Mesenchymal Stromal Cells Improve Renovascular Function in Polycystic Kidney Disease

Inflammatory Alterations to Renal Lymphatic Endothelial Cell Gene Expression in Mouse Models of Hypertension

INTRODUCTION

Hypertension (HTN) is a major cardiovascular disease that can cause and be worsened by renal damage and inflammation. We previously reported that renal lymphatic endothelial cells (LECs) increase in response to HTN and that augmenting lymphangiogenesis in the kidneys reduces blood pressure and renal pro-inflammatory immune cells in mice with various forms of HTN. Our aim was to evaluate the specific changes that renal LECs undergo in HTN.

METHODS

We performed single-cell RNA sequencing. Using the angiotensin II-induced and salt-sensitive mouse models of HTN, we isolated renal CD31+ and podoplanin+ cells.

RESULTS

Sequencing of these cells revealed three distinct cell types with unique expression profiles, including LECs. The number and transcriptional diversity of LECs increased in samples from mice with HTN, as demonstrated by 597 differentially expressed genes (p < 0.01), 274 significantly enriched pathways (p < 0.01), and 331 regulons with specific enrichment in HTN LECs. These changes demonstrate a profound inflammatory response in renal LECs in HTN, leading to an increase in genes and pathways associated with inflammation-driven growth and immune checkpoint activity in LECs.

CONCLUSION

These results reinforce and help to further explain the benefits of renal LECs and lymphangiogenesis in HTN.

Experimental Models of Polycystic Kidney Disease: Applications and Therapeutic Testing

Polycystic kidney diseases (PKDs) are genetic disorders characterized by the formation and expansion of numerous fluid-filled renal cysts, damaging normal parenchyma and often leading to kidney failure. Although PKDs comprise a broad range of different diseases, with substantial genetic and phenotypic heterogeneity, an association with primary cilia represents a common theme. Great strides have been made in the identification of causative genes, furthering our understanding of the genetic complexity and disease mechanisms, but only one therapy so far has shown success in clinical trials and advanced to US Food and Drug Administration approval. A key step in understanding disease pathogenesis and testing potential therapeutics is developing orthologous experimental models that accurately recapitulate the human phenotype. This has been particularly important for PKDs because cellular models have been of limited value; however, the advent of organoid usage has expanded capabilities in this area but does not negate the need for whole-organism models where renal function can be assessed. Animal model generation is further complicated in the most common disease type, autosomal dominant PKD, by homozygous lethality and a very limited cystic phenotype in heterozygotes while for autosomal recessive PKD, mouse models have a delayed and modest kidney disease, in contrast to humans. However, for autosomal dominant PKD, the use of conditional/inducible and dosage models have resulted in some of the best disease models in nephrology. These have been used to help understand pathogenesis, to facilitate genetic interaction studies, and to perform preclinical testing. Whereas for autosomal recessive PKD, using alternative species and digenic models has partially overcome these deficiencies. Here, we review the experimental models that are currently available and most valuable for therapeutic testing in PKD, their applications, success in preclinical trials, advantages and limitations, and where further improvements are needed.

Reduced inflammation following human endometrial stromal/stem cell injection into male Wistar rats with cisplatin-induced acute kidney injury

Introduction: Inflammation is one of the most important mechanisms involved in cisplatin-induced acute kidney injury (AKI). Mesenchymal stromal/stem cells (MSCs) exhibit anti-inflammatory and immunomodulatory abilities. Human endometrial stromal/stem cells (hEnSCs) exhibit similar properties to MSCs. These cells secrete immunoregulators, so we investigated the inflammatory aspect of hEnSCs in the treatment of cisplatin-induced AKI in Wistar rats.

Methods: Each group consisted of 6 male Wistar rats. Groups were as follows: sham, model (5 mg/kg cisplatin, IP), and treatment (1 million hEnSCs, IV, 3 hours after cisplatin). Renal function, histopathology, proliferation rate, infiltration of CD3⁺ T cell, and expression of Il-10 and cystatin c (Cst3) were assessed on day 5. DiI-labeled cells were tracked in kidney and liver on days 4 and 14.

