Bone marrow mesenchymal stem cells inhibit the response of naive and memory antigen-specific T cells to their cognate peptide

Roles of Microenvironment on Mesenchymal Stem Cells Therapy for Osteoarthritis

Osteoarthritis (OA) induced microenvironmental alterations are a common and unavoidable phenomenon that greatly exacerbate the pathologic process of OA. Imbalances in the synthesis and degradation of cartilage extracellular matrix (ECM) have been reported to be associated with an adverse microenvironment. Stem cell therapy is a promising treatment for OA, and mesenchymal stem cells (MSCs) are the main cell sources for this therapy. With multispectral differentiation and immunomodulation, MSCs can effectively regulate the microenvironment of articular cartilage, ameliorate inflammation, promote regeneration of damaged cartilage, and ultimately alleviate OA symptoms. However, the efficacy of MSCs in the treatment of OA is greatly influenced by articular cavity microenvironments. This article reviews the five microenvironments of OA articular cavity, including inflammatory microenvironment, senescence microenvironment, hypoxic microenvironment, high glucose microenvironment and high lipid environment, focus on the positive and negative effects of OA microenvironments on the fate of MSCs. In this regard, we emphasize the mechanisms of the current use of MSCs in OA treatment, as well as its limitations and challenges.

International Society for Cell and Gene Therapy Clinical Translation Committee recommendations on mesenchymal stromal cells in graft-versus-host disease: easy manufacturing is faced with standardizing and commercialization challenges

Mesenchymal stromal cells (MSCs) have been used in multiple clinical trials for steroid-refractory moderate-severe (grade II-IV) acute graft-versus-host disease (aGVHD) across the world over the last two decades. Despite very promising results in a variety of trials, it failed to get widespread approval by regulatory agencies such as the U.S. Food and Drug Administration and the European Medicines Agency. What lessons can we learn from this for future studies on MSCs and other cell therapy products? Broad heterogeneity among published trials using MSCs in aGVHD was likely the core problem. We propose a standardized approach in regards to donor-related factors, MSCs-related characteristics, as well as clinical trial design, to limit heterogeneity in trials for aGVHD and to fulfill the requirements of regulatory agencies. This approach may be expanded beyond MSCs to other Cell and Gene therapy products and trials in other diseases.

Exogenous MSC based tissue regeneration: a review of immuno-protection strategies from biomaterial scaffolds

Mesenchymal stem cell (MSC)-based tissue engineering holds great potential for regenerative medicine as a means of replacing damaged or lost tissues to restore their structure and function. However, the efficacy of MSC-based regeneration is frequently limited by the low survival rate and limited survival time of transplanted MSCs. Despite the inherent immune privileges of MSCs, such as low expression of major histocompatibility complex antigens, tolerogenic properties, local immunosuppressive microenvironment creation, and induction of immune tolerance, immune rejection remains a major obstacle to their survival and regenerative potential. Evidence suggests that immune protection strategies can enhance MSC therapeutic efficacy by prolonging their survival and maintaining their biological functions. Among various immune protection strategies, biomaterial-based scaffolds or cell encapsulation systems that mediate the interaction between transplanted MSCs and the host immune system or spatially isolate MSCs from the immune system for a specific time period have shown great promise. In this review, we provide a comprehensive overview of these biomaterial-based immune protection strategies employed for exogenous MSCs, highlighting the crucial role of modulating the immune microenvironment. Each strategy is critically examined, discussing its strengths, limitations, and potential applications in MSC-based tissue engineering. By elucidating the mechanisms behind immune rejection and exploring immune protection strategies, we aim to address the challenges faced by MSC-based tissue engineering and pave the way for enhancing the therapeutic outcomes of MSC therapies. The insights gained from this review will contribute to the development of more effective strategies to protect transplanted MSCs from immune rejection and enable their successful application in regenerative medicine.

Therapeutic Potential and Mechanisms of Mesenchymal Stem Cell and Mesenchymal Stem Cell-Derived Extracellular Vesicles in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic and inflammatory skin disease with intense itchiness that is highly prevalent worldwide.The pathogenesis of AD is complex and closely related to genetic factors, immunopathogenic factors, environmental factors, and skin infections. Mesenchymal stem cells (MSCs) are non-hematopoietic progenitor cells derived from the mesenchymal stroma. They have anti-inflammatory, anti-apoptotic, and regenerative properties. Numerous studies demonstrate that MSCs can play a therapeutic role in AD by regulating various immune cells, maintaining immune homeostasis, and promoting the repair of damaged tissues. The key mediators for their biological functions are extracellular vesicles (MSC-Evs) and soluble cytokines derived from MSCs. The safety and efficacy of MSCs have been demonstrated in clinical Phase I / IIa trials for AD. This paper provides a comprehensive review of the pathogenesis of AD and the currently published studies on the function of MSCs and MSC-Evs in AD, primarily including the pathogenesis and the immunomodulatory impacts of MSCs and MSC-Evs, along with advancements in clinical studies. It provides insights for comprehending AD pathogenesis and investigating treatments based on MSCs.

Metformin rejuvenates Nap1l2-impaired immunomodulation of bone marrow mesenchymal stem cells via metabolic reprogramming

Ageing and cell senescence of mesenchymal stem cells (MSCs) limited their immunomodulation properties and therapeutic application. We previously reported that nucleosome assembly protein 1-like 2 (Nap1l2) contributes to MSCs senescence and osteogenic differentiation. Here, we sought to evaluate whether Nap1l2 impairs the immunomodulatory properties of MSCs and find a way to rescue the deficient properties. We demonstrated that metformin could rescue the impaired migration properties and T cell regulation properties of OE-Nap1l2 BMSCs. Moreover, metformin could improve the impaired therapeutic efficacy of OE-Nap1l2 BMSCs in the treatment of colitis and experimental autoimmune encephalomyelitis in mice. Mechanistically, metformin was capable of upregulating the activation of AMPK, synthesis of l-arginine and expression of inducible nitric oxide synthase in OE-Nap1l2 BMSCs, leading to an increasing level of nitric oxide. This study indicated that Nap1l2 negatively regulated the immunomodulatory properties of BMSCs and that the impaired functions could be rescued by metformin pretreatment via metabolic reprogramming. This strategy might serve as a practical therapeutic option to rescue impaired MSCs functions for further application.

Stem cell-based therapy for systemic lupus erythematous

Systemic lupus erythematosus (SLE), an autoimmune disease, is among the most prevalent rheumatic autoimmune disorders. It affects autologous connective tissues caused by the breakdown of self-tolerance mechanisms. During the last two decades, stem cell therapy has been increasingly considered as a therapeutic option in various diseases, including parkinson's disease, alzheimer, stroke, spinal cord injury, multiple sclerosis, inflammatory bowel disease, liver disease, diabete, heart disease, bone disease, renal disease, respiratory diseases, and hematological abnormalities such as anemia. This is due to the unique properties of stem cells that divide and differentiate to the specialized cells in the damaged tissues. Moreover, they impose immunomodulatory properties affecting the diseases caused by immunological abnormalities such as rheumatic autoimmune disorders. In the present manuscript, efficacy of stem cell therapy with two main types of stem cells, including mesenchymal stem cell (MSC), and hematopoietic stem cells (HSC) in animal models or human patients of SLE, has been reviewed. Taken together, MSC and HSC therapies improved the disease activity, and severity in kidney, lung, liver, and bone (improvement in the clinical manifestation). In addition, a change in the immunological parameters occurred (improvement in immunological parameters). The level of autoantibodies, including antinuclear antibody (ANA), and anti-double-stranded deoxyribonucleic acid antibodies (dsDNA Abs) reduced. A conversion of Th1/Th2 ratio (in favor of Th2), and Th17/Treg (in favor of Treg) was also detected. In spite of many advantages of MSC and HSC transplantations, including efficacy, safety, and increased survival rate of SLE patients, some complications, including recurrence of the disease, occurrence of infections, and secondary autoimmune diseases (SAD) were observed after transplantation that should be addressed in the next studies.

Human lung cancer-derived mesenchymal stem cells promote tumor growth and immunosuppression

BACKGROUND

The presence of mesenchymal stem cells has been confirmed in some solid tumors where they serve as important components of the tumor microenvironment; however, their role in cancer has not been fully elucidated. The aim of this study was to investigate the functions of mesenchymal stem cells isolated from tumor tissues of patients with non-small cell lung cancer.

RESULTS

Human lung cancer-derived mesenchymal stem cells displayed the typical morphology and immunophenotype of mesenchymal stem cells; they were nontumorigenic and capable of undergoing multipotent differentiation. These isolated cells remarkably enhanced tumor growth when incorporated into systems alongside tumor cells in vivo. Importantly, in the presence of mesenchymal stem cells, the ability of peripheral blood mononuclear cell-derived natural killer and activated T cells to mediate tumor cell destruction was significantly compromised.

