Mesenchymal Stromal Cell Uses for Acute Kidney Injury-Current Available Data and Future Perspectives: A Mini-Review

Clinical-grade human skin-derived ABCB5+ mesenchymal stromal cells exert anti-apoptotic and anti-inflammatory effects in vitro and modulate mRNA expression in a cisplatin-induced kidney injury murine model

Acute kidney injury (AKI) is characterized by a rapid reduction in renal function and glomerular filtration rate (GFR). The broadly used anti-cancer chemotherapeutic agent cisplatin often induces AKI as an adverse drug side effect. Therapies targeted at the reversal of AKI and its potential progression to chronic kidney disease or end-stage renal disease are currently insufficiently effective. Mesenchymal stromal cells (MSCs) possess diverse immunomodulatory properties that confer upon them significant therapeutic potential for the treatment of diverse inflammatory disorders. Human dermal MSCs expressing ATP-Binding Cassette member B5 (ABCB5) have shown therapeutic efficacy in clinical trials in chronic skin wounds or recessive dystrophic epidermolysis bullosa. In preclinical studies, ABCB5+ MSCs have also shown to reverse metabolic reprogramming in polycystic kidney cells, suggesting a capacity for this cell subset to improve also organ function in kidney diseases. Here, we aimed to explore the therapeutic capacity of ABCB5+ MSCs to improve renal function in a preclinical rat model of cisplatin-induced AKI. First, the anti-apoptotic and immunomodulatory capacity was compared against research-grade adipose stromal cells (ASCs). Then, cross-species immunomodulatory capacity was checked, testing first inhibition of mitogen-driven peripheral blood mononuclear cells and then modulation of macrophage function. Finally, therapeutic efficacy was evaluated in a cisplatin AKI model. First, ABCB5+ MSCs suppressed cisplatin-induced apoptosis of human conditionally-immortalized proximal tubular epithelial cells in vitro, most likely by reducing oxidative stress. Second, ABCB5+ MSCs inhibited the proliferation of either human or rat peripheral blood mononuclear cells, in the human system via the Indoleamine/kynurenine axis and in the murine context via nitric oxide/nitrite. Third, ABCB5+ MSCs decreased TNF-α secretion after lipopolysaccharide stimulation and modulated phagocytosis and in both human and rat macrophages, involving prostaglandin E2 and TGF-β1, respectively. Fourth, clinical-grade ABCB5+ MSCs grafted intravenously and intraperitoneally to a cisplatin-induced AKI murine model exerted modulatory effects on mRNA expression patterns toward an anti-inflammatory and pro-regenerative state despite an apparent lack of amelioration of renal damage at physiologic, metabolic, and histologic levels. Our results demonstrate anti-inflammatory and pro-regenerative effects of clinical grade ABCB5+ MSCs in vitro and in vivo and suggest potential therapeutic utility of this cell population for treatment or prevention of cisplatin chemotherapy-induced tissue toxicity.

Mesenchymal stem cells protect against sepsis-associated acute kidney injury by inducing Gal-9/Tim-3 to remodel immune homeostasis

OBJECTIVE

The present study investigated the specific mechanism by which mesenchymal stem cells (MSCs) protect against sepsis-associated acute kidney injury (SA-AKI).

METHODS

Male C57BL/6 mice underwent cecal ligation and puncture surgery to induce sepsis and then received either normal IgG or MSCs (1 × 10⁶ cells, intravenously) plus Gal-9 or soluble Tim-3 3 h after surgery.

RESULTS

After cecal ligation and puncture surgery, the mice injected with Gal-9 or MSCs plus Gal-9 had a higher survival rate than the mice in the IgG treatment group. Treatment with MSCs plus Gal-9 decreased serum creatinine and blood urea nitrogen levels, improved tubular function recovery, reduced IL-17 and RORγt levels and induced IL-10 and FOXP3 expression. Additionally, the Th17/Treg cell balance was altered. However, when soluble Tim-3 was used to block the Gal-9/Tim-3 pathway, the septic mice developed kidney injury and exhibited increased mortality. Treatment with MSCs plus soluble Tim-3 blunted the therapeutic effect of MSCs, inhibited the induction of Tregs, and suppressed the inhibition of differentiation into Th17 cells.

