathology: hemodynamic overload (17 comparisons), metabolic alteration (16 comparisons) or ageing (3 comparisons). Meta-analysis showed that echocardiographic parameters were not consistently altered in LVDD/HFpEF with invasive hemodynamic measurements better representing LVDD. Increased myocardial fibrotic area indicated comparable characteristics between hemodynamic and metabolic models. Regarding MMPs and TIMPs; MMP2 and MMP9 activity and protein and TIMP1 protein levels were mainly enhanced in hemodynamic models. In most cases only mRNA was assessed and there were no correlations between cardiac tissue and plasma levels. Female gender, a known risk factor for LVDD and HFpEF, was underrepresented. Novel studies should detail relevant model characteristics and focus on MMP and TIMP protein expression and activity to identify predictive circulating markers in cardiac ECM remodeling.

Adipose stem cells exhibit mechanical memory and reduce fibrotic contracture in a rat elbow injury model

Fibrosis is driven by a misdirected cell response causing the overproduction of extracellular matrix and tissue dysfunction. Numerous pharmacological strategies have attempted to prevent fibrosis but have attained limited efficacy with some detrimental side effects. While stem cell treatments have provided more encouraging results, they have exhibited high variability and have not always improved tissue function. To enhance stem cell efficacy, we evaluated whether mechanical memory could direct cell response. We hypothesized that mechanically pre-conditioning on a soft matrix (soft priming) will delay adipose-derived stem cell (ASC) transition to a pro-fibrotic phenotype, expanding their regenerative potential, and improving healing in a complex tissue environment. Primary ASCs isolated from rat and human subcutaneous fat exhibited mechanical memory, demonstrated by a delayed cell response to stiffness following two weeks of soft priming including decreased cell area, actin coherency, and extracellular matrix production compared to cells on stiff substrates. Soft primed ASCs injected into our rat model of post-traumatic elbow contracture decreased histological evidence of anterior capsule fibrosis and increased elbow range-of-motion when evaluated by joint mechanics. These findings suggest that exploiting mechanical memory by strategically controlling the culture environment during cell expansion may improve the efficacy of stem cell-based therapies targeting fibrosis.

Regulatory T Cells as a Novel Candidate for Cell-Based Therapy in Kidney Disease

Kidney disease is a significant health concern worldwide. Ineffective treatment can lead to disastrous consequences, such as organ failure and death. Research has turned to cell-based therapy, but has yet to produce an effective and reliable treatment for kidney disease. To address this problem, we examined four datasets of gene expression profiles from diseased and healthy kidney tissue in humans, mice, and rats. Differentially expressed genes (DEGs) were screened and subjected to enrichment analyses. Up-regulated genes in diseased kidney tissue were significantly enriched in pathways associated with regulatory T cells (Tregs). Analysis with the xCell tool showed that Tregs were generally increased in diseased kidney tissue in all species. To validate these results in vivo, kidneys were removed from mice with Adriamycin-induced nephropathy, and histology confirmed increase of Tregs. Furthermore, Tregs were adoptively transferred from healthy mice into mice with kidney injury, restoring normal structure to the damaged kidneys. Treg cells that were co-cultured with M2c macrophages exhibited up-regulation of chemokine receptors CCR2, CCR5, CCR7, CD62L, and CX3CR1. This may be the mechanism by which M2c cells enhance the migration of Tregs to the site of inflammation. We propose that Tregs may be an effective, novel candidate for cell-based therapy in pre-clinical kidney injury models.

A Novel Approach to Deliver Therapeutic Extracellular Vesicles Directly into the Mouse Kidney via Its Arterial Blood Supply

Diseases of the kidney contribute a significant morbidity and mortality burden on society. Localized delivery of therapeutics directly into the kidney, via its arterial blood supply, has the potential to enhance their therapeutic efficacy while limiting side effects associated with conventional systemic delivery. Targeted delivery in humans is feasible given that we can access the renal arterial blood supply using minimally invasive endovascular techniques and imaging guidance. However, there is currently no described way to reproduce or mimic this approach in a small animal model. Here, we develop in mice a reproducible microsurgical technique for the delivery of therapeutics directly into each kidney, via its arterial blood supply. Using our technique, intra-arterially (IA) injected tattoo dye homogenously stained both kidneys, without staining any other organ. Survival studies showed no resulting mortality or iatrogenic kidney injury. We demonstrate the therapeutic potential of our technique in a mouse model of cisplatin-induced acute kidney injury (AKI). IA injection of mesenchymal stromal cell (MSC)-derived extracellular vesicles (EVs) successfully reversed AKI, with reduced physiological and molecular markers of kidney injury, attenuated inflammation, and restoration of proliferation and regeneration markers. This reproducible delivery technique will allow for further pre-clinical translational studies investigating other therapies for the treatment of renal pathologies.

Adipose Mesenchymal Cells-Derived EVs Alleviate DOCA-Salt-Induced Hypertension by Promoting Cardio-Renal Protection

Hypertension is a long-term condition that can increase organ susceptibility to insults and lead to severe complications such as chronic kidney disease (CKD). Extracellular vesicles (EVs) are cell-derived membrane structures that participate in cell-cell communication by exporting encapsulated molecules to target cells, regulating physiological and pathological processes. We here demonstrate that multiple administration of EVs from adipose-derived mesenchymal stromal cells (ASC-EVs) in deoxycorticosterone acetate (DOCA)-salt hypertensive model can protect renal tissue by maintaining its filtration capacity. Indeed, ASC-EVs downregulated the pro-inflammatory molecules monocyte chemoattracting protein-1 (MCP-1) and plasminogen activating inhibitor-1 (PAI1) and reduced recruitment of macrophages in the kidney. Moreover, ASC-EVs prevented cardiac tissue fibrosis and maintained blood pressure within normal levels, thus demonstrating their multiple favorable effects in different organs. By applying microRNA (miRNA) microarray profile of the kidney of DOCA-salt rats, we identified a selective miRNA signature associated with epithelial-mesenchymal transition (EMT). One of the key pathways found was the axis miR-200-TGF-β, that was significantly altered by EV administration, thereby affecting the EMT signaling and preventing renal inflammatory response and fibrosis development. Our results indicate that EVs can be a potent therapeutic tool for the treatment of hypertension-induced CKD in cardio-renal syndrome.

Targeting the progression of chronic kidney disease

Chronic kidney disease (CKD) is a devastating condition that is reaching epidemic levels owing to the increasing prevalence of diabetes mellitus, hypertension and obesity, as well as ageing of the population. Regardless of the underlying aetiology, CKD is slowly progressive and leads to irreversible nephron loss, end-stage renal disease and/or premature death. Factors that contribute to CKD progression include parenchymal cell loss, chronic inflammation, fibrosis and reduced regenerative capacity of the kidney. Current therapies have limited effectiveness and only delay disease progression, underscoring the need to develop novel therapeutic approaches to either stop or reverse progression. Preclinical studies have identified several approaches that reduce fibrosis in experimental models, including targeting cytokines, transcription factors, developmental and signalling pathways and epigenetic modulators, particularly microRNAs. Some of these nephroprotective strategies are now being tested in clinical trials. Lessons learned from the failure of clinical studies of transforming growth factor β1 (TGFβ1) blockade underscore the need for alternative approaches to CKD therapy, as strategies that target a single pathogenic process may result in unexpected negative effects on simultaneously occurring processes. Additional promising avenues include preventing tubular cell injury and anti-fibrotic therapies that target activated myofibroblasts, the main collagen-producing cells.

Protective Effects of Human Nonrenal and Renal Stromal Cells and Their Conditioned Media in a Rat Model of Chronic Kidney Disease

Mesenchymal stromal cells (MSCs) are emerging as a novel therapeutic option for limiting chronic kidney disease progression. Conditioned medium (CM) containing bioactive compounds could convey similar benefits, avoiding the potential risks of cell therapy. This study compared the efficacy of nonrenal and renal cell-based therapy with the corresponding CM in rats with renal mass reduction (RMR). Infusions of human kidney stromal cells (kPSCs) and CM-kPSCs, but not umbilical cord (uc) MSCs or CM-ucMSCs, reduced proteinuria and preserved podocyte number and nephrin expression in RMR rats. Glomerular fibrosis, microvascular rarefaction, and apoptosis were reduced by all treatments, while the peritubular microvascular loss was reduced by kPSCs and CM-kPSCs treatment only. Importantly, kPSCs and CM-kPSCs reduced NG2-positive pericytes, and all therapies reduced α-smooth muscle actin expression, indicating reduced myofibroblast expansion. Treatment with kPSCs also significantly inhibited the accumulation of ED1-positive macrophages in the renal interstitium of RMR rats. These findings demonstrate that the CM of ucMSCs and kPSCs confers similar renoprotection as the cells. kPSCs and CM-kPSCs may be superior in attenuating chronic renal injury as a cell source.

