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

Low white blood cell count is independently associated with chronic kidney disease progression in the elderly: the CKD-ROUTE study

BACKGROUND

Elevated white blood cell (WBC) count is a well-known predictor of chronic kidney disease (CKD) progression. However, elderly patients commonly fail to develop a high WBC count in response to several diseased states and may instead present a low WBC count. Therefore, we hypothesized that low WBC count, in addition to high WBC count, is associated with CKD progression in the elderly.

METHODS

We conducted a prospective cohort study using 3-year follow-up data from the CKD Research of Outcomes in Treatment and Epidemiology study. In the present study, participants aged over 60 years with pre-dialysis CKD stages G2-G5 were eligible. Patients were stratified into three groups according to WBC count using tertiles (T). The primary outcome was a composite of end-stage renal disease and a 50% reduction in estimated glomerular filtration rate. Data were analyzed using Cox proportional hazard models with adjustments for covariates.

RESULTS

We enrolled 697 patients (males, 69%). The median WBC count was 6100 cells/µl (T1, <5400, n =  222; T2, 5400-6900, n =  235; T3, ≥6900, n = 240). During a median follow-up of 868 days, the primary outcome was observed in 170 patients, whereas 54 patients died. T1 and T3 had significantly higher hazard ratios (HR) than T2 (T1, HR 1.69, 95% confidence interval 1.14-2.51; T3, HR 1.63, 95% confidence interval 1.10-2.41). Moreover, T1 had a significantly higher adjusted HR (1.54, 95% confidence interval 1.00-2.37).

CONCLUSION

Low WBC count is independently associated with CKD progression in the elderly.

T-cells contribute to hypertension but not to renal injury in mice with subtotal nephrectomy

Background

The pathological condition of chronic kidney disease may not be adequately recapitulated in immunocompromised mice due to the lack of T-cells, which are important for the development of hypertension and renal injury. We studied the role of the immune system in relation to salt-sensitive hypertension and renal injury in mice with subtotal nephrectomy (SNX).

Methods

Wild-type immunocompetent (WT) and Foxn1^nu/nu athymic immunodeficient (AT) CD-1 mice underwent SNX to induce renal injury after which they received standard chow or a high salt diet (HSD). Four weeks after SNX blood pressure and kidney function parameters were measured.

Results

HSD increased albumin excretion independent of immune status. Systolic blood pressure increased only in WT mice on HSD, not in AT mice. Uremia and morphological damage after SNX were not affected by either HSD or immune status.

Conclusions

For the development of hypertension after SNX in CD-1 mice mature T-cells and a high salt diet are required. SNX induced albuminuria was independent of the presence of T-cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0555-0) contains supplementary material, which is available to authorized users.

Immune involvement in the pathogenesis of schizophrenia: a meta-analysis on postmortem brain studies

Although the precise pathogenesis of schizophrenia is unknown, genetic, biomarker and imaging studies suggest involvement of the immune system. In this study, we performed a systematic review and meta-analysis of studies investigating factors related to the immune system in postmortem brains of schizophrenia patients and healthy controls. Forty-one studies were included, reporting on 783 patients and 762 controls. We divided these studies into those investigating histological alterations of cellular composition and those assessing molecular parameters; meta-analyses were performed on both categories. Our pooled estimate on cellular level showed a significant increase in the density of microglia (P=0.0028) in the brains of schizophrenia patients compared with controls, albeit with substantial heterogeneity between studies. Meta-regression on brain regions demonstrated this increase was most consistently observed in the temporal cortex. Densities of macroglia (astrocytes and oligodendrocytes) did not differ significantly between schizophrenia patients and healthy controls. The results of postmortem histology are paralleled on the molecular level, where we observed an overall increase in expression of proinflammatory genes on transcript and protein level (P=0.0052) in patients, while anti-inflammatory gene expression levels were not different between schizophrenia and controls. The results of this meta-analysis strengthen the hypothesis that components of the immune system are involved in the pathogenesis of schizophrenia.