CONCLUSION

Treatment with MSCs significantly reversed the Th1/Th2 balance. Thus, the Gal-9/Tim-3 pathway may be an important mechanism of MSC-mediated protection against SA-AKI.

Drug Delivery Systems in Regenerative Medicine: An Updated Review

Modern drug discovery methods led to evolving new agents with significant therapeutic potential. However, their properties, such as solubility and administration-related challenges, may hinder their benefits. Moreover, advances in biotechnology resulted in the development of a new generation of molecules with a short half-life that necessitates frequent administration. In this context, controlled release systems are required to enhance treatment efficacy and improve patient compliance. Innovative drug delivery systems are promising tools that protect therapeutic proteins and peptides against proteolytic degradation where controlled delivery is achievable. The present review provides an overview of different approaches used for drug delivery.

Update on the application of mesenchymal stem cell-derived exosomes in the treatment of Parkinson's disease: A systematic review

Parkinson's disease (PD) has become the second largest neurodegenerative disease after Alzheimer's disease, and its incidence is increasing year by year. Traditional dopamine replacement therapy and deep brain stimulation can only alleviate the clinical symptoms of patients with PD but cannot cure the disease. In recent years, stem cell therapy has been used to treat neurodegenerative diseases. Many studies have shown that stem cell transplantation has a therapeutic effect on PD. Here, we review recent studies indicating that exosomes derived from mesenchymal stem cells also have the potential to treat PD in animal models, but the exact mechanism remains unclear. This article reviews the mechanisms through which exosomes are involved in intercellular information exchange, promote neuroprotection and freely cross the blood-brain barrier in the treatment of PD. The increase in the incidence of PD and the decline in the quality of life of patients with advanced PD have placed a heavy burden on patients, families and society. Therefore, innovative therapies for PD are urgently needed. Herein, we discuss the mechanisms underlying the effects of exosomes in PD, to provide new insights into the treatment of PD. The main purpose of this article is to explore the therapeutic potential of exosomes derived from mesenchymal stem cells and future research directions for this degenerative disease.

Ultrasound-Guided Transplantation of Mesenchymal Stem Cells Improves Adriamycin Nephropathy in Rats Through the RIPK3/MLKL and TLR-4/NF-κB Signaling

Bone marrow stromal cell (BMSC) treatment has been shown to be beneficial for Adriamycin nephropathy (ADR). However, the low transplantation rate is still the key factor that affects this strategy. This study is the first to investigate the efficacy and potential mechanism of ultrasound-guided transrenal arterial transfer of BMSCs for the treatment of ADR in rats. The ADR rat model was established by two injections of doxorubicin. In addition, the rats were randomly divided into four groups (10 rats per group): the normal group (no treatment), the medium control group (treated with medium), the Adriamycin group (treated with phosphate buffer), and the BMSC group (treated with BMSCs). After 4 weeks, the levels of serum creatinine (SCr), blood urea nitrogen (BUN), and urine albumin (ALb) were measured. In addition, pathological changes in kidney tissue were evaluated by pathological sectioning and electron microscopy. Western blotting was used to determine the levels of proteins in rat kidneys. Ultrasound-guided renal artery transplantation of BMSCs reduced the levels of SCr, BUN, and ALb and improved the pathological structure of rat kidneys compared with those in the Adriamycin group. This treatment inhibited renal cell necrosis by reducing the expression of receptor-interacting Serine/threonine Kinase 3 (RIPK3) and Mixed lineage kinase domain-like pseudokinase (MLKL) and inhibited renal inflammation and fibrosis by reducing the expression of Toll-Like receptor 4 (TLR4) and nuclear factor κB (NF-κB). Our study shows that ultrasound-guided transrenal artery transplantation of BMSCs can improve adriamycin-induced renal injury in rats by regulating the RIPK3/MLKL and TLR-4/NF-κB pathways and inhibiting renal necrosis, inflammation, and fibrosis.

Protective action of ultrasound-guided intraparenchymal transplantation of BMSCs in adriamycin nephropathy rats through the RIPK3/MLKL and NLRP3 pathways

BACKGROUND

Bone marrow stromal cells (BMSCs) are an effective new strategy for the treatment of kidney diseases. At present, noninvasive and efficient transplantation approaches to homing BMSCs to the renal parenchyma is still a serious challenge. The aim of this study was to investigate the feasibility and potential mechanism of ultrasound-guided intraparenchymal transplantation of BMSCs for the treatment of adriamycin nephropathy (AN) in rats.

