Immunomodulatory and Regenerative Effects of Mesenchymal Stem Cell-Derived Extracellular Vesicles in Renal Diseases

The Role of Viral Infections in Acute Kidney Injury and Mesenchymal Stem Cell-Based Therapy

Viruses may cause a wide range of renal problems. Furthermore, many kidney diseases may be brought on by viral infections. Both the primary cause and a contributing factor of acute kidney injury (AKI) may be viral infections. As an example, it is recommended that patients with dengue virus (DENV) infections undergo careful monitoring of their AKI levels. Also, researchers' data so far lend credence to the several hypothesized pathophysiological mechanisms via which AKI can develop in SARS-CoV- 2 infection. Thus, it is critical to comprehend how viral infections cause AKI. Finding an effective method of treating AKI caused by viruses is also vital. Thus, a potential cell-free method for treating AKI that uses regenerative and anti-inflammatory processes is mesenchymal stem cells (MSCs) and their exosomes (MSC-EXOs). MSCs alleviate tissue damage and enhance protective effects on damaged kidneys in AKI. Furthermore, MSC-EXOs have exhibited substantial regulatory impact on a range of immune cells and exhibit robust immune regulation in the therapy of AKI. Thus, in models of AKI caused by ischemia-reperfusion damage, nephrotoxins, or sepsis, MSCs and MSC-EXOs improved renal function, decreased inflammation, and improved healing. Therefore, MSCs and MSC-EXOs may help treat AKI caused by different viruses. Consequently, we have explored several innovative and significant processes in this work that pertain to the role of viruses in AKI and the significance of viral illness in the onset of AKI. After that, we assessed the key aspects of MSCs and MSC-EXOs for AKI therapy. We have concluded by outlining the current state of and plans for future research into MSC- and EXO-based therapeutic approaches for the treatment of AKI brought on by viruses.

The Role of Dental-derived Stem Cell-based Therapy and Their Derived Extracellular Vesicles in Post-COVID-19 Syndrome-induced Tissue Damage

Long coronavirus disease 2019 (COVID-19) is linked to an increased risk of post-acute sequelae affecting the pulmonary and extrapulmonary organ systems. Up to 20% of COVID-19 patients may proceed to a more serious form, such as severe pneumonia, acute respiratory distress syndrome (ARDS), or pulmonary fibrosis. Still, the majority of patients may only have mild, self-limiting sickness. Of particular concern is the possibility of parenchymal fibrosis and lung dysfunction in long-term COVID-19 patients. Furthermore, it has been observed that up to 43% of individuals hospitalized with COVID-19 also had acute renal injury (AKI). Care for kidney, brain, lung, cardiovascular, liver, ocular, and tissue injuries should be included in post-acute COVID-19 treatment. As a powerful immunomodulatory tool in regenerative medicine, dental stem cells (DSCs) have drawn much interest. Numerous immune cells and cytokines are involved in the excessive inflammatory response, which also has a significant effect on tissue regeneration. A unique reservoir of stem cells (SCs) for treating acute lung injury (ALI), liver damage, neurological diseases, cardiovascular issues, and renal damage may be found in tooth tissue, according to much research. Moreover, a growing corpus of in vivo research is connecting DSC-derived extracellular vesicles (DSC-EVs), which are essential paracrine effectors, to the beneficial effects of DSCs. DSC-EVs, which contain bioactive components and therapeutic potential in certain disorders, have been shown as potentially effective therapies for tissue damage after COVID-19. Consequently, we explore the properties of DSCs in this work. Next, we'll look at how SARS-CoV-2 affects tissue damage. Lastly, we have looked at the use of DSCs and DSC-EVs in managing COVID-19 and chronic tissue damage, such as injury to the heart, brain, lung, and other tissues.

Frontier role of extracellular vesicles in kidney disease

Kidney diseases represent a diverse range of conditions that compromise renal function and structure which characterized by a progressive deterioration of kidney function, may ultimately necessitate dialysis or kidney transplantation as end-stage treatment options. This review explores the complex landscape of kidney diseases, highlighting the limitations of existing treatments and the pressing need for innovative strategies. The paper delves into the role of extracellular vesicles (EVs) as emerging biomarkers and therapeutic agents in the context of kidney pathophysiology. Urinary extracellular vesicles (uEVs), in particular, offer a non-invasive means of assessing renal injury and monitoring disease progression. Additionally, mesenchymal stem cell-derived EVs (MSC-EVs) are examined for their immunomodulatory and tissue repair capabilities, presenting a promising avenue for novel therapeutic interventions. And discusses the potential of engineering EVs to enhance their targeting and therapeutic efficacy. This paper systematically integrates the latest research findings and aims to provide a comprehensive overview of the role of EVs in kidney disease, providing cutting-edge insights into their potential as a diagnostic and therapeutic tool.

