Transplanted mesenchymal stem cells accelerate glomerular healing in experimental glomerulonephritis

Bone marrow-derived mesenchymal stem cells reduce CCl4-induced kidney injury and fibrosis in male Wistar rats

AIM

This study explores the possible therapeutic role of rats and mice bone marrow-derived mesenchymal stem cells (BM-MSCs) on renal damage and toxicity brought on by carbon tetrachloride (CCl4) in Wistar rats.

METHODS

Following an intraperitoneal injection of CCl4 (0.5 mL/kg b.w. twice weekly) for eight weeks, male Wistar rats were intravenously treated with rats and mice BM-MSCs (1 × 106 cells in 0.2 mL Dulbecco's Modified Eagle Medium (DMEM)/rat/week) a week for four weeks. Kidney functions were evaluated and kidney samples were examined using hematoxylin and eosin (H&E), Masson's trichrome (MT) staining techniques, and electron microscopy analysis. Kidney cyclooxygenase-2 (COX-2), protein 53 (p53), and tumor necrosis factor-α (TNF-α) were detected by immunohistochemical staining techniques. Additionally, bioindicators of oxidative stress and antioxidant defense systems were identified in kidney tissue.

RESULTS

In CCl4-injected rats, serum creatinine, urea, and uric acid levels significantly increased, as did renal lipid peroxidation (LPO), while superoxide dismutase, glutathione peroxidase (GPx), glutathione (GSH) transferase, and GSH levels significantly dropped in the kidneys. Histologically, the kidneys displayed a wide range of structural abnormalities, such as glomerular shrinkage, tubular dilations, inflammatory leukocytic infiltration, fibroblast proliferation, and elevated collagen content. Inflammatory cytokines like COX-2 and TNF-α as well as the pro-apoptotic mediator p53 were considerably upregulated. Treatment of BM-MSCs from mice and rats with CCl4-injected rats considerably reduced the previously noted abnormalities.

CONCLUSIONS

By boosting antioxidant defense and reducing apoptosis and inflammation, BM-MSCs from mice and rats were able to enhance kidney function and histological integrity in rats that had received CCl4 injections.

Bone marrow-derived c-kit positive stem cell administration protects against diabetes-induced nephropathy in a rat model by reversing PI3K/AKT/GSK-3β pathway and inhibiting cell apoptosis

Stem cell-based therapy has been proposed as a novel therapeutic strategy for diabetic nephropathy. This study was designed to evaluate the effect of systemic administration of rat bone marrow-derived c-kit positive (c-kit+) cells on diabetic nephropathy in male rats, focusing on PI3K/AKT/GSK-3β pathway and apoptosis as a possible therapeutic mechanism. Twenty-eight animals were randomly classified into four groups: Control group (C), diabetic group (D), diabetic group, intravenously received 50 μl phosphate-buffered saline (PBS) containing 3 × 105 c-kit- cells (D + ckit-); and diabetic group, intravenously received 50 μl PBS containing 3 × 105 c-Kit positive cells (D + ckit+). Control and diabetic groups intravenously received 50 μl PBS. C-kit+ cell therapy could reduce renal fibrosis, which was associated with attenuation of inflammation as indicated by decreased TNF-α and IL-6 levels in the kidney tissue. In addition, c-kit+ cells restored the expression levels of PI3K, pAKT, and GSK-3β proteins. Furthermore, renal apoptosis was decreased following c-kit+ cell therapy, evidenced by the lower apoptotic index in parallel with the increased Bcl-2 and decreased Bax and Caspase-3 levels. Our results showed that in contrast to c-kit- cells, the administration of c-kit+ cells ameliorate diabetic nephropathy and suggested that c-kit+ cells could be an alternative cell source for attenuating diabetic nephropathy.

Canine Mesenchymal-Stem-Cell-Derived Extracellular Vesicles Attenuate Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease that is associated with systemic inflammation and immune modulation. Previously, we have shown that extracellular vesicles resulting from human adipose-tissue-derived mesenchymal stem cells (ASC-EVs) attenuated AD-like symptoms by reducing the levels of multiple inflammatory cytokines. Here, we aimed to investigate the improvement of canine AD upon using canine ASC-exosomes in a Biostir-induced AD mouse model. Additionally, we conducted in vivo toxicity studies to determine whether they targeted organs and their potential toxicity. Firstly, we isolated canine ASCs (cASCs) from the adipose tissue of a canine and characterized the cASCs-EVs. Interestingly, we found that cASC-EVs improved AD-like dermatitis and markedly decreased the levels of serum IgE, ear thickness, inflammatory cytokines, and chemokines such as IL-4 and IFN-γ in a dose-dependent manner. Moreover, there was no systemic toxicity in single- or repeat-dose toxicity studies using ICR mice. In addition, we analyzed miRNA arrays from cASC-EVs using next-generation sequencing (NGS) to investigate the role of miRNAs in improving inflammatory responses. Collectively, our results suggest that cASC-EVs effectively attenuate AD by transporting anti-inflammatory miRNAs to atopic lesions alongside no toxicological findings, resulting in a promising cell-free therapeutic option for treating canine AD.

Mesenchymal stem cells therapy for acute kidney injury: A systematic review with meta-analysis based on rat model

Objective: To systematically evaluate the efficacy of mesenchymal stem cells (MSCs) for acute kidney injury (AKI) in preclinical studies and to explore the optimal transplantation strategy of MSCs by network meta-analysis with the aim of improving the efficacy of stem cell therapy. Methods: Computer searches of PubMed, Web of Science, Cochrane, Embase, CNKI, Wanfang, VIP, and CBM databases were conducted until 17 August 2022. Literature screening, data extraction and quality evaluation were performed independently by two researchers. Results and Discussion: A total of 50 randomized controlled animal studies were included. The results of traditional meta-analysis showed that MSCs could significantly improve the renal function and injured renal tissue of AKI rats in different subgroups. The results of network meta-analysis showed that although there was no significant difference in the therapeutic effect between different transplant routes and doses of MSCs, the results of surface under the cumulative ranking probability curve (SUCRA) showed that the therapeutic effect of intravenous transplantation of MSCs was better than that of arterial and intrarenal transplantation, and the therapeutic effect of high dose (>1×10⁶) was better than that of low dose (≤1×10⁶). However, the current preclinical studies have limitations in experimental design, measurement and reporting of results, and more high-quality studies, especially direct comparative evidence, are needed in the future to further confirm the best transplantation strategy of MSCs in AKI. Systematic Review Registration: identifier https://CRD42022361199, https://www.crd.york.ac.uk/prospero.

Intercellular mitochondrial transfer as a means of revitalizing injured glomerular endothelial cells

BACKGROUND

Recent studies have demonstrated that mesenchymal stem cells (MSCs) can rescue injured target cells via mitochondrial transfer. However, it has not been fully understood how bone marrow-derived MSCs repair glomeruli in diabetic kidney disease (DKD).

AIM

To explore the mitochondrial transfer involved in the rescue of injured glomerular endothelial cells (GECs) by MSCs, both in vitro and in vivo.

METHODS

In vitro experiments were performed to investigate the effect of co-culture with MSCs on high glucose-induced GECs. The transfer of mitochondria was visualized using fluorescent microscopy. GECs were freshly sorted and ultimately tested for apoptosis, viability, mRNA expression by real-time reverse transcriptase-polymerase chain reaction, protein expression by western blot, and mitochondrial function. Moreover, streptozotocin-induced DKD rats were infused with MSCs, and renal function and oxidative stress were detected with an automatic biochemical analyzer and related-detection kits after 2 wk. Kidney histology was analyzed by hematoxylin and eosin, periodic acid-Schiff, and immunohistochemical staining.