CONCLUSION

Collectively, these data support the notion that human lung cancer-derived mesenchymal stem cells protect tumor cells from immune-mediated destruction by inhibiting the antitumor activities of natural killer and T cells.

The use of stem cells in the treatment of mastitis in dairy cows

Mastitis is a multifactorial inflammatory disease. The increase in antibiotic resistance of bacteria that cause mastitis means that cattle breeders would prefer to reduce the use of antibiotics. Recently, therapies using mesenchymal stem cells (MSCs) from various sources have gained significant interest in the development of regenerative medicine in humans and animals, due to their extraordinary range of properties and functions. The aim of this study was to analyze the effectiveness of an allogeneic stem cells derived from bone marrow (BMSC) and adipose tissue (ADSC) in treating mastitis in dairy cattle. The research material consisted of milk and blood samples collected from 39 Polish Holstein-Friesian cows, 36 of which were classified as having mastitis, based on cytological evaluation of their milk. The experimental group was divided into subgroups according to the method of MSC administration: intravenous, intramammary, and intravenous + intramammary, and according to the allogeneic stem cells administered: BMSC and ADSC. The research material was collected at several time intervals: before the administration of stem cells, after 24 and 72 h, and after 7 days. Blood samples were collected to assess hematological parameters and the level of pro-inflammatory cytokines, while the milk samples were used for microbiological assessment and to determine the somatic cells count (SCC). The administration of allogeneic MSCs resulted in a reduction in the total number of bacterial cells, Staphylococcus aureus, bacteria from the Enterobacteriaceae group, and a systematic decrease in SCC in milk. The therapeutic effect was achieved via intravenous + intramammary or intramammary administration.

Exosomal mediators in sepsis and inflammatory organ injury: unraveling the role of exosomes in intercellular crosstalk and organ dysfunction

Sepsis, a severe systemic inflammatory response to infection, remains a leading cause of morbidity and mortality worldwide. Exosomes, as mediators of intercellular communication, play a pivotal role in the pathogenesis of sepsis through modulating immune responses, metabolic reprogramming, coagulopathy, and organ dysfunction. This review highlights the emerging significance of exosomes in these processes. Initially, it provides an in-depth insight into exosome biogenesis and characterization, laying the groundwork for understanding their diverse and intricate functions. Subsequently, it explores the regulatory roles of exosomes in various immune cells such as neutrophils, macrophages, dendritic cells, T cells, and B cells. This analysis elucidates how exosomes are pivotal in modulating immune responses, thus contributing to the complexity of sepsis pathophysiology. Additionally, this review delves into the role of exosomes in the regulation of metabolism and subsequent organ dysfunction in sepsis. It also establishes a connection between exosomes and the coagulation cascade, which affects endothelial integrity and promotes thrombogenesis in sepsis. Moreover, the review discusses the dual role of exosomes in the progression and resolution of sepsis, exploring their complex involvement in inflammation and healing processes. Furthermore, it underscores their potential as biomarkers and therapeutic targets. Understanding these mechanisms presents new opportunities for novel interventions to mitigate the severe outcomes of sepsis, emphasizing the therapeutic promise of exosome research in critical care settings.

Embryonic-stem-cell-derived mesenchymal stem cells relieve experimental contact urticaria by regulating the functions of mast cells and T cells

Contact urticaria (CU) is an inflammatory skin disorder triggered by specific substances upon skin contact, leading to immediate acute or chronic manifestations characterized by swelling and redness. While mesenchymal stem cells (MSCs) are increasingly recognized for their therapeutic potential in immune diseases, research on the efficacy and mechanisms of stem cell therapy for urticaria remains scarce. This study investigates the regulatory role of embryonic-stem-cell-derived multipotent MSCs (M-MSCs) administered in a CU mouse model. Therapeutic effects of M-MSC administration were assessed in a Trimellitic anhydride-induced contact urticaria model, revealing significant inhibition of urticarial reactions, including ear swelling, itchiness, and skin lesion. Moreover, M-MSC administration exerted control over effector T cell activities in major lymphoid and peripheral tissues, while also suppressing mast cell degranulation in peripheral tissues. Notably, the inhibitory effects mediated by M-MSCs were found to be TGF-β-dependent. Our study demonstrates the capacity of M-MSCs to regulate contact urticaria in a murine model, harmonizing the activation of inflammatory T cells and mast cells. Additionally, we suggest that TGF-β derived from M-MSCs could play a pivotal role as an inhibitory mechanism in contact urticaria.

Tumor necrosis factor α, and agonist and antagonists of cannabinoid receptor type 1 and type 2 alter the immunophenotype of stem cells from human exfoliated deciduous teeth

OBJECTIVE

To verify the involvement of the endocannabinoid system in the immunomodulatory profile of stem cells from human exfoliated deciduous teeth, in the presence or absence of TNF-α, and agonist and antagonists of CB1 and CB2.

METHODS

Stem cells from human exfoliated deciduous teeth were cultured in the presence or absence of an agonist, anandamide, and two antagonists, AM251 and SR144528, of CB1 and CB2 receptors, with or without TNF-α stimulation. For analysis of immunomodulation, surface molecules linked to immunomodulation, namely human leukocyte antigen-DR isotype (HLA-DR), and programmed death ligands 1 (PD-L1) and 2 (PD-L2) were measured using flow cytometry.

RESULTS

The inhibition of endocannabinoid receptors together with the proinflammatory effect of TNF-α resulted in increased HLA-DR expression in stem cells from human exfoliated deciduous teeth, as well as, in these cells acquiring an anti-inflammatory profile by enhancing the expression of PD-L1 and PD-L2.

CONCLUSION

Stem cells from human exfoliated deciduous teeth respond to the endocannabinoid system and TNF-α by altering key immune response molecules. Inhibition of endocannabinoid receptors and TNF-α led to an increase in HLA-DR, PD-L1, and PD-L2 levels in stem cells from human exfoliated deciduous teeth. This study shows the interaction between mesenchymal stromal cells and the immune and endocannabinoid systems.

Potential role of mesenchymal stem cells in T cell aging

Immunosenescence occurs with progressive age. T cell aging is manifested by immunodeficiency and inflammation. The main mechanisms are thymic involution, mitochondrial dysfunction, genetic and epigenetic alterations, loss of protein stability, reduction of T cell receptor (TCR) repertoire, naïve-memory T cell ratio imbalance, T cell senescence, and lack of effector plasticity. Mesenchymal stem cells (MSCs) are thought to hold great potential as anti-aging therapy. However, the role of MCSs in T cell aging remains elusive. This review makes a tentative summary of the potential role of MSCs in the protection against T cell aging. It might provide a new idea to intervene in the aging of the immune system.

Stromal-Modulated Epithelial-to-Mesenchymal Transition in Cancer Cells

The ability of cancer cells to detach from the primary site and metastasize is the main cause of cancer- related death among all cancer types. Epithelial-to-mesenchymal transition (EMT) is the first event of the metastatic cascade, resulting in the loss of cell-cell adhesion and the acquisition of motile and stem-like phenotypes. A critical modulator of EMT in cancer cells is the stromal tumor microenvironment (TME), which can promote the acquisition of a mesenchymal phenotype through direct interaction with cancer cells or changes to the broader microenvironment. In this review, we will explore the role of stromal cells in modulating cancer cell EMT, with particular emphasis on the function of mesenchymal stromal/stem cells (MSCs) through the activation of EMT-inducing pathways, extra cellular matrix (ECM) remodeling, immune cell alteration, and metabolic rewiring.

Mesenchymal stem/stromal cells- a principal element for tumour microenvironment heterogeneity

The heterogeneity of the tumor microenvironment (TME) is a major obstacle in cancer treatment, making most therapeutic interventions palliative rather than curative. Previous studies have suggested that the reason for the low efficacy of immunotherapy and the relapse of the original responders over time may be due to the complex network of mesenchymal stem/stromal cells (MSCs), a population of multipotent progenitor cells existing in a variety of tissues. Cancer-associated MSCs (CA-MSCs) have already been isolated from various types of tumors and are characterized by their vigorous pro-tumorigenic functions. Although the roles of CA-MSCs from different sources vary widely, their origins are still poorly understood. Current evidence suggests that when local resident or distally recruited MSCs interact with tumor cells and other components in the TME, "naïve" MSCs undergo genetic and functional changes to form CA-MSCs. In this review, we mainly focus on the multiple roles of CA-MSCs derived from different sources, which may help in elucidating the formation and function of the entire TME, as well as discover innovative targets for anti-cancer therapies.

Evaluation of safety and efficacy of allogeneic adipose tissue-derived mesenchymal stem cells in pediatric bronchiolitis obliterans syndrome (BoS) after allogeneic hematopoietic stem cell transplantation (allo-HSCT)

BACKGROUND

Allo-HSCT is a definite approach for the management of a wide variety of lethal and debilitating malignant and non-malignant disorders. However, its two main complications, acute and chronic graft-versus-host disease (GVHD), exert significant morbidities and mortalities. BoS, as a manifestation of chronic lung GVHD, is a gruesome complication of allo-HSCT, and for those with steroid-refractory disease, no approved second-line therapies exist. Mesenchymal stem cells (MSCs) exert anti-inflammatory and growth-promoting effects, and their administration against a wide range of inflammatory and neurologic disorders, as well as GVHD, has been associated with promising outcomes. However, literature on the safety and effectiveness of MSC therapy for BoS and pediatric cGVHD is scarce.

METHODS

We designed a single-arm trial to administer adipose tissue (AT)-derived MSCs to pediatric patients with refractory BoS after allo-HSCT. AT-MSCs from obese, otherwise healthy donors were cultured in an ISO class 1 clean room and injected into the antecubital vein of eligible patients with a dose of 1 × 106/kg. The primary endpoints included a complete or partial response to therapy [in terms of increased forced expiratory volume in one second (FEV1) values and steroid dose reduction] and its safety profile.

RESULTS

Four eligible patients with a median age of 6.5 years were enrolled in the study. Steroid-induced osteoporosis and myopathy were present in three cases. A partial response was evident in three cases after a single injection of AT-MSCs. The treatment was safe and tolerable, and no treatment-related adverse events were noted. Two patients developed manageable COVID-19 infections one and 4 months after AT-MSC injection. After a median follow-up duration of 19 months, all cases are still alive and have had no indications for lung transplantation.

CONCLUSIONS

AT-MSCs could be safely administered to our pediatric cases with BoS post-allo-HSCT. Considering their advanced stage of disease, their sub-optimal functional capacity due to steroid-induced complications, and COVID-19 infection post-treatment, we believe that AT-MSC therapy can have possible efficacy in the management of pediatric BoS. The conduction of further studies with larger sample sizes and more frequent injections is prudent for further optimization of AT-MSC therapy against BoS. Trial registration Iranian Registry of Clinical Trials (IRCT), IRCT20201202049568N2. Registered 22 February 2021, https://en.irct.ir/trial/53143 .

Defining the optimal historical control group for a phase 1 trial of mesenchymal stromal cell delivery through cardiopulmonary bypass in neonates and infants

OBJECTIVE

The Mesenchymal Stromal Cell Delivery through Cardiopulmonary Bypass in Pediatric Cardiac Surgery study is a prospective, open-label, single-centre, dose-escalation phase 1 trial assessing the safety/feasibility of delivering mesenchymal stromal cells to neonates/infants during cardiac surgery. Outcomes will be compared with historical data from a similar population. We aim to define an optimal control group for use in the Mesenchymal Stromal Cell Delivery through Cardiopulmonary Bypass in Pediatric Cardiac Surgery trial.

METHODS

Consecutive patients who underwent a two-ventricle repair without aortic arch reconstruction within the first 6 months of life between 2015 and 2020 were studied using the same inclusion/exclusion criteria as the Phase 1 Mesenchymal Stromal Cell Delivery through Cardiopulmonary Bypass in Pediatric Cardiac Surgery trial (n = 169). Patients were allocated into one of three diagnostic groups: ventricular septal defect type, Tetralogy of Fallot type, and transposition of the great arteries type. To determine era effect, patients were analysed in two groups: Group A (2015-2017) and B (2018-2020). In addition to biological markers, three post-operative scoring methods (inotropic and vasoactive-inotropic scores and the Pediatric Risk of Mortality-III) were assessed.

RESULTS

All values for three scoring systems were consistent with complexity of cardiac anomalies. Max inotropic and vasoactive-inotropic scores demonstrated significant differences between all diagnosis groups, confirming high sensitivity. Despite no differences in surgical factors between era groups, we observed lower inotropic and vasoactive-inotropic scores in group B, consistent with improved post-operative course in recent years at our centre.

CONCLUSIONS

Our studies confirm max inotropic and vasoactive-inotropic scores as important quantitative measures after neonatal/infant cardiac surgery. Clinical outcomes should be compared within diagnostic groupings. The optimal control group should include only patients from a recent era. This initial study will help to determine the sample size of future efficacy/effectiveness studies.

Control of the post-infarct immune microenvironment through biotherapeutic and biomaterial-based approaches

Ischemic heart failure (IHF) is a leading cause of morbidity and mortality worldwide, for which heart transplantation remains the only definitive treatment. IHF manifests from myocardial infarction (MI) that initiates tissue remodeling processes, mediated by mechanical changes in the tissue (loss of contractility, softening of the myocardium) that are interdependent with cellular mechanisms (cardiomyocyte death, inflammatory response). The early remodeling phase is characterized by robust inflammation that is necessary for tissue debridement and the initiation of repair processes. While later transition toward an immunoregenerative function is desirable, functional reorientation from an inflammatory to reparatory environment is often lacking, trapping the heart in a chronically inflamed state that perpetuates cardiomyocyte death, ventricular dilatation, excess fibrosis, and progressive IHF. Therapies can redirect the immune microenvironment, including biotherapeutic and biomaterial-based approaches. In this review, we outline these existing approaches, with a particular focus on the immunomodulatory effects of therapeutics (small molecule drugs, biomolecules, and cell or cell-derived products). Cardioprotective strategies, often focusing on immunosuppression, have shown promise in pre-clinical and clinical trials. However, immunoregenerative therapies are emerging that often benefit from exacerbating early inflammation. Biomaterials can be used to enhance these therapies as a result of their intrinsic immunomodulatory properties, parallel mechanisms of action (e.g., mechanical restraint), or by enabling cell or tissue-targeted delivery. We further discuss translatability and the continued progress of technologies and procedures that contribute to the bench-to-bedside development of these critically needed treatments.

Immunomodulatory Mechanisms and Therapeutic Potential of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are regarded as highly promising cells for allogeneic cell therapy, owing to their multipotent nature and ability to display potent and varied functions in different diseases. The functions of MSCs, including native immunomodulation, high self-renewal characteristic, and secretory and trophic properties, can be employed to improve the immune-modulatory functions in diseases. MSCs impact most immune cells by directly contacting and/or secreting positive microenvironmental factors to influence them. Previous studies have reported that the immunomodulatory role of MSCs is basically dependent on their secretion ability from MSCs. This review discusses the immunomodulatory capabilities of MSCs and the promising strategies to successfully improve the potential utilization of MSCs in clinical research.

Mesenchymal Stem/Stromal Cell-Based Therapies in Systemic Rheumatic Disease: From Challenges to New Approaches for Overcoming Restrictions

Systemic rheumatic diseases, such as rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis, are chronic autoimmune diseases affecting multiple organs and tissues. Despite recent advances in treatment, patients still experience significant morbidity and disability. Mesenchymal stem/stromal cell (MSC)-based therapy is promising for treating systemic rheumatic diseases due to the regenerative and immunomodulatory properties of MSCs. However, several challenges need to be overcome to use MSCs in clinical practice effectively. These challenges include MSC sourcing, characterization, standardization, safety, and efficacy issues. In this review, we provide an overview of the current state of MSC-based therapies in systemic rheumatic diseases, highlighting the challenges and limitations associated with their use. We also discuss emerging strategies and novel approaches that can help overcome the limitations. Finally, we provide insights into the future directions of MSC-based therapies for systemic rheumatic diseases and their potential clinical applications.

Engineering tandem CD33xCD146 CAR CIK (cytokine-induced killer) cells to target the acute myeloid leukemia niche

In acute myeloid leukemia (AML), malignant stem cells hijack the normal bone marrow niche where they are largely protected from the current therapeutic approaches. Thus, eradicating these progenitors is the ultimate challenge in the treatment of this disease. Specifically, the development of chimeric antigen receptors (CARs) against distinct mesenchymal stromal cell subpopulations involved in the maintenance of leukemic stem cells within the malignant bone marrow microenvironment could represent a new strategy to improve CAR T-cell therapy efficacy, which is still unsuccessful in AML. As a proof of concept, we generated a novel prototype of Tandem CAR, with one specificity directed against the leukemic cell marker CD33 and the other against the mesenchymal stromal cell marker CD146, demonstrating its capability of simultaneously targeting two different cell types in a 2D co-culture system. Interestingly, we could also observe an in vitro inhibition of CAR T cell functionality mediated by stromal cells, particularly in later effector functions, such as reduction of interferon-gamma and interleukin-2 release and impaired proliferation of the CAR⁺ effector Cytokine-Induced Killer (CIK) cells. Taken together, these data demonstrate the feasibility of a dual targeting model against two molecules, which are expressed on two different target cells, but also highlight the immunomodulatory effect on CAR CIK cells exerted by stromal cells, confirming that the niche could be an obstacle to the efficacy of CAR T cells. This aspect should be considered in the development of novel CAR T cell approaches directed against the AML bone marrow niche.

