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

The Mechanism of Hyperoxia-Induced Neonatal Renal Injury and the Possible Protective Effect of Resveratrol

With recent advances in neonatal intensive care, preterm infants are surviving into adulthood. Nonetheless, epidemiological data on the health status of these preterm infants have begun to reveal a worrying theme; prematurity and the supplemental oxygen therapy these infants receive after birth appear to be risk factors for kidney disease in adulthood, affecting their quality of life. As the incidence of chronic kidney disease and the survival time of preterm infants both increase, the management of the hyperoxia-induced renal disease is becoming increasingly relevant to neonatologists. The mechanism of this increased risk is currently unknown, but prematurity itself and hyperoxia exposure after birth may predispose to disease by altering the normal trajectory of kidney maturation. This article reviews altered renal reactivity due to hyperoxia, the possible mechanisms of renal injury due to hyperoxia, and the role of resveratrol in renal injury. KEY POINTS: · Premature infants commonly receive supplementary oxygen.. · Hyperoxia can cause kidney damage via signal pathways.. · We should reduce the occurrence of late sequelae..

Utilization of Hydrogels in Mesenchymal Stem Cell-Based Therapy for Kidney Diseases

Kidney diseases are major global health problems, with high prevalence and mortality. However, current treatment strategies for kidney diseases fail to achieve satisfactory efficacy. Mesenchymal stem cell (MSC)-based therapy has been a promising strategy for treating kidney diseases. Preclinical studies have proven their safety and effectiveness in treating acute kidney injury (AKI) and chronic kidney disease (CKD), but the outcomes of clinical trials have shown very limited clinical efficacy. A variety of innovative approaches have been proposed to enhance the therapeutic potential of MSCs, and hydrogels are attractive candidates. Hydrogels are three-dimensional (3D) networks formed by hydrophilic polymers of natural or synthetic origin with diverse physical and chemical properties. They have been widely applied in the field of drug delivery and regenerative medicine, including MSC-based therapy. Many studies have proven that hydrogels can improve the therapeutic efficacy of MSCs for kidney diseases, but there are still challenges limiting the widespread application of this method. In this review, we introduce the application of MSCs in kidney diseases and the factors that influence therapeutic efficiency and focus on the beneficial effects of hydrogels in MSC-based therapy for AKI and CKD.

Evaluation of the effect of dimethyl fumarate on human bone marrow-derived mesenchymal stem cells using bottom-up proteomics

Mesenchymal stem cells (MSCs) have potential as a viable treatment option in the field of regenerative medicine, but MSC-based therapy needs to be more efficient. Preconditioning is a method to improve MSC-based therapy, and dimethyl fumarate (DMF) - an agent that can enhance the antioxidative capacity of cells - can be considered for preconditioning of MSCs. In this study, we treated bone marrow-derived MSCs with DMF and evaluated their proteome using bottom-up proteomics. The MSCs were exposed to 10 μM DMF for 24 h, followed by lysis with an SDS solution, digestion with trypsin using an s-trap column, and analysis using nanoLC-MS/MS, which identified 2262 proteins with confidence. Bioinformatic analysis of the identified proteins revealed 47 upregulated proteins and 81 downregulated proteins upon DMF treatment. Pathway enrichment analysis suggested a possible decrease in autophagy and a decrease in the activity of the TCA cycle, while indicating a potential increase in proliferation and antioxidant activity in DMF-treated MSCs compared to untreated MSCs. Our findings suggest that DMF can enhance the proliferation of MSCs and increase their stability, and that preconditioning could improve the therapeutic efficacy of MSCs for the treatment of regenerative diseases.