RESULTS

Fluorescence imaging confirmed that MSCs transferred mitochondria to injured GECs when co-cultured in vitro. We found that the apoptosis, proliferation, and mitochondrial function of injured GECs were improved following co-culture. Additionally, MSCs decreased pro-inflammatory cytokines [interleukin (IL)-6, IL-1β, and tumor necrosis factor-α] and pro-apoptotic factors (caspase 3 and Bax). Mitochondrial transfer also enhanced the expression of superoxide dismutase 2, B cell lymphoma-2, glutathione peroxidase (GPx) 3, and mitofusin 2 and inhibited reactive oxygen species (ROS) and dynamin-related protein 1 expression. Furthermore, MSCs significantly ameliorated functional parameters (blood urea nitrogen and serum creatinine) and decreased the production of malondialdehyde, advanced glycation end products, and ROS, whereas they increased the levels of GPx and superoxide dismutase in vivo. In addition, significant reductions in the glomerular basement membrane and renal interstitial fibrosis were observed following MSC treatment.

CONCLUSION

MSCs can rejuvenate damaged GECs via mitochondrial transfer. Additionally, the improvement of renal function and pathological changes in DKD by MSCs may be related to the mechanism of mitochondrial transfer.

Dosing Limitation for Intra-Renal Arterial Infusion of Mesenchymal Stromal Cells

The immunomodulatory and regenerative properties of mesenchymal stromal cells (MSCs) make MSC therapy a promising therapeutic strategy in kidney disease. A targeted MSC administration via the renal artery offers an efficient delivery method with limited spillover to other organs. Although local administration alleviates safety issues with MSCs in systemic circulation, it introduces new safety concerns in the kidneys. In a porcine model, we employed intra-renal arterial infusion of ten million allogenic adipose tissue-derived MSCs. In order to trigger any potential adverse events, a higher dose (hundred million MSCs) was also included. The kidney function was studied by magnetic resonance imaging after the MSC infusion and again at two weeks post-treatment. The kidneys were assessed by single kidney glomerular filtration rate (skGFR) measurements, histology and inflammation, and fibrosis-related gene expression. None of the measured parameters were affected immediately after the administration of ten million MSCs, but the administration of one hundred million MSCs induced severe adverse events. Renal perfusion was reduced immediately after MSC administration which coincided with the presence of microthrombi in the glomeruli and signs of an instant blood-mediated inflammatory reaction. At two weeks post-treatment, the kidneys that were treated with one hundred million MSCs showed reduced skGFR, signs of tissue inflammation, and glomerular and tubular damage. In conclusions, the intra-renal administration of ten million MSCs is well-tolerated by the porcine kidney. However, higher concentrations (one hundred million MSCs) caused severe kidney damage, implying that very high doses of intra-renally administered MSCs should be undertaken with caution.

Mesenchymal Stem Cells and Extracellular Vesicles Derived from Canine Adipose Tissue Ameliorates Inflammation, Skin Barrier Function and Pruritus by Reducing JAK/STAT Signaling in Atopic Dermatitis

Canine atopic dermatitis (AD) is a common chronic inflammatory skin disorder resulting from imbalance between T lymphocytes. Current canine AD treatments use immunomodulatory drugs, but some of the dogs have limitations that do not respond to standard treatment, or relapse after a period of time. Thus, the purpose of this study was to evaluate the immunomodulatory effect of mesenchymal stem cells derived from canine adipose tissue (cASCs) and cASCs-derived extracellular vesicles (cASC-EVs) on AD. First, we isolated and characterized cASCs and cASCs-EVs to use for the improvement of canine atopic dermatitis. Here, we investigated the effect of cASCs or cASC-EVs on DNCB-induced AD in mice, before using for canine AD. Interestingly, we found that cASCs and cASC-EVs improved AD-like dermatitis, and markedly decreased levels of serum IgE, (49.6%, p = 0.002 and 32.1%, p = 0.016 respectively) epidermal inflammatory cytokines and chemokines, such as IL-4 (32%, p = 0.197 and 44%, p = 0.094 respectively), IL-13 (47.4%, p = 0.163, and 50.0%, p = 0.039 respectively), IL-31 (64.3%, p = 0.030 and 76.2%, p = 0.016 respectively), RANTES (66.7%, p = 0.002 and 55.6%, p = 0.007) and TARC (64%, p = 0.016 and 86%, p = 0.010 respectively). In addition, cASCs or cASC-EVs promoted skin barrier repair by restoring transepidermal water loss, enhancing stratum corneum hydration and upregulating the expression levels of epidermal differentiation proteins. Moreover, cASCs or cASC-EVs reduced IL-31/TRPA1-mediated pruritus and activation of JAK/STAT signaling pathway. Taken together, these results suggest the potential of cASCs or cASC-EVs for the treatment of chronic inflammation and damaged skin barrier in AD or canine AD.

Deficiency of the kidney tubular angiotensin II type1 receptor-associated protein ATRAP exacerbates streptozotocin-induced diabetic glomerular injury via reducing protective macrophage polarization

Although activation of the renin-angiotensin system and of its glomerular components is implicated in the pathogenesis of diabetic nephropathy, the functional roles of the tubular renin-angiotensin system with AT1 receptor signaling in diabetic nephropathy are unclear. Tissue hyperactivity of the renin-angiotensin system is inhibited by the angiotensin II type 1 receptor-associated protein ATRAP, which negatively regulates receptor signaling. The highest expression of endogenous ATRAP occurs in the kidney, where it is mainly expressed by tubules but rarely in glomeruli. Here, we found that hyperactivation of angiotensin II type 1 receptor signaling in kidney tubules exacerbated diabetic glomerular injury in a mouse model of streptozotocin-induced diabetic nephropathy. These phenomena were accompanied by decreased expression of CD206, a marker of alternatively activated and tissue-reparative M2 macrophages, in the kidney tubulointerstitium. Additionally, adoptive transfer of M2- polarized macrophages into diabetic ATRAP-knockout mice ameliorated the glomerular injury. As a possible mechanism, the glomerular mRNA levels of tumor necrosis factor-α and oxidative stress components were increased in diabetic knockout mice compared to non-diabetic knockout mice, but these increases were ameliorated by adoptive transfer. Furthermore, proximal tubule-specific ATRAP downregulation reduced tubulointerstitial expression of CD206, the marker of M2 macrophages in diabetic mice. Thus, our findings indicate that tubular ATRAP-mediated functional modulation of angiotensin II type 1 receptor signaling modulates the accumulation of tubulointerstitial M2 macrophages, thus affecting glomerular manifestations of diabetic nephropathy via tubule-glomerular crosstalk.

Effect of Everolimus versus Bone Marrow-Derived Stem Cells on Glomerular Injury in a Rat Model of Glomerulonephritis: A Preventive, Predictive and Personalized Implication

Glomerular endothelial injury and effectiveness of glomerular endothelial repair play a crucial role in the progression of glomerulonephritis. Although the potent immune suppressive everolimus is increasingly used in renal transplant patients, adverse effects of its chronic use have been reported clinically in human glomerulonephritis and experimental renal disease. Recent studies suggest that progenitor stem cells could enhance glomerular endothelial repair with minimal adverse effects. Increasing evidence supports the notion that stem cell therapy and regenerative medicine can be effectively used in pathological conditions within the predictive, preventive and personalized medicine (PPPM) paradigm. In this study, using an experimental model of glomerulonephritis, we tested whether bone marrow-derived stem cells (BMDSCs) could provide better effect over everolimus in attenuating glomerular injury and improving the repair process in a rat model of glomerulonephritis. Anti-Thy1 glomerulonephritis was induced in male Sprague Dawley rats by injection of an antibody against Thy1, which is mainly expressed on glomerular mesangial cells. Additional groups of rats were treated with the immunosuppressant everolimus daily after the injection of anti-Thy1 or injected with single bolus dose of BMDSCs after one week of injection of anti-Thy1 (n = 6-8). Nine days after injection of anti-Thy1, glomerular albumin permeability and albuminuria were significantly increased when compared to control group (p < 0.05). Compared to BMDSCs, everolimus was significantly effective in attenuating glomerular injury, nephrinuria and podocalyxin excretion levels as well as in reducing inflammatory responses and apoptosis. Our findings suggest that bolus injection of BMDSCs fails to improve glomerular injury whereas everolimus slows the progression of glomerular injury in Anti-Thy-1 induced glomerulonephritis. Thus, everolimus could be used at the early stage of glomerulonephritis, suggesting potential implications of PPPM in the treatment of progressive renal injury.