Hydrogel-Based Cell Therapies for Kidney Regeneration: Current Trends in Biofabrication and In Vivo Repair

Facing the problems of limited renal regeneration capacity and the persistent shortage of donor kidneys, dialysis remains the only treatment option for many end-stage renal disease patients. Unfortunately, dialysis is only a medium-term solution because large and protein-bound uremic solutes are not efficiently cleared from the body and lead to disease progression over time. Current strategies for improved renal replacement therapies (RRTs) range from whole organ engineering to biofabrication of renal assist devices and biological injectables for in vivo regeneration. Notably, all approaches coincide with the incorporation of cellular components and biomimetic micro-environments. Concerning the latter, hydrogels form promising materials as scaffolds and cell carrier systems due to the demonstrated biocompatibility of most natural hydrogels, tunable biochemical and mechanical properties, and various application possibilities. In this review, the potential of hydrogel-based cell therapies for kidney regeneration is discussed. First, we provide an overview of current trends in the development of RRTs and in vivo regeneration options, before examining the possible roles of hydrogels within these fields. We discuss major application-specific hydrogel design criteria and, subsequently, assess the potential of emergent biofabrication technologies, such as micromolding, microfluidics and electrodeposition for the development of new RRTs and injectable stem cell therapies.

A perspective on chronic kidney disease progression

Chronic kidney disease (CKD) will progress to end stage without treatment, but the decline of renal function may not be linear. Compared with glomerular filtration rate and proteinuria, new surrogate markers, such as kidney injury molecule-1, neutrophil gelatinase-associated protein, apolipoprotein A-IV, and soluble urokinase receptor, may allow potential intervention and treatment in the earlier stages of CKD, which could be useful for clinical trials. New omic-based technologies reveal potential new genomic and epigenomic mechanisms that appear different from those causing the initial disease. Various clinical studies also suggest that acute kidney injury is a major risk for progressive CKD. To ameliorate the progression of CKD, the first step is optimizing renin-angiotensin-aldosterone system blockade. New drugs targeting endothelin, transforming growth factor-β, oxidative stress, and inflammatory- and cell-based regenerative therapy may have add-on benefit.

Allogeneic Mesenchymal Precursor Cells (MPC) in Diabetic Nephropathy: A Randomized, Placebo-controlled, Dose Escalation Study

BACKGROUND

Diabetic nephropathy is the most common cause of end stage renal failure. We assessed the safety, tolerability, and explored therapeutic effects of adult allogeneic bone-marrow derived mesenchymal precursor cells (MPC) in patients with moderate to severe diabetic nephropathy.

METHODS

Multicenter, randomized, double-blind, dose-escalating, sequential, placebo-controlled trial assessing a single intravenous (IV) infusion of allogeneic MPC (United States adopted name: rexlemestrocel-L) 150×106 (n=10), 300×106 (n=10) or placebo (n=10) in adults with diabetic nephropathy with an estimated glomerular filtration rate (eGFR) 20-50ml/min/1.73m2. Thirty patients at three Australian centers were enrolled between July 2013 and June 2014 and randomized 2:1, in two sequential dose cohorts, to receive rexlemestrocel-L or placebo. Study duration was 60weeks. Primary endpoint was safety and tolerability. Primary exploratory efficacy endpoint was change from baseline in eGFR and directly measured GFR by 99Tc-DTPA plasma clearance (mGFR) at 12weeks post-infusion. The trial was registered on ClinicalTrials.gov (NCT01843387).

FINDINGS

All patients completed the study and were included in analyses applied to the intention to treat population. There were no acute adverse events (AEs) associated with infusion and no treatment-related AEs or serious AEs were deemed treatment-related by investigators. No patients developed persistent donor specific anti-HLA antibodies. Relative to placebo, a single IV rexlemestrocel-L infusion showed trends of stabilizing or improving eGFR and mGFR at week 12. The adjusted least squares mean (LSM±SE) differences from placebo in changes from baseline at 12weeks in the rexlemestrocel-L groups were 4.4±2.16 and 1.6±2.15ml/min/1.73m2 for eGFR and 4.1±2.75 and 3.9±2.75 for mGFR for the 150×106 and 300×106 cell groups, respectively.

INTERPRETATION

This study demonstrates the safety of rexlemestrocel-L in diabetic nephropathy with suggestive effects on renal function to be confirmed in larger, appropriately powered trials.

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

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

Mesenchymal stem cell therapy promotes the improvement and recovery of renal function in a preclinical model

Acute renal failure (ARF) is an extremely important public health issue in need of novel therapies. The present study aimed to evaluate the capacity of mesenchymal stem cell (MSC) therapy to promote the improvement and recovery of renal function in a preclinical model. Wistar rats were used as the experimental model, and our results show that cisplatin (5mg/kg) can efficiently induce ARF, as measured by changes in biochemical (urea and creatinine) and histological parameters. MSC therapy performed 24h after the administration of chemotherapy resulted in normalized plasma urea and creatinine levels 30 and 45d after the onset of kidney disease. Furthermore, MSC therapy significantly reduced histological changes (intratubular cast formation in protein overload nephropathy and tubular hydropic degeneration) in this ARF model. Thus, considering that current therapies for ARF are merely palliative and that MSC therapy can promote the improvement and recovery of renal function in this model system, we suggest that innovative/alternative therapies involving MSCs should be considered for clinical studies in humans to treat ARF.