Efficacy of adipose-derived mesenchymal stem cell therapy in the treatment of chronic micro- and macrovascular complications of diabetes

Diabetes mellitus is a highly prevalent disease characterized by hyperglycaemia that damages the vascular system, leading to micro- (retinopathy, neuropathy, nephropathy) and macrovascular diseases (cardiovascular disease). There are also secondary complications of diabetes (cardiomyopathy, erectile dysfunction or diabetic foot ulcers). Stem cell-based therapies have become a promising tool targeting diabetes symptoms and its chronic complications. Among all stem cells, adipose-derived mesenchymal stem cells (ADMSCs) are of great importance because of their abundance, non-invasive isolation and no ethical limitations. Characteristics that make ADMSCs good candidates for cell-based therapy are their wide immunomodulatory properties and paracrine activities through the secretion of an array of growth factors, chemokines, cytokines, angiogenic factors and anti-apoptotic molecules. Besides, after transplantation, ADMSCs show great ex vivo expansion capacity and differentiation to other cell types, including insulin-producing cells, cardiomyocytes, chondrocytes, hepatocyte-like cells, neurons, endothelial cells, photoreceptor-like cells, or astrocytes. Preclinical studies have shown that ADMSC-based therapy effectively improved visual acuity, ameliorated polyneuropathy and foot ulceration, arrested the development and progression of diabetic kidney disease, or alleviated the diabetes-induced cardiomyocyte hypertrophy. However, despite the positive results obtained in animal models, there are still several challenges that need to be overcome before the results of preclinical studies can be translated into clinical applications. To date, there are several clinical trials or ongoing trials using ADMSCs in the treatment of diabetic complications, most of them in the treatment of diabetic foot ulcers. This narrative review summarizes the most recent outcomes on the usage of ADMSCs in the treatment of long-term complications of diabetes in both animal models and clinical trials.

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.

Canine adipose tissue-derived MSCs engineered with mRNA to overexpress TSG-6 and enhance the anti-inflammatory effects in canine macrophages

Background

Mesenchymal stem cells (MSCs) are useful agents in the treatment of various inflammatory diseases. The immunomodulatory effects of MSCs are largely related to their secretory properties. mRNA engineering emerged as a safe alternative to enhance the secretory function of MSCs. Optimization of the untranslated region (UTR) sequence is important for enhancing the translational efficiency of exogenous mRNAs. However, research on the optimization of UTR in canine MSCs has not yet been conducted.

Objectives

We aimed to identify the UTR sequence related to the expression efficiency of in vitro transcription (IVT) mRNA in canine MSCs and investigate whether mRNA-engineered MSCs that overexpress TSG-6 exhibit enhanced anti-inflammatory effects.

Methods

Canine adipose tissue-derived (cAT)-MSCs were transfected with green fluorescence protein (GFP) mRNA with three different UTRs: canine hemoglobin subunit alpha-like 1 (HBA1), HBA2, and hemoglobin subunit beta-like (HBB). The translation efficacy of each mRNA was evaluated using relative fluorescence. TSG-6 mRNA was produced with the UTR optimized according to relative fluorescence results. cAT-MSCs were transfected with TSG-6 mRNA (MSCTSG-6), and TSG-6 expression was analyzed using real-time quantitative PCR, ELISA, and western blotting. To evaluate the anti-inflammatory effects of MSCsTSG-6, DH82 cells were co-cultured with MSCsTSG-6 or treated with dexamethasone, and changes in the expression of inflammatory cytokines were analyzed using qPCR.

Results

The highest fluorescence level was observed in the HBA1 UTR at 24 h post-transfection. TSG-6 mRNA transfection yielded high levels of TSG-6 in the cAT-MSCs. In DH82 cells co-cultured with MSCsTSG-6, the expression of inflammatory cytokines decreased compared to that in co-culturing with naïve MSCs and dexamethasone treatment.

Conclusions

Optimization of the HBA1 UTR improved the translation efficiency of IVT mRNA in canine MSCs. cAT-MSCs engineered with TSG-6 mRNA effectively enhanced the anti-inflammatory effects of the MSCs when co-cultured with LPS-activated DH82 cells.

Effect of Melatonin on Alpha Synuclein and Autophagy in Dopaminergic Neuronal Differentiation of Adipose Mesenchymal Stem Cells

Background

The current work investigated the effect of melatonin on differentiation of adipose mesenchymal stem cells (AD-MSCs) into dopamine producing cells and its effect on autophagy process and alpha-Synuclein (α-Syn) secretion.