Current advances of stem cell-based therapy for kidney diseases

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

Extracellular Vesicles Derived from Endothelial Progenitor Cells Protect Human Glomerular Endothelial Cells and Podocytes from Complement- and Cytokine-Mediated Injury

Glomerulonephritis are renal inflammatory processes characterized by increased permeability of the Glomerular Filtration Barrier (GFB) with consequent hematuria and proteinuria. Glomerular endothelial cells (GEC) and podocytes are part of the GFB and contribute to the maintenance of its structural and functional integrity through the release of paracrine mediators. Activation of the complement cascade and pro-inflammatory cytokines (CK) such as Tumor Necrosis Factor α (TNF-α) and Interleukin-6 (IL-6) can alter GFB function, causing acute glomerular injury and progression toward chronic kidney disease. Endothelial Progenitor Cells (EPC) are bone-marrow-derived hematopoietic stem cells circulating in peripheral blood and able to induce angiogenesis and to repair injured endothelium by releasing paracrine mediators including Extracellular Vesicles (EVs), microparticles involved in intercellular communication by transferring proteins, lipids, and genetic material (mRNA, microRNA, lncRNA) to target cells. We have previously demonstrated that EPC-derived EVs activate an angiogenic program in quiescent endothelial cells and renoprotection in different experimental models. The aim of the present study was to evaluate in vitro the protective effect of EPC-derived EVs on GECs and podocytes cultured in detrimental conditions with CKs (TNF-α/IL-6) and the complement protein C5a. EVs were internalized in both GECs and podocytes mainly through a L-selectin-based mechanism. In GECs, EVs enhanced the formation of capillary-like structures and cell migration by modulating gene expression and inducing the release of growth factors such as VEGF-A and HGF. In the presence of CKs, and C5a, EPC-derived EVs protected GECs from apoptosis by decreasing oxidative stress and prevented leukocyte adhesion by inhibiting the expression of adhesion molecules (ICAM-1, VCAM-1, E-selectin). On podocytes, EVs inhibited apoptosis and prevented nephrin shedding induced by CKs and C5a. In a co-culture model of GECs/podocytes that mimicked GFB, EPC-derived EVs protected cell function and permeselectivity from inflammatory-mediated damage. Moreover, RNase pre-treatment of EVs abrogated their protective effects, suggesting the crucial role of RNA transfer from EVs to damaged glomerular cells. In conclusion, EPC-derived EVs preserved GFB integrity from complement- and cytokine-induced damage, suggesting their potential role as therapeutic agents for drug-resistant glomerulonephritis.

Endothelial Progenitor Cell-Derived Extracellular Vesicles: Potential Therapeutic Application in Tissue Repair and Regeneration

Recently, many studies investigated the role of a specific type of stem cell named the endothelial progenitor cell (EPC) in tissue regeneration and repair. EPCs represent a heterogeneous population of mononuclear cells resident in the adult bone marrow. EPCs can migrate and differentiate in injured sites or act in a paracrine way. Among the EPCs’ secretome, extracellular vesicles (EVs) gained relevance due to their possible use for cell-free biological therapy. They are more biocompatible, less immunogenic, and present a lower oncological risk compared to cell-based options. EVs can efficiently pass the pulmonary filter and deliver to target tissues different molecules, such as micro-RNA, growth factors, cytokines, chemokines, and non-coding RNAs. Their effects are often analogous to their cellular counterparts, and EPC-derived EVs have been tested in vitro and on animal models to treat several medical conditions, including ischemic stroke, myocardial infarction, diabetes, and acute kidney injury. EPC-derived EVs have also been studied for bone, brain, and lung regeneration and as carriers for drug delivery. This review will discuss the pre-clinical evidence regarding EPC-derived EVs in the different disease models and regenerative settings. Moreover, we will discuss the translation of their use into clinical practice and the possible limitations of this process.

Safety and therapeutic potential of human bone marrow-derived mesenchymal stromal cells in regenerative medicine

Regenerative medicine is considered as an alternative approach to healthcare. Owing to their pluripotent abilities and their relative lack of ethical and legal issues, adult stem cells are considered as optimal candidates for use in the treatment of various diseases. Bone marrow-derived mesenchymal stem cells are among the most promising candidates for clinical applications as they have expressed a higher degree of plasticity in vitro. Many investigators have begun to examine how bone marrow stem cells might be used to rebuild damaged tissues. The systemic administration of cells for therapeutic applications requires efficient migration and homing of cells to the target site. Cell adhesion molecules and their ligands, chemokines, extracellular matrix components and specialized bone marrow niches all participate in the proper regulation of this process. MSCs suppress the pathophysiological process that is mediated by chronic inflammation and contributes to a modification of the microenvironment and tissue regeneration. Due to the intricacy of the mesenchymal stem cell, there is ever-increasing amount of data emerging about their migration and regenerative mechanisms. Many factors influence MSC mobilization and their homing to injured tissues. This review summarizes the current clinical and pre-clinical data available in literature regarding the use of MSC in tissue repair and their prospective therapeutic role in various diseases and the underlying repair mechanisms will be discussed.

Optimization of oxidative stress for mesenchymal stromal/stem cell engraftment, function and longevity

Mesenchymal stromal/stem cells (MSCs) are multipotent cells that possess great potential as a cellular therapeutic based on their ability to differentiate to different lineages and to modulate immune responses. However, their potential is limited by their low tissue abundance, and thus the need for robust ex vivo expansion prior to their application. This creates its own issues, namely replicative senescence, which could lead to reduced MSC functionality and negatively impact their engraftment. Ex vivo expansion and MSC aging are associated with greater oxidative stress. Therefore, there is great need to identify strategies to reduce oxidative stress in MSCs. This review summarizes the achievements made to date in addressing oxidative stress in MSCs and speculates about interesting avenues of future investigation to solve this critical problem.

Injection of hybrid 3D spheroids composed of podocytes, mesenchymal stem cells, and vascular endothelial cells into the renal cortex improves kidney function and replenishes glomerular podocytes

Podocytes are highly differentiated epithelial cells that are crucial for maintaining the glomerular filtration barrier in the kidney. Podocyte injury followed by depletion is the major cause of pathological progression of kidney diseases. Although cell therapy has been considered a promising alternative approach to kidney transplantation for the treatment of kidney injury, the resultant therapeutic efficacy in terms of improved renal function is limited, possibly owing to significant loss of engrafted cells. Herein, hybrid three-dimensional (3D) cell spheroids composed of podocytes, mesenchymal stem cells, and vascular endothelial cells were designed to mimic the glomerular microenvironment and as a cell delivery vehicle to replenish the podocyte population by cell transplantation. After creating a native glomerulus-like condition, the expression of multiple genes encoding growth factors and basement membrane factors that are strongly associated with podocyte maturation and functionality was significantly enhanced. Our in vivo results demonstrated that intrarenal transplantation of podocytes in the form of hybrid 3D cell spheroids improved engraftment efficiency and replenished glomerular podocytes. Moreover, the proteinuria of the experimental mice with hypertensive nephropathy was effectively reduced. These data clearly demonstrated the potential of hybrid 3D cell spheroids for repairing injured kidneys.

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.

Mesenchymal stem cells: Biological characteristics and application in disease therapy

Mesenchymal stem cells (MSCs) are multipotent stem cells. In addition to the capacity for self-renewal and multipotential differentiation, MSCs also have the following characteristics. MSCs can exert immunomodulatory functions through interaction with innate or adaptive immune cells, MSCs with poor immunogenicity can be used for allogeneic transplantation, and MSCs can "home" to inflammation and tumour sites. Based on these biological properties, MSCs demonstrate broad clinical application prospects in the treatment of tissue injury, autoimmune diseases, transplantation, cancer and other inflammation-related diseases. In this review we describe the biological characteristics of MSCs and discuss the research advances of MSCs in regenerative medicine, immunomodulation, oncology, and COVID-19, to fully understand the range of diseases in which MSC therapy may be beneficial.