Paracrine Proangiogenic Function of Human Bone Marrow-Derived Mesenchymal Stem Cells Is Not Affected by Chronic Kidney Disease

Background

Cell-based therapies are being developed to meet the need for curative therapy in chronic kidney disease (CKD). Bone marrow- (BM-) derived mesenchymal stromal cells (MSCs) enhance tissue repair and induce neoangiogenesis through paracrine action of secreted proteins and extracellular vesicles (EVs). Administration of allogeneic BM MSCs is less desirable in a patient population likely to require a kidney transplant, but potency of autologous MSCs should be confirmed, given previous indications that CKD-induced dysfunction is present. While the immunomodulatory capacity of CKD BM MSCs has been established, it is unknown whether CKD affects wound healing and angiogenic potential of MSC-derived CM and EVs.

Methods

MSCs were cultured from BM obtained from kidney transplant recipients (N = 15) or kidney donors (N = 17). Passage 3 BM MSCs and BM MSC-conditioned medium (CM) were used for experiments. EVs were isolated from CM by differential ultracentrifugation. BM MSC differentiation capacity, proliferation, and senescence-associated β-galactosidase activity was assessed. In vitro promigratory and proangiogenic capacity of BM MSC-derived CM and EVs was assessed using an in vitro scratch wound assay and Matrigel angiogenesis assay.

Results

Healthy and CKD BM MSCs exhibited similar differentiation capacity, proliferation, and senescence-associated β-galactosidase activity. Scratch wound migration was not significantly different between healthy and CKD MSCs (P = 0.18). Healthy and CKD BM MSC-derived CM induced similar tubule formation (P = 0.21). There was also no difference in paracrine regenerative function of EVs (scratch wound: P = 0.6; tubulogenesis: P = 0.46).

Conclusions

Our results indicate that MSCs have an intrinsic capacity to produce proangiogenic paracrine factors, including EVs, which is not affected by donor health status regarding CKD. This suggests that autologous MSC-based therapy is a viable option in CKD.

Melatonin preconditioning is an effective strategy for mesenchymal stem cell-based therapy for kidney disease

Based on multiple studies in animal models, mesenchymal stem cell (MSC)‐based therapy appears to be an innovative intervention approach with tremendous potential for the management of kidney disease. However, the clinical therapeutic effects of MSCs in either acute kidney injury (AKI) or chronic kidney disease (CKD) are still under debate. Hurdles originate from the harsh microenvironment in vivo that decreases the cell survival rate, paracrine activity and migratory capacity of MSCs after transplantation, which are believed to be the main reasons for their limited effects in clinical applications. Melatonin is traditionally regarded as a circadian rhythm‐regulated neurohormone but in recent years has been found to exhibit antioxidant and anti‐inflammatory properties. Because inflammation, oxidative stress, thermal injury, and hypoxia are abnormally activated in kidney disease, application of melatonin preconditioning to optimize the MSC response to the hostile in vivo microenvironment before transplantation is of great importance. In this review, we discuss current knowledge concerning the beneficial effects of melatonin preconditioning in MSC‐based therapy for kidney disease. By summarizing the available information and discussing the underlying mechanisms, we aim to improve the therapeutic effects of MSC‐based therapy for kidney disease and accelerate translation to clinical application.