Imaging technologies for monitoring the safety, efficacy and mechanisms of action of cell-based regenerative medicine therapies in models of kidney disease

The incidence of end stage kidney disease is rising annually and it is now a global public health problem. Current treatment options are dialysis or renal transplantation, which apart from their significant drawbacks in terms of increased morbidity and mortality, are placing an increasing economic burden on society. Cell-based Regenerative Medicine Therapies (RMTs) have shown great promise in rodent models of kidney disease, but clinical translation is hampered due to the lack of adequate safety and efficacy data. Furthermore, the mechanisms whereby the cell-based RMTs ameliorate injury are ill-defined. For instance, it is not always clear if the cells directly replace damaged renal tissue, or whether paracrine effects are more important. Knowledge of the mechanisms responsible for the beneficial effects of cell therapies is crucial because it could lead to the development of safer and more effective RMTs in the future. To address these questions, novel in vivo imaging strategies are needed to monitor the biodistribution of cell-based RMTs and evaluate their beneficial effects on host tissues and organs, as well as any potential adverse effects. In this review we will discuss how state-of-the-art imaging modalities, including bioluminescence, magnetic resonance, nuclear imaging, ultrasound and an emerging imaging technology called multispectral optoacoustic tomography, can be used in combination with various imaging probes to track the fate and biodistribution of cell-based RMTs in rodent models of kidney disease, and evaluate their effect on renal function.

An Innovative, Comprehensive Mapping and Multiscale Analysis of Registered Trials for Stem Cell-Based Regenerative Medicine

We aim to provide an innovative, comprehensive way of mapping the profusion of stem cell-based clinical trials registered at ClinicalTrials.gov to explore the diversity of the fields of application and the temporal complexity of the domain. We used a chord diagram and phylogenetic-like tree visualizations to assist in data mining and knowledge discovery. The search strategy used the following terms: "stromal OR stem OR mesenchymal OR progenitor." The Medical Subject Headings (MeSH) thesaurus was used to more finely classify diseases treated by stem cells, from large fields of application to specific diseases. Of the 5,788 trials screened, 939 were included, 51.1% of which were related to mesenchymal stem cells (MSCs). No real specificity emerged as to the therapeutic uses of the different types of stem cells. More than half the MSC studies concerned allogeneic MSCs and received more support from industry than autologous MSC studies (p < .001). Over time, the uses of cultured cells have increased greatly, particularly since 2009. Cells derived from adipose tissue are also increasingly used in trials compared with bone marrow cells. The use of adipose-derived stromal cells was predominantly autologous (p < .001), restricted to European countries (p < .01), and supported by industry (p = .02) compared with other MSCs. Details about MeSH keywords are available at http://multireview.perso.sfr.fr/. In conclusion, mapping may reveal a lack of global strategy despite the regulations and the related costs associated with good manufacturing practices. A systematic approach to preclinical data, intended to objectively and robustly reveal the most appropriate fields with the most efficient cells, is needed. Repeated exchanges between the bench and the bedside are necessary.

SIGNIFICANCE

Except for a few trials concerning specific tissue stem cells used in their corresponding tissues, this global analysis revealed no real specificity of stem cell uses (including mesenchymal stromal cells). This raised the question of the physiopathological rationale for these uses and the lack of a global strategy despite the regulations and the related costs associated with good manufacturing practices. This original method, leading to the development of new concepts from already available data, would help policymakers to optimize resources and investments in terms of public health priorities. Such an approach should draw parallels between in vitro, in vivo, and human data. Exchanges in both directions between preclinical and clinical research could optimize the parameters of clinical trials step by step.

Stem Cell Therapy: Current Applications and Potential for Urology

Stem cell therapy holds the potential to revolutionize the treatment of a number of chronic conditions. Stem cells ability to home in on injured sites of the body, stimulate angiogenesis, tissue regeneration, immunomodulation, anti-inflammatory, and anti-fibrotic factors have attracted their use in the treatment of many conditions. Urology has registered one of the highest experimental successes using stem cell therapy. However, the rate of clinical applications is comparatively lower. This review takes a look at our efforts so far and what needs to be done in order to maximize the clinical benefit we can derive from stem cells.