Mesenchymal Stem Cell Therapy for Diabetic Kidney Disease: A Review of the Studies Using Syngeneic, Autologous, Allogeneic, and Xenogeneic Cells

Diabetic kidney disease (DKD) is a microvascular complication of diabetes mellitus (DM) and comprises multifactorial pathophysiologic mechanisms. Despite current treatment, around 30-40% of individuals with type 1 and type 2 DM (DM1 and DM2) have progressive DKD, which is the most common cause of end-stage chronic kidney disease worldwide. Mesenchymal stem cell- (MSC-) based therapy has important biological and therapeutic implications for curtailing DKD progression. As a chronic disease, DM may impair MSC microenvironment, but there is compelling evidence that MSC derived from DM1 individuals maintain their cardinal properties, such as potency, secretion of trophic factors, and modulation of immune cells, so that both autologous and allogeneic MSCs are safe and effective. Conversely, MSCs derived from DM2 individuals are usually dysfunctional, exhibiting higher rates of senescence and apoptosis and a decrease in clonogenicity, proliferation, and angiogenesis potential. Therefore, more studies in humans are needed to reach a conclusion if autologous MSCs from DM2 individuals are effective for treatment of DM-related complications. Importantly, the bench to bedside pathway has been constructed in the last decade for assessing the therapeutic potential of MSCs in the DM setting. Laboratory research set the basis for establishing further translation research including preclinical development and proof of concept in model systems. Phase I clinical trials have evaluated the safety profile of MSC-based therapy in humans, and phase II clinical trials (proof of concept in trial participants) still need to answer important questions for treating DKD, yet metabolic control has already been documented. Therefore, randomized and controlled trials considering the source, optimal cell number, and route of delivery in DM patients are further required to advance MSC-based therapy. Future directions include strategies to reduce MSC heterogeneity, standardized protocols for isolation and expansion of those cells, and the development of well-designed large-scale trials to show significant efficacy during a long follow-up, mainly in individuals with DKD.

Human mesenchymal stromal cells and derived extracellular vesicles: Translational strategies to increase their proangiogenic potential for the treatment of cardiovascular disease

Mesenchymal stromal cells (MSCs) offer great potential for the treatment of cardiovascular diseases (CVDs) such as myocardial infarction and heart failure. Studies have revealed that the efficacy of MSCs is mainly attributed to their capacity to secrete numerous trophic factors that promote angiogenesis, inhibit apoptosis, and modulate the immune response. There is growing evidence that MSC‐derived extracellular vesicles (EVs) containing a cargo of lipids, proteins, metabolites, and RNAs play a key role in this paracrine mechanism. In particular, encapsulated microRNAs have been identified as important positive regulators of angiogenesis in pathological settings of insufficient blood supply to the heart, thus opening a new path for the treatment of CVD. In the present review, we discuss the current knowledge related to the proangiogenic potential of MSCs and MSC‐derived EVs as well as methods to enhance their biological activities for improved cardiac tissue repair. Increasing our understanding of mechanisms supporting angiogenesis will help optimize future approaches to CVD intervention.

Understanding Mesangial Pathobiology in AL-Amyloidosis and Monoclonal Ig Light Chain Deposition Disease

Patients with plasma cell dyscrasias produce free abnormal monoclonal Ig light chains that circulate in the blood stream. Some of them, termed glomerulopathic light chains, interact with the mesangial cells and trigger, in a manner dependent of their structural and physicochemical properties, a sequence of pathological events that results in either light chain–derived (AL) amyloidosis (AL-Am) or light chain deposition disease (LCDD). The mesangial cells play a key role in the pathogenesis of both diseases. The interaction with the pathogenic light chain elicits specific cellular processes, which include apoptosis, phenotype transformation, and secretion of extracellular matrix components and metalloproteinases. Monoclonal light chains associated with AL-Am but not those producing LCDD are avidly endocytosed by mesangial cells and delivered to the mature lysosomal compartment where amyloid fibrils are formed. Light chains from patients with LCDD exert their pathogenic signaling effect at the cell surface of mesangial cells. These events are generic mesangial responses to a variety of adverse stimuli, and they are similar to those characterizing other more frequent glomerulopathies responsible for many cases of end-stage renal disease. The pathophysiologic events that have been elucidated allow to propose future therapeutic approaches aimed at preventing, stopping, ameliorating, or reversing the adverse effects resulting from the interactions between glomerulopathic light chains and mesangium.

Mesenchymal stromal cell-based therapies for acute kidney injury: progress in the last decade

A little over 10 years ago, the therapeutic potential of mesenchymal stromal cells (MSCs) for the treatment of acute kidney injury (AKI) was becoming widely recognized. Since then, there has been further intensive study of this topic with a clear translational intent. Over the past decade, many more animal model studies have strengthened the evidence that systemically or locally delivered MSCs ameliorate renal injury in sterile and sepsis-associated AKI. Some of these preclinical studies have also provided a range of compelling new insights into the in vivo fate and mechanisms of action of MSCs in the setting of AKI and other inflammatory conditions. Coupled with increased knowledge of the functional roles of resident and infiltrating immune cell mediators in determining the severity and outcome of AKI, the progress made in the past decade would appear to have significantly strengthened the translational pathway for MSC-based therapies. In contrast, however, the extent of the clinical experience with MSC administration in human subjects with AKI or sepsis-associated AKI has been limited to a small number of early-phase clinical trials, which appear to demonstrate safety but have not thus far delivered a strong signal of efficacy. In this review, we summarize the most significant new developments in the field of MSC-based therapies as they relate to AKI and reflect on the key gaps in knowledge and technology that remain to be addressed for the true clinical potential of MSCs and, perhaps, other emerging cellular therapies to be realized.

Review of clinical nerve repair strategies for neurorestoration of central nervous system tumor damage

Central nervous system (CNS) tumors are common. In recent years, with the continuous development and popularization of neurosurgery and the advancement of diagnostic and therapeutic instruments, the diagnosis and treatment of diseases have made great progress, but the prognosis of patients depends on multiple clinical factors. In this study, we selected various literatures in the PubMed and Google Scholar search engines using the keywords "nerve repair strategies" , "central nervous system tumor" as well as searched scientifically reviewed historical perspectives and recent advancements and achievements in Neurorestoratology of the CNS. Therefore, this study focuses on the Neurorestoratology of the CNS and its prospects, aiming to provide scientific guidance for the clinical diagnosis and treatment of CNS tumors in the future, and improve the prognosis and quality of life of patients.

Mesenchymal Stromal Cells Induce Podocyte Protection in the Puromycin Injury Model

Podocytes are specialized cells with a limited capacity for cell division that do not regenerate in response to injury and loss. Insults that compromise the integrity of podocytes promote proteinuria and progressive renal disease. The aim of this study was to evaluate the potential renoprotective and regenerative effects of mesenchymal stromal cells (mSC) in a severe form of the podocyte injury model induced by intraperitoneal administration of puromycin, aggravated by unilateral nephrectomy. Bone derived mSC were isolated and characterized according to flow cytometry analyses and to their capacity to differentiate into mesenchymal lineages. Wistar rats were divided into three groups: Control, PAN, and PAN+ mSC, consisting of PAN rats treated with 2 × 10⁵ mSC. PAN rats developed heavy proteinuria, hypertension, glomerulosclerosis and significant effacement of the foot process. After 60 days, PAN rats treated with mSC presented a significant amelioration of all these abnormalities. In addition, mSC treatment recovered WT1 expression, improved nephrin, podocin, synaptopodin, podocalyxin, and VEGF expression, and downregulated proinflammatory Th1 cytokines in the kidney with a shift towards regulatory Th2 cytokines. In conclusion, mSC administration induced protection of podocytes in this experimental PAN model, providing new perspectives for the treatment of renal diseases associated with podocyte damage.