Results: HEnSC transplantation improved cisplatin-induced injuries such as renal dysfunction and tissue damage. The highest levels of pathologic scores and hyaline cast formation were observed in the model group while hEnSCs transplantation resulted in their reduction (154.00 ± 14.95, 8.00 ± 1.41 vs. 119.40 ± 5.43, 2.50 ± 1.05). The percentage of Ki-67 positive cells in the treatment group increased while cisplatin decreased proliferation (39.91 ± 5.33 vs. 23.91 ± 3.57 in glomeruli and 39.07 ± 2.95 vs. 16.61 ± 3.25 in tubules). The expression of Cst3 and Il-10 was higher in the model and treatment groups, respectively. DiI-labeled cells were observed in the renal tubules and liver lobes on days 4 and 14.

Conclusion: HEnSCs may ameliorate cisplatin-induced AKI through anti-inflammatory and immunomodulatory effects and/or through paracrine effects.

Mesenchymal stem cells: A new therapeutic tool for chronic kidney disease

Chronic kidney disease (CKD) has a major impact on public health, which could progress to end-stage kidney disease (ESRD) and consume many medical resources. Currently, the treatment for CKD has many flaws, so more effective treatment tools are urgently required for CKD. Mesenchymal stem cells (MSCs) are primitive cells with self-renewal and proliferation capacity and differentiation potential. Extensive preclinical and clinical data has shown that cell-based therapies using MSCs can modulate immunity, inhibit inflammatory factors, and improve renal function in CKD, suggesting that MSCs have the potential to be a new, effective therapeutic tool for CKD. In this review, we will describe different kinds of MSCs and MSCs products for the treatment of CKD in experimental models and clinical trials, potential signaling pathways, therapeutic efficacy, and critical issues that need to be addressed before therapeutic application in humans.

Therapeutic advances in ADPKD: the future awaits

Autosomal dominant polycystic kidney disease (ADPKD) is a heterogeneous genetic disorder included in ciliopathies, representing the fourth cause of end stage renal disease (ESRD), with an estimated prevalence between 1:1000 and 1:2500. It is mainly caused by mutations in the PKD1 and PKD2 genes encoding for polycystin 1 (PC1) and polycystin 2 (PC2), which regulate differentiation, proliferation, survival, apoptosis, and autophagy. The advances in the knowledge of multiple molecular pathways involved in the pathophysiology of ADPKD led to the development of several treatments which are currently under investigation. Recently, the widespread approval of tolvaptan and, in Italy, of long-acting release octreotide (octreotide-LAR), represents but the beginning of the new therapeutic management of ADPKD patients. Encouraging results are expected from ongoing randomized controlled trials (RCTs), which are investigating not only drugs acting on the calcium/cyclic adenosin monoposphate (cAMP) pathway, the most studied target so far, but also molecules targeting specific pathophysiological pathways (e.g. epidermal growth factor (EGF) receptor, AMP-activated protein kinase (AMPK) and KEAP1-Nrf2) and sphingolipids. Moreover, studies on animal models and cultured cells have also provided further promising therapeutic strategies based on the role of intracellular calcium, cell cycle regulation, MAPK pathway, epigenetic DNA, interstitial inflammation, and cell therapy. Thus, in a near future, tailored therapy could be the key to changing the natural history of ADPKD thanks to the vigorous efforts that are being made to implement clinical and preclinical studies in this field. Our review aimed to summarize the spectrum of drugs that are available in the clinical practice and the most promising molecules undergoing clinical, animal, and cultured cell studies.