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

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

Human Fetal Bone Marrow-Derived Mesenchymal Stem Cells Promote the Proliferation and Differentiation of Pancreatic Progenitor Cells and the Engraftment Function of Islet-Like Cell Clusters

Pancreatic progenitor cells (PPCs) are the primary source for all pancreatic cells, including beta-cells, and thus the proliferation and differentiation of PPCs into islet-like cell clusters (ICCs) opens an avenue to providing transplantable islets for diabetic patients. Meanwhile, mesenchymal stem cells (MSCs) can enhance the development and function of different cell types of interest, but their role on PPCs remains unknown. We aimed to explore the mechanism-of-action whereby MSCs induce the in vitro and in vivo PPC/ICC development by means of our established co-culture system of human PPCs with human fetal bone marrow-derived MSCs. We examined the effect of MSC-conditioned medium on PPC proliferation and survival. Meanwhile, we studied the effect of MSC co-culture enhanced PPC/ICC function in vitro and in vivo co-/transplantation. Furthermore, we identified IGF1 as a critical factor responsible for the MSC effects on PPC differentiation and proliferation via IGF1-PI3K/Akt and IGF1-MEK/ERK1/2, respectively. In conclusion, our data indicate that MSCs stimulated the differentiation and proliferation of human PPCs via IGF1 signaling, and more importantly, promoted the in vivo engraftment function of ICCs. Taken together, our protocol may provide a mechanism-driven basis for the proliferation and differentiation of PPCs into clinically transplantable islets.

Effect of Bone Marrow-Derived Mesenchymal Stem Cells on Ischaemic-Reperfused Hearts in Adult Rats with Established Chronic Kidney Disease

Background and Objectives

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are adult multipotent non-haematopoietic stem cells that have regeneration potential. The current study aimed to detect the ability of BM-MSCs to improve kidney and cardiac functions in adult rats with established chronic kidney disease.

Methods

Rats were divided into sham-operated control, untreated sub totally nephrectomised and treated sub totally nephrectomised groups. Body weight, kidney and cardiac tissue weights, plasma creatinine and urea levels and arterial blood pressure were measured. ECG was recorded, and an in vitro isolated heart study was performed.

Results

Stem cell treatment decreased the elevated plasma creatinine and urea levels and decreased systolic, diastolic and mean arterial blood pressure values. These changes were accompanied by a decrease in glomerular hypertrophy with apparent normal renal parenchyma. Additionally, BM-MSCs shortened Q-To and Q-Tc intervals, all time to peak tension values, the half relaxation value at 30 min of reperfusion and the contraction time at 15 and 30 min of reperfusion. Moreover, stem cell treatment significantly increased the heart rate, QRS voltage, the peak tension at the 15- and 30-min reperfusion time points and the peak tension per left ventricle at the 30-min reperfusion time point compared to the pre-ischaemia baseline. BM-MSCs resolve inter muscular oedema and lead to the re-appearance of normal cardiomyocytes. This improvement occurs with the observations of BM-MSCs in renal and heart tissues.

Conclusions

BM-MSCs can attenuate chronic kidney disease progression and the associated cardiac electrophysiological and inotropic dysfunction.

Adipose tissue-derived mesenchymal stromal cells for treating chronic kidney disease: A pilot study assessing safety and clinical feasibility

Background

Chronic kidney disease (CKD) is a growing public health concern, and available treatments are insufficient in limiting disease progression. New strategies, including regenerative cell-based therapies, have emerged as therapeutic alternatives. Results from several groups, including our own, have reported evidence of a supportive role for mesenchymal stromal cells (MSCs) in functional recovery and prevention of tissue damage in murine models of CKD. Prompted by these data, an open pilot study was conducted to assess the safety and efficacy of a single injection of autologous adipose tissue-derived MSCs (AT-MSCs) for treatment of CKD.

Methods

AT-MSCs were infused intravenously into six CKD patients at a dose of 1 million cells/kg. Patients were stabilized and followed for one year prior to MSC infusion and one year following infusion.

Results

No patients presented with adverse effects. Statistically significant improvement in urinary protein excretion was observed in AT-MSCs transplanted patients, from a median of 0.75 g/day (range, 0.15-9.57) at baseline to 0.54 g/day (range, 0.01-2.66) at month 12 (P = 0.046). The glomerular filtration rate was not significantly decreased post-infusion of AT-MSCs.

Conclusion

Findings from this pilot study demonstrate that intravenous infusion of autologous expanded AT-MSCs into CKD patients was not associated with adverse effects and could benefit patients already undergoing standard medical treatment.