Advancements in diabetic foot ulcer research: Focus on mesenchymal stem cells and their exosomes

Diabetes represents a widely acknowledged global public health concern. Diabetic foot ulcer (DFU) stands as one of the most severe complications of diabetes, its occurrence imposing a substantial economic burden on patients, profoundly impacting their quality of life. Despite the deepening comprehension regarding the pathophysiology and cellular as well as molecular responses of DFU, the current therapeutic arsenal falls short of efficacy, failing to offer a comprehensive remedy for deep-seated chronic wounds and microvascular occlusions. Conventional treatments merely afford symptomatic alleviation or retard the disease's advancement, devoid of the capacity to effectuate further restitution of compromised vasculature and nerves. An escalating body of research underscores the prominence of mesenchymal stem cells (MSCs) owing to their paracrine attributes and anti-inflammatory prowess, rendering them a focal point in the realm of chronic wound healing. Presently, MSCs have been validated as a highly promising cellular therapeutic approach for DFU, capable of effectuating cellular repair, epithelialization, granulation tissue formation, and neovascularization by means of targeted differentiation, angiogenesis promotion, immunomodulation, and paracrine activities, thereby fostering wound healing. The secretome of MSCs comprises cytokines, growth factors, chemokines, alongside exosomes harboring mRNA, proteins, and microRNAs, possessing immunomodulatory and regenerative properties. The present study provides a systematic exposition on the etiology of DFU and elucidates the intricate molecular mechanisms and diverse functionalities of MSCs in the context of DFU treatment, thereby furnishing pioneering perspectives aimed at harnessing the therapeutic potential of MSCs for DFU management and advancing wound healing processes.

Preventive effect of culture supernatant of epithelial-like peritoneal mesothelial cells on peritoneal fibrosis

Peritoneal fibrosis (PF) is a primary reason for discontinuing peritoneal dialysis, which involves characteristic changes of peritoneal mesothelial cells (PMCs). We previously reported preventive effects of implanting human epithelial-like PMCs (P-Epi) for mouse PF caused by mechanical peritoneum scrapings. In the present study, we analysed the preventive effects of culture supernatant of P-Epi in PF. Concentrated culture supernatant of P-Epi or human fibroblast-like PMCs (P-Fibro) or vehicles was injected into nude mice that had undergone mechanical scraping of the parietal and visceral peritoneum, and thickness and amount of adhesions were analysed. Although increased peritoneal adhesions and peritoneum thickening were observed in the vehicle-injected positive control group compared to the sham operation group, fewer number of adhesions and less thickness were observed in the mice treated with culture supernatant of P-Epi, but not P-Fibro, compared to the vehicle-injected positive controls. Immunofluorescent analysis revealed that the expression of extracellular matrix, type I collagen and fibronectin, was lower in the mice treated with culture supernatant of P-Epi than in the vehicle-injected positive controls. In addition, exosomes from P-Epi significantly reduced transforming growth factor-β (TGF-β)-induced expressions of type I collagen and fibronectin in 3T3 fibroblast cells. Collectively, culture supernatant of P-Epi has preventive effects on PF, thus cell therapy is not necessarily required. Further exploration of substances secreted by P-Epi and their protective mechanisms could lead to the development of therapeutic strategies to limit PF.

MicroRNAs as Biomarkers and Therapeutic Targets for Acute Kidney Injury

Acute kidney injury (AKI) is a clinical syndrome where a rapid decrease in kidney function and/or urine output is observed, which may result in the imbalance of water, electrolytes and acid base. It is associated with poor prognosis and prolonged hospitalization. Therefore, an early diagnosis and treatment to avoid the severe AKI stage are important. While several biomarkers, such as urinary L-FABP and NGAL, can be clinically useful, there is still no gold standard for the early detection of AKI and there are limited therapeutic options against AKI. miRNAs are non-coding and single-stranded RNAs that silence their target genes in the post-transcriptional process and are involved in a wide range of biological processes. Recent accumulated evidence has revealed that miRNAs may be potential biomarkers and therapeutic targets for AKI. In this review article, we summarize the current knowledge about miRNAs as promising biomarkers and potential therapeutic targets for AKI, as well as the challenges in their clinical use.

Cellular nanovesicles for therapeutic immunomodulation: A perspective on engineering strategies and new advances

Cellular nanovesicles which are referred to as cell-derived, nanosized lipid bilayer structures, have emerged as a promising platform for regulating immune responses. Owing to their outstanding advantages such as high biocompatibility, prominent structural stability, and high loading capacity, cellular nanovesicles are suitable for delivering various immunomodulatory molecules, such as small molecules, nucleic acids, peptides, and proteins. Immunomodulation induced by cellular nanovesicles has been exploited to modulate immune cell behaviors, which is considered as a novel cell-free immunotherapeutic strategy for the prevention and treatment of diverse diseases. Here we review emerging concepts and new advances in leveraging cellular nanovesicles to activate or suppress immune responses, with the aim to explicate their applications for immunomodulation. We overview the general considerations and principles for the design of engineered cellular nanovesicles with tailored immunomodulatory activities. We also discuss new advances in engineering cellular nanovesicles as immunotherapies for treating major diseases.

Cell therapy for the treatment of reproductive diseases and infertility: an overview from the mechanism to the clinic alongside diagnostic methods

Infertility is experienced by 8%-12% of adults in their reproductive period globally and has become a prevalent concern. Besides routine therapeutic methods, stem cells are rapidly being examined as viable alternative therapies in regenerative medicine and translational investigation. Remarkable progress has been made in understanding the biology and purpose of stem cells. The affected pluripotent stem cells (iPSCs) and mesenchymal stem cells (MSCs) are further studied for their possible use in reproductive medicine, particularly for infertility induced by premature ovarian insufficiency and azoospermia. Accordingly, this study discusses current developments in the use of some kinds of MSCs such as adipose-derived stem cells, bone marrow stromal cells, umbilical cord MSCs, and menstrual blood MSCs. These methods have been used to manage ovarian and uterine disorders, and each technique presents a novel method for the therapy of infertility.

Type-2 epithelial-mesenchymal transition in oral mucosal nonneoplastic diseases

The oral mucosa is a membranous structure comprising epithelial and connective tissue that covers the oral cavity. The oral mucosa is the first immune barrier to protect the body against pathogens for systemic protection. It is frequently exposed to mechanical abrasion, chemical erosion, and pathogenic invasion, resulting in oral mucosal lesions, particularly inflammatory diseases. Epithelial-mesenchymal transition (EMT) is a crucial biological process in the pathogenesis of oral mucosal disorders, which are classified into three types (types 1, 2, and 3) based on their physiological consequences. Among these, type-2 EMT is crucial in wound repair, organ fibrosis, and tissue regeneration. It causes infectious and dis-infectious immunological diseases, such as oral lichen planus (OLP), oral leukoplakia, oral submucosal fibrosis, and other precancerous lesions. However, the mechanism and cognition between type-2 EMT and oral mucosal inflammatory disorders remain unknown. This review first provides a comprehensive evaluation of type-2 EMT in chronically inflammatory oral mucosal disorders. The aim is to lay a foundation for future research and suggest potential treatments.

CD73-Adenosinergic Axis Mediates the Protective Effect of Extracellular Vesicles Derived from Mesenchymal Stromal Cells on Ischemic Renal Damage in a Rat Model of Donation after Circulatory Death

We propose a new organ-conditioning strategy based on mesenchymal stromal cell (MSCs)/extracellular vesicle (EVs) delivery during hypothermic perfusion. MSCs/EVs marker CD73 is present on renal proximal tubular cells, and it protects against renal ischemia-reperfusion injury by converting adenosine monophosphate into adenosine (ADO). In this study, after checking if CD73-silenced EVs (EVsi) would impact in vitro tubular-cell proliferation, we perfused kidneys of a rat model of donation after circulatory death, with Belzer solution (BS) alone, BS supplemented with MSCs, EVs, or EVsi. The ADO and ATP levels were measured in the effluents and tissues. Global renal ischemic damage score (GRS), and tubular cell proliferation index (IPT) were evaluated in the tissue. EVsi did not induce cell proliferation in vitro. Ex vivo kidneys perfused with BS or BS + EVsi showed the worst GRS and higher effluent ADO levels than the MSC- and EV-perfused kidneys. In the EV-perfused kidneys, the tissue and effluent ATP levels and IPT were the highest, but not if CD73 was silenced. Tissue ATP content was positively correlated with tissue ADO content and negatively correlated with effluent ADO level in all groups. In conclusion, kidney conditioning with EVs protects against ischemic damage by activating the CD73/ADO system.