Methods

AD-MSCs were characterized by flow cytometry and divided into 4 groups; i) control group (AD-MSCs without any treatment), ii) M+MSCs group (MSCs treated with 1 µM melatonin for 12 days), iii) DN group (MSCs cultured in neurobasal A medium and essential neuronal growth factors for 12 days) and iv) DN+M group (MSCs cultured in neurobasal A medium and 1µM melatonin for 12 days. By the end of experiments, the dopamine and α-Syn levels using ELISA, the expression of MAP-2, m-TOR and α-Syn genes at the level of mRNA and detection of autophagosomes formation using transmission electron microscope were performed.

Results

We found that the isolated cells were MSCs due to their positivity expression for CD105 and CD90 and negativity expression for CD34 and CD45. The concentration of dopamine was significantly higher and α-Syn concentration was significantly lower in DN+M group when compared to other groups (P< 0.005). Also, this group showed the highly expression for MAP-2 gene and less expression for m-TOR and α-Syn genes (P< 0.005). Moreover, there was significantly increase in autophagosomes formation in this group than another group (P< 0.005).

Conclusions

It is concluded that the melatonin promotes the differentiation of rat AD-MSCs into dopaminergic cells via induction of autophagy process and reduction of α-Syn secretion.

Melatonin ameliorates renal dysfunction in glyphosate- and hard water-treated mice

Chronic interstitial nephritis in agricultural communities (CINAC) is a severe and widespread disease that has been associated with environmental and occupational exposure to glyphosate and hard water. However, the potential underlying mechanisms remain incompletely understood. Melatonin is reported to exert protective effects on the kidney, but whether melatonin can attenuate renal tubular injury in mice exposed to glyphosate combined with hard water is unclear. Here, mice were treated with high doses and environmentally relevant doses of glyphosate (100 mg/kg·bw and 0.7 mg/L, respectively) and/or hard water (2500 mg/L CaCO₃ and 250 mg/L Ca²⁺, respectively) via their drinking water for 12 weeks. We found that high-dose glyphosate or hard water treatment significantly increased the levels of biomarkers of renal damage, including β₂-microglobulin, neutrophil gelatinase-associated lipid carrier protein, and/or albumin, in the urine; these increased biomarker levels were correlated with obvious morphological changes, and all of these changes were also observed in animals exposed to environmentally relevant doses of glyphosate and/or high Ca²⁺ water. Melatonin (10 mg/kg·bw, intraperitoneal injection, daily for 12 weeks) administered concomitantly with high doses of glyphosate and hard water inhibited the glyphosate- and hard water-induced increases in the levels of kidney injury biomarkers and changes in morphology; this result was intriguing. Additionally, glyphosate combined with hard water at both high and environmentally relevant doses significantly upregulated the expression of the endoplasmic reticulum (ER) stress marker proteins Bip, ATF6, and PERK as well as the pyroptosis-related proteins (NLRP3 and caspase 1 signaling proteins) in renal tissues. Similarly, melatonin significantly attenuated the increased ER stress and pyroptosis induced by high doses of glyphosate and hard water. In summary, we conclude that exposure to glyphosate and hard water at both high doses and environmentally relevant doses causes renal dysfunction in mice, and this dysfunction can be attenuated by melatonin, possibly through the inhibition of ER stress and pyroptosis. Our results support the notion that melatonin may have therapeutic potential for the treatment of chronic kidney diseases.

Targeted Therapy for Inflammatory Diseases with Mesenchymal Stem Cells and Their Derived Exosomes: From Basic to Clinics

Inflammation is a beneficial and physiological process, but there are a number of inflammatory diseases which have detrimental effects on the body. In addition, the drugs used to treat inflammation have toxic side effects when used over a long period of time. Mesenchymal stem cells (MSCs) are pluripotent stem cells that can be isolated from a variety of tissues and can be differentiate into diverse cell types under appropriate conditions. They also exhibit noteworthy anti-inflammatory properties, providing new options for the treatment of inflammatory diseases. The therapeutic potential of MSCs is currently being investigated for various inflammatory diseases, such as kidney injury, lung injury, osteoarthritis (OA), rheumatoid arthritis (RA), and inflammatory bowel disease (IBD). MSCs can perform multiple functions, including immunomodulation, homing, and differentiation, to enable damaged tissues to form a balanced inflammatory and regenerative microenvironment under severe inflammatory conditions. In addition, accumulated evidence indicates that exosomes from extracellular vesicles of MSCs (MSC-Exos) play an extraordinary role, mainly by transferring their components to recipient cells. In this review, we summarize the mechanism and clinical trials of MSCs and MSC-Exos in various inflammatory diseases in detail, with a view to contributing to the treatment of MSCs and MSC-Exos in inflammatory diseases.