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.

Potential and Therapeutic Efficacy of Cell-based Therapy Using Mesenchymal Stem Cells for Acute/chronic Kidney Disease

Kidney disease can be either acute kidney injury (AKI) or chronic kidney disease (CKD) and it can lead to the development of functional organ failure. Mesenchymal stem cells (MSCs) are derived from a diverse range of human tissues. They are multipotent and have immunomodulatory effects to assist in the recovery from tissue injury and the inhibition of inflammation. Numerous studies have investigated the feasibility, safety, and efficacy of MSC-based therapies for kidney disease. Although the exact mechanism of MSC-based therapy remains uncertain, their therapeutic value in the treatment of a diverse range of kidney diseases has been studied in clinical trials. The use of MSCs is a promising therapeutic strategy for both acute and chronic kidney disease. The mechanism underlying the effects of MSCs on survival rate after transplantation and functional repair of damaged tissue is still ambiguous. The paracrine effects of MSCs on renal recovery, optimization of the microenvironment for cell survival, and control of inflammatory responses are thought to be related to their interaction with the damaged kidney environment. This review discusses recent experimental and clinical findings related to kidney disease, with a focus on the role of MSCs in kidney disease recovery, differentiation, and microenvironment. The therapeutic efficacy and current applications of MSC-based kidney disease therapies are also discussed.

Alterations in genetic and protein content of swine adipose tissue-derived mesenchymal stem cells in the metabolic syndrome

INTRODUCTION

Mesenchymal stem cells (MSCs) possess endogenous reparative properties and may serve as an exogenous therapeutic intervention in patients with chronic kidney disease. Cardiovascular risk factors clustering in the metabolic syndrome (MetS) might adversely affect cellular properties. To test the hypothesis that Mets interferes with MSC characteristics, we performed comprehensive comparison of the mRNA, microRNA, and protein content of MSCs isolated from Lean and MetS pigs.

METHODS

Domestic pigs were fed a 16-week Lean or MetS diet (n = 4 each). Expression profiles of co-existing microRNAs, mRNAs, and proteins were obtained by high-throughput sequencing and liquid chromatography-mass spectrometry. TargetScan and ComiR were used to predict target genes of differentially expressed microRNAs, and DAVID 6.7 for functional annotation analysis to rank primary gene ontology categories for the microRNA target genes, mRNAs, and proteins.

RESULTS

Differential expression analysis revealed 12 microRNAs upregulated in MetS-MSCs compared to Lean-MSCs (fold change>1.4, p < .05), which target 7728 genes, whereas 33 mRNAs and 78 proteins were downregulated (fold change<0.7, p < .05). Integrated analysis showed that targets of those microRNAs upregulated in MetS-MSCs overlap with at least half of mRNAs and proteins dysregulated in those cells. Functional analysis of overlapping mRNAs and proteins suggest that they are primarily involved in mitochondria, inflammation and transcription. MetS-MSCs also exhibited increased nuclear translocation of nuclear factor kappa-B, associated with increased SA-β-Galactosidase and decreased cytochrome-c oxidase-IV activity.

CONCLUSION

MetS alters the transcriptome and proteome of swine adipose tissue-derived MSCs particularly genes involved in mitochondria, inflammation and transcription regulation. These alterations might limit the reparative function of endogenous MSC and their use as an exogenous regenerative therapy.

Human umbilical cord-derived mesenchymal stem cells enhanced HK-2 cell autophagy through MicroRNA-145 by inhibiting the PI3K/AKT/mTOR signaling pathway