MATERIALS AND METHODS

A rat AN model was induced by 2 injections of doxorubicin. The rats were randomly divided into 4 groups (n = 10 animals in each group) : normal group (N group, no treatment), control medium group (CM group, transplant medium 1.0 mL), adriamycin nephropathy group (ADR group, phosphate buffered saline 1.0 mL), or BMSCs group (BMSCs fluid 1.0 mL). Intraparenchymal injection was completed under ultrasound guidance. After 4 weeks of treatment, blood samples were collected for serum biochemical measurements and ELISAs. The kidneys were removed for histopathological examination, electron microscopy, terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL), and western blot analysis.

RESULTS

No deaths occurred in any group after BMSCs transplantation through the renal parenchyma under ultrasound guidance. Compared with the N and CM groups, in the ADR group, blood serum creatinine (SCr), blood urea nitrogen (BUN) and urine albumin (ALb) were higher, glomerular and tubular dilatation was observed, the number of apoptotic cells was higher, and the protein levels of receptor-interacting protein kinase 3 (RIPK3)/mixed lineage kinase domain-like protein (MLKL) and nucleotide leukin-rich polypeptide 3 (NLRP3), key components of pathways in rat kidney, were significantly higher. Compared with those in the ADR group, the levels of SCr, BUN, ALb and serum proinflammatory cytokines in the BMSCs group were lower, the pathological structure of the kidney was improved, the number of apoptotic cells was lower, and the levels of RIPK3/MLKL and NLRP3 were significantly lower.

CONCLUSION

Ultrasound-guided intraparenchymal transplantation of BMSCs regulated the RIPK3/MLKL and NLRP3 pathways in a minimally invasive and safe manner, thereby inhibiting renal necrosis and inflammation and playing a protective role in rat AN.

Integrated Analysis of Prognostic Genes Associated With Ischemia-Reperfusion Injury in Renal Transplantation

Background

Ischemia–reperfusion injury (IRI) remains an inevitable and major challenge in renal transplantation. The current study aims to obtain deep insights into underlying mechanisms and seek prognostic genes as potential therapeutic targets for renal IRI (RIRI).

Methods

After systematically screening the Gene Expression Omnibus (GEO) database, we collected gene expression profiles of over 1,000 specimens from 11 independent cohorts. Differentially expressed genes (DEGs) were identified by comparing allograft kidney biopsies taken before and after reperfusion in the discovery cohort and further validated in another two independent transplant cohorts. Then, graft survival analysis and immune cell analysis of DEGs were performed in another independent renal transplant cohort with long-term follow-ups to further screen out prognostic genes. Cell type and time course analyses were performed for investigating the expression pattern of prognostic genes in more dimensions utilizing a mouse RIRI model. Finally, two novel genes firstly identified in RIRI were verified in the mouse model and comprehensively analyzed to investigate potential mechanisms.

Results

Twenty DEGs upregulated in the process of RIRI throughout different donor types (living donors, cardiac and brain death donors) were successfully identified and validated. Among them, upregulation of 10 genes was associated with poor long-term allograft outcomes and exhibited strong correlations with prognostic immune cells, like macrophages. Furthermore, certain genes were found to be only differentially expressed in specific cell types and remained with high expression levels even months after RIRI in the mouse model, which processed the potential to serve as therapeutic targets. Importantly, two newly identified genes in RIRI, Btg2 and Rhob, were successfully confirmed in the mouse model and found to have strong connections with NF-κB signaling.

Conclusions

We successfully identified and validated 10 IRI-associated prognostic genes in renal transplantation across different donor types, and two novel genes with crucial roles in RIRI were recognized for the first time. Our findings offered promising potential therapeutic targets for RIRI in renal transplantation.