Hypoxia and chronic kidney disease

Hypoxia is an inherent pathophysiological characteristic of chronic kidney disease (CKD), which is closely associated with the development of renal inflammation and fibrosis, as well as CKD-related complications such as anaemia, cardiovascular events, and sarcopenia. This review outlined the characteristics of oxygen supply in the kidney, changes in oxygen metabolism and factors leading to hypoxia in CKD. Mechanistically, we discussed how hypoxia contributes to renal injury as well as complications associated with CKD. Furthermore, we also discussed the potential therapeutic approaches that target chronic hypoxia, as well as the challenges in the study of oxygen homeostasis imbalance in CKD.

Characteristics and regulation of mesenchymal stem cell plasticity by the microenvironment — specific factors involved in the regulation of MSC plasticity

Mesenchymal stem cells (MSCs), multipotent stromal cells, have attracted extensive attention in the field of regenerative medicine and cell therapy due to the capacity of self-renewal, multilineage differentiation, and immune regulation. MSCs have different cellular effects in different diseases, and even have markedly different curative effects with different tissue sources, indicating the plasticity of MSCs. The phenotypes, secreted factors, and proliferative, migratory, differentiating, and immunomodulatory effects of MSCs depend on certain mediators present in their microenvironment. Understanding microenvironmental factors and their internal mechanisms in MSC responses may help in subsequent prediction and improvement of clinical benefits. This review highlighted the recent advances in MSC plasticity in the physiological and pathological microenvironment and multiple microenvironmental factors regulating MSC plasticity. It also highlighted some progress in the underlying molecular mechanisms of MSC remodeling in the microenvironment. It might provide references for the improvement in vitro culture of MSCs, clinical application, and in vivo induction.

Targeting Programmed Cell Death to Improve Stem Cell Therapy: Implications for Treating Diabetes and Diabetes-Related Diseases

Stem cell therapies have shown promising therapeutic effects in restoring damaged tissue and promoting functional repair in a wide range of human diseases. Generations of insulin-producing cells and pancreatic progenitors from stem cells are potential therapeutic methods for treating diabetes and diabetes-related diseases. However, accumulated evidence has demonstrated that multiple types of programmed cell death (PCD) existed in stem cells post-transplantation and compromise their therapeutic efficiency, including apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis. Understanding the molecular mechanisms in PCD during stem cell transplantation and targeting cell death signaling pathways are vital to successful stem cell therapies. In this review, we highlight the research advances in PCD mechanisms that guide the development of multiple strategies to prevent the loss of stem cells and discuss promising implications for improving stem cell therapy in diabetes and diabetes-related diseases.

Future Perspectives in Spinal Cord Repair: Brain as Saviour? TSCI with Concurrent TBI: Pathophysiological Interaction and Impact on MSC Treatment

Traumatic spinal cord injury (TSCI), commonly caused by high energy trauma in young active patients, is frequently accompanied by traumatic brain injury (TBI). Although combined trauma results in inferior clinical outcomes and a higher mortality rate, the understanding of the pathophysiological interaction of co-occurring TSCI and TBI remains limited. This review provides a detailed overview of the local and systemic alterations due to TSCI and TBI, which severely affect the autonomic and sensory nervous system, immune response, the blood-brain and spinal cord barrier, local perfusion, endocrine homeostasis, posttraumatic metabolism, and circadian rhythm. Because currently developed mesenchymal stem cell (MSC)-based therapeutic strategies for TSCI provide only mild benefit, this review raises awareness of the impact of TSCI-TBI interaction on TSCI pathophysiology and MSC treatment. Therefore, we propose that unravelling the underlying pathophysiology of TSCI with concomitant TBI will reveal promising pharmacological targets and therapeutic strategies for regenerative therapies, further improving MSC therapy.

