Immunomodulatory Properties Of Mesenchymal Stem Cells Research Articles

An in vitro pilot study investigating placenta-derived mesenchymal stem cell coating on polypropylene mesh materials.

Polypropylene meshes (PM) used in pelvic organ prolapse surgery are being withdrawn from the market. Although concerns about the usage of PMs in stress incontinence surgery have been raised, it is still one of the best methods of curing stress urinary incontinence. With advancements in stem cell-based therapies, especially mesenchymal stem cells (MSCs), it is believed that coating the synthetic meshes with MSCs may minimize excessive tissue reactions ultimately leading to clinical problems such as pain, erosion or extrusion of the implanted material. In our study we tried to show the possibility of coating the PM with placenta-derived MSCs. Mesenchymal stem cells obtained from six placentas were isolated, cultured, and identified. MSCs were then soaked in either fibronectin or collagen prior to co-culturing with strips of PMs. One group is used as a control, and hence was not pretreated before co-culturing. Specimens were fixed and stained with both Gram and hematoxylin and eosin and marked with Vybran Dil and DAPI. All preparations were examined under a light microscope. The IMAGEJ program was utilized to determine the surface area of meshes coated with MSCs. We clearly showed that PMs can be coated successfully with placenta-derived MSCs. The percentage of the coated area is significantly increased when meshes were pretreated with fibronectin or collagen (p<0.0001). Placenta-derived MSCs can successfully coat PMs. The immunomodulatory properties of MSCs, which may be of great advantage in preventing the side effects of meshes, should be tested by in vivo and hopefully human studies before clinical applications.

Current status and prospects of basic research and clinical application of mesenchymal stem cells in acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is a common and clinically devastating disease that causes respiratory failure. Morbidity and mortality of patients in intensive care units are stubbornly high, and various complications severely affect the quality of life of survivors. The pathophysiology of ARDS includes increased alveolar-capillary membrane permeability, an influx of protein-rich pulmonary edema fluid, and surfactant dysfunction leading to severe hypoxemia. At present, the main treatment for ARDS is mechanical treatment combined with diuretics to reduce pulmonary edema, which primarily improves symptoms, but the prognosis of patients with ARDS is still very poor. Mesenchymal stem cells (MSCs) are stromal cells that possess the capacity to self-renew and also exhibit multilineage differentiation. MSCs can be isolated from a variety of tissues, such as the umbilical cord, endometrial polyps, menstrual blood, bone marrow, and adipose tissues. Studies have confirmed the critical healing and immunomodulatory properties of MSCs in the treatment of a variety of diseases. Recently, the potential of stem cells in treating ARDS has been explored via basic research and clinical trials. The efficacy of MSCs has been shown in a variety of in vivo models of ARDS, reducing bacterial pneumonia and ischemia-reperfusion injury while promoting the repair of ventilator-induced lung injury. This article reviews the current basic research findings and clinical applications of MSCs in the treatment of ARDS in order to emphasize the clinical prospects of MSCs.

Intra-Articular Mesenchymal Stem Cell Injection for Knee Osteoarthritis: Mechanisms and Clinical Evidence

Knee osteoarthritis presents higher incidences than other joints, with increased prevalence during aging. It is a progressive process and may eventually lead to disability. Mesenchymal stem cells (MSCs) are expected to repair damaged issues due to trilineage potential, trophic effects, and immunomodulatory properties of MSCs. Intra-articular MSC injection was reported to treat knee osteoarthritis in many studies. This review focuses on several issues of intra-articular MSC injection for knee osteoarthritis, including doses of MSCs applied for injection and the possibility of cartilage regeneration following MSC injection. Intra-articular MSC injection induced hyaline-like cartilage regeneration, which could be seen by arthroscopy in several studies. Additionally, anatomical, biomechanical, and biochemical changes during aging and other causes participate in the development of knee osteoarthritis. Conversely, appropriate intervention based on these anatomical, biomechanical, biochemical, and functional properties and their interactions may postpone the progress of knee OA and facilitate cartilage repair induced by MSC injection. Hence, post-injection rehabilitation programs and related mechanisms are discussed.

The Multifunction Role of Tumour-Associated Mesenchymal Stem Cells and their Interaction with Immune Cells

Mesenchymal Stem Cells (MSCs) are multipotent stromal cells that are present in the various parts of the body. MSCs tends to migrate towards inflamed regions and they are also seen to migrate to a tumour. The immunomodulatory properties of the MSCs were being studied for the past decade and it has been observed that these immunomodulatory properties of MSCs have been exploited by the cancer stoma.