Recent studies have shown that autophagy exhibits a protective role in acute kidney injury (AKI), and the accumulation of advanced oxidation protein products (AOPP) participates in the progression of kidney diseases. Our previous study indicated that AOPP induced injury in renal tubular epithelial cells (RTECs) through autophagy inhibition. Besides, we found that human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) enhanced autophagy in AOPP-treated RTECs, but the underlying mechanism remains unclear. We regulated microRNA-145 (miR-145) expression in HK-2 cells (a cell line of RTECs), or co-cultured hUC-MSCs with HK-2 cells and studied the autophagic activity in HK-2 cells to explore the underlying mechanism. Our data demonstrated that upregulated miR-145 increased LC3 II and Beclin 1 levels, decreased p62 level, three autophagy related proteins, inhibited the phosphorylation of PI3K/AKT/mTOR, and increased LC3B-positive staining and the autophagosome number. Furthermore, hUC-MSCs enhanced autophagy and inhibited phosphorylation of PI3K/AKT/mTOR in AOPP-treated HK-2 cells, which was then partially rescued using miR-145 knockdown in the hUC-MSCs co-culture system. In conclusion, our study showed that hUC-MSCs enhanced autophagy in AOPP-treated HK-2 cells mediated by miR-145 via inhibition of the PI3K/AKT/mTOR pathway, which indicated that hUC-MSCs might serve as a prospective therapy for AKI.

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.

Non-invasive imaging reveals conditions that impact distribution and persistence of cells after in vivo administration

Background

Cell-based regenerative medicine therapies are now frequently tested in clinical trials. In many conditions, cell therapies are administered systemically, but there is little understanding of their fate, and adverse events are often under-reported. Currently, it is only possible to assess safety and fate of cell therapies in preclinical studies, specifically by monitoring animals longitudinally using multi-modal imaging approaches. Here, using a suite of in vivo imaging modalities to explore the fate of a range of human and murine cells, we investigate how route of administration, cell type and host immune status affect the fate of administered cells.

Methods

We applied a unique imaging platform combining bioluminescence, optoacoustic and magnetic resonance imaging modalities to assess the safety of different human and murine cell types by following their biodistribution and persistence in mice following administration into the venous or arterial system.

Results

Longitudinal imaging analyses (i) suggested that the intra-arterial route may be more hazardous than intravenous administration for certain cell types, (ii) revealed that the potential of a mouse mesenchymal stem/stromal cell (MSC) line to form tumours depended on administration route and mouse strain and (iii) indicated that clinically tested human umbilical cord (hUC)-derived MSCs can transiently and unexpectedly proliferate when administered intravenously to mice.

Conclusions

In order to perform an adequate safety assessment of potential cell-based therapies, a thorough understanding of cell biodistribution and fate post administration is required. The non-invasive imaging platform used here can expose not only the general organ distribution of these therapies, but also a detailed view of their presence within different organs and, importantly, tumourigenic potential. Our observation that the hUC-MSCs but not the human bone marrow (hBM)-derived MSCs persisted for a period in some animals suggests that therapies with these cells should proceed with caution.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1076-x) contains supplementary material, which is available to authorized users.

Concise Reviews: Stem Cells and Kidney Regeneration: An Update

Significant progress has been made to advance stem cell products as potential therapies for kidney diseases: various kinds of stem cells can restore renal function in preclinical models of acute and chronic kidney injury. Nonetheless this literature contains contradictory results, and for this reason, we focus this review on reasons for apparent discrepancies in the literature, because they contribute to difficulty in translating renal regenerative therapies. Differences in methodologies used to derive and culture stem cells, even those from the same source, in addition to the lack of standardized renal disease animal models (both acute and chronic), are important considerations underlying contradictory results in the literature. We propose that harmonized rigorous protocols for characterization, handling, and delivery of stem cells in vivo could significantly advance the field, and present details of some suggested approaches to foster translation in the field of renal regeneration. Our goal is to encourage coordination of methodologies (standardization) and long‐lasting collaborations to improve protocols and models to lead to reproducible, interpretable, high‐quality preclinical data. This approach will certainly increase our chance to 1 day offer stem cell therapeutic options for patients with all‐too‐common renal diseases. Stem Cells Translational Medicine2019;8:82–92