Tailored Extracellular Vesicles: Novel Tool for Tissue Regeneration

Extracellular vesicles (EVs) play an essential part in multiple pathophysiological processes including tissue injury and regeneration because of their inherent characteristics of small size, low immunogenicity and toxicity, and capability of carrying a variety of bioactive molecules and mediating intercellular communication. Nevertheless, accumulating studies have shown that the application of EVs faces many challenges such as insufficient therapeutic efficacy, a lack of targeting capability, low yield, and rapid clearance from the body. It is known that EVs can be engineered, modified, and designed to encapsulate therapeutic cargos like proteins, peptides, nucleic acids, and drugs to improve their therapeutic efficacy. Targeted peptides, antibodies, aptamers, magnetic nanoparticles, and proteins are introduced to modify various cell-derived EVs for increasing targeting ability. In addition, extracellular vesicle mimetics (EMs) and self-assembly EV-mimicking nanocomplex are applied to improve production and simplify EV purification process. The combination of EVs with biomaterials like hydrogel, and scaffolds dressing endows EVs with long-term therapeutic efficacy and synergistically enhanced regenerative outcome. Thus, we will summarize recent developments of EV modification strategies for more extraordinary regenerative effect in various tissue injury repair. Subsequently, opportunities and challenges of promoting the clinical application of engineered EVs will be discussed.

Extracellular Vesicles Released from Stem Cells as a New Therapeutic Strategy for Primary and Secondary Glomerulonephritis

Current treatment of primary and secondary glomerulopathies is hampered by many limits and a significant proportion of these disorders still evolves towards end-stage renal disease. A possible answer to this unmet challenge could be represented by therapies with stem cells, which include a variety of progenitor cell types derived from embryonic or adult tissues. Stem cell self-renewal and multi-lineage differentiation ability explain their potential to protect and regenerate injured cells, including kidney tubular cells, podocytes and endothelial cells. In addition, a broad spectrum of anti-inflammatory and immunomodulatory actions appears to interfere with the pathogenic mechanisms of glomerulonephritis. Of note, mesenchymal stromal cells have been particularly investigated as therapy for Lupus Nephritis and Diabetic Nephropathy, whereas initial evidence suggest their beneficial effects in primary glomerulopathies such as IgA nephritis. Extracellular vesicles mediate a complex intercellular communication network, shuttling proteins, nucleic acids and other bioactive molecules from origin to target cells to modulate their functions. Stem cell-derived extracellular vesicles recapitulate beneficial cytoprotective, reparative and immunomodulatory properties of parental cells and are increasingly recognized as a cell-free alternative to stem cell-based therapies for different diseases including glomerulonephritis, also considering the low risk for potential adverse effects such as maldifferentiation and tumorigenesis. We herein summarize the renoprotective potential of therapies with stem cells and extracellular vesicles derived from progenitor cells in glomerulonephritis, with a focus on their different mechanisms of actions. Technological progress and growing knowledge are paving the way for wider clinical application of regenerative medicine to primary and secondary glomerulonephritis: this multi-level, pleiotropic therapy may open new scenarios overcoming the limits and side effects of traditional treatments, although the promising results of experimental models need to be confirmed in the clinical setting.

Potential Strategies for Kidney Regeneration With Stem Cells: An Overview

Kidney diseases are a major health problem worldwide. Despite advances in drug therapies, they are only capable of slowing the progression of kidney diseases. Accordingly, potential kidney regeneration strategies with stem cells have begun to be explored. There are two different directions for regenerative strategies, de novo whole kidney fabrication with stem cells, and stem cell therapy. De novo whole kidney strategies include: 1) decellularized scaffold technology, 2) 3D bioprinting based on engineering technology, 3) kidney organoid fabrication, 4) blastocyst complementation with chimeric technology, and 5) the organogenic niche method. Meanwhile, stem cell therapy strategies include 1) injection of stem cells, including mesenchymal stem cells, nephron progenitor cells, adult kidney stem cells and multi-lineage differentiating stress enduring cells, and 2) injection of protective factors secreted from these stem cells, including growth factors, chemokines, and extracellular vesicles containing microRNAs, mRNAs and proteins. Over the past few decades, there have been remarkable step-by-step developments in these strategies. Here, we review the current advances in the potential strategies for kidney regeneration using stem cells, along with their challenges for possible clinical use in the future.

Stem Cell-Derived Extracellular Vesicles as Potential Therapeutic Approach for Acute Kidney Injury

Acute kidney injury is a frequent complication of hospitalized patients and significantly increases morbidity and mortality, worsening costs and length of hospital stay. Despite this impact on healthcare system, treatment still remains only supportive (dialysis). Stem cell-derived extracellular vesicles are a promising option as they recapitulate stem cells properties, overcoming safety issues related to risks or rejection or aberrant differentiation. A growing body of evidence based on pre-clinical studies suggests that extracellular vesicles may be effective to treat acute kidney injury and to limit fibrosis through direct interference with pathogenic mechanisms of vascular and tubular epithelial cell damage. We herein analyze the state-of-the-art knowledge of therapeutic approaches with stem cell-derived extracellular vesicles for different forms of acute kidney injury (toxic, ischemic or septic) dissecting their cytoprotective, regenerative and immunomodulatory properties. We also analyze the potential impact of extracellular vesicles on the mechanisms of transition from acute kidney injury to chronic kidney disease, with a focus on the pivotal role of the inhibition of complement cascade in this setting. Despite some technical limits, nowadays the development of therapies based on stem cell-derived extracellular vesicles holds promise as a new frontier to limit acute kidney injury onset and progression.

Klotho and Mesenchymal Stem Cells: A Review on Cell and Gene Therapy for Chronic Kidney Disease and Acute Kidney Disease

Chronic kidney disease (CKD) and acute kidney injury (AKI) are public health problems, and their prevalence rates have increased with the aging of the population. They are associated with the presence of comorbidities, in particular diabetes mellitus and hypertension, resulting in a high financial burden for the health system. Studies have indicated Klotho as a promising therapeutic approach for these conditions. Klotho reduces inflammation, oxidative stress and fibrosis and counter-regulates the renin-angiotensin-aldosterone system. In CKD and AKI, Klotho expression is downregulated from early stages and correlates with disease progression. Therefore, the restoration of its levels, through exogenous or endogenous pathways, has renoprotective effects. An important strategy for administering Klotho is through mesenchymal stem cells (MSCs). In summary, this review comprises in vitro and in vivo studies on the therapeutic potential of Klotho for the treatment of CKD and AKI through the administration of MSCs.

Extracellular Vesicle-Based Therapy for COVID-19: Promises, Challenges and Future Prospects

The COVID-19 pandemic has become a serious concern and has negatively impacted public health and the economy. It primarily targets the lungs, causing acute respiratory distress syndrome (ARDS); however, it may also lead to multiple organ failure (MOF) and enhanced mortality rates. Hence, there is an urgent need to develop potential effective therapeutic strategies for COVID-19 patients. Extracellular vesicles (EVs) are released from various types of cells that participate in intercellular communication to maintain physiological and pathological processes. EVs derived from various cellular origins have revealed suppressive effects on the cytokine storm during systemic hyper-inflammatory states of severe COVID-19, leading to enhanced alveolar fluid clearance, promoted epithelial and endothelial recovery, and cell proliferation. Being the smallest subclass of EVs, exosomes offer striking characteristics such as cell targeting, being nano-carriers for drug delivery, high biocompatibility, safety, and low-immunogenicity, thus rendering them a potential cell-free therapeutic candidate against the pathogeneses of various diseases. Due to these properties, numerous studies and clinical trials have been performed to assess their safety and therapeutic efficacy against COVID-19. Hence, in this review, we have comprehensively described current updates on progress and challenges for EVs as a potential therapeutic agent for the management of COVID-19.

Therapeutic Role of Mesenchymal Stem Cell-Derived Extracellular Vesicles in Female Reproductive Diseases

Reproductive disorders, including intrauterine adhesion (IUA), premature ovarian insufficiency (POI), and polycystic ovary syndrome (PCOS), are great threats to female reproduction. Recently, mesenchymal stem cells derived-extracellular vesicles (MSC-EVs) have presented their potentials to cure these diseases, not only for the propensity ability they stemmed from the parent cells, but also for the higher biology stability and lower immunogenicity, compared to MSCs. EVs are lipid bilayer complexes, functional as mediators by transferring multiple molecules to recipient cells, such as proteins, microRNAs, lipids, and cytokines. EVs appeared to have a therapeutic effect on the female reproductive disorder, such as repairing injured endometrium, suppressing fibrosis of endometrium, regulating immunity and anti-inflammatory, and repressing apoptosis of granulosa cells (GCs) in ovaries. Although the underlying mechanisms of MSC-EVs have reached a consensus, several theories have been proposed, including promoting angiogenesis, regulating immunity, and reducing oxidate stress levels. In the current study, we summarized the current knowledge of functions of MSC-EVs on IUA, POI, and PCOS. Given the great potentials of MSC-EVs on reproductive health, the critical issues discussed will guide new insights in this rapidly expanding field.