Thymoquinone-treated mouse mesenchymal stem cells-derived conditioned medium inhibits human breast cancer cells in vitro

Breast cancer is now the most prevalent cancer in females, therefore, it is essential to identify factors affecting its initiation and progression. Mesenchymal stem cells (MSCs) have received considerable attention in stem cell-based therapies and drug delivery applications. Because the therapeutic potential of MSCs is primarily achieved by their paracrine effects, thus identifying and employing bioactive molecules that promote the paracrine activity of MSCs is crucial for their efficient use in cancer treatment. Thymoquinone (TQ) has many biomedical properties, including anti-inflammatory, anti-diabetic, anti-aging, anti-cancer, etc. In addition, it has been found that TQ affects the self-renewal and immunomodulatory properties of MSCs. The present study aimed to investigate the effect of TQ-treated mouse bone marrow-derived MSCs conditioned medium (TQ-MSC-CM) on the biological characteristics of breast cancer cell line MCF7. MSCs were cultured and treated with TQ for 24 h. The TQ-MSC-CM and MSC-CM were collected, and their effects were investigated on ROS production, mitochondrial membrane potential (MMP), cell death, cell cycle, and migration of MCF7 cells by DCFDA-cellular ROS assay, Rhodamine-123 MMP assay, Annexin-PI staining and Caspase-3/7 activity assays, PI-staining and flow-cytometry, and in vitro wound healing assay, respectively. Moreover, the effects of TQ-MSC-CM and MSC-CM were studied on Cdk4, Sox2, c-Met, and Bcl2 gene expression by real-time PCR. Results demonstrated that MSC-CM and TQ-MSC-CM did not have a significant effect on the apoptosis induction in MCF7 cells; however, they significantly stimulated necrosis in the cells. Although TQ-MSC-CM promoted ROS production in MCF7 cells, it decreased the MMP of the cells. TQ-MSC-CM also induced Bcl2 anti-apoptosis gene expression and Casp-3/7 activity in cells. In addition, although MSC-CM induced MCF7 cells to enter the cell cycle, TQ-MSC-CM inhibited its progression. TQ-MSC-CM also downregulated the Cdk4 and Sox2 gene expression. Furthermore, TQ-MSC-CM induced the migration potential of MCF7 in a c-Met-independent manner. Altogether, we conclude that TQ may induce programmed necrosis and inhibits the proliferation and migration of the breast cancer cells by affecting the paracrine activity of MSCs.

Adipose tissue-derived mesenchymal stem cells' acellular product extracellular vesicles as a potential therapy for Crohn's disease.

The breakdown of gastrointestinal tract immune homeostasis leads to Crohn's disease (CD). Mesenchymal stem cells (MSCs) have demonstrated clinical efficacy in treating CD in clinical trials, but there is little known about the mechanism of healing. Considering the critical roles of macrophage polarization in CD and immunomodulatory properties of MSCs, we sought to decipher the interaction between adipose‐derived MSCs and macrophages, including their cytokine production, regulation of differentiation, and pro‐/anti‐inflammatory function. RNA extraction and next generation sequencing was performed in adipose tissue from healthy control patients' mesentery (n = 3) and CD mesentery (n = 3). Infiltrated macrophage activation in the CD mesentery was tested, MSCs and extracellular vesicles (EVs) were isolated to compare the regulation of macrophage differentiation, cytokines production, and self‐renewal capacities in vitro. CD patients' mesentery has increased M1 macrophage polarization and elevated activation. MSCs and their derived EVs, isolated from inflamed Crohn's mesentery, leads to a rapid differentiation of monocytes to a M1‐like polarized phenotype. Conversely, MSCs and their derived EVs from healthy, non‐Crohn's patients results in monocyte polarization into a M2 phenotype; this is seen regardless of the adipose source of MSCs (subcutaneous fat, omentum, normal mesentery). EVs derived from MSCs have the ability to regulate macrophage differentiation. Healthy MSCs and their associated EVs have the ability to drive monocytes to a M2 subset, effectively reversing an inflammatory phenotype. This mechanism supports why MSCs may be an effective therapeutic in CD and highlights EVs as a novel therapeutic for further exploration.

The influence of association between aging and reduced protein intake on some immunomodulatory aspects of bone marrow mesenchymal stem cells: an experimental study.

Dietary protein deficiency is common in the elderly, compromising hematopoiesis and the immune response, and may cause a greater susceptibility to infections. Mesenchymal stem cells (MSCs) have immunomodulatory properties and are essential to hematopoiesis. Therefore, this study aimed to investigate, in an aging model subjected to malnutrition due a reduced protein intake, aspects related to the immunomodulatory capacity of MSCs. Male C57BL/6 mice from young and elderly groups were fed with normoproteic or hypoproteic diets (12% and 2% of protein, respectively) and nutritional, biochemical and hematological parameters were evaluated. MSCs from bone marrow were isolated, characterized and their secretory parameters evaluated, along with gene expression. Additionally, the effects of aging and protein malnutrition on MSC immunomodulatory properties were assessed. Malnourished mice lost weight and demonstrated anemia, leukopenia, and bone marrow hypoplasia. MSCs from elderly animals from both groups showed reduced CD73 expression and higher senescence rate; also, the malnourished state affected CD73 expression in young animals. The production of IL-1β and IL-6 by MSCs was affected by aging and malnutrition, but the IL-10 production not. Aging also increased the expression of NFκB, reducing the expression of STAT-3. However, MSCs from malnourished groups, regardless of age, showed decreased TGF-β and PGE2 production. Evaluation of the immunomodulatory capacity of MSCs revealed that aging and malnutrition affected, mainly in lymphocytes, the production of IFN-γ and IL-10. Aging and reduced protein intake are factors that, alone or together, influence the immunomodulatory properties of MSCs and provide basic knowledge that can be further investigated to explore whether MSCs' therapeutic potential may be affