Contribution of microRNAs to the immunosuppressive function of mesenchymal stem cells

The Immunoregulatory and Regenerative Potential of Activated Human Stem Cell Secretome Mitigates Acute-on-Chronic Liver Failure in a Rat Model

Acute-on-chronic liver failure (ACLF) is a syndrome marked by sudden liver function decline and multiorgan failure, predominantly acute kidney injury (AKY), in patients with chronic liver disease. Unregulated inflammation is a hallmark of ACLF; however, the key drivers of ACLF are not fully understood. This study explores the therapeutic properties of human mesenchymal stem cell (MSC) secretome, particularly focusing on its enhanced anti-inflammatory and pro-regenerative properties after the in vitro preconditioning of the cells. We evaluated the efficacy of the systemic administration of MSC secretome in preventing liver failure and AKI in a rat ACLF model where chronic liver disease was induced using by the administration of porcine serum, followed by D-galN/LPS administration to induce acute failure. After ACLF induction, animals were treated with saline (ACLF group) or MSC-derived secretome (ACLF-secretome group). The study revealed that MSC-secretome administration strongly reduced liver histological damage in the ACLF group, which was correlated with higher hepatocyte proliferation, increased hepatic and systemic anti-inflammatory molecule levels, and reduced neutrophil and macrophage infiltration. Additionally, renal examination revealed that MSC-secretome treatment mitigated tubular injuries, reduced apoptosis, and downregulated injury markers. These improvements were linked to increased survival rates in the ACLF-secretome group, endorsing MSC secretomes as a promising therapy for multiorgan failure in ACLF.

Unveiling Mesenchymal Stem Cells' Regenerative Potential in Clinical Applications: Insights in miRNA and lncRNA Implications

It is now widely recognized that mesenchymal stem cells (MSCs) possess the capacity to differentiate into a wide array of cell types. Numerous studies have identified the role of lncRNA in the regulation of MSC differentiation. It is important to elucidate the role and interplay of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in the regulation of signalling pathways that govern MSC function. Furthermore, miRNAs and lncRNAs are important clinical for innovative strategies aimed at addressing a wide spectrum of existing and emerging disease. Hence it is important to consider their impact on MSC function and differentiation. Examining the data available in public databases, we have collected the literature containing the latest discoveries pertaining to human stem cells and their potential in both fundamental research and clinical applications. Furthermore, we have compiled completed clinical studies that revolve around the application of MSCs, shedding light on the opportunities presented by harnessing the regulatory potential of miRNAs and lncRNAs. This exploration of the therapeutic possibilities offered by miRNAs and lncRNAs within MSCs unveils exciting prospects for the development of precision therapies and personalized treatment approaches. Ultimately, these advancements promise to augment the efficacy of regenerative strategies and produce positive outcomes for patients. As research in this field continues to evolve, it is imperative to explore and exploit the vast potential of miRNAs and lncRNAs as therapeutic agents. The findings provide a solid basis for ongoing investigations, fuelling the quest to fully unlock the regenerative potential of MSCs.

Host and Pathogen-Directed Therapies against Microbial Infections Using Exosome- and Antimicrobial Peptide-derived Stem Cells with a Special look at Pulmonary Infections and Sepsis

Microbial diseases are a great threat to global health and cause considerable mortality and extensive economic losses each year. The medications for treating this group of diseases (antibiotics, antiviral, antifungal drugs, etc.) directly attack the pathogenic agents by recognizing the target molecules. However, it is necessary to note that excessive use of any of these drugs can lead to an increase in microbial resistance and infectious diseases. New therapeutic methods have been studied recently using emerging drugs such as mesenchymal stem cell-derived exosomes (MSC-Exos) and antimicrobial peptides (AMPs), which act based on two completely different strategies against pathogens including Host-Directed Therapy (HDT) and Pathogen-Directed Therapy (PDT), respectively. In the PDT approach, AMPs interact directly with pathogens to interrupt their intrusion, survival, and proliferation. These drugs interact directly with the cell membrane or intracellular components of pathogens and cause the death of pathogens or inhibit their replication. The mechanism of action of MSC-Exos in HDT is based on immunomodulation and regulation, promotion of tissue regeneration, and reduced host toxicity. This review studies the potential of mesenchymal stem cell-derived exosomes/ATPs therapeutic properties against microbial infectious diseases especially pulmonary infections and sepsis.

Managing the Heterogeneity of Mesenchymal Stem Cells for Cartilage Regenerative Therapy: A Review

Articular cartilage defects commonly result from trauma and are associated with significant morbidity. Since cartilage is an avascular, aneural, and alymphatic tissue with a poor intrinsic healing ability, the regeneration of functional hyaline cartilage remains a difficult clinical problem. Mesenchymal stem cells (MSCs) are multipotent cells with multilineage differentiation potential, including the ability to differentiate into chondrocytes. Due to their availability and ease of ex vivo expansion, clinicians are increasingly applying MSCs in the treatment of cartilage lesions. However, despite encouraging pre-clinical and clinical data, inconsistencies in MSC proliferative and chondrogenic potential depending on donor, tissue source, cell subset, culture conditions, and handling techniques remain a key barrier to widespread clinical application of MSC therapy in cartilage regeneration. In this review, we highlight the strategies to manage the heterogeneity of MSCs ex vivo for more effective cartilage repair, including reducing the MSC culture expansion period, and selecting MSCs with higher chondrogenic potential through specific genetic markers, surface markers, and biophysical attributes. The accomplishment of a less heterogeneous population of culture-expanded MSCs may improve the scalability, reproducibility, and standardisation of MSC therapy for clinical application in cartilage regeneration.

Adipose-Derived Mesenchymal Stromal Cells in Basic Research and Clinical Applications

Adipose-derived mesenchymal stromal cells (AD-MSCs) have been extensively studied in recent years. Their attractiveness is due to the ease of obtaining clinical material (fat tissue, lipoaspirate) and the relatively large number of AD-MSCs present in adipose tissue. In addition, AD-MSCs possess a high regenerative potential and immunomodulatory activities. Therefore, AD-MSCs have great potential in stem cell-based therapies in wound healing as well as in orthopedic, cardiovascular, or autoimmune diseases. There are many ongoing clinical trials on AD-MSC and in many cases their effectiveness has been proven. In this article, we present current knowledge about AD-MSCs based on our experience and other authors. We also demonstrate the application of AD-MSCs in selected pre-clinical models and clinical studies. Adipose-derived stromal cells can also be the pillar of the next generation of stem cells that will be chemically or genetically modified. Despite much research on these cells, there are still important and interesting areas to explore.

Mechanisms behind therapeutic potentials of mesenchymal stem cell mitochondria transfer/delivery

Mesenchymal stromal/stem cells (MSCs) perform their therapeutic effects through various mechanisms, including their ability to differentiate, producing different growth factors, immunomodulatory factors, and extracellular vesicles (EVs). In addition to the mentioned mechanisms, a new aspect of the therapeutic potential of MSCs has recently been noticed, which occurs through mitochondrial transfer. Various methods of MSCs mitochondria transfer have been used in studies to benefit from their therapeutic potential. Among these methods, mitochondrial transfer after MSCs transplantation in cell-to-cell contact, EVs-mediated transfer of mitochondria, and the use of MSCs isolated mitochondria (MSCs-mt) are well studied. Pathological conditions can affect the cells in the damaged microenvironment and lead to cells mitochondrial damage. Since the defect in the mitochondrial function of the cell leads to a decrease in ATP production and the subsequent cell death, restoring the mitochondrial content, functions, and hemostasis can affect the functions of the damaged cell. Various studies show that the transfer of MSCs mitochondria to other cells can affect vital processes such as proliferation, differentiation, cell metabolism, inflammatory responses, cell senescence, cell stress, and cell migration. These changes in cell attributes and behavior are very important for therapeutic purposes. For this reason, their investigation can play a significant role in the direction of the researchers'.

microRNA-93 packaged in extracellular vesicles from mesenchymal stem cells reduce neonatal hypoxic-ischemic brain injury

OBJECTIVE

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have been proposed as a promising strategy for treating ischemia-related diseases. Herein, we probed into the role of miR-93 delivered by BMSC-EVs in hypoxic-ischemic brain injury (HIBD).

METHODS

Neonatal HIBD mouse models and hippocampal neuron models of oxygen glucose deprivation (OGD) were constructed. EVs were isolated from the culture medium of bone marrow MSCs (BMSCs). After co-culture of BMSC-EVs with OGD-exposed hippocampal neurons, the effect of microRNA-93 (miR-93) delivered by BMSC-EVs on OGD-induced hippocampal neurons as well as on HIBD in vivo under transfection of miR-93 mimic or inhibitor was explored. The interaction among miR-93, JMJD3, and p53/KLF2 axis was assessed.

RESULTS

BMSC-EVs prevented OGD-induced hippocampal neuron apoptosis and inflammation, which was associated with their transfer of miR-93 into the hippocampal neurons. miR-93 targeted JMJD3 and downregulated its expression, thus inhibiting the OGD-induced hippocampal neuron apoptosis. By regulating the JMJD3/p53/KLF2 axis, miR-93 in BMSC-EVs reduced the OGD-induced hippocampal neuron apoptosis in vitro as well as alleviating HIBD in vivo.

CONCLUSIONS

The current study highlighted that miR-93 delivered by BMSC-EVs alleviated HIBD in neonatal mice through the JMJD3-dependent p53/KLF2 axis.

Mesenchymal Stem Cell-Based Therapy as a New Approach for the Treatment of Systemic Sclerosis

Systemic sclerosis (SSc) is an intractable autoimmune disease with unmet medical needs. Conventional immunosuppressive therapies have modest efficacy and obvious side effects. Targeted therapies with small molecules and antibodies remain under investigation in small pilot studies. The major breakthrough was the development of autologous haematopoietic stem cell transplantation (AHSCT) to treat refractory SSc with rapidly progressive internal organ involvement. However, AHSCT is contraindicated in patients with advanced visceral involvement. Mesenchymal stem cells (MSCs) which are characterized by immunosuppressive, antifibrotic and proangiogenic capabilities may be a promising alternative option for the treatment of SSc. Multiple preclinical and clinical studies on the use of MSCs to treat SSc are underway. However, there are several unresolved limitations and safety concerns of MSC transplantation, such as immune rejections and risks of tumour formation, respectively. Since the major therapeutic potential of MSCs has been ascribed to their paracrine signalling, the use of MSC-derived extracellular vesicles (EVs)/secretomes/exosomes as a "cell-free" therapy might be an alternative option to circumvent the limitations of MSC-based therapies. In the present review, we overview the current knowledge regarding the therapeutic efficacy of MSCs in SSc, focusing on progresses reported in preclinical and clinical studies using MSCs, as well as challenges and future directions of MSC transplantation as a treatment option for patients with SSc.

Effects of Adipose-Derived Biogenic Nanoparticle-Associated microRNA-451a on Toll-like Receptor 4-Induced Cytokines

Extracellular vesicles (EVs) are cell-released nanoparticles that transfer biomolecular content between cells. Among EV-associated biomolecules, microRNAs (miRNAs/miRs) represent one of the most important modulators of signaling pathways in recipient cells. Previous studies have shown that EVs from adipose-derived mesenchymal stromal cells (MSCs) and adipose tissue modulate inflammatory pathways in macrophages. In this study, the effects of miRNAs that are abundant in adipose tissue EVs and other biogenic nanoparticles (BiNPs) were assessed in terms of altering Toll-like receptor 4 (TLR4)-induced cytokines. TLR-4 signaling in macrophages is often triggered by pathogen or damage-induced inflammation and is associated with several diseases. This study demonstrates that miR-451a, which is abundant in adipose tissue BiNPs, suppresses pro-inflammatory cytokines and increases anti-inflammatory cytokines associated with the TLR4 pathway. Therefore, miR-451a may be partially responsible for immunomodulatory effects of adipose tissue-derived BiNPs.

Therapeutic effects of mesenchymal stem cells-derived extracellular vesicles' miRNAs on retinal regeneration: a review

Extracellular vesicles (EVs), which consist of microvesicles and exosomes, are secreted from all cells to transform vital information in the form of lipids, proteins, mRNAs and small RNAs such as microRNAs (miRNAs). Many studies demonstrated that EVs' miRNAs have effects on target cells. Numerous people suffer from the blindness caused by retinal degenerations. The death of retinal neurons is irreversible and creates permanent damage to the retina. In the absence of acceptable cures for retinal degenerative diseases, stem cells and their paracrine agents including EVs have become a promising therapeutic approach. Several studies showed that the therapeutic effects of stem cells are due to the miRNAs of their EVs. Considering the effects of microRNAs in retinal cells development and function and studies which provide the possible roles of mesenchymal stem cells-derived EVs miRNA content on retinal diseases, we focused on the similarities between these two groups of miRNAs that could be helpful for promoting new therapeutic techniques for retinal degenerative diseases.

miR-155 Contributes to the Immunoregulatory Function of Human Mesenchymal Stem Cells

Objectives

Mesenchymal stem/stromal cells (MSCs) are widely investigated in regenerative medicine thanks to their immunomodulatory properties. They exert their anti-inflammatory function thanks to the secretion of a number of mediators, including proteins and miRNAs, which can be released in the extracellular environment or in the cargo of extracellular vesicles (EVs). However, the role of miRNAs in the suppressive function of MSCs is controversial. The aim of the study was to identify miRNAs that contribute to the immunomodulatory function of human bone marrow-derived MSCs (BM-MSCs).

Methods

Human BM-MSCs were primed by coculture with activated peripheral blood mononuclear cells (aPBMCs). High throughput miRNA transcriptomic analysis was performed using Human MicroRNA TaqMan® Array Cards. The immunosuppressive function of miRNAs was investigated in mixed lymphocyte reactions and the delayed type hypersensitivity (DTH) murine model.

Results

Upon priming, 21 out of 377 tested miRNAs were significantly modulated in primed MSCs. We validated the up-regulation of miR-29a, miR-146a, miR-155 and the down-regulation of miR-149, miR-221 and miR-361 in additional samples of primed MSCs. We showed that miR-155 significantly reduced the proliferation of aPBMCs in vitro and inflammation in vivo, using the DTH model. Analysis of miRNA-mRNA interactions revealed miR-221 as a potential target gene that is down-regulated by miR-155 both in primed MSCs and in aPBMCs.

Conclusion

Here, we present evidence that miR-155 participates to the immunosuppressive function of human BM-MSCs and down-regulates the expression of miR-221 as a possible inflammatory mediator.

Functional Characteristics and Application of Mesenchymal Stem Cells in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a rare, heterogeneous autoimmune and autoinflammatory disease that affects both sexes and all races, although this disease exhibits its highest incidence/prevalence among the black population and shows a predilection for women of reproductive age. Although SLE has no cure, treatment can help decrease its signs and symptoms. Thus, we should focus primarily on personalized treatment. Mesenchymal stem/stromal cells (MSCs), which are multipotent cells capable of differentiating into osteoblasts, chondrocytes, adipocytes, and myoblasts, among other cell types, are potential candidates for use in a promising strategy to treat severe and refractory SLE. MSCs have an immunomodulatory function that can suppress the proliferation and activities of many immune cells, such as T lymphocytes, B lymphocytes, natural killer cells, macrophages and dendritic cells. Substantial progress has recently been made in MSC therapy, and experimental and clinical data suggest that such a therapy is a promising strategy for the treatment of severe and refractory SLE. In this review, we highlight the effects of MSCs on different immune cell types, describe the mechanisms underlying MSC-mediated immunoregulation, and discuss the treatment of SLE with MSCs from different sources in various animal models and clinical applications.