Imaging the Renal Microcirculation in Cell Therapy

Renal microvascular rarefaction plays a pivotal role in progressive kidney disease. Therefore, modalities to visualize the microcirculation of the kidney will increase our understanding of disease mechanisms and consequently may provide new approaches for evaluating cell-based therapy. At the moment, however, clinical practice is lacking non-invasive, safe, and efficient imaging modalities to monitor renal microvascular changes over time in patients suffering from renal disease. To emphasize the importance, we summarize current knowledge of the renal microcirculation and discussed the involvement in progressive kidney disease. Moreover, an overview of available imaging techniques to uncover renal microvascular morphology, function, and behavior is presented with the associated benefits and limitations. Ultimately, the necessity to assess and investigate renal disease based on in vivo readouts with a resolution up to capillary level may provide a paradigm shift for diagnosis and therapy in the field of nephrology.

Stem/progenitor cell in kidney: characteristics, homing, coordination, and maintenance

Renal failure has a high prevalence and is becoming a public health problem worldwide. However, the renal replacement therapies such as dialysis are not yet satisfactory for its multiple complications. While stem/progenitor cell-mediated tissue repair and regenerative medicine show there is light at the end of tunnel. Hence, a better understanding of the characteristics of stem/progenitor cells in kidney and their homing capacity would greatly promote the development of stem cell research and therapy in the kidney field and open a new route to explore new strategies of kidney protection. In this review, we generally summarize the main stem/progenitor cells derived from kidney in situ or originating from the circulation, especially bone marrow. We also elaborate on the kidney-specific microenvironment that allows stem/progenitor cell growth and chemotaxis, and comment on their interaction. Finally, we highlight potential strategies for improving the therapeutic effects of stem/progenitor cell-based therapy. Our review provides important clues to better understand and control the growth of stem cells in kidneys and develop new therapeutic strategies.

Impaired Hedgehog-Gli1 Pathway Activity Underlies the Vascular Phenotype of Polycystic Kidney Disease

Polycystic kidney disease (PKD) has been linked to abnormal structure/function of ciliary proteins, leading to renal dysfunction. Recently, attention has been focused in the significant vascular abnormalities associated with PKD, but the mechanisms underlying this phenomenon remain elusive. Here, we seek to define the molecular events regulating the angiogenic imbalance observed in PKD. Using micro computed tomography (n=7) and protein expression analysis (n=5), we assessed the vascular density and the angiogenic profile of noncystic organs in a well-established PKD rat model (Polycystic Kidney-PCK rat). Heart and lungs of PCK rats have reduced vascular density and decreased expression of angiogenic factors compared with wild type. Similarly, PCK-vascular smooth muscle cells (VSMCs; n=4) exhibited lower levels of vascular markers. Then, using small interfering RNA (n=4), we determined the role of the ciliary protein fibrocystin in wild type-VSMCs, a critical component/regulator of vascular structure and function. Reduction of fibrocystin in wild type-VSMCs (n=4) led to an abnormal angiogenic potential similar to that observed in PCK-VSMCs. Furthermore, we investigated the involvement of the hedgehog signaling, a pathway closely linked to the primary cilium and associated with vascular development, in PKD. Mechanistically, we demonstrated that impairment of the hedgehog signaling mediates, in part, this abnormal angiogenic phenotype. Lastly, overexpression of Gli1 in PCK-VSMCs (n=4) restored the expression levels of proangiogenic molecules. Our data support a critical role of fibrocystin in the abnormal vascular phenotype of PKD and indicate that a dysregulation of hedgehog may be responsible, at least in part, for these vascular deficiencies.

Nephroprotective Potential of Mesenchymal Stromal Cells and Their Extracellular Vesicles in a Murine Model of Chronic Cyclosporine Nephrotoxicity

Background

Cell therapies and derived products have a high potential in aiding tissue and organ repairing and have therefore been considered as potential therapies for treating renal diseases. However, few studies have evaluated the impact of these therapies according to the stage of chronic kidney disease. The aim of this study was to evaluate the renoprotective effect of murine bone marrow mesenchymal stromal cells (BM-MSCs), their extracellular vesicles (EVs) and EVs-depleted conditioned medium (dCM) in an aggressive mouse model of chronic cyclosporine (CsA) nephrotoxicity in a preventive and curative manner.

Methods

After 4 weeks of CsA-treatment (75 mg/kg daily) mice developed severe nephrotoxicity associated with a poor survival rate of 25%, and characterized by tubular vacuolization, casts, and cysts in renal histology. BM-MSC, EVs and dCM groups were administered as prophylaxis or as treatment of CsA nephrotoxicity. The effect of the cell therapies was analyzed by assessing renal function, histological damage, apoptotic cell death, and gene expression of fibrotic mediators.

Results

Combined administration of CsA and BM-MSCs ameliorated the mice survival rates (6-15%), but significantly renal function, and histological parameters, translating into a reduction of apoptosis and fibrotic markers. On the other hand, EVs and dCM administration were only associated with a partial recovery of renal function or histological damage. Better results were obtained when used as treatment rather than as prophylactic regimen i.e., cell therapy was more effective once the damage was established.

Conclusion

In this study, we showed that BM-MSCs induce an improvement in renal outcomes in an animal model of CsA nephrotoxicity, particularly if the inflammatory microenvironment is already established. EVs and dCM treatment induce a partial recovery, indicating that further experiments are required to adjust timing and dose for better long-term outcomes.

Mesenchymal Stromal Cells Are Retained in the Porcine Renal Cortex Independently of Their Metabolic State After Renal Intra-Arterial Infusion

The regenerative capacities of mesenchymal stromal cells (MSCs) make them suitable for renal regenerative therapy. The most common delivery route of MSC is through intravenous infusion, which is associated with off-target distribution. Renal intra-arterial delivery offers a targeted therapy, but limited knowledge is available regarding the fate of MSCs delivered through this route. Therefore, we studied the efficiency and tissue distribution of MSCs after renal intra-arterial delivery to a porcine renal ischemia-reperfusion model. MSCs were isolated from adipose tissue of healthy male pigs, fluorescently labeled and infused into the renal artery of female pigs. Flow cytometry allowed MSC detection and quantification in tissue and blood. In addition, quantitative polymerase chain reaction was used to trace MSCs by their Y-chromosome. During infusion, a minor number of MSCs left the kidney through the renal vein, and no MSCs were identified in arterial blood. Ischemic and healthy renal tissues were analyzed 30 min and 8 h after infusion, and 1-4 × 10⁴ MSCs per gram of tissue were detected, predominantly, in the renal cortex, with a viability >70%. Confocal microscopy demonstrated mainly glomerular localization of MSCs, but they were also observed in the capillary network around tubuli. The infusion of heat-inactivated (HI) MSCs, which are metabolically inactive, through the renal artery showed that HI-MSCs were distributed in the kidney in a similar manner to regular MSCs, suggesting a passive retention mechanism. Long-term MSC survival was analyzed by Y-chromosome tracing, and demonstrated that a low percentage of the infused MSCs were present in the kidney 14 days after administration, while HI-MSCs were completely undetectable. In conclusion, renal intra-arterial MSC infusion limited off-target engraftment, leading to efficient MSC delivery to the kidney, most of them being cleared within 14 days. MSC retention was independent of the metabolic state of MSC, indicating a passive mechanism.

Recent advances in management of autosomal-dominant polycystic kidney disease

PURPOSE

Promising developments in the search for effective pharmacotherapies for autosomal-dominant polycystic kidney disease (ADPKD) are reviewed.

SUMMARY

The formation and development of cysts characteristic of ADPKD result in inexorable renal and extrarenal manifestations that give rise to more rapid disease progression and more widespread complications than are seen with other forms of chronic kidney disease. To date, no agent has gained Food and Drug Administration marketing approval for use in patients with ADPKD, complicating efforts to meet the medical needs of this population. Although definitive ultrasonographic diagnostic strategies are available, molecular screening approaches lack sufficient evidence and patient outcomes data to support broad clinical application. Recently completed and ongoing clinical trials point to a number of encouraging platforms for evidence-based ADPKD management. Tolvaptan therapy significantly improved cyst burden and slowed disease progression among patients with early-stage ADPKD in a large-scale trial, while somatostatin therapies may also be useful in halting disease progression and managing comorbid polycystic liver disease. Stem cell research and nanomedicine might represent novel approaches to gaining comprehensive insights on ADPKD and, ultimately, to targeting the disease's origins, thereby making restoration of kidney function possible.