Wound-Healing Effects of Mesenchymal Stromal Cell Secretome in the Cornea and the Role of Exosomes

Mesenchymal stromal/stem cells (MSCs) and their secreted factors have been shown to have immunomodulatory and regenerative effects. In this study, we investigated human bone-marrow-derived MSC secretome (MSC-S) for the treatment of corneal epithelial wounds. Specifically, we evaluated the role of MSC extracellular vesicles (EV)/exosomes in mediating the wound-healing effects of the MSC-S. In vitro studies using human corneal epithelial cells showed that MSC-CM increased cell proliferation in HCEC and HCLE cells, while EV-depleted MSC-CM showed lower cell proliferation in both cell lines compared to the MSC-CM group. In vitro and in vivo experiments revealed that 1X MSC-S consistently promoted wound healing more effectively than 0.5X MSC-S, and MSC-CM promoted wound healing in a dose-dependent manner, while exosome deprivation delayed wound healing. We further evaluated the incubation period of MSC-CM on corneal wound healing and showed that MSC-S collected for 72 h is more effective than MSC-S collected for 48 h. Finally, we evaluated the stability of MSC-S under different storage conditions and found that after one cycle of freeze-thawing, MSC-S is stable at 4 °C for up to 4 weeks. Collectively, we identified the following: (i) MSC-EV/Exo as the active ingredient in MSC-S that mediates the wound-healing effects in the corneal epithelium, providing a measure to optimize its dosing for a potential clinical product; (ii) Treatment with EV/Exo-containing MSC-S resulted in an improved corneal barrier and decreased corneal haze/edema relative to EV/Exo-depleted MSC-S; (iii) The stability of MSC-CM for up to 4 weeks showed that the regular storage condition did not significantly impact its stability and therapeutic functions.

Evaluation of the relationship between mesenchymal stem cells and immune system in vitro conditions

BACKGROUND

Mesenchymal stem cells (MSCs), are a novel therapeutic option as the most common cell source, play an important role in the immunomodulation. In this study, it was aimed to determine the effect of MSCs on cytokines secreted by the immune system cells.

METHODS

Intracellular cytokine levels (Interleukin-4 (IL-4), Interferon-γ (IFN-γ), and Interleukin-17 (IL-17)) detected by flow cytometry before and after co-culture between peripheral blood mononuclear cells (PBMCs) and MCSs. At the same time, supernatant cytokine levels were measured using the ELISA.

RESULTS

In our study, MSCs were isolated from cord blood (CB) and Wharton's Jelly (WJ), and their surface markers (CD44 (100%), CD73 (99.6%), CD90 (100%), CD105 (88%)) shown by flow cytometry method. Both CB-MSCs and WJ-MSCs were used in co-culture MSC/PBMC ratios of 1/5 and 1/10, incubation times of 24 h and 72 h. In the present study, when we compared co-cultures of CB-MSC or WJ-MSC with PBMCs, intracellular levels of cytokines IFN-γ, IL-17 (pro-inflamatory) and IL-4 (anti-inflamatory) were increased, and supernatant levels were decreased significantly (p < 0.05). The level of transforming growth factor beta (TGF-β) (anti-inflamatory) was significantly decreased for both CB-MSC and WJ-MSC in supernatant (p < 0.05).

CONCLUSIONS

It was investigated pro-inflammatory and anti-inflammatory effects of CB-MSCs and WJ-MSCs on PBMCs with the obtained results. According to the results, MSCs demonstrated different immunologic effects after the incubation time and ratios. For further studies, it should be known between interaction of MSCs and immune system.

Allogenic bone marrow-derived mesenchymal stem cells and its conditioned media for repairing acute and sub-acute peripheral nerve injuries in a rabbit model

The present study evaluated healing potential of bone marrow-derived mesenchymal stem cells (BM-MSCs) and BM-MSCs-conditioned medium (BM-MSCs-CM) for acute and subacute injuries in the rabbit peripheral nerve injury model. The regenerative capacity of MSCs was evaluated in 40 rabbits divided into eight groups, four groups each for acute and subacute injury models. BM-MSCs and BM-MSCS-CM were prepared by isolating allogenic bone marrow from the iliac crest. After inducing sciatic nerve crush injury, different treatments consisting of PBS, Laminin, BM-MSCs + laminin, and BM-MSCS-CM + laminin were used on the day of injury in the acute injury model and after ten days of crush injury in the subacute groups. The parameters studied included: pain, total neurological score, gastrocnemius muscle weight and volume ratio, histopathology of the sciatic nerve and gastrocnemius muscle, and scanning electron microscopy (SEM). Findings indicate that BM-MSCs and BM-MSCS-CM have augmented the regenerative capacity in acute and subacute injury groups with a slightly better improvement in the subacute groups than the animals in acute injury groups. Histopathology data revealed different levels of regenerative process undergoing in the nerve. Neurological observations, gastrocnemius muscle evaluation, muscle histopathology, and the SEM results depicted better healing in animals treated with BM-MSCs and BM-MSCS-CM. With this data, it could be concluded that BM-MSCs support the healing of injured peripheral nerves, and the BM-MSCS-CM does accelerate the healing of acute and subacute peripheral nerve injuries in rabbits. However, stem cell therapy may be indicated during the subacute phase for better results.

Interferon-γ-Treated Mesenchymal Stem Cells Modulate the T Cell-Related Chemokines and Chemokine Receptors in an Animal Model of Experimental Autoimmune Encephalomyelitis

BACKGROUND

Mesenchymal stem cells (MSCs) modulate immune responses, and their immunomodulatory potential can be enhanced using inflammatory cytokines. Here, the modulatory effects of IFN-γ-licensed MSCs on expression of T cell-related chemokines and chemokine receptors were evaluated using an experimental autoimmune encephalomyelitis (EAE) model.

MATERIAL AND METHODS

EAE was induced in 3 groups of C57bl/6 mice and then treated with PBS, MSCs and IFN-γ-treated MSCs. The EAE manifestations were registered daily and finally, the brain and spinal cords were isolated for histopathological and gene expression studies.

RESULTS

The clinical scores were lowered in MSCs and IFN-γ-licensed MSCs groups, however, mice treated with IFN-γ-licensed MSCs exhibited lower clinical scores than MSCs-treated mice. Leukocyte infiltration into the brain was reduced after treatment with MSCs or IFN-γ-licensed MSCs compared to untreated group (P<0.05 and P<0.01, respectively). In comparison with untreated EAE mice, treatment with MSCs reduced CCL20 expression (P<0.001) and decreased CXCR3 and CCR6 expression (P<0.02 and P<0.04, respectively). In comparison with untreated EAE mice, treatment with IFN-γ-licensed MSCs reduced CXCL10, CCL17 and CCL20 expression (P<0.05, P<0.05, and P<0.001, respectively) as well as decreased CXCR3 and CCR6 expression (P<0.002 and P<0.02, respectively), whilst promoting expression of CCL22 and its receptor CCR4 (P<0.0001 and P<0.02, respectively). In comparison with MSC-treated group, mice treated with IFN-γ-licensed MSCs exhibited lower CXCL10 and CCR6 expression (P<0.002 and P<0.01, respectively), whereas greater expression of CCL22 and CCR4 (P<0.0001 and P<0.01, respectively).

CONCLUSION

Priming the MSC with IFN-γ can be an efficient approach to enhance the immunomodulatory potential of MSCs.

Modulation of Mesenchymal Stem Cells-Mediated Adaptive Immune Effectors' Repertoire in the Recovery of Systemic Lupus Erythematosus

The breakdown of self-tolerance of the immune response can lead to autoimmune conditions in which chronic inflammation induces tissue damage. Systemic lupus erythematosus (SLE) is a debilitating multisystemic autoimmune disorder with a high prevalence in women of childbearing age; however, SLE incidence, prevalence, and severity are strongly influenced by ethnicity. Although the mystery of autoimmune diseases remains unsolved, disturbance in the proportion and function of B cell subsets has a major role in SLE's pathogenesis. Additionally, colocalizing hyperactive T helper cell subgroups within inflammatory niches are indispensable. Despite significant advances in standard treatments, nonspecific immunosuppression, the risk of serious infections, and resistance to conventional therapies in some cases have raised the urgent need for new treatment strategies. Without the need to suppress the immune system, mesenchymal stem cells (MSCs), as ''smart" immune modulators, are able to control cellular and humoral auto-aggression responses by participating in precursor cell development. In lupus, due to autologous MSCs disorder, the ability of allogenic engrafted MSCs in tissue regeneration and resetting immune homeostasis with the provision of a new immunocyte repertoire has been considered simultaneously. In Brief The bone marrow mesenchymal stem cells (BM-MSCs) lineage plays a critical role in maintaining the hematopoietic stem-cell microstructure and modulating immunocytes. The impairment of BM-MSCs and their niche partially contribute to the pathogenesis of SLE-like diseases. Allogenic MSC transplantation can reconstruct BM microstructure, possibly contributing to the recovery of immunocyte phenotype restoration of immune homeostasis. In terms of future prospects of MSCs, artificially gained by ex vivo isolation and culture adaptation, the wide variety of potential mediators and mechanisms might be linked to the promotion of the immunomodulatory function of MSCs.