The Application Potential and Advance of Mesenchymal Stem Cell-Derived Exosomes in Myocardial Infarction

Myocardial infarction (MI) is a devastating disease with high morbidity and mortality caused by the irreversible loss of functional cardiomyocytes and heart failure (HF) due to the restricted blood supply. Mesenchymal stem cells (MSCs) have been emerging as lead candidates to treat MI and subsequent HF mainly through secreting multitudinous factors of which exosomes act as the most effective constituent to boost the repair of heart function through carrying noncoding RNAs and proteins. Given the advantages of higher stability in the circulation, lower toxicity, and controllable transplantation dosage, exosomes have been described as a wonderful and promising cell-free treatment method in cardiovascular disease. Nowadays, MSC-derived exosomes have been proposed as a promising therapeutic approach to improve cardiac function and reverse heart remodeling. However, exosomes' lack of modification cannot result in desired therapeutic effect. Hence, optimized exosomes can be developed via various engineering methods such as pharmacological compound preconditioned MSCs, genetically modified MSCs, or miRNA-loaded exosomes and peptide tagged exosomes to improve the targeting and therapeutic effects of exosomes. The biological characteristics, therapeutic potential, and optimizing strategy of exosomes will be described in our review.

Extracellular Vesicles as a Therapeutic Tool for Kidney Disease: Current Advances and Perspectives

Extracellular vesicles (EVs) have been described as important mediators of cell communication, regulating several physiological processes, including tissue recovery and regeneration. In the kidneys, EVs derived from stem cells have been shown to support tissue recovery in diverse disease models and have been considered an interesting alternative to cell therapy. For this purpose, however, several challenges remain to be overcome, such as the requirement of a high number of EVs for human therapy and the need for optimization of techniques for their isolation and characterization. Moreover, the kidney’s complexity and the pathological process to be treated require that EVs present a heterogeneous group of molecules to be delivered. In this review, we discuss the recent advances in the use of EVs as a therapeutic tool for kidney diseases. Moreover, we give an overview of the new technologies applied to improve EVs’ efficacy, such as novel methods of EV production and isolation by means of bioreactors and microfluidics, bioengineering the EV content and the use of alternative cell sources, including kidney organoids, to support their transfer to clinical applications.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles in the Treatment of Diabetic Foot Ulcers: Application and Challenges

Diabetic foot ischemia and ulcer (DFU) persists as a serious diabetes mellitus complication in spite of increased understanding of the pathophysiology and the cellular and molecular responses. Contributing to this pessimistic situation is the lack of effective treatments that are slow to heal the deep chronic wounds and microvascular obstruction. Mesenchymal stromal cells (MSCs) have been tested as a promising cell-based therapy for diabetes in vitro and in vivo, which is able to accelerate wound closure with increased epithelialization, granulation tissue formation and angiogenesis by differentiation into skin cells and paracrine pathways to repair injured cells. The secretomes of MSCs, including cytokines, growth factors, chemokines, and extracellular vesicles containing mRNA, proteins and microRNAs, have immunomodulatory and regenerative effects. This review will shed new light on the therapeutic potential of MSC-derived extracellular vesicles (MSC-EVs) for the treatment of diabetes-induced lower limb ischemia and ulcers. The identification of underlying mechanisms for MSC-EVs regulation on impaired diabetic wound healing might provide a new direction for MSC-centered treatment for diabetic lower limb ischemia and ulcers. Immunomodulatory and angiogenic effects of MSC-derived extracellular vesicles on diabetic foot ulcer.

Effects of the secretome of human Wharton's jelly mesenchymal stem cells on the proliferation and apoptosis gene expression of the retinal pigmented epithelium

Human retinal pigmented epithelium (RPE) can undergo an uncontrolled proliferation in some disorders such as retinal detachment associated with proliferative vitreoretinopathy (PVR). The present study was conducted to evaluate the effect of the conditioned medium secreted by human Wharton's jelly mesenchymal stem cells (WJMSCs-CM) on the proliferation and apoptosis gene expression of the RPE. WJMSCs-CM was collected from WJMSCs after two periods of 24-h and 9-h culture in serum-free medium. RPE cells were cultured in WJMSCs-CM versus serum-deprived media for 24 h. The effect of WJMSCs-CM on RPE cell proliferation was determined using the MTT assay. Relative expression of apoptotic genes (Bcl2, Bax, and IL-1B) was also assessed by real-time PCR. MTT assay demonstrated that RPE cell viability was reduced significantly in WJMSCs-CM treated RPE cells compared to those cultured in serum-deprived medium (64.23 ± 2.44 vs 100.10 ± 5.68; P = 0.006). Moreover, the expression of anti-apoptotic Bcl2 was significantly decreased in WJMSCs-CM compared to serum-deprived medium (0.52 ± 0.06 in WJMSCs-CM vs 1.02 ± 0.2 in serum-free treatment; P = 0.03), while the expression of pro-apoptotic biomarkers of Bax and IL-1B was not significantly different between the two treatments. The represented data showed that WJMSCs-CM can induce apoptosis in RPE cells in vitro through activating apoptosis pathways. This proof-of-the-concept study provides basic evidence for the possible effect of WJMSCs-CM on preventing PVR.