CONCLUSION

A number of pharmacotherapy approaches to ADPKD management show promise but are unlikely to be curative, fueling interest among researchers in finding new applications for nanomedicine and stem cell technologies that can slow ADPKD progression and better control complications of the disease.

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.

Autosomal dominant polycystic kidney disease: Disrupted pathways and potential therapeutic interventions

Autosomal dominant polycystic kidney disease (ADPKD) is a monogenic inherited renal cystic disease that occurs in different races worldwide. It is characterized by the development of a multitude of renal cysts, which leads to massive enlargement of the kidney and often to renal failure in adulthood. ADPKD is caused by a mutation in PKD1 or PKD2 genes encoding the proteins polycystin-1 and polycystin-2, respectively. Recent studies showed that cyst formation and growth result from deregulation of multiple cellular pathways like proliferation, apoptosis, metabolic processes, cell polarity, and immune defense. In ADPKD, intracellular cyclic adenosine monophosphate (cAMP) promotes cyst enlargement by stimulating cell proliferation and transepithelial fluid secretion. Several interventions affecting many of these defective signaling pathways have been effective in animal models and some are currently being tested in clinical trials. Moreover, the stem cell therapy can improve nephropathies and according to studies were done in this field, can be considered as a hopeful therapeutic approach in future for PKD. This study provides an in-depth review of the relevant molecular pathways associated with the pathogenesis of ADPKD and their implications in development of potential therapeutic strategies.

Unmet needs and challenges for follow-up and treatment of autosomal dominant polycystic kidney disease: the paediatric perspective

Awareness is growing that the clinical course of autosomal dominant polycystic kidney disease (ADPKD) already begins in childhood, with a broad range of both symptomatic and asymptomatic features. Knowing that parenchymal destruction with cyst formation and growth starts early in life, it seems reasonable to assume that early intervention may yield the best chances for preserving renal outcome. Interventions may involve lifestyle modifications, hypertension control and the use of disease-modifying treatments once these become available for the paediatric population with an acceptable risk and side-effect profile. Until then, screening of at-risk children is controversial and not generally recommended since this might cause psychosocial and financial harm. Also, the clinical and research communities are facing important questions as to the nature of potential interventions and their optimal indications and timing. Indeed, challenges include the identification and validation of indicators, both measuring and predicting disease progression from childhood, and the discrimination of slow from rapid progressors in the paediatric population. This discrimination will improve both the cost-effectiveness and benefit-to-risk ratio of therapies. Furthermore, we will need to define outcome measures, and to evaluate the possibility of a potential therapeutic window of opportunity in childhood. The recently established international register ADPedKD will help in elucidating these questions. In this review, we provide an overview of the current knowledge on paediatric ADPKD as a future therapeutic target population and its unmet challenges.

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

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

Safety and tolerability of autologous bone marrow mesenchymal stromal cells in ADPKD patients

Background

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic ciliopathy disease characterized by progressive formation and enlargement of cysts in multiple organs. The kidneys are particularly affected and patients may eventually develop end-stage renal disease (ESRD). We hypothesize that bone marrow mesenchymal stromal cells (BMMSCs) are renotropic and may improve kidney function via anti-apoptotic, anti-fibrotic, and anti-inflammatory effects. In this study, we aim to assess the safety and tolerability of a BMMSC infusion in ADPKD patients.

Methods

We performed a single-arm phase I clinical trial with a 12-month follow-up. This study enrolled six eligible ADPKD patients with an estimated glomerular filtration rate (eGFR) of 25–60 ml/min/1.73 m². Patients received autologous cultured BMMSCs (2 × 10⁶ cells/kg) through the cubital vein according to our infusion protocol. We investigated safety issues and kidney function during the follow-up visits, and compared the findings to baseline and 1 year prior to the intervention.

Results

There were no patients lost to follow-up. We observed no cell-related adverse events (AE) and serious adverse events (SAE) after 12 months of follow-up. The mean eGFR value of 33.8 ± 5.3 ml/min/1.73 m² 1 year before cell infusion declined to 26.7 ± 3.1 ml/min/1.73 m² at baseline (P = 0.03) and 25.8 ± 6.2 ml/min/1.73 m² at the 12-month follow-up visit (P = 0.62). The mean serum creatinine (SCr) level of 2 ± 0.3 mg/dl 1 year before the infusion increased to 2.5 ± 0.4 mg/dl at baseline (P = 0.04) and 2.5 ± 0.6 mg/dl at the 12-month follow-up (P = 0.96). This indicated significant changes between the differences of these two periods (12 months before infusion to baseline, and 12 months after infusion to baseline) in SCr (P = 0.05), but not eGFR (P = 0.09).

Conclusions

This trial demonstrated the safety and tolerability of an intravenous transplantation of autologous BMMSCs. BMMSC efficacy in ADPKD patients should be investigated in a randomized placebo-controlled trial with a larger population, which we intend to perform.

Trial registration

ClinicalTrials.gov, NCT02166489. Registered on June 14, 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0557-7) contains supplementary material, which is available to authorized users.

A new scaffold containing small intestinal submucosa and mesenchymal stem cells improves pancreatic islet function and survival in vitro and in vivo

It is unknown whether a scaffold containing both small intestinal submucosa (SIS) and mesenchymal stem cells (MSCs) for transplantation may improve pancreatic islet function and survival. In this study, we examined the effects of a SIS-MSC scaffold on islet function and survival in vitro and in vivo. MSCs and pancreatic islets were isolated from Sprague-Dawley rats, and SIS was isolated from Bamei pigs. The islets were apportioned among 3 experimental groups as follows: SIS-islets, SIS-MSC-islets and control-islets. In vitro, islet function was measured by a glucose-stimulated insulin secretion test; cytokines in cultured supernatants were assessed by enzyme-linked immunosorbent assay; and gene expression was analyzed by reverse transcription-quantitative PCR. In vivo, islet transplantation was performed in rats, and graft function and survival were monitored by measuring the blood glucose levels. In vitro, the SIS-MSC scaffold was associated with improved islet viability and enhanced insulin secretion compared with the controls, as well as with the increased the expression of insulin 1 (Ins1), pancreatic and duodenal homeobox 1 (Pdx1), platelet endothelial cell adhesion molecule 1 [Pecam1; also known as cluster of differentiation 31 (CD31)] and vascular endothelial growth factor A (Vegfa) in the islets, increased growth factor secretion, and decreased tumor necrosis factor (TNF) secretion. In vivo, the SIS-MSC scaffold was associated with improved islet function and graft survival compared with the SIS and control groups. On the whole, our findings demonstrate that the SIS-MSC scaffold significantly improved pancreatic islet function and survival in vitro and in vivo. This improvement may be associated with the upregulation of insulin expression, the improvement of islet microcirculation and the secretion of cytokines.

Therapeutic application of extracellular vesicles in acute and chronic renal injury

A new cell-to-cell communication system was discovered in the 1990s, which involves the release of vesicles into the extracellular space. These vesicles shuttle bioactive particles, including proteins, mRNA, miRNA, metabolites, etc. This particular communication has been conserved throughout evolution, which explains why most cell types are capable of producing vesicles. Extracellular vesicles (EVs) are involved in the regulation of different physiological processes, as well as in the development and progression of several diseases. EVs have been widely studied over recent years, especially those produced by embryonic and adult stem cells, blood cells, immune system and nervous system cells, as well as tumour cells. EV analysis from bodily fluids has been used as a diagnostic tool for cancer and recently for different renal diseases. However, this review analyses the importance of EVs generated by stem cells, their function and possible clinical application in renal diseases and kidney transplantation.