Empowering Melatonin Therapeutics with Drosophila Models

Melatonin functions as a central regulator of cell and organismal function as well as a neurohormone involved in several processes, e.g., the regulation of the circadian rhythm, sleep, aging, oxidative response, and more. As such, it holds immense pharmacological potential. Receptor-mediated melatonin function mainly occurs through MT1 and MT2, conserved amongst mammals. Other melatonin-binding proteins exist. Non-receptor-mediated activities involve regulating the mitochondrial function and antioxidant cascade, which are frequently affected by normal aging as well as disease. Several pathologies display diseased or dysfunctional mitochondria, suggesting melatonin may be used therapeutically. Drosophila models have extensively been employed to study disease pathogenesis and discover new drugs. Here, we review the multiple functions of melatonin through the lens of functional conservation and model organism research to empower potential melatonin therapeutics to treat neurodegenerative and renal diseases.

PSC-MSC-Derived Exosomes Protect against Kidney Fibrosis In Vivo and In Vitro through the SIRT6/β-Catenin Signaling Pathway

Background and Objectives

Chronic kidney disease (CKD) has a major impact on the quality of life of patients, and renal fibrosis is a critical pathological change in the disease. It is very important to control the process of renal fibrosis to improve the quality of life of patients with CKD. The pathological mechanism of renal fibrosis is very complicated, and the current treatment strategy also has many flaws.

Methods and Results

To explore a better treatment, we collected exosomes from pluripotent stem cell (PSC)-derived mesenchymal stem cells (MSC) and verified their therapeutic effect on renal fibrosis through in vivo and in vitro experiments. In this study, we found that PSC-MSC-derived comes could prevent the epithelial differentiation of NRK-52E cells, and with increasing exosome concentrations, the effect was improved. Furthermore, PSC-MSC-derived exosomes could reduce the pathological process of renal fibrosis, reduce inflammatory reactions and improve renal function in UUO mice. Moreover, the protective effect of exosomes against renal fibrosis may be achieved by increasing the expression of SIRT6 and decreasing the expression of β-catenin and its downstream products.

Conclusions

These findings suggest the possibility of PSC-MSC-derived exosomes as a new, effective therapeutic tool for kidney fibrosis.

Effects of different doses of melatonin on rat adipose derived mesenchymal stem cells

OBJECTIVES

Stem cell treatment is based on Melatonin which is crucial for lots of pathological and physiological pathways. Our aim is determining the most appropriate dose of melatonin affecting the rat adipose tissue mesenchymal stem cells.

METHODS

Stem cells were isolated from male rat adipose tissue. Differentiation and characterization experiments were performed. Cell viability analyses in stem cells were used the XTT [2,3-Bis-(2-methoxy-4-Nitro-5-Sulfophenyl)-2H-Tetrazolium-5-Carboxanilide] assay. After 24 h incubation, different concentrations (0.5, 1, 5, 10, 50 µM) of extract were treated to the stem cells for 24 h, 48 and 72 h considering time and dose dependent manner. Total antioxidant status (TAS) and the total oxidant status (TOS) in control cells and melatonin treated cells (5, 10 µM) were determined Rel Assay commercial kits.

RESULTS

In 24 h, melatonin increased cell viability in all groups. When we evaluate the effect of melatonin in 48 h, the most proliferation increase was seen at 5, 10 µM doses. When the total oxidant activity melatonin was found to be significantly lower in 5 and 10 µM dose groups of melatonin.

CONCLUSIONS

Melatonin increases the survivor of stem cells and the most effective dose is 5 and 10 µM. The reduction of the oxidative stress index as a result of treating melatonin to mesenchymal stem cells showed that melatonin is a powerful antioxidant for stem cells.

An Examination of the Putative Role of Melatonin in Exosome Biogenesis

During the last two decades, melatonin has been found to have pleiotropic effects via different mechanisms on its target cells. Data are abundant for some aspects of the signaling pathways within cells while other casual mechanisms have not been adequately addressed. From an evolutionary perspective, eukaryotic cells are equipped with a set of interrelated endomembrane systems consisting of intracellular organelles and secretory vesicles. Of these, exosomes are touted as cargo-laden secretory vesicles that originate from the endosomal multivesicular machinery which participate in a mutual cross-talk at different cellular interfaces. It has been documented that cells transfer various biomolecules and genetic elements through exosomes to sites remote from the original cell in a paracrine manner. Findings related to the molecular mechanisms between melatonin and exosomal biogenesis and cargo sorting are the subject of the current review. The clarification of the interplay between melatonin and exosome biogenesis and cargo sorting at the molecular level will help to define a cell's secretion capacity. This review precisely addresses the role and potential significance of melatonin in determining the efflux capacity of cells via the exosomal pathway. Certain cells, for example, stem cells actively increase exosome efflux in response to melatonin treatment which accelerates tissue regeneration after transplantation into the injured sites.