Therapeutic Potential of Mesenchymal Stem Cells in a Pre-Clinical Model of Diabetic Kidney Disease and Obesity

Diabetic kidney disease (DKD) is a worldwide microvascular complication of type 2 diabetes mellitus (T2DM). From several pathological mechanisms involved in T2DM-DKD, we focused on mitochondria damage induced by hyperglycemia-driven reactive species oxygen (ROS) accumulation and verified whether mesenchymal stem cells (MSCs) anti-oxidative, anti-apoptotic, autophagy modulation, and pro-mitochondria homeostasis therapeutic potential curtailed T2DM-DKD progression. For that purpose, we grew immortalized glomerular mesangial cells (GMCs) in hyper glucose media containing hydrogen peroxide. MSCs prevented these cells from apoptosis-induced cell death, ROS accumulation, and mitochondria membrane potential impairment. Additionally, MSCs recovered GMCs' biogenesis and mitophagy-related gene expression that were downregulated by stress media. In BTBRob/ob mice, a robust model of T2DM-DKD and obesity, MSC therapy (1 × 106 cells, two doses 4-weeks apart, intra-peritoneal route) led to functional and structural kidney improvement in a time-dependent manner. Therefore, MSC-treated animals exhibited lower levels of urinary albumin-to-creatinine ratio, less mesangial expansion, higher number of podocytes, up-regulation of mitochondria-related survival genes, a decrease in autophagy hyper-activation, and a potential decrease in cleaved-caspase 3 expression. Collectively, these novel findings have important implications for the advancement of cell therapy and provide insights into cellular and molecular mechanisms of MSC-based therapy in T2DM-DKD setting.

MicroRNAs as Biomarkers for Nephrotic Syndrome

Nephrotic syndrome represents the clinical situation characterized by presence of massive proteinuria and low serum protein caused by a variety of diseases, including minimal change nephrotic syndrome (MCNS), focal segmental glomerulosclerosis (FSGS) and membranous glomerulonephropathy. Differentiating between diagnoses requires invasive renal biopsies in general. Even with the biopsy, we encounter difficulties to differentiate MCNS and FSGS in some cases. There is no other better option currently available for the diagnosis other than renal biopsy. MicroRNAs (miRNAs) are no-coding RNAs of approximately 20 nucleotides in length, which regulate target genes in the post-transcriptional processes and have essential roles in many diseases. MiRNAs in serum and urine have been shown as non-invasive biomarkers in multiple diseases, including renal diseases. In this article, we summarize the current knowledge of miRNAs as the promising biomarkers for nephrotic syndrome.

Differentially expressed urinary exo-miRs and clinical outcomes in kidney recipients on short-term tacrolimus therapy: a pilot study

Aim: To analyze the expression of urinary exosome-derived miRNAs (exo-miRs) in kidney recipients on tacrolimus-based therapy. Patients & methods: Clinical and drug monitoring data were recorded from 23 kidney recipients. Expression of 93 exo-miRs was measured by quantitative PCR array and mRNA targets were explored. Results: 16 exo-miRs were differentially expressed, including marked upregulation of miR-155-5p, and downregulation of miR-223-3p and miR-1228-3p. Expression of miR-155-5p and miR-223-3p correlated with tacrolimus dose (p < 0.05), miR-223-3p with serum creatinine (p < 0.05), and miR-223-3p and miR-1228-3p with blood leukocytes (p < 0.05). 12 miRNAs have predicted targets involved in cell proliferation, apoptosis, stress response, PIK3/AKT/mTOR and TGF-β signaling pathways. Conclusion: Differentially expressed urinary exo-miRs may be useful markers to monitor tacrolimus therapy and graft function in kidney transplantation.

COVID-19 therapy with mesenchymal stromal cells (MSC) and convalescent plasma must consider exosome involvement: Do the exosomes in convalescent plasma antagonize the weak immune antibodies?