Skin Immunomodulation during Regeneration: Emerging New Targets

Adipose-Derived Stem Cells (ADSC) are present within the hypodermis and are also expected to play a pivotal role in wound healing, immunomodulation, and rejuvenation activities. They orchestrate, through their exosome, the mechanisms associated to cell differentiation, proliferation, and cell migration by upregulating genes implicated in different functions including skin barrier, immunomodulation, cell proliferation, and epidermal regeneration. ADSCs directly interact with their microenvironment and specifically the immune cells, including macrophages and T and B cells, resulting in differential inflammatory and anti-inflammatory mechanisms impacting, in return, ADSCs microenvironment and thus skin function. These useful features of ADSCs are involved in tissue repair, where the required cell proliferation, angiogenesis, and anti-inflammatory responses should occur rapidly in damaged sites. Different pathways involved have been reported such as Growth Differentiation Factor-11 (GDF11), Tumor Growth Factor (TGF)-β, Metalloproteinase (MMP), microRNA, and inflammatory cytokines that might serve as specific biomarkers of their immunomodulating capacity. In this review, we try to highlight ADSCs’ network and explore the potential indicators of their immunomodulatory effect in skin regeneration and aging. Assessment of these biomarkers might be useful and should be considered when designing new clinical therapies using ADSCs or their specific exosomes focusing on their immunomodulation activity.

Mesenchymal Stromal Cell Immunology for Efficient and Safe Treatment of Osteoarthritis

Mesenchymal stem cell (MSC) therapy represents a promising approach for the treatment of osteoarthritis (OA). MSCs can be readily isolated from multiple sources and expanded ex vivo for possible clinical application. They possess a unique immunological profile and regulatory machinery that underline their therapeutic effects. They also have the capacity to sense the changes within the tissue environment to display the adequate response. Indeed, there is a close interaction between MSCs and the host cells. Accordingly, MSCs demonstrate encouraging results for a variety of diseases including OA. However, their effectiveness needs to be improved. In this review, we selected to discuss the importance of the immunological features of MSCs, including the type of transplantation and the immune and blood compatibility. It is important to consider MSC immune evasive rather than immune privileged. We also highlighted some of the actions/mechanisms that are displayed during tissue healing including the response of MSCs to injury signals, their interaction with the immune system, and the impact of their lifespan. Finally, we briefly summarized the results of clinical studies reporting on the application of MSCs for the treatment of OA. The research field of MSCs is inspiring and innovative but requires more knowledge about the immunobiological properties of these cells. A better understanding of these features will be key for developing a safe and efficient medicinal product for clinical use in OA.

Short and Long Term Clinical and Immunologic Follow up after Bone Marrow Mesenchymal Stromal Cell Therapy in Progressive Multiple Sclerosis-A Phase I Study

Bone marrow derived mesenchymal stromal cells (BM-MSCs) have emerged as a possible new therapy for Multiple Sclerosis (MS), however studies regarding efficacy and in vivo immune response have been limited and inconclusive. We conducted a phase I clinical study assessing safety and clinical and peripheral immune responses after MSC therapy in MS. Seven patients with progressive MS were intravenously infused with a single dose of autologous MSC (1–2 × 10⁶ MSCs/kg body weight). The infusions were safe and well tolerated when given during clinical remission. Five out of seven patients completed the follow up of 48 weeks post-infusion. Brain magnetic resonance imaging (MRI) showed the absence of new T2 lesions at 12 weeks in 5/6 patients, while 3/5 had accumulated new T2 lesions at 48 weeks. Patient expanded disability status scales (EDSS) were stable in 6/6 at 12 weeks but declined in 3/5 patients at 48 weeks. Early changes of circulating microRNA levels (2 h) and increased proportion of FOXP3⁺ Tregs were detected at 7 days post-infusion compared to baseline levels. In conclusion, MSC therapy was safe and well tolerated and is associated with possible transient beneficial clinical and peripheral immunotolerogenic effects.