Possible benefits of exogenous melatonin for individuals on dialysis: a narrative review on potential mechanisms and clinical implications

Prevention of oxidative stress and inflammation in chronic kidney disease patients (CKD) on dialysis may reduce dialysis-associated complications. Administration of powerful antioxidants may improve the consequences of peritoneal dialysis (PD) and hemodialysis (HD). This narrative review aimed to show the potential therapeutic effects of melatonin (MLT) on the consequences of CKD patients receiving HD or PD. The results of preclinical and clinical studies have proven that CKD and dialysis are accompanied by reduced endogenous MLT levels and related complications such as sleep disorders. Enhanced oxidative stress, inflammation, cellular damages, and renal fibrosis, along with dysregulation of the renin-angiotensin system (RAS), have been observed in CKD and patients on dialysis. Results of studies have revealed that the restoration of MLT via the exogenous source may regulate oxidative stress, inflammation, and RAS functions, inhibit fibrosis, and improve complications in patients with long-term dialysis patients. In summary, treatment of patients with CKD and dialysis with exogenous MLT is suggested as a practical approach in reducing the outcomes and improving the quality of life in patients via antioxidant, anti-inflammatory, and anti-fibrotic signaling pathways. Therefore, this hormone can be considered in clinical practice to manage dialysis-related complications.

Programmed cell death in stem cell-based therapy: Mechanisms and clinical applications

Stem cell-based therapy raises hopes for a better approach to promoting tissue repair and functional recovery. However, transplanted stem cells show a high death percentage, creating challenges to successful transplantation and prognosis. Thus, it is necessary to investigate the mechanisms underlying stem cell death, such as apoptotic cascade activation, excessive autophagy, inflammatory response, reactive oxygen species, excitotoxicity, and ischemia/hypoxia. Targeting the molecular pathways involved may be an efficient strategy to enhance stem cell viability and maximize transplantation success. Notably, a more complex network of cell death receives more attention than one crucial pathway in determining stem cell fate, highlighting the challenges in exploring mechanisms and therapeutic targets. In this review, we focus on programmed cell death in transplanted stem cells. We also discuss some promising strategies and challenges in promoting survival for further study.

Ultrasound enhances the therapeutic potential of mesenchymal stem cells wrapped in greater omentum for aristolochic acid nephropathy

Background

Mesenchymal stem cells (MSCs) have been reported to promote regeneration in both subjects with acute kidney injury (AKI) and chronic kidney disease (CKD), but their efficacy remains limited, probably because most of the cells accumulate in the lungs, liver, and spleen after an intravenous infusion. Therefore, ultrasound-guided administration of MSCs represents a possible approach to solve this problem. The greater omentum is used to promote cell survival due to its rich vasculature. We hypothesized that ultrasound-guided administration of MSCs combined with greater omentum might be more curative than currently available approaches.

Methods

In this study, we established an aristolochic acid nephropathy (AAN) model by intraperitoneally administering aristolochic acid I sodium salt (AA-I) at a dose of 5 mg/kg body weight on alternate days for 4 weeks. Subsequently, a laparotomy was performed, and the left kidney from which the capsule had been removed was wrapped with the greater omentum. A dose of 2 × 10⁷ MSCs was injected into the space between the greater omentum and the left kidney. Equal amounts of MSCs were administered under ultrasound guidance every second week for a total of 4 treatments. Mice were sacrificed 4 weeks after surgery. Serum creatinine and blood urea levels were measured to assess renal function. qPCR, Western blot, and histological analyses were conducted to further investigate the therapeutic mechanism of MSCs.