The use of hydrogels for cell-based treatment of chronic kidney disease

Chronic kidney disease (CKD) is a major and growing public health concern with increasing incidence and prevalence worldwide. The therapeutic potential of stem cell therapy, including mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) holds great promise for treatment of CKD. However, there are significant bottlenecks in the clinical translation due to the reduced number of transplanted cells and the duration of their presence at the site of tissue damage. Bioengineered hydrogels may provide a route of cell delivery to enhance treatment efficacy and optimise the targeting effectiveness while minimising any loss of cell function. In this review, we highlight the advances in stem cell therapy targeting kidney disease and discuss the emerging role of hydrogel delivery systems to fully realise the potential of adult stem cells as a regenerative therapy for CKD in humans. MSCs and EPCs mediate kidney repair through distinct paracrine effects. As a delivery system, hydrogels can prolong these paracrine effects by improving retention at the site of injury and protecting the transplanted cells from the harsh inflammatory microenvironment. We also discuss the features of a hydrogel, which may be tuned to optimise the therapeutic potential of encapsulated stem cells, including cell-adhesive epitopes, material stiffness, nanotopography, modes of gelation and degradation and the inclusion of bioactive molecules. This review concludes with a discussion of the challenges to be met for the widespread clinical use of hydrogel delivery system of stem cell therapy for CKD.

Therapeutic potential of stromal cells of non-renal or renal origin in experimental chronic kidney disease

Background

Mesenchymal stromal cell (MSC)-based therapy is a promising strategy for preventing the progression of chronic kidney disease (CKD), with the potential to induce tissue regeneration. In search of the best cellular source we compared, in the rat model of adriamycin (ADR) nephropathy, the regenerative potential of human stromal cells of non-renal origin, such as bone marrow (bm) MSCs and umbilical cord (uc) MSCs, with that of newly discovered stromal cells of renal origin, the kidney perivascular cells (kPSCs) known to exhibit tissue-specific properties.

Methods

The therapeutic effect of repeated infusions of human bmMSCs, ucMSCs, kPSCs (1.5 × 10⁶ cells/rats) or conditioned medium from ucMSCs was studied in athymic rats with ADR-induced nephropathy (7.9 mg/kg). The ability of the three stromal cell populations to engraft the damaged kidney was evaluated by detecting the presence of human nuclear antigen^pos cells. Glomerular podocyte loss and endothelial damage, sclerotic lesions and inflammation were assessed at 14 and 28 days. In-vitro experiments with a transwell system were performed to investigate the effects of different stromal cell populations on parietal epithelial cells (PECs) activated or not with albumin or angiotensin II for 24 h.

Results

Infusions of non-renal and renal stromal cells resulted in a comparable engraftment into the kidney, in the peritubular areas and around the glomerular structures. All three cell populations limited podocyte loss and glomerular endothelial cell injury, and attenuated the formation of podocyte and PEC bridges. This translated into a reduction of glomerulosclerosis and fibrosis. Human ucMSCs had an anti-inflammatory effect superior to that of the other stromal cells, reducing macrophage infiltration and inducing polarisation towards the M2 macrophage phenotype. Conditioned medium from ucMSCs shared the same renoprotective effects of the cells. Consistent with in-vivo data, bmMSCs and kPSCs, but even more so ucMSCs, limited proliferation, migratory potential and extracellular matrix production of activated PECs, when cultured in a transwell system.

Conclusions

Our data indicate that either non-renal or renal stromal cells induce renal tissue repair, highlighting ucMSCs and their conditioned medium as the most reliable clinical therapeutic tool for CKD patients.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0960-8) contains supplementary material, which is available to authorized users.

Co-Administration of Melatonin Effectively Enhances the Therapeutic Effects of Pioglitazone on Mesenchymal Stem Cells Undergoing Indoxyl Sulfate-Induced Senescence through Modulation of Cellular Prion Protein Expression

Background: Mesenchymal stem cells (MSCs) are a promising source for regenerative medicine. However, their therapeutic potential in patients with chronic kidney disease (CKD) is restricted by the presence of uremic toxins. To address this limitation, we explored the protective effect of melatonin and pioglitazone on MSCs undergoing senescence induced by the uremic toxin, indoxyl sulfate (IS). Methods: MSC senescence was induced by IS, and the therapeutic effects of melatonin and pioglitazone were identified. The expression of cellular prion protein (PrP^C) was suppressed by transfection of MSCs with prion protein gene (PRNP) siRNA. Subsequently, these cells were used to study the protective effects of melatonin and pioglitazone against IS-induced senescence; Results: The IS-induced senescence of MSCs was significantly reduced by co-treatment with melatonin and pioglitazone compared to treatment with melatonin or pioglitazone alone. In the presence of IS, the reduced MSC proliferation was rescued by co-treatment with melatonin and pioglitazone. Melatonin and pioglitazone enhanced the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) in MSCs, which resulted in the augmentation of PrP^C level. The inhibitory effect of the co-treatment with melatonin and pioglitazone on IS-induced senescence in MSCs was blocked by the knockdown of PRNP. In addition, the restorative effect of the co-treatment on the reduced MSC proliferation induced by IS was also blocked by the knockdown of PRNP. These findings indicate that co-treatment with melatonin and pioglitazone protected MSCs from uremic toxin-induced senescence through the regulation of the PPAR-γ-PrP^C axis. Conclusions: Our study suggests that co-treatment of MSCs with melatonin and pioglitazone may represent a novel strategy for the development of MSC-based therapies for patients with CKD.