Intrarenal Transplantation of Hypoxic Preconditioned Mesenchymal Stem Cells Improves Glomerulonephritis through Anti-Oxidation, Anti-ER Stress, Anti-Inflammation, Anti-Apoptosis, and Anti-Autophagy

To confer further therapeutic potential and prevent some adverse effects by the mesenchymal stem cells (MSCs) transplantation, we explored the effects of locally intrarenal arterial administration of hypoxic preconditioned MSCs in the anti-Thy1.1 induced rat glomerulonephritis. Proteinuria, histochemical staining, and western blotting were used to explore the therapeutic effects and mechanisms. Locally intrarenal arterial MSCs transplantation successfully implanted the fluorescent or CD44 labeled MSCs in the nephritic glomeruli, ameliorated proteinuria, and glomerulosclerosis in nephritic rats. Hypoxic preconditioning significantly upregulated hypoxic inducible factor-1α/VEGF (HIF-1α/VEGF) in the MSCs and was more efficient than normoxic MSCs in reducing the degree of urinary protein, glomerulosclerosis, fibrosis, macrophage/monocyte infiltration, GRP78 mediated endoplasmic reticulum stress, Beclin-1/LC3-II mediated autophagy, and Bax/Bcl-2/caspase 3 mediated apoptosis. Hypoxic MSCs could further promote intranuclear nuclear factor (erythroid-derived 2, Nrf2) and reduce nuclear factor kappa B expression in nephritic kidneys. As compared to normoxic MSCs, hypoxic MSCs transplantation significantly upregulated the renal expression of anti-oxidative response elements/enzymes including glutamate-cysteine ligase catalytic subunit, glutamate-cysteine ligase modifier subunit, glutathione peroxidase, catalase, Mn, and Cu/Zn superoxide dismutase. In summary, intrarenal hypoxic preconditioning MSCs transplantation was more effective to activate hypoxic inducible factor-1α/VEGF/Nrf2 (HIF-1α/VEGF/Nrf2) signaling, preserve anti-oxidant proteins and anti-oxidative responsive element proteins, and subsequently reduce glomerular apoptosis, autophagy, and inflammation.

Progenitor/Stem Cell Delivery by Suprarenal Aorta Route in Acute Kidney Injury

Progenitor/stem cell-based kidney regenerative strategies are a key step towards the development of novel therapeutic regimens for kidney disease treatment. However, the route of cell delivery, e.g., intravenous, intra-arterial, or intra-parenchymal, may affect the efficiency for kidney repair in different models of acute and chronic injury. Here, we describe a protocol of intra-aorta progenitor/stem cell injection in rats following either acute ischemia-reperfusion injury or acute proteinuria induced by puromycin aminonucleoside (PAN) – the experimental prototype of human minimal change disease and early stages of focal and segmental glomerulosclerosis. Vascular clips were applied across both renal pedicles for 35 min, or a single dose of PAN was injected via intra-peritoneal route, respectively. Subsequently, 2 x 10⁶ stem cells [green fluorescent protein (GFP)-labeled c-Kit+ progenitor/stem cells or GFP-mesenchymal stem cells] or saline were injected into the suprarenal aorta, above the renal arteries, after application of a vascular clip to the abdominal aorta below the renal arteries. This approach contributed to engraftment rates of ∼10% at day 8 post ischemia-reperfusion injury, when c-Kit+ progenitor/stem cells were injected, which accelerated kidney recovery. Similar rates of engraftment were found after PAN-induced podocyte damage at day 21. With practice and gentle surgical technique, 100% of the rats could be injected successfully, and, in the week following injection, ∼ 85% of the injected rats will recover completely. Given the similarities in mammals, much of the data obtained from intra-arterial delivery of progenitor/stem cells in rodents can be tested in translational research and clinical trials with endovascular catheters in humans.

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.

Bone marrow transplant with post-transplant cyclophosphamide for recessive dystrophic epidermolysis bullosa expands the related donor pool and permits tolerance of nonhaematopoietic cellular grafts

BACKGROUND

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe systemic genodermatosis lacking therapies beyond supportive care for its extensive, life-limiting manifestations.

OBJECTIVES

To report the safety and preliminary responses of 10 patients with RDEB to bone marrow transplant (BMT) with post-transplant cyclophosphamide (PTCy BMT) after reduced-intensity conditioning with infusions of immunomodulatory donor-derived mesenchymal stromal cells (median follow-up 16 months).

METHODS

BMT toxicities, donor blood and skin engraftment, skin biopsies, photographic and dynamic assessments of RDEB disease activity were obtained at intervals from pre-BMT to 1 year post-BMT.

RESULTS

Related donors varied from haploidentical (n = 6) to human leucocyte antigen (HLA)-matched (n = 3), with one HLA-matched unrelated donor. Transplant complications included graft failure (n = 3; two pursued a second PTCy BMT), veno-occlusive disease (n = 2), posterior reversible encephalopathy (n = 1) and chronic graft-versus-host disease (n = 1; this patient died). In the nine ultimately engrafted patients, median donor chimerism at 180 days after transplant was 100% in peripheral blood and 27% in skin. Skin biopsies showed stable (n = 7) to improved (n = 2) type VII collagen protein expression by immunofluorescence and gain of anchoring fibril components (n = 3) by transmission electron microscopy. Early signs of clinical response include trends toward reduced body surface area of blisters/erosions from a median of 49·5% to 27·5% at 100 days after BMT (P = 0·05), with parental measures indicating stable quality of life.

CONCLUSIONS

PTCy BMT in RDEB provides a means of attaining immunotolerance for future donor-derived cellular grafts (ClinicalTrials.gov identifier NCT02582775). What's already known about this topic? Severe, generalized recessive dystrophic epidermolysis bullosa (RDEB) is marked by great morbidity and early death. No cure currently exists for RDEB. Bone marrow transplant (BMT) is the only described systemic therapy for RDEB. What does this study add? The first description of post-transplant cyclophosphamide (PTCy) BMT for RDEB. PTCy was well tolerated and provided excellent graft-versus-host disease prophylaxis, replacing long courses of calcineurin inhibitors in patients receiving human leucocyte antigen-matched sibling BMT. What is the translational message? The PTCy BMT platform permits identification of a suitable related donor for most patients and for subsequent adoptive transfer of donor nonhaematopoietic cells after establishment of immunological tolerance.

Effects of Human Placental Amnion Derived Mesenchymal Stem Cells on Proliferation and Apoptosis Mechanisms in Chronic Kidney Disease in the Rat

Background and Objectives

The feature of chronic kidney failure (CKF) is loss of kidney functions due to erosion of healthy tissue and fibrosis. Recent studies showed that Mesenchymal stem cells (MSCs) differentiated into tubular epithelial cells thus renal function and structures renewed. Furthermore, MSCs protect renal function in CKF. Therefore, we aimed to investigate whether human amnion-derived mesenchymal stem cells (hAMSCs) can repair fibrosis and determine the effects on proliferation and apoptosis mechanisms in chronic kidney failure.

Methods and Results

In this study, rat model of CKF was constituted by applying Aristolochic acid (AA). hAMSCs were isolated from term placenta amnion membrane and transplanted into tail vein of rats. At the end of 30 days and 60 days of recovery period, we examined expressions of PCNA, p57 and Parp-1 by western blotting. Immunoreactivity of PCNA, Ki67, IL-6 and Collagen type I were detected by immunohistochemistry. Besides, apoptosis was detected by TUNEL. Serum creatinine and urea were measured. Expressions of PCNA and Ki67 increased in hAMSC groups compared with AA group. Furthermore, expressions of PARP-1 apoptosis marker and p57 cell cycle inhibitory protein increased in AA group significantly according to control, hAMSC groups and sham groups. IL-6 proinflammatory cytokine increased in AA group significantly according to control, hAMSCs groups and sham groups. Expressions of Collagen type I protein reduced in hAMSCs groups compared to AA group. After hAMSC treatment, serum creatinine and urea levels significantly decreased compared to AA group. After injection of hAMSC to rats, Masson’s Trichrome and Sirius Red staining showed fibrosis reduction in kidney.

Conclusions

According to our results hAMSCs can be ameliorate renal failure.