Results

Ultrasound-guided injection of MSCs into the greater omentum that surrounds the kidney enriched cells in the kidney region for up to 5 days. Renal function tests indicated that MSCs improved renal function to a great extent, as reflected by decreased blood urea nitrogen and serum creatinine levels. In addition, histological analyses showed that MSCs noticeably attenuated kidney injury, as evidenced by the amelioration of tubular necrosis and peritubular interstitial fibrosis. Mitigation of renal interstitial fibrosis was further confirmed by immunohistochemistry, qPCR, and western blotting after MSC treatment. Moreover, immunofluorescence staining revealed that MSCs alleviated inflammatory responses by increasing the counts of CD206+ cells and decreasing the counts of CD68+ cells. MSC migration was initiated in response to AA-I-treated renal epithelial cells in an in vitro migration assay.

Conclusions

These findings suggested that administration of MSCs into the cavity formed by the injured kidney and the greater omentum under ultrasound guidance improved renal function, attenuated kidney injury, and mitigated renal interstitial fibrosis and inflammatory responses. Thus, this approach might be a safe and effective therapy for CKD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02243-7.

Modeling Neoplastic Growth in Renal Cell Carcinoma and Polycystic Kidney Disease

Renal cell carcinoma (RCC) and autosomal dominant polycystic kidney disease (ADPKD) share several characteristics, including neoplastic cell growth, kidney cysts, and limited therapeutics. As well, both exhibit impaired vasculature and compensatory VEGF activation of angiogenesis. The PI3K/AKT/mTOR and Ras/Raf/ERK pathways play important roles in regulating cystic and tumor cell proliferation and growth. Both RCC and ADPKD result in hypoxia, where HIF-α signaling is activated in response to oxygen deprivation. Primary cilia and altered cell metabolism may play a role in disease progression. Non-coding RNAs may regulate RCC carcinogenesis and ADPKD through their varied effects. Drosophila exhibits remarkable conservation of the pathways involved in RCC and ADPKD. Here, we review the progress towards understanding disease mechanisms, partially overlapping cellular and molecular dysfunctions in RCC and ADPKD and reflect on the potential for the agile Drosophila genetic model to accelerate discovery science, address unresolved mechanistic aspects of these diseases, and perform rapid pharmacological screens.

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.

Progress toward the Clinical Application of Mesenchymal Stromal Cells and Other Disease-Modulating Regenerative Therapies: Examples from the Field of Nephrology

Drawing from basic knowledge of stem-cell biology, embryonic development, wound healing, and aging, regenerative medicine seeks to develop therapeutic strategies that complement or replace conventional treatments by actively repairing diseased tissue or generating new organs and tissues. Among the various clinical-translational strategies within the field of regenerative medicine, several can be broadly described as promoting disease resolution indirectly through local or systemic interactions with a patient's cells, without permanently integrating or directly forming new primary tissue. In this review, we focus on such therapies, which we term disease-modulating regenerative therapies (DMRT), and on the extent to which they have been translated into the clinical arena in four distinct areas of nephrology: renovascular disease (RVD), sepsis-associated AKI (SA-AKI), diabetic kidney disease (DKD), and kidney transplantation (KTx). As we describe, the DMRT that has most consistently progressed to human clinical trials for these indications is mesenchymal stem/stromal cells (MSCs), which potently modulate ischemic, inflammatory, profibrotic, and immune-mediated tissue injury through diverse paracrine mechanisms. In KTx, several early-phase clinical trials have also tested the potential for ex vivo-expanded regulatory immune cell therapies to promote donor-specific tolerance and prevent or resolve allograft injury. Other promising DMRT, including adult stem/progenitor cells, stem cell-derived extracellular vesicles, and implantable hydrogels/biomaterials remain at varying preclinical stages of translation for these renal conditions. To date (2021), no DMRT has gained market approval for use in patients with RVD, SA-AKI, DKD, or KTx, and clinical trials demonstrating definitive, cost-effective patient benefits are needed. Nonetheless, exciting progress in understanding the disease-specific mechanisms of action of MSCs and other DMRT, coupled with increasing knowledge of the pathophysiologic basis for renal-tissue injury and the experience gained from pioneering early-phase clinical trials provide optimism that influential, regenerative treatments for diverse kidney diseases will emerge in the years ahead.