Bone marrow-mesenchymal stromal cell infusion in patients with chronic kidney disease: A safety study with 18 months of follow-up

BACKGROUND

Chronic kidney disease (CKD) is a progressive loss of kidney function and structure that affects approximately 13% of the population worldwide. A recent meta-analysis revealed that cell-based therapies improve impaired renal function and structure in preclinical models of CKD. We assessed the safety and tolerability of bone marrow-mesenchymal stromal cell (MSC) infusion in patients with CKD.

METHODS

A single-arm study was carried out at one center with 18-month follow-up in seven eligible patients with CKD due to different etiologies such as hypertension, nephrotic syndrome (NS) and unknown etiology. We administered an intravenous infusion (1-2 × 10⁶ cells/kg) of autologous cultured MSCs. The primary endpoint was safety, which was measured by number and severity of adverse events. The secondary endpoint was decrease in the rate of decrease in estimated glomerular filtration rate (eGFR). We compared kidney function during the follow-up visits to baseline and 18 months prior to the intervention.

RESULTS

Follow-up visits of all seven patients were completed; however, we have not observed any cell-related adverse events during the trial. Changes in eGFR (P = 0.10) and serum creatinine (P = 0.24) from 18 months before cell infusion to baseline in comparison with baseline to 18 months were not statistically significant.

CONCLUSIONS

We showed safety and tolerability of a single-dose infusion of autologous MSCs in patients with CKD.

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.

Prospect of alternative therapies to kidney transplantation

[no abstract available]

Role of ESAT-6 in renal injury by regulating microRNA-155 expression via TLR4/MyD88 signaling pathway in mice with Mycobacterium tuberculosis infection

The study aims to investigate the underlying mechanism involved in the early secretory antigenic target-6 (ESAT-6) in renal injury through regulation of the expression of miR-155 through the oll-like receptor (TLR)-4 (TLR4)/myeloid differentiation factor 88 (MyD88) signaling pathway in Mycobacterium tuberculosis (MTB)-infected mice. Sixty C57BL/6 mice with MTB-induced renal injury were randomly assigned into control, MTB, mimic, inhibitor, inhibitor + ESAT6, and inhibitor + ESAT6 + TAK242 groups. Body weight, the ratio of kidney weight to body weight (Kw/Bw), blood urea nitrogen (BUN), and serum creatinine (Scr) of mice were measured. Flow cytometry was used to detect renal activation in mice. Expressions of miR-155 and ESAT6 were detected by quantitative real-time PCR (qRT-PCR), and Western blotting was used to examine the expressions of ESAT6, TLR4, and MyD88. Expressions of tumor necrosis factor-α (TNF-α), interleukin-17 (IL-17), and interferon-γ (IFN-γ) were measured by qRT-PCR and ELISA. Compared with the control group, the BUN and Scr levels as well as the expression levels of miR-155, TLR4, MyD88, TNF-α, IL-17, and IFN-γ increased, while Kw/Bw decreased in the MTB and mimic groups. In comparison with the MTB group, the above indexes except Kw/Bw were elevated in the mimic group, but were reduced in the inhibitor group, while the Kw/Bw dropped in the mimic group but increased in the inhibitor group. Compared with the inhibitor group, the Kw/Bw decreased while the rest of the indexes increased in the inhibitor + ESAT6 group. ESAT6 may induce renal injury by promoting miR-155 expression through the TLR-4/MyD88 signaling pathway in MTB-infected mice.