Challenges and opportunities for stem cell therapy in patients with chronic kidney disease

Chronic kidney disease (CKD) is a global health care burden affecting billions of individuals worldwide. The kidney has limited regenerative capacity from chronic insults, and for the most common causes of CKD, no effective treatment exists to prevent progression to end-stage kidney failure. Therefore, novel interventions, such as regenerative cell-based therapies, need to be developed for CKD. Given the risk of allosensitization, autologous transplantation of cells to boost regenerative potential is preferred. Therefore, verification of cell function and vitality in CKD patients is imperative. Two cell types have been most commonly applied in regenerative medicine. Endothelial progenitor cells contribute to neovasculogenesis primarily through paracrine angiogenic activity and partly by differentiation into mature endothelial cells in situ. Mesenchymal stem cells also exert paracrine effects, including proangiogenic, anti-inflammatory, and antifibrotic activity. However, in CKD, multiple factors may contribute to reduced cell function, including older age, coexisting cardiovascular disease, diabetes, chronic inflammatory states, and uremia, which may limit the effectiveness of an autologous cell-based therapy approach. This Review highlights current knowledge on stem and progenitor cell function and vitality, aspects of the uremic milieu that may serve as a barrier to therapy, and novel methods to improve stem cell function for potential transplantation.

Recent Progress in Stem Cell Therapy for Diabetic Nephropathy

BACKGROUND

Diabetic nephropathy (DN) represents the leading cause of end-stage renal disease. Current therapeutic strategies for DN are very limited, and none of them can stop end-stage renal disease progression. Stem cell-based therapy showed encouraging outcomes in kidney disease, including experimental DN.

SUMMARY

Both podocytes and proximal tubular epithelial cells play key roles in the pathogenesis of DN and, accordingly, could be regarded as treatment targets. Multiple kinds of stem cells contribute to the regeneration of the injured kidney, including embryonic stem cells (ESCs), mesenchymal stem cells, and induced pluripotent stem cells (iPSCs). Stem cells exert reparatory effects mainly by homing to injured sites, directing differentiation, paracrine action, and immunoregulation. However, poor survival after transplantation under diabetic conditions and unsatisfactory animal models of advanced DN are major obstacles for achieving an efficacious therapeutic effect from stem cell transplantation. Recently, remarkable progress has been made both in the direct differentiation of human ESCs and iPSCs into renal cells and in the generation of tissue- and patient-specific iPSCs, offering a powerful tool to investigate DN mechanisms and to identify the ideal candidate cell for future clinical application.

KEY MESSAGE

This review provides updated information on recent progress and limitations of stem cell-based therapy for DN.

Drug therapies to delay the progression of chronic kidney disease

Chronic kidney disease (CKD) is associated with significant morbidity and mortality, impacted not alone by progression to end-stage kidney disease, but also by the high associated incidence of cardiovascular events and related mortality. Despite our current understanding of the pathogenesis of CKD and the treatments available, the reported incidence of CKD continues to rise worldwide, and is often referred to as the silent public healthcare epidemic. The significant cost to patient wellbeing and to the economy of managing the later stages of CKD have prompted efforts to develop interventions to delay the development and progression of this syndrome. In this article, we review established and novel agents that may aid in delaying the progression of CKD and improve patient outcomes.

Stem cell therapy for kidney disease

INTRODUCTION

Kidney diseases are a global public health problem whose incidence is rapidly growing due to a global rise in the aged population and the increasing prevalence of cardiovascular disease, hypertension and diabetes. With the emergence of stem cells as potential therapeutic agents, attempts in using them to significantly reduce the burden of these diseases have increased.

AREAS COVERED

Several types of stem cells have been proven to be likely candidates for treating kidney diseases. We discuss in detail the potential use of mesenchymal stem cells in preclinical and clinical works, with additional populations that have been studied briefly described. Moreover, we discuss current knowledge on endogenous kidney regeneration ability and on the possibility to modulate it using chemical and biological agents.

EXPERT OPINION

Stem cell therapy is a promising new treatment for kidney disease documented in many animal studies. Mesenchymal stem cells have emerged as a promising cell type, but their efficacy in clinical trials is still controversial. Identification of progenitor cells in the adult kidney is another step forward in regenerative medicine, suggesting the repair potential of the adult kidney and the possible modulation of renal progenitors in situ using pharmacological approaches.