Exosome extracellular vesicles as biologic therapy for COVID-19 are discussed for two areas. The first involves the growing use of mesenchymal stromal cells (MSCs) for the profound clinical cytokine storm and severe pneumonia in COVID-19 patients. Instead, it is recommended to treat alternatively with their MSC-released exosomes. This is because many reports in the literature and our data have shown that the release of exosomes from the in vivo administered MSC is actually responsible for their beneficial effects. Further, the exosomes are superior, simpler and clinically more convenient compared to their parental MSC. Additionally, in the context of COVID-19, the known tendency of MSC to intravascularly aggregate causing lung dysfunction might synergize with the pneumonia aspects, and the tendency of MSC peripheral vascular micro aggregates might synergize with the vascular clots of the COVID-19 disease process, causing significant central or peripheral vascular insufficiency. The second exosome therapeutic area for severe COVID-19 involves use of convalescent plasma for its content of acquired immune antibodies that must consider the role in this therapy of contained nearly trillions of exosomes. Many of these derive from activated immune modulating cells and likely can function to transfer miRNAs that acting epigenetically to also influence the convalescent plasma recipient response to the virus. There is sufficient evidence, like recovery of patients with antibody deficiencies, to postulate that the antibodies actually have little effect and that immune resistance is principally due to T cell mechanisms. Further, COVID-19 convalescent plasma has remarkably weak beneficial effects if compared to what was expected from many prior studies. This may be due to the dysfunctional immune response to the infection and resulting weak Ab that may be impaired further by antagonistic exosomes in the convalescent plasma. At the least, pre selection of plasma for the best antibodies and relevant exosomes would produce the most optimum therapy for very severely affected COVID-19 patients.

Hypothesizing the therapeutic potential of mesenchymal stem cells in oral submucous fibrosis

Oral submucous fibrosis is the direct consequence of a sustained pro-inflammatory environment characterized by excessive collagen deposition causing tissue fibrosis, and progressive degeneration of vital structures including muscle. The pathogenesis of oral submucous fibrosis is largely mediated by the pro-inflammatory, pro-fibrotic cytokines, excessive oxidative stress, abnormal angiogenesis, and epithelial to mesenchymal transition. Mesenchymal stem cells largely known for their regenerative potential have shown to have an immunomodulatory, anti-fibrotic, anti-oxidative, and angiogenic potential. Thus, mesenchymal stem cells, when introduced in an oral submucous fibrosis micro-environment, could potentially counter the progressive fibrosis. The present hypotheses discuss the various pathogenic aspects of oral submucous fibrosis and the properties of mesenchymal stem cells which could aid in halting the disease progression.

Growth Factor Gene-Modified Mesenchymal Stem Cells in Tissue Regeneration

There have been marked changes in the field of stem cell therapeutics in recent years, with many clinical trials having been conducted to date in an effort to treat myriad diseases. Mesenchymal stem cells (MSCs) are the cell type most frequently utilized in stem cell therapeutic and tissue regenerative strategies, and have been used with excellent safety to date. Unfortunately, these MSCs have limited ability to engraft and survive, reducing their clinical utility. MSCs are able to secrete growth factors that can support the regeneration of tissues, and engineering MSCs to express such growth factors can improve their survival, proliferation, differentiation, and tissue reconstructing abilities. As such, it is likely that such genetically modified MSCs may represent the next stage of regenerative therapy. Indeed, increasing volumes of preclinical research suggests that such modified MSCs expressing growth factors can effectively treat many forms of tissue damage. In the present review, we survey recent approaches to producing and utilizing growth factor gene-modified MSCs in the context of tissue repair and discuss its prospects for clinical application.

Clinical Efficacy and Safety of Mesenchymal Stem Cells for Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a polymorphic, multisystemic autoimmune disease that causes multiorgan damage in which cellular communication occurs through the involvement of autoantibodies directed against autoantigen production. Mesenchymal stem cells (MSCs), which have strong protective and immunomodulatory abilities, are obtained not only from bone marrow but also from medical waste such as adipose tissue and umbilical cord tissue and have been recognized as a promising tool for the treatment of various autoimmune diseases and inflammatory disorders. This meta-analysis is aimed at assessing whether MSCs can become a new treatment for SLE with good efficacy and safety. Based on predetermined criteria, a bibliographical search was performed from January 1, 2000, to July 31, 2019, by searching the following databases: ISI Web of Science, Embase, PubMed, the Cochrane Library, and the Chinese Biomedical Literature Database (CBM). Eligible studies and data were identified. Statistical analysis was conducted to assess the efficacy (proteinuria, systemic lupus erythematosus disease activity index (SLEDAI), Scr, BUN, albumin, C3, and C4) and safety (rate of adverse events) of MSCs for SLE using Cochrane Review Manager Version 5.3. Ten studies fulfilled the inclusion criteria and were eligible for this meta-analysis, which comprised 8 prospective or retrospective case series and four randomized controlled trails (RCTs) studies. In the RCT, the results indicated that the MSC group had lower proteinuria than the control group at 3 months and 6 months and the MSC group displayed a lower SLEDAI than the control group at 2 months and 6 months. Furthermore, the MSC group showed a lower rate of adverse events than the control group (OR = 0.26, 95% CI: 0.07, 0.89, P = 0.03). In the case series trials, the results indicated that the MSC group had lower proteinuria at 1 month, 2 months, 3 months, 4 months, 6 months, and 12 months. In conclusion, MSCs might be a promising therapeutic agent for patients with SLE.