Mesenchymal stromal cell therapy for patients with rheumatoid arthritis

Management of relapses and refractory rheumatoid arthritis (RA) patients is complex and difficult. Even after the administration of new biological disease-modifying anti-rheumatic drugs (DMARDs), only a few patients achieve the complete remission phase. DMARDs help only in modifying the disease activity, which sooner or later fails. They do not manage the disease at the patho-etiological level. There are some serious side effects as well as drug interaction with DMARDs. There are few subsets of RA patients who do not respond to DMARDs, reasons unknown. Mesenchymal stem cells (MSCs) provide a promising alternative, especially in such cases. This review elaborates on the studies pertaining to the application of MSCs in rheumatoid arthritis over the last two decades. A total of 14 studies (one review article) including 447 patients were included in the study. Most of the studies administered MSCs in refractory RA patients through the intravenous route with varied dosages and frequency of administration. MSCs help in RA treatment via various mechanisms including paracrine effects. All the studies depicted a better clinical outcome with minimal adverse events. The functional scores including the VAS scores improved significantly in all studies irrespective of dosage and source of MSCs. The majority of the studies depicted no complications. Although the use of MSCs in RA is still in the early stages requiring further refinement in the source of MSCs, dosage, and frequency. The role of MSCs in the management of RA has a promising prospect. MSCs target the RA at the molecular level and has the potential to manage refractory RA cases not responding to conventional treatment. Multicentric, large sample populations, and long-term studies are required to ascertain efficacy and safety.

Assessment of therapeutic role of mesenchymal stromal cells in mouse models of graft-versus-host disease using cryo-imaging

Insights regarding the biodistribution and homing of mesenchymal stromal cells (MSCs), as well as their interaction with alloreactive T-cells are critical for understanding how MSCs can regulate graft-versus-host disease (GVHD) following allogeneic (allo) bone marrow transplantation (BMT). We developed novel assays based on 3D, microscopic, cryo-imaging of whole-mouse-sized volumes to assess the therapeutic potential of human MSCs using an established mouse GVHD model. Following infusion, we quantitatively tracked fluorescently labeled, donor-derived, T-cells and third party MSCs in BMT recipients using multispectral cryo-imaging. Specific MSC homing sites were identified in the marginal zones in the spleen and the lymph nodes, where we believe MSC immunomodulation takes place. The number of MSCs found in spleen of the allo BMT recipients was about 200% more than that observed in the syngeneic group. To more carefully define the effects MSCs had on T cell activation and expansion, we developed novel T-cell proliferation assays including secondary lymphoid organ (SLO) enlargement and Carboxyfluoescein succinimidyl ester (CFSE) dilution. As anticipated, significant SLO volume enlargement and CFSE dilution was observed in allo but not syn BMT recipients due to rapid proliferation and expansion of labeled T-cells. MSC treatment markedly attenuated CFSE dilution and volume enlargement of SLO. These assays confirm evidence of potent, in vivo, immunomodulatory properties of MSC following allo BMT. Our innovative platform includes novel methods for tracking cells of interest as well as assessing therapeutic function of MSCs during GVHD induction. Our results support the use of MSCs treatment or prevention of GVHD and illuminate the wider adoption of MSCs as a standard medicinal cell therapy.

Transfer of mesenchymal stem cell mitochondria to CD4+ T cells contributes to repress Th1 differentiation by downregulating T-bet expression

BACKGROUND

Mesenchymal stem/stromal cells (MSCs) are multipotent cells with strong tissue repair and immunomodulatory properties. Due to their ability to repress pathogenic immune responses, and in particular T cell responses, they show therapeutic potential for the treatment of autoimmune diseases, organ rejection and graft versus host disease. MSCs have the remarkable ability to export their own mitochondria to neighboring cells in response to injury and inflammation. However, whether mitochondrial transfer occurs and has any role in the repression of CD4⁺ Th1 responses is unknown.

METHODS AND RESULTS

In this report we have utilized CD4⁺ T cells from HNT TCR transgenic mice that develop Th1-like responses upon antigenic stimulation in vitro and in vivo. Allogeneic bone marrow-derived MSCs reduced the diabetogenic potential of HNT CD4⁺ T cells in vivo in a transgenic mouse model of disease. In co-culture experiments, we have shown that MSCs were able to reduce HNT CD4⁺ T cell expansion, expression of key effector markers and production of the effector cytokine IFNγ after activation. This was associated with the ability of CD4⁺ T cells to acquire mitochondria from MSCs as evidenced by FACS and confocal microscopy. Remarkably, transfer of isolated MSC mitochondria to CD4⁺ T cells resulted in decreased T cell proliferation and IFNγ production. These effects were additive with those of prostaglandin E2 secreted by MSCs. Finally, we demonstrated that both co-culture with MSCs and transfer of isolated MSC mitochondria prevent the upregulation of T-bet, the master Th1 transcription factor, on activated CD4⁺ T cells.

CONCLUSION

The present study demonstrates that transfer of MSC mitochondria to activated CD4⁺ T cells results in the suppression of Th1 responses in part by downregulating T-bet expression. Furthermore, our studies suggest that MSC mitochondrial transfer might represent a general mechanism of MSC-dependent immunosuppression.

iPSC-Derived MSCs Are a Distinct Entity of MSCs with Higher Therapeutic Potential than Their Donor-Matched Parental MSCs

Mesenchymal stromal cells derived from induced pluripotent stem cells (iMSCs) have been proposed as alternative sources of primary MSCs with various advantages for cell therapeutic trials. However, precise evaluation of the differences between iMSCs and primary MSCs is lacking due to individual variations in the donor cells, which obscure direct comparisons between the two. In this study, we generated donor-matched iMSCs from individual bone marrow-derived MSCs and directly compared their cell-autonomous and paracrine therapeutic effects. We found that the transition from primary MSCs to iMSCs is accompanied by a functional shift towards higher proliferative activity, with variations in differentiation potential in a donor cell-dependent manner. The transition from MSCs to iMSCs was associated with common changes in transcriptomic and proteomic profiles beyond the variations of their individual donors, revealing expression patterns unique for the iMSCs. These iMSC-specific patterns were characterized by a shift in cell fate towards a pericyte-like state and enhanced secretion of paracrine cytokine/growth factors. Accordingly, iMSCs exhibited higher support for the self-renewing expansion of primitive hematopoietic progenitors and more potent immune suppression of allogenic immune responses than MSCs. Our study suggests that iMSCs represent a separate entity of MSCs with unique therapeutic potential distinct from their parental MSCs, but points to the need for iMSC characterization in the individual basis.

Mesenchymal "stem" cells, or facilitators for the development of regenerative macrophages? Pericytes at the interface of wound healing

Cultured mesenchymal stromal cells are among the most used cells in clinical trials. Currently, their potential benefits include provision of mature cell types through differentiation, and secretion of various types of paracrine signaling molecules. Even though research on these cells has spanned some decades now, surprisingly, their therapeutic potential has not been fully translated into clinical practice yet, which calls for further understanding of their intrinsic nature and modes of action. In this review, after discussing pieces of evidence that suggest that some perivascular cells may exhibit mesenchymal stem cell characteristics in vivo, we examine the possibility that subpopulations of perivascular and/or adventitial cells activated after tissue injury behave as MSCs and contribute to the resolution of tissue injury by providing cues for the development of regenerative macrophages at injured sites. Under this perspective, an important contribution of cultured MSCs (or their acellular products, such as extracellular vesicles) used in cell therapies would be to instigate the development of M2-like macrophages that support the tissue repair process.

Human Mesenchymal Stem Cell Secretome Driven T Cell Immunomodulation Is IL-10 Dependent

The Human Mesenchymal Stem Cell (hMSC) secretome has pleiotropic effects underpinning its therapeutic potential. hMSC serum-free conditioned media (SFCM) contains a variety of cytokines, with previous studies linking a changed secretome composition to physoxia. The Jurkat T cell model allowed the efficacy of SFCM vs. serum-free media (SFM) in the suppression of immunological aspects, including proliferation and polarisation, to be explored. Cell growth in SFM was higher [(21% O2 = 5.3 × 105 ± 1.8 × 104 cells/mL) and (2% O2 = 5.1 × 105 ± 3.0 × 104 cells/mL)], compared to SFCM [(21% O2 = 2.4 × 105 ± 2.5 × 104 cells/mL) and (2% O2 = 2.2 × 105 ± 5.8 × 103 cells/mL)]. SFM supported IL-2 release following activation [(21% O2 = 5305 ± 211 pg/mL) and (2% O2 = 5347 ± 327 pg/mL)] whereas SFCM suppressed IL-2 secretion [(21% O2 = 2461 ± 178 pg/mL) and (2% O2 = 1625 ± 159 pg/mL)]. Anti-inflammatory cytokines, namely IL-4, IL-10, and IL-13, which we previously confirmed as components of hMSC SFCM, were tested. IL-10 neutralisation in SFCM restored proliferation in both oxygen environments (SFM/SFCM+antiIL-10 ~1-fold increase). Conversely, IL-4/IL-13 neutralisation showed no proliferation restoration [(SFM/SFM+antiIL-4 ~2-fold decrease), and (SFM/SFCM+antiIL-13 ~2-fold decrease)]. Present findings indicate IL-10 played an immunosuppressive role by reducing IL-2 secretion. Identification of immunosuppressive components of the hMSC secretome and a mechanistic understanding of their action allow for the advancement and refinement of potential future cell-free therapies.

Functional in vitro models of the inhibitory effect of adipose tissue-derived stromal cells on lymphocyte proliferation: Improved sensitivity and quantification through flow cytometric analysis

As the interest in cell-based therapies continue to increase, so does the need for assays detailing potency and providing platforms for identifying mechanisms of action. For most clinical implications of mesenchymal stromal cells, the immunomodulatory effect is crucial. While the suppressive potential on lymphocyte proliferation is well-described in literature, reproducible and standardized assays to document and quantify it varies from research group to research group and between methodologies. The aim of the present study was to utilize flowcytometry to quantify proliferation and identify measurements to increase the assay sensitivity to treatment with adipose tissue-derived stromal cells (ASC). Lymphocyte proliferation was induced by the unspecific mitogen phytohemagglutinin or by alloreactivity towards an irradiated donor in a mixed lymphocyte reaction. Addition of ASC did not change the composition of T cells, B cells, NK cells, NKT cell types considerably; likewise, no increases in proliferation were observed upon inclusion of ASC, demonstrating that ASC does not evoke an additive response. On the contrary, the suppressive effect of ASC was documented. By applying different gating strategies and curve fitting, the sensitivity was increased, and dose-response relationships established. Flow cytometric evaluation allows for more detailed identification of the lymphocytes affected by ASC and constitute a significant asset in future unraveling of modes and mechanisms of action, as well as quantification of potency.

The interaction of Helicobacter pylori with cancer immunomodulatory stromal cells: New insight into gastric cancer pathogenesis

Gastric cancer is the fourth most common cause of cancer-linked deaths in the world. Gastric tumor cells have biological characteristics such as rapid proliferation, high invasiveness, and drug resistance, which result in recurrence and poor survival. Helicobacter pylori (H. pylori) has been proposed as a first-class carcinogen for gastric cancer according to the 1994 world health organization (WHO) classification. One of the important mechanisms by which H. pylori affects the gastric environment and promotes carcinogenesis is triggering inflammation. H. pylori induces an inflammatory response and a plethora of different signal transduction processes, leading to gastric mucosal disturbance, chronic gastritis, and a multi-step complex pathway that initiates carcinogenesis. It seems undeniable that the interaction between various cell types, including immune cells, gastric epithelium, glands, and stem cells, is vital for the progression and development of carcinogenesis concerning H. pylori. The interactions of H. pylori with surrounding cells play a key role in cancer progression. In this review, we discuss the interplay between H. pylori and tumor-supportive cells, including mesenchymal stem cells (MSCs), cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and myeloid derived-suppressor cells (MDSCs) in gastric cancer. It is hoped that clarifying the specific mechanisms for 'cross-talk' between H. pylori and these cells will provide promising strategies for developing new treatments.

Perinatal derivatives: How to best validate their immunomodulatory functions

Perinatal tissues, mainly the placenta and umbilical cord, contain a variety of different somatic stem and progenitor cell types, including those of the hematopoietic system, multipotent mesenchymal stromal cells (MSCs), epithelial cells and amnion epithelial cells. Several of these perinatal derivatives (PnDs), as well as their secreted products, have been reported to exert immunomodulatory therapeutic and regenerative functions in a variety of pre-clinical disease models. Following experience with MSCs and their extracellular vesicle (EV) products, successful clinical translation of PnDs will require robust functional assays that are predictive for the relevant therapeutic potency. Using the examples of T cell and monocyte/macrophage assays, we here discuss several assay relevant parameters for assessing the immunomodulatory activities of PnDs. Furthermore, we highlight the need to correlate the in vitro assay results with preclinical or clinical outcomes in order to ensure valid predictions about the in vivo potency of therapeutic PnD cells/products in individual disease settings.

Safety of autologous freshly expanded mesenchymal stromal cells for the treatment of graft-versus-host disease

Despite the curative potential of hematopoietic cell transplantation (HCT) for hematologic malignancies, graft-versus-host disease (GVHD) remains a substantial cause of morbidity and mortality, particularly if treatment is refractory. Treatment with additional immunosuppression including steroids often leads to opportunistic infections and organ dysfunction. Novel therapies are greatly needed, specifically ones that lead to responses in treatment-refractory patients and are better tolerated. Mesenchymal stromal cells (MSCs) are non-hematopoietic tolerogenic cells present in normal bone marrow (BM), which can be expanded ex vivo to therapeutic doses. Their safety and efficacy have been assessed in inflammatory disorders including GVHD, but heterogeneity in clinical responses has led some to examine MSC manufacturing and administration procedures, which may impact in vivo efficacy. We hypothesized that autologous, early-passage, and culture-recovered (after freeze and thaw) MSCs would be safe and may have superior efficacy. In this phase I single-center trial, we assessed MSC safety and early efficacy of an escalating number of doses (2 × 10⁶/kg doses; dose level 1, single dose; dose level 2, two weekly doses; dose level 3, four weekly doses) in patients aged ≥12 years with treatment-refractory acute or chronic GVHD. Eleven enrolled patients received some or all planned MSC infusions, with a median age at enrollment of 37 years. The most common primary HCT indication was leukemia, and the median time from HCT to first MSC infusion was 2.6 years. MSC infusion was well tolerated, with all severe adverse events expected and determined to be unlikely or definitely not related to the study. Thus, no dose-limiting toxicities occurred in the three dose levels. Three of four patients with acute GVHD (or overlap with acute features) had responses seen at any timepoint, ranging from partial to complete. In those with a chronic GVHD indication (n = 7), an overall response at 3 months was partial in five, stable in one, and progressive in one. No appreciable differences were seen between dose levels in peripheral blood lymphocyte subsets. In conclusion, autologous and culture-recovered MSCs were safe in the setting of refractory GVHD following HCT for hematologic malignancy, and clinical responses were most notable in patients with acute GVHD.

Fused Cells between Human-Adipose-Derived Mesenchymal Stem Cells and Monocytes Keep Stemness Properties and Acquire High Mobility

Human-adipose-derived mesenchymal stem cells (hADMSCs) are multipotent stem cells which have become of great interest in stem-cell therapy due to their less invasive isolation. However, they have limited migration and short lifespans. Therefore, understanding the mechanisms by which these cells could migrate is of critical importance for regenerative medicine. Methods: Looking for novel alternatives, herein, hADMSCs were isolated from adipose tissue and co-cultured with human monocytes ex vivo. Results: A new fused hybrid entity, a foam hybrid cell (FHC), which was CD90⁺CD14⁺, resulted from this co-culture and was observed to have enhanced motility, proliferation, immunomodulation properties, and maintained stemness features. Conclusions: Our study demonstrates the generation of a new hybrid cellular population that could provide migration advantages to MSCs, while at the same time maintaining stemness properties.

Perivascular Mesenchymal Stem/Stromal Cells, an Immune Privileged Niche for Viruses?

Mesenchymal stem cells (MSCs) play a critical role in response to stress such as infection. They initiate the removal of cell debris, exert major immunoregulatory activities, control pathogens, and lead to a remodeling/scarring phase. Thus, host-derived ‘danger’ factors released from damaged/infected cells (called alarmins, e.g., HMGB1, ATP, DNA) as well as pathogen-associated molecular patterns (LPS, single strand RNA) can activate MSCs located in the parenchyma and around vessels to upregulate the expression of growth factors and chemoattractant molecules that influence immune cell recruitment and stem cell mobilization. MSC, in an ultimate contribution to tissue repair, may also directly trans- or de-differentiate into specific cellular phenotypes such as osteoblasts, chondrocytes, lipofibroblasts, myofibroblasts, Schwann cells, and they may somehow recapitulate their neural crest embryonic origin. Failure to terminate such repair processes induces pathological scarring, termed fibrosis, or vascular calcification. Interestingly, many viruses and particularly those associated to chronic infection and inflammation may hijack and polarize MSC’s immune regulatory activities. Several reports argue that MSC may constitute immune privileged sanctuaries for viruses and contributing to long-lasting effects posing infectious challenges, such as viruses rebounding in immunocompromised patients or following regenerative medicine therapies using MSC. We will herein review the capacity of several viruses not only to infect but also to polarize directly or indirectly the functions of MSC (immunoregulation, differentiation potential, and tissue repair) in clinical settings.

The Role of Hypoxia in Improving the Therapeutic Potential of Mesenchymal Stromal Cells. A Comparative Study From Healthy Lung and Congenital Pulmonary Airway Malformations in Infants

Mesenchymal stromal cells (MSCs) play an important role in the field of regenerative medicine thanks to their immunomodulatory properties and their ability to secrete paracrine factors. The use of MSCs has also been tested in children with congenital lung diseases inducing fibrosis and a decrease in lung function. Congenital malformations of the pulmonary airways (CPAM) are the most frequently encountered lung lesion that results from defects in early development of airways. Despite the beneficial properties of MSCs, interventions aimed at improving the outcome of cell therapy are needed. Hypoxia may be an approach aimed to ameliorate the therapeutic potential of MSCs. In this regard, we evaluated the transcriptomic profile of MSCs collected from pediatric patients with CPAM, analyzing similarities and differences between healthy tissue (MSCs-lung) and cystic tissue (MSCs-CPAM) both in normoxia and in cells preconditioned with hypoxia (0.2%) for 24 h. Study results showed that hypoxia induces cell cycle activation, increasing in such a way the cell proliferation ability, and enhancing cell anaerobic metabolism in both MSCs-lung and MSCs-CPAM-lung. Additionally, hypoxia downregulated several pro-apoptotic genes preserving MSCs from apoptosis and, at the same time, improving their viability in both comparisons. Finally, data obtained indicates that hypoxia leads to a greater expression of genes involved in the regulation of the cytoskeleton in MSCs-lung than MSCs-CPAM.

Mesenchymal Stem Cell Application and Its Therapeutic Mechanisms in Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH), a common lethal subtype of stroke accounting for nearly 10–15% of the total stroke disease and affecting two million people worldwide, has a high mortality and disability rate and, thus, a major socioeconomic burden. However, there is no effective treatment available currently. The role of mesenchymal stem cells (MSCs) in regenerative medicine is well known owing to the simplicity of acquisition from various sources, low immunogenicity, adaptation to the autogenic and allogeneic systems, immunomodulation, self-recovery by secreting extracellular vesicles (EVs), regenerative repair, and antioxidative stress. MSC therapy provides an increasingly attractive therapeutic approach for ICH. Recently, the functions of MSCs such as neuroprotection, anti-inflammation, and improvement in synaptic plasticity have been widely researched in human and rodent models of ICH. MSC transplantation has been proven to improve ICH-induced injury, including the damage of nerve cells and oligodendrocytes, the activation of microglia and astrocytes, and the destruction of blood vessels. The improvement and recovery of neurological functions in rodent ICH models were demonstrated via the mechanisms such as neurogenesis, angiogenesis, anti-inflammation, anti-apoptosis, and synaptic plasticity. Here, we discuss the pathological mechanisms following ICH and the therapeutic mechanisms of MSC-based therapy to unravel new cues for future therapeutic strategies. Furthermore, some potential strategies for enhancing the therapeutic function of MSC transplantation have also been suggested.

Interferon-γ enhances the immunosuppressive ability of canine bone marrow-derived mesenchymal stem cells by activating the TLR3-dependent IDO/kynurenine pathway

BACKGROUND

The immunomodulatory function of mesenchymal stem cells (MSCs) has been considered to be vital for MSC-based therapies. Many works have been devoted to excavate effective strategies for enhancing the immunomodulation effect of MSCs. Nonetheless, canine MSC-mediated immunomodulation is still poorly understood.

METHODS AND RESULTS

The inflammatory microenvironment was simulated through the employment of interferon-γ (IFN-γ) in a culture system. Compared with unstimulated cBMSCs, IFN-γ stimulation increased the mRNA levels of Toll-like receptor 3 (TLR3) and indoleamine 2, 3-dioxygenase 1 (IDO-1), and simultaneously enhanced the secretion of immunosuppressive molecules, including interleukin (IL)-10, hepatocyte growth factor (HGF), and kynurenine in cBMSCs. IFN-γ stimulation significantly enhanced the ability of cBMSCs and their supernatant to suppress the proliferation of murine spleen lymphocytes. Lymphocyte subtyping evaluation revealed that cBMSCs and their supernatant diminished the percentage of CD3⁺CD4⁺ and CD3⁺CD8⁺ lymphocytes compared with the control group, with a decreasing CD4⁺/CD8⁺ ratio. Notably, exposure to IFN-γ decreased the CD4⁺/CD8⁺ ratio more effectively than unstimulated cells or supernatant. Additionally, IFN-γ-stimulation increased the mRNA levels of the Th1 cytokines TNF-α, and remarkably decreased the mRNA level of the Th2 cytokine IL-4 and IL-10.

CONCLUSION

Our findings substantiate that IFN-γ stimulation can enhance the immunomodulatory properties of cBMSCs by promoting TLR3-dependent activation of the IDO/kynurenine pathway, increasing the secretion of immunoregulatory molecules and strengthening interactions with T lymphocytes, which may provide a meaningful strategy for the clinical application of cBMSCs in immune-related diseases.

Structural and Temporal Dynamics of Mesenchymal Stem Cells in Liver Diseases From 2001 to 2021: A Bibliometric Analysis

Background

Mesenchymal stem cells (MSCs) have important research value and broad application prospects in liver diseases. This study aims to comprehensively review the cooperation and influence of countries, institutions, authors, and journals in the field of MSCs in liver diseases from the perspective of bibliometrics, evaluate the clustering evolution of knowledge structure, and discover hot trends and emerging topics.

Methods

The articles and reviews related to MSCs in liver diseases were retrieved from the Web of Science Core Collection using Topic Search. A bibliometric study was performed using CiteSpace and VOSviewer.

Results

A total of 3404 articles and reviews were included over the period 2001-2021. The number of articles regarding MSCs in liver diseases showed an increasing trend. These publications mainly come from 3251 institutions in 113 countries led by China and the USA. Li L published the most papers among the publications, while Pittenger MF had the most co-citations. Analysis of the most productive journals shows that most are specialized in medical research, experimental medicine and cell biology, and cell & tissue engineering. The macroscopical sketch and micro-representation of the whole knowledge field are realized through co-citation analysis. Liver scaffold, MSC therapy, extracellular vesicle, and others are current and developing areas of the study. The keywords "machine perfusion", "liver transplantation", and "microRNAs" also may be the focus of new trends and future research.

Conclusions

In this study, bibliometrics and visual methods were used to review the research of MSCs in liver diseases comprehensively. This paper will help scholars better understand the dynamic evolution of the application of MSCs in liver diseases and point out the direction for future research.

Influence of exposure to microbial ligands, immunosuppressive drugs and chronic kidney disease on endogenous immunomodulatory gene expression in feline adipose-derived mesenchymal stem cells

OBJECTIVES

Feline autologous mesenchymal stem cells (MSCs) show promise for immunomodulatory activity, but the functional impact of chronic kidney disease (CKD), concurrent immunosuppressive drug administration or infection is unknown. The study objectives compare endogenous cytokine gene expression (interleukin [IL]-6, IL-10, IL-12p40, IL-18 and transforming growth factor beta [TGF-β]) in adipose-derived MSCs (aMSCs) from cats with and without CKD, following in vitro exposure to microbial ligands and treatment with common immunosuppressive drugs.

METHODS

Previously obtained aMSCs, phenotype CD44+, CD90+, CD105+ and MHCII-, from cats with (n = 6) and without (n = 6) CKD were compared via real-time PCR (RT-PCR) for immunomodulatory gene expression. aMSCs were exposed in vitro to lipopolysaccharide (LPS), peptidoglycan or polyinosinic:polycytidylic acid (Poly I:C), simulating bacterial or viral exposure, respectively. aMSCs were also exposed to ciclosporin, dexamethasone or methotrexate. Gene expression was measured using RT-PCR, and Cq was utilized after each run to calculate the delta cycle threshold.