The therapeutic application of mesenchymal stem cells at the ocular surface

The therapeutic potential of mesenchymal stem cells (MSCs) has been heralded by their multipotentiality and immunomodulatory capacity. MSCs migrate toward sites of tissue damage, where specific pro-inflammatory factors 'license' their immunosuppressive functions. Recent studies in animal models of ocular surface disease have demonstrated the potential of MSC-derived therapies to limit inflammation and promote tissue repair. Herein, we review the immunoregulatory mechanisms of MSCs, as well as strategies to harness their regenerative function at the cornea. We examine reports of the therapeutic application of MSCs in the setting of ocular surface inflammation; including corneal injury, transplantation, ocular surface autoimmunity and allergy.

Muse cells and Neurorestoratology

Multilineage-differentiating stress-enduring (Muse) cells were discovered in 2010 as a subpopulation of mesenchymal stroma cells (MSCs). Muse cells can self-renew and tolerate severe culturing conditions. These cells can differentiate into three lineage cells spontaneously or in induced medium but do not form teratoma in vitro or in vivo. Central nervous system (CNS) diseases, such as intracerebral hemorrhage (ICH), cerebral infarction, and spinal cord injury are normally disastrous. Despite numerous therapy strategies, CNS diseases are difficult to recover. As a novel kind of pluripotent stem cells, Muse cells have shown great regeneration capacity in many animal models, including acute myocardial infarction, hepatectomy, and acute cerebral ischemia (ACI). After injection into injury sites, Muse cells survived, migrated, and differentiated into functional neurons with synaptic junctions to local neurons and contributed to recovery of function. Furthermore, Muse cell differentiation did not need to be induced pre-transplantation and no tumors were observed post- transplantation. The Muse cell population is promising and may lead to a revolution in regenerative medicine. This review focuses on recent advances regarding the Muse cells therapies in Neurorestoratology and discusses future perspectives in this field.

The Transcriptome of Human Endometrial Mesenchymal Stem Cells Under TGFβR Inhibition Reveals Improved Potential for Cell-Based Therapies

Mesenchymal stem/stromal cells (MSCs) are multipotent cells with favorable properties for cell therapies and regenerative medicine. Human endometrium harbors a small population of perivascular, clonogenic MSCs (eMSCs) identified by the SUSD2 marker. As for other MSCs, eMSCs require extensive in vitro expansion to generate clinically relevant numbers of cells, resulting in spontaneous differentiation, replicative senescence and cell death, decreasing therapeutic potency. We previously demonstrated that A83-01, a TGF-β receptor inhibitor, maintained eMSC clonogenicity, promoted proliferation, prevented apoptosis and maintained MSC function in vitro. Here we compare the transcriptome of passaged eMSCs from six women cultured with and without A83-01 for 7 days. We identified 1206 differentially expressed genes (DEG) using a false discovery rate cut-off at 0.01 and fold change >2. Significant enrichment of genes involved in anti-inflammatory responses, angiogenesis, cell migration and proliferation, and collagen fibril and extracellular matrix organization were revealed. TGF-β, Wnt and Akt signaling pathways were decreased. Anti-fibrotic and anti-apoptotic genes were induced, and fibroblast proliferation and myofibroblast related genes were downregulated. We found increased MSC potency genes (TWIST1, TWIST2, JAG1, LIFR, and SLIT2) validating the enhanced potency of A83-01-treated eMSCs, and importantly no pluripotency gene expression. We also identified eMSCs’ potential for secreting exosomes, possibly explaining their paracrine properties. Angiogenic and cytokine protein arrays confirmed the angiogenic, anti-fibrotic and immunomodulatory phenotype of A83-01-treated eMSCs, and increased angiogenic activity was functionally demonstrated in vitro. eMSCs culture expanded with A83-01 have enhanced clinically relevant properties, suggesting their potential for cell-therapies and regenerative medicine applications.

Kidney-derived c-kit+ progenitor/stem cells contribute to podocyte recovery in a model of acute proteinuria

Kidney-derived c-kit⁺ cells exhibit progenitor/stem cell properties and can regenerate epithelial tubular cells following ischemia-reperfusion injury in rats. We therefore investigated whether c-kit⁺ progenitor/stem cells contribute to podocyte repair in a rat model of acute proteinuria induced by puromycin aminonucleoside (PAN), the experimental prototype of human minimal change disease and early stages of focal and segmental glomerulosclerosis. We found that c-kit⁺ progenitor/stem cells accelerated kidney recovery by improving foot process effacement (foot process width was lower in c-kit group vs saline treated animals, P = 0.03). In particular, these cells engrafted in small quantity into tubules, vessels, and glomeruli, where they occasionally differentiated into podocyte-like cells. This effect was related to an up regulation of α-Actinin-4 and mTORC2-Rictor pathway. Activation of autophagy by c-kit⁺ progenitor/stem cells also contributed to kidney regeneration and intracellular homeostasis (autophagosomes and autophagolysosomes number and LC3A/B-I and LC3A/B-II expression were higher in the c-kit group vs saline treated animals, P = 0.0031 and P = 0.0009, respectively). Taken together, our findings suggest that kidney-derived c-kit⁺ progenitor/stem cells exert reparative effects on glomerular disease processes through paracrine effects, to a lesser extent differentiation into podocyte-like cells and contribution to maintenance of podocyte cytoskeleton after injury. These findings have clinical implications for cell therapy of glomerular pathobiology.

Bioengineering in renal transplantation: technological advances and novel options

End-stage kidney disease (ESKD) is one of the most prevalent diseases in the world with significant morbidity and mortality. Current modes of renal replacement therapy include dialysis and renal transplantation. Although dialysis is an acceptable mode of renal replacement therapy, it does have its shortcomings, which include poorer life expectancy compared with renal transplantation, risk of infections and vascular thrombosis, lack of vascular access and absence of biosynthetic functions of the kidney. Renal transplantation, in contrast, is the preferred option of renal replacement therapy, with improved morbidity and mortality rates and quality of life, compared with dialysis. Renal transplantation, however, may not be available to all patients with ESKD. Some of the key factors limiting the availability and efficiency of renal transplantation include shortage of donor organs and the constant risk of rejection with complications associated with over-immunosuppression respectively. This review focuses chiefly on the potential roles of bioengineering in overcoming limitations in renal transplantation via the development of cell-based bioartificial dialysis devices as bridging options before renal transplantation, and the development of new sources of organs utilizing cell and organ engineering.

A Systematic Review and Meta-analysis of Mesenchymal Stem Cell Injections for the Treatment of Perianal Crohn's Disease: Progress Made and Future Directions

BACKGROUND

There has been a surge in clinical trials studying the safety and efficacy of mesenchymal stem cells for the treatment of perianal Crohn's disease.

OBJECTIVE

The purpose of this work was to systematically review the literature to determine safety and efficacy of mesenchymal stem cells for the treatment of refractory perianal Crohn's disease.

DATA SOURCES

Sources included PubMed, Cochrane Library Central Register of Controlled Trials, and Embase.

STUDY SELECTION

Studies that reported safety and/or efficacy of mesenchymal stem cells for the treatment of perianal Crohn's disease were included. Two independent assessors reviewed eligible articles.

INTERVENTION

The study intervention was delivery of mesenchymal stem cells to treat perianal Crohn's disease.

MAIN OUTCOMES MEASURES

Safety and efficacy of mesenchymal stem cells used to treat perianal Crohn's disease were measured.

RESULTS

Eleven studies met the inclusion criteria and were included in the systematic review. Three trials with a comparison arm were included in the meta-analysis. There were no significant increases in adverse events (OR = 1.07 (95% CI, 0.61-1.89); p = 0.81) or serious adverse events (OR = 0.53 (95% CI, 0.28-0.98); p = 0.04) in patients treated with mesenchymal stem cells. Mesenchymal stem cells were associated with improved healing as compared with control subjects at primary end points of 6 to 24 weeks (OR = 3.06 (95% CI, 1.05-8.90); p = 0.04) and 24 to 52 weeks (OR = 2.37 (95% CI, 0.90-6.25); p = 0.08).