Novel insights for improving the therapeutic safety and efficiency of mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) have attracted great interest in the field of regenerative medicine. They can home to damaged tissue, where they can exert pro-regenerative and anti-inflammatory properties. These therapeutic effects involve the secretion of growth factors, cytokines, and chemokines. Moreover, the functions of MSCs could be mediated by extracellular vesicles (EVs) that shuttle various signaling messengers. Although preclinical studies and clinical trials have demonstrated promising therapeutic results, the efficiency and the safety of MSCs need to be improved. After transplantation, MSCs face harsh environmental conditions, which likely dampen their therapeutic efficacy. A possible strategy aiming to improve the survival and therapeutic functions of MSCs needs to be developed. The preconditioning of MSCs ex vivo would strength their capacities by preparing them to survive and to better function in this hostile environment. In this review, we will discuss several preconditioning approaches that may improve the therapeutic capacity of MSCs. As stated above, EVs can recapitulate the beneficial effects of MSCs and may help avoid many risks associated with cell transplantation. As a result, this novel type of cell-free therapy may be safer and more efficient than the whole cell product. We will, therefore, also discuss current knowledge regarding the therapeutic properties of MSC-derived EVs.

Cyst Reduction by Melatonin in a Novel Drosophila Model of Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) causes progressive cystic degeneration of the renal tubules, the nephrons, eventually severely compromising kidney function. ADPKD is incurable, with half of the patients eventually needing renal replacement. Treatments for ADPKD patients are limited and new effective therapeutics are needed. Melatonin, a central metabolic regulator conserved across all life kingdoms, exhibits oncostatic and oncoprotective activity and no detected toxicity. Here, we used the Bicaudal C (BicC) Drosophila model of polycystic kidney disease to test the cyst-reducing potential of melatonin. Significant cyst reduction was found in the renal (Malpighian) tubules upon melatonin administration and suggest mechanistic sophistication. Similar to vertebrate PKD, the BicC fly PKD model responds to the antiproliferative drugs rapamycin and mimics of the second mitochondria-derived activator of caspases (Smac). Melatonin appears to be a new cyst-reducing molecule with attractive properties as a potential candidate for PKD treatment.

Bone marrow derived mesenchymal stem cells pretreated with erythropoietin accelerate the repair of acute kidney injury

Background

Mesenchymal stem cells (MSCs) represent a promising treatment option for acute kidney injury (AKI). The main drawbacks of MSCs therapy, including the lack of specific homing after systemic infusion and early cell death in the inflammatory microenvironment, directly affect the therapeutic efficacy of MSCs. Erythropoietin (EPO)-preconditioning of MSCs promotes their therapeutic effect, however, the underlying mechanism remains unknown. In this study, we sought to investigate the efficacy and mechanism of EPO in bone marrow derived mesenchymal stem cells (BMSCs) for AKI treatment.

Results

We found that incubation of BMSCs with ischemia/reperfusion(I/R)-induced AKI kidney homogenate supernatant (KHS) caused apoptosis in BMSCs, which was decreased by EPO pretreatment, indicating that EPO protected the cells from apoptosis. Further, we showed that EPO up-regulated silent information regulator 1 (SIRT1) and Bcl-2 expression and down-regulated p53 expression. This effect was partially reversed by SIRT1 siRNA intervention. The anti-apoptotic effect of EPO in pretreated BMSCs may be mediated through the SIRT1 pathway. In a rat AKI model, 24 h after intravenous infusion, GFP-BMSCs were predominantly located in the lungs. However, EPO pretreatment reduced the lung entrapment of BMSCs and increased their distribution in the target organs. AKI rats infused with EPO-BMSCs had significantly lower levels of serum IL-1β and TNF-α, and a significantly higher level of IL-10 as compared to rats infused with untreated BMSCs. The administration of EPO-BMSCs after reperfusion reduced serum creatinine, blood urea nitrogen, and pathological scores in I/R-AKI rats more effectively than BMSCs treatment did.

Conclusions

Our data suggest that EPO pretreatment enhances the efficacy of BMSCs to improve the renal function and pathological presentation of I/R-AKI rats.

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.