RESULTS

aMSCs isolated from healthy and CKD cats showed no significant differences in gene expression in the five measured cytokines. No significant changes in measured gene expression after drug treatment or microbial ligand stimulation were observed between normal or CKD affected cats. Proinflammatory genes (IL-6, IL-12p40 and IL-18) showed altered expression in aMSCs from both groups when compared with the same cells in standard culture after exposure to methotrexate. Poly I:C altered IL-6 and TGF-β gene expression in aMSCs from both healthy and CKD cats when compared with the same cells in standard culture.

CONCLUSIONS AND RELEVANCE

The five genes tested showed no statistical differences between aMSCs from healthy or CKD cats. There was altered cytokine gene expression between the control and treatment groups of both healthy and CKD cats suggesting feline aMSCs have altered function with immunosuppressive treatment or microbial ligand exposure. Although the current clinical relevance of this pilot study comparing brief exposure to select agents in vitro in aMSCs from a small number of cats is unknown, the study highlights a need for continued investigation into the effects of disease and concurrent therapies on use of cell-based therapies in feline patients.

The Therapeutic Potential of Secreted Factors from Dental Pulp Stem Cells for Various Diseases

An alternative source of mesenchymal stem cells has recently been discovered: dental pulp stem cells (DPSCs), including deciduous teeth, which can thus comprise potential tools for regenerative medicine. DPSCs derive from the neural crest and are normally implicated in dentin homeostasis. The clinical application of mesenchymal stem cells (MSCs) involving DPSCs contains various limitations, such as high cost, low safety, and cell handling issues, as well as invasive sample collection procedures. Although MSCs implantation offers favorable outcomes on specific diseases, implanted MSCs cannot survive for a long period. It is thus considered that their mediated mechanism of action involves paracrine effects. It has been recently reported that secreted molecules in DPSCs-conditioned media (DPSC-CM) contain various trophic factors and cytokines and that DPSC-CM are effective in models of various diseases. In the current study, we focus on the characteristics of DPSC-CM and their therapeutic potential against various disorders.

Neuroinflammation, Stem Cells, and Stroke

Stroke remains a significant unmet clinical need with few treatment options that have a very narrow therapeutic window, thereby causing massive mortality and morbidity in the United States and around the world. Accordingly, finding safe and effective novel treatments with a wider therapeutic window stands as an urgent need in stroke. The progressive inflammation that occurs centrally and peripherally after stroke serves as a unique therapeutic target to retard and even halt the secondary cell death. Stem cell therapy represents a potent approach that can diminish inflammation in both the stroke brain and periphery (eg, spleen), advancing a paradigm shift from a traditionally brain-focused therapy to treating stroke as a neurological disorder with a significant peripheral pathology. The purpose of this review article is to highlight the inflammation-mediated secondary cell death that plagues both brain and spleen in stroke and to evaluate the therapeutic potential of stem cell therapy in dampening these inflammatory responses.

Menstrual blood-derived mesenchymal stromal cells efficiently ameliorate experimental autoimmune encephalomyelitis by inhibiting T cell activation in mice

Background

Immunosuppressive properties grant mesenchymal stromal cells (MSCs) promising potential for treating autoimmune diseases. As autologous MSCs suffer from limited availability, the readily available allogeneic MSCs isolated from menstrual blood (MB-MSCs) donated by young, healthy individuals offer great potential. Here, we evaluate the therapeutic potential of MB-MSCs as ready-to-use allo-MSCs in multiple sclerosis, an autoimmune disease developed by the activation of myelin sheath-reactive Th1 and Th17 cells, by application in its animal model experimental autoimmune encephalomyelitis (EAE).

Methods

We assessed the therapeutic effect of MB-MSCs transplanted via either intravenous (i.v.) or intraperitoneal (i.p.) route in EAE in comparison with umbilical cord-derived MSCs (UC-MSCs). We used histology to assess myelin sheath integrity and infiltrated immune cells in CNS and flow cytometry to evaluate EAE-associated inflammatory T cells and antigen-presenting cells in lymphoid organs.

Results

We observed disease-ameliorating effects of MB-MSCs when transplanted at various stages of EAE (day − 1, 6, 10, and 19), via either i.v. or i.p. route, with a potency comparable to UC-MSCs. We observed reduced Th1 and Th17 cell responses in mice that had received MB-MSCs via either i.v. or i.p. injection. The repressed Th1 and Th17 cell responses were associated with a reduced frequency of plasmacytoid dendritic cells (pDCs) and a suppressed co-stimulatory capacity of pDCs, cDCs, and B cells.

Conclusions

Our data demonstrate that the readily available MB-MSCs significantly reduced the disease severity of EAE upon transplantation. Thus, they have the potential to be developed as ready-to-use allo-MSCs in MS-related inflammation.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02838-8.

A Brief Overview of Global Trends in MSC-Based Cell Therapy

Human mesenchymal stem cells (MSCs), also known as mesenchymal stromal cells or medicinal signaling cells, are important adult stem cells for regenerative medicine, largely due to their regenerative characteristics such as self-renewal, secretion of trophic factors, and the capability of inducing mesenchymal cell lineages. MSCs also possess homing and trophic properties modulating immune system, influencing microenvironment around damaged tissues and enhancing tissue repair, thus offering a broad perspective in cell-based therapies. Therefore, it is not surprising that MSCs have been the broadly used adult stem cells in clinical trials. To gain better insights into the current applications of MSCs in clinical applications, we perform a comprehensive review of reported data of MSCs clinical trials conducted globally. We summarize the biological effects and mechanisms of action of MSCs, elucidating recent clinical trials phases and findings, highlighting therapeutic effects of MSCs in several representative diseases, including neurological, musculoskeletal diseases and most recent Coronavirus infectious disease. Finally, we also highlight the challenges faced by many clinical trials and propose potential solutions to streamline the use of MSCs in routine clinical applications and regenerative medicine.

Human Mesenchymal Stem/Stromal Cells in Immune Regulation and Therapy

Studies of mesenchymal stem (or stromal) cells (MSCs) have moved from bedside to bench and back again. The stromal cells or fibroblasts are found in all tissues and participate in building the extracellular matrix (ECM). Bone marrow (BM)-derived MSCs have been studied for more than 50 years and have multiple roles. They function as stem cells and give rise to bone, cartilage, and fat in the BM (these are stem cells); support hematopoiesis (pericytes); and participate in sensing environmental changes and balancing pro- and anti-inflammatory conditions. In disease states, they migrate to sites of injury and release cytokines, hormones, nucleic acids depending on the microenvironment they find. Clinicians have begun to exploit these properties of BM, adipose tissue, and umbilical cord MSCs because they are easy to harvest and expand in culture. In this review, I describe the uses to which MSCs have been put, list ongoing clinical trials by organ system, and outline how MSCs are thought to regulate the innate and adaptive immune systems. I will discuss some of the reasons why clinical applications are still lacking. Much more work will have to be done to find the sources, doses, and culture conditions needed to exploit MSCs optimally and learn their healing potential. They are worth the effort.

Alloreactivity of Allogeneic Mesenchymal Stem/Stromal Cells and Other Cellular Therapies: A Concise Review

Cellular therapies, deemed live medicine, have brought a wave of new generation biological therapies to treat previously untreatable diseases such as cancers and degenerative diseases like osteoarthritis. These cellular therapies have gained significant recognition in clinical research. The area has been further strengthened with the approval of Chimeric Antigen Receptor added on T cells (CAR-T) therapies by the regulatory authorities USA's Food and Drugs Administration (FDA), European Medical Agency (EMA), the Australian Therapeutic Goods Administration (TGA), and in many countries in 2017 to treat hematological cancers. Another milestone was achieved when allogeneic Mesenchymal Stem Cell- (MSC-) based therapy was approved by the EMA to treat Chrohn's disease in 2018. Allogeneic donor-derived MSC therapies in particular hold great promise and real hope because of their ‘off-the shelf' availability and accessibility for patients in need of urgent treatment. So far, thousands of clinical trials have explored the safety and efficacy of both autologous and allogeneic cell therapies, deeming them safe, however with varying degrees of efficacy. In the current pandemic, clinical trials have begun in many parts of the world to treat severe cases of COVID with MSCs. However, the risk of tissue rejection and the development of undesirable effects due to alloreactivity of allogeneic cells are currently not adequately addressed. Therefore, this warrants careful investigation and detailed reporting of such events by clinical researchers. This review aims at discussing the current landscape of approved allogeneic MSCs along with a few other cellular therapies. We explore any possible reactivity reported to inform the readers of any safety concern and on the efficacy of such therapies.