LIMITATIONS

The study was limited by its multiple centers and heterogeneity in the study inclusion criteria, mesenchymal stem cell origin, dose and frequency of delivery, use of scaffolding, and definition and time point of fistula healing.

CONCLUSIONS

Although there have been only 3 trials conducted with control arms, existing data demonstrate improved efficacy and no increase in adverse or serious adverse events with mesenchymal stem cells as compared with control subjects for the treatment of perianal Crohn's disease.

Isolation of a multipotent mesenchymal stem cell-like population from human adrenal cortex

BACKGROUND

The highly plastic nature of adrenal cortex suggests the presence of adrenocortical stem cells (ACSC), but the exact in vivo identity of ACSC remains elusive. A few studies have demonstrated the differentiation of adipose or bone marrow-derived mesenchymal stem cells (MSC) into steroid-producing cells. We therefore investigated the isolation of multipotent MSC from human adrenal cortex.

METHODS

Human adrenals were obtained as discarded surgical material. Single-cell suspensions from human adrenal cortex (n = 3) were cultured onto either complete growth medium (CM) or MSC growth promotion medium (MGPM) in hypoxic condition. Following ex vivo expansion, their multilineage differentiation capacity was evaluated. Phenotype markers were analysed by immunocytochemistry and flow cytometry for cell-surface antigens associated with bone marrow MSCs and adrenocortical-specific phenotype. Expression of mRNAs for pluripotency markers was assessed by q-PCR.

RESULTS

The formation of colony-forming unit fibroblasts comprising adherent cells with fibroblast-like morphology were observed from the monolayer cell culture, in both CM and MGPM. Cells derived from MGPM revealed differentiation towards osteogenic and adipogenic cell lineages. These cells expressed cell-surface MSC markers (CD44, CD90, CD105 and CD166) but did not express the haematopoietic, lymphocytic or HLA-DR markers. Flow cytometry demonstrated significantly higher expression of GLI1 in cell population harvested from MGPM, which were highly proliferative. They also exhibited increased expression of the pluripotency markers.

CONCLUSION

Our study demonstrates that human adrenal cortex harbours a mesenchymal stem cell-like population. Understanding the cell biology of adrenal cortex- derived MSCs will inform regenerative medicine approaches in autoimmune Addison's disease.

Phenotypic plasticity of mesenchymal stem cells is crucial for mesangial repair in a model of immunoglobulin light chain-associated mesangial damage

Mesangiopathies produced by glomerulopathic monoclonal immunoglobulin light chains (GLCs) acting on the glomerular mesangium produce two characteristic lesions: AL-amyloidosis (AL-Am) and light chain deposition disease (LCDD). In both cases, the pathology is centered in the mesangium, where initial and progressive damage occurs. In AL-Am the mesangial matrix is destroyed and replaced by amyloid fibrils and in LCDD, the mesangial matrix is increased and remodeled. The collagen IV rich matrix is replaced by tenascin. In both conditions, mesangial cells (MCs) become apoptotic as a direct effect of the GLCs. MCs were incubated in-vitro with GLCs and animal kidneys were perfused ex-vivo via the renal artery with GLCs, producing expected lesions, and then mesenchymal stem cells (MSCs) were added to both platforms. Each of the two platforms provided unique information that when put together created a comprehensive evaluation of the processes involved. A "cocktail" with growth and differentiating factors was used to study its effect on mesangial repair. MSCs displayed remarkable phenotypic plasticity during the repair process. The first role of the MSCs after migrating to the affected areas was to dispose of the amyloid fibrils (in AL-Am), the altered mesangial matrix (in LCDD) and apoptotic MCs/debris. To accomplish this task, MSCs transformed into facultative macrophages acquiring an abundance of lysosomes and endocytotic capabilities required to engage in phagocytic functions. Once the mesangial cleaning was completed, MSCs transformed into functional MCs restoring the mesangium to normal. "Cocktail" made the repair process more efficient.

Dexamethasone-Activated MSCs Release MVs for Stimulating Osteogenic Response

The extracellular microvesicles (MVs) are attracting much attention because they are found to be the key paracrine mediator participating in tissue regeneration. Dexamethasone (DXM) is widely accepted as an important regulator in tailoring the differentiation potential of mesenchymal stem cells (MSCs). However, the effect of DXM on the paracrine signaling of MSCs remains unknown. To this point, we aimed to explore the role of DXM in regulating the paracrine activity of MSCs through evaluating the release and function of MSC-MVs, based on their physicochemical characteristics and support on osteogenic response. Results showed that DXM had no evident impact on the release of MSC-MVs but played a pivotal role in regulating the function of MSC-MVs. MVs obtained from the DXM-stimulated MSCs (DXM-MVs) increased MC3T3 cell proliferation and migration and upregulated Runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), and osteopontin (OPN) expression. The repair efficiency of DXM-MVs for femur defects was further investigated in an established rat model. It was found that DXM-MVs accelerated the healing process of bone formation in the defect area. Thus, we conclude that using DXM as stimuli to obtain functional MSCs-MVs could become a valuable tool for promoting bone regeneration.

Strategies to enhance paracrine potency of transplanted mesenchymal stem cells in intractable neonatal disorders

Mesenchymal stem cell (MSC) transplantation represents the next breakthrough in the treatment of currently intractable and devastating neonatal disorders with complex multifactorial etiologies, including bronchopulmonary dysplasia, hypoxic ischemic encephalopathy, and intraventricular hemorrhage. Absent engraftment and direct differentiation of transplanted MSCs, and the "hit-and-run" therapeutic effects of these MSCs suggest that their pleiotropic protection might be attributable to paracrine activity via the secretion of various biologic factors rather than to regenerative activity. The transplanted MSCs, therefore, exert their therapeutic effects not by acting as "stem cells," but rather by acting as "paracrine factors factory." The MSCs sense the microenvironment of the injury site and secrete various paracrine factors that serve several reparative functions, including antiapoptotic, anti-inflammatory, antioxidative, antifibrotic, and/or antibacterial effects in response to environmental cues to enhance regeneration of the damaged tissue. Therefore, the therapeutic efficacy of MSCs might be dependent on their paracrine potency. In this review, we focus on recent investigations that elucidate the specifically regulated paracrine mechanisms of MSCs by injury type and discuss potential strategies to enhance paracrine potency, and thus therapeutic efficacy, of transplanted MSCs, including determining the appropriate source and preconditioning strategy for MSCs and the route and timing of their administration.

Mesenchymal Stem Cells in Kidney Repair

Every year 13.3 million people suffer acute kidney injury (AKI), which is associated with a high risk of death or development of long-term chronic kidney disease (CKD) in a substantial percentage of patients besides other organ dysfunctions. To date, the mortality rate per year for AKI exceeds 50 % at least in patients requiring early renal replacement therapy and is higher than the mortality for breast and prostate cancer, heart failure and diabetes combined.Until now, no effective treatments able to accelerate renal recovery and improve survival post AKI have been developed. In search of innovative and effective strategies to foster the limited regeneration capacity of the kidney, several studies have evaluated the ability of mesenchymal stem cells (MSCs) of different origin as an attractive therapeutic tool. The results obtained in several models of AKI and CKD document that MSCs have therapeutic potential in repair of renal injury, preserving renal function and structure thus prolonging animal survival through differentiation-independent pathways. In this chapter, we have summarized the mechanisms underlying the regenerative processes triggered by MSC treatment, essentially due to their paracrine activity. The capacity of MSC to migrate to the site of injury and to secrete a pool of growth factors and cytokines with anti-inflammatory, mitogenic, and immunomodulatory effects is described. New modalities of cell-to-cell communication via the release of microvesicles and exosomes by MSCs to injured renal cells will also be discussed. The translation of basic experimental data on MSC biology into effective care is still limited to preliminary phase I clinical trials and further studies are needed to definitively assess the efficacy of MSC-based therapy in humans.

Mesenchymal Stem Cell Injections for the Treatment of Perianal Crohn's Disease: What We Have Accomplished and What We Still Need to Do

Perianal Crohn's disease [CD] is found in a quarter of patients with CD and remains notoriously difficult to treat. Several medical and surgical therapies are available. However, none is particularly effective nor reliably provides sustained remission. In addition, surgical intervention is complicated by poor healing and the potential for incontinence. Mesenchymal stem cell-based therapies provide a promising treatment alternative for perianal CD, with demonstrated safety, improved efficacy, and a decreased side effect profile. Several phase I, II, and now III randomised controlled trials have now reported safety and efficacy in treating perianal CD. The aim of this review is to discusses the outcomes of conventional treatment approaches, outcomes of mesenchymal stem cell therapies, considerations specific to stem cell-based therapies, and future directions for research.

Therapeutic efficacy of bone marrow derived mesenchymal stromal cells versus losartan on adriamycin-induced renal cortical injury in adult albino rats

BACKGROUND

Renal disease is a major health problem. Recent studies have reported the efficacy of stem cell therapy in nephropathy animal models.

AIM OF THE WORK

This study was designed to investigate the therapeutic effectiveness of bone marrow-derived mesenchymal stromal cells (MSCs) versus losartan in the treatment of renal alterations induced by adriamycin (ADR).

MATERIALS AND METHODS

Thirty-five adult male albino rats were divided into four groups. Group I was the control group. Group II (adriamycin-treated group),which included ten rats that were injected with a single dose of adriamycin (15 mg/kg) intraperitoneally, was subdivided into subgroup IIa and IIb and they were sacrificed 1 week and 5 weeks after adriamycin injection, respectively. Group III was the adriamycin + losartan-treated group and 1 week after adriamycin injection five rats received 10 mg/kg of losartan orally and daily for 4 weeks. Group IV was the adriamycin + MSC-treated group); five rats were injected with adriamycin as group II then supplied with MSCs at a dose of 1 × 10(6) cells suspended in 0.5 mL of phosphate-buffered saline (PBS) per rat in the tail vein 1 week after adriamycin injection. Rats of this group were sacrificed 4 weeks after the stem cell injection. Blood urea nitrogen and serum creatinine were measured. Samples from renal cortex were processed for light and electron microscope examination. As regards light microscope, sections were stained with hematoxylin and eosin (H-E), periodic acid-Schiff (PAS), masson trichrome, proliferating cell nuclear antigen (PCNA) and Caspase-3 immunohistochemical stains. Morphometrical and statistical analyses were also conducted.

RESULTS

Examination of adriamycin-treated group revealed deterioration of renal functions and various degrees of renal structural alterations as vacuolated cytoplasm, dark nuclei and detached epithelial lining. Administration of losartan partially improved ADR-induced kidney dysfunction, whereas MSCs denoted a more ameliorative role evidenced by structural and functional recovery.

CONCLUSION

MSCs have a relevant therapeutic potential against ADR-induced renal damage. MSCs may accomplish this role by decreasing caspase-3 expression and increasing proliferating cell nuclear antigen staining which influence the regeneration of the kidney.

A canine liver fibrosis model to develop a therapy for liver cirrhosis using cultured bone marrow-derived cells

We have been developing a therapy for liver cirrhosis using cultured autologous bone marrow-derived mesenchymal stem cells (BMSCs). Before human clinical trials can be considered, the safety and efficacy of BMSC infusion in medium to large animals must be confirmed; thus, we developed a canine liver fibrosis model. A small amount of bone marrow fluid was aspirated from the canine humerus to assess the characteristics of BMSCs. We implanted a venous catheter in the stomach and a subcutaneous infusion port in the back of the neck of each canine. Repeated injection of CCl₄ through the catheter was performed to induce liver cirrhosis. After 10 weeks of CCl₄ injection, eight canines were equally divided into two groups: no cell infusion (control group) and autologous BMSC infusion through the peripheral vein (BMSC group). A variety of assays were carried out before and 4 weeks after the infusion. The area of liver fibrosis stained with sirius red was significantly reduced in the BMSC group 4 weeks after BMSC infusion, consistent with a significantly shortened half-life of indocyanine green and improved liver function. Conclusion: We established a useful canine liver fibrosis model and confirmed that cultured autologous BMSC infusion improved liver fibrosis without adverse effects. (Hepatology Communications 2017;1:691-703).

Investigational drugs in development for focal segmental glomerulosclerosis

INTRODUCTION

Focal segmental glomerulosclerosis is an important cause of end stage kidney disease and is a paradigm for the study of glomerular scarring. There are no FDA approved treatments for this condition. Current therapies, assessed based on reduction in proteinuria, are generally effective in a subset of patients which suggests that FSGS is a heterogeneous group of glomerular disorders or podocytopathies that converge on a common histopathological phenotype. Areas covered: We searched for investigational drugs agents that target different pathophysiological pathways using the key words 'FSGS' and 'podocyte' in American and European clinical trial registers (clinicaltrials.gov; clinicaltrialsregister.eu). Published articles were searched in PubMed, Medline, the Web of Science and the Cochrane Central Register of Controlled Trials Library. Expert opinion: Progress is being made in defining the mechanism of action of subtypes of FSGS. Current and investigational therapies for FSGS target these different pathways of injury. It is anticipated that advances in systems biology will further refine the classification of FSGS by subdividing the disease based on the primary mechanism of glomerular injury, identify biomarkers to discriminate between different subtypes, and enable appropriate selection of appropriate therapy for each individual in accordance with the goals of precision medicine.

Beneficial Effects of Systemically Administered Human Muse Cells in Adriamycin Nephropathy

Multilineage-differentiating stress-enduring (Muse) cells are nontumorigenic endogenous pluripotent-like stem cells that can be collected from various organs. Intravenously administered Muse cells have been shown to spontaneously migrate to damaged tissue and replenish lost cells, but the effect in FSGS is unknown. We systemically administered human bone marrow-derived Muse cells without concurrent administration of immunosuppressants to severe combined immune-deficient (SCID) and BALB/c mouse models with adriamycin-induced FSGS (FSGS-SCID and FSGS-BALB/c, respectively). In FSGS-SCID mice, human Muse cells preferentially integrated into the damaged glomeruli and spontaneously differentiated into cells expressing markers of podocytes (podocin; 31%), mesangial cells (megsin; 13%), and endothelial cells (CD31; 41%) without fusing to the host cells; attenuated glomerular sclerosis and interstitial fibrosis; and induced the recovery of creatinine clearance at 7 weeks. Human Muse cells induced similar effects in FSGS-BALB/c mice at 5 weeks, despite xenotransplant without concurrent immunosuppressant administration, and led to improvement in urine protein, creatinine clearance, and plasma creatinine levels more impressive than that in the FSGS-SCID mice at 5 weeks. However, functional recovery in FSGS-BALB/c mice was impaired at 7 weeks due to immunorejection, suggesting the importance of Muse cell survival as glomerular cells in the FSGS kidney for tissue repair and functional recovery. In conclusion, Muse cells are unique reparative stem cells that preferentially home to damaged glomeruli and spontaneously differentiate into glomerular cells after systemic administration. Introduction of genes to induce differentiation is not required before Muse cell administration; thus, Muse cells may be a feasible therapeutic strategy in FSGS.

Rapid deterioration of preexisting renal insufficiency after autologous mesenchymal stem cell therapy

Administration of autologous mesenchymal stem cells (MSCs) has been shown to improve renal function and histological findings in acute kidney injury (AKI) models. However, its effects in chronic kidney disease (CKD) are unclear, particularly in the clinical setting. Here, we report our experience with a CKD patient who was treated by intravenous infusion of autologous MSCs derived from adipose tissue in an unknown clinic outside of Korea. The renal function of the patient had been stable for several years before MSC administration. One week after the autologous MSC infusion, the preexisting renal insufficiency was rapidly aggravated without any other evidence of AKI. Hemodialysis was started 3 months after MSC administration. Renal biopsy findings at dialysis showed severe interstitial fibrosis and inflammatory cell infiltration, with a few cells expressing CD34 and CD117, 2 surface markers of stem cells. This case highlights the potential nephrotoxicity of autologous MSC therapy in CKD patients.