Extracellular Vesicles in Regenerative Medicine: Potentials and Challenges

The ultimate goal of regenerative medicine is to regain or restore the damaged or lost function of tissues and organs. Several therapeutic strategies are currently being explored to achieve this goal. From the point of view of regenerative medicine, extracellular vesicles (EVs) are exceptionally attractive due to the fact that they can overcome the limitations faced by many cell therapies and can be engineered according to their purpose through various technical modifications. EVs are biological nanoscale vesicles naturally secreted by all forms of living organisms, including prokaryotes and eukaryotes, and act as vehicles of communication between cells and their surrounding environment. Over the past decade, EVs have emerged as a new therapeutic agent for various diseases and conditions owing to their multifaceted biological functions. This is reflected by the number of publications on this subject found in the Web of Science database, which currently exceeds 12,300, over 85% of which were published within the last decade, demonstrating the increasing global trends of this innovative field. The reviews collected in this special issue provide an overview of the different approaches being explored in the use of EVs for regenerative medicine.

Mesenchymal Stem Cell Protects Injured Renal Tubular Epithelial Cells by Regulating mTOR-Mediated Th17/Treg Axis

The increase in T helper 17 cell (Th17)-mediated pro-inflammatory response and decrease in regulatory T cell (Treg)-mediated anti-inflammatory effect aggravate renal tubular epithelial cell (RTEC) injury. However, increasing evidence indicated that mesenchymal stem cell (MSC) possessed the ability to control the imbalance between Th17 and Treg. Given that Th17 and Treg are derived from a common CD4⁺ T cell precursor, we summarize the current knowledge of MSC-mediated inhibition of the mammalian target of rapamycin (mTOR), which is a master regulator of CD4⁺ T cell polarization. During CD4⁺ T cell differentiation, mTOR signaling mediates Th17 and Treg differentiation via hypoxia-inducible factor-1α (HIF-1α)-dependent metabolic regulation and signaling pathway, as well as mTOR-mediated phosphorylation of signal transducer and activator of transcription (STAT) 3 and 5. Through interfering with mTOR signaling, MSC restrains CD4⁺ T cell differentiation into Th17, but in turn promotes Treg generation. Thus, this review indicates that MSC-mediated Th17-to-Treg polarization is expected to act as new immunotherapy for kidney injury.

Therapeutic potential of mesenchymal stem cells in multiple organs affected by COVID-19

Currently, the world has been devastated by an unprecedented pandemic in this century. The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the agent of coronavirus disease 2019 (COVID-19), has been causing disorders, dysfunction and morphophysiological alterations in multiple organs as the disease evolves. There is a great scientific community effort to obtain a therapy capable of reaching the multiple affected organs in order to contribute for tissue repair and regeneration. In this regard, mesenchymal stem cells (MSCs) have emerged as potential candidates concerning the promotion of beneficial actions at different stages of COVID-19. MSCs are promising due to the observed therapeutic effects in respiratory preclinical models, as well as in cardiac, vascular, renal and nervous system models. Their immunomodulatory properties and secretion of paracrine mediators, such as cytokines, chemokines, growth factors and extracellular vesicles allow for long range tissue modulation and, particularly, blood-brain barrier crossing. This review focuses on SARS-CoV-2 impact to lungs, kidneys, heart, vasculature and central nervous system while discussing promising MSC's therapeutic mechanisms in each tissue. In addition, MSC's therapeutic effects in high-risk groups for COVID-19, such as obese, diabetic and hypertensive patients are also explored.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: A Potential Therapeutic Strategy for Acute Kidney Injury

Acute kidney injury (AKI) is a common and potential life-threatening disease in patients admitted to hospital, affecting 10%-15% of all hospitalizations and around 50% of patients in the intensive care unit. Severe, recurrent, and uncontrolled AKI may progress to chronic kidney disease or end-stage renal disease. AKI thus requires more efficient, specific therapies, rather than just supportive therapy. Mesenchymal stem cells (MSCs) are considered to be promising cells for cellular therapy because of their ease of harvesting, low immunogenicity, and ability to expand in vitro. Recent research indicated that the main therapeutic effects of MSCs were mediated by MSC-derived extracellular vesicles (MSC-EVs). Furthermore, compared with MSCs, MSC-EVs have lower immunogenicity, easier storage, no tumorigenesis, and the potential to be artificially modified. We reviewed the therapeutic mechanism of MSCs and MSC-EVs in AKI, and considered recent research on how to improve the efficacy of MSC-EVs in AKI. We also summarized and analyzed the potential and limitations of EVs for the treatment of AKI to provide ideas for future clinical trials and the clinical application of MSC-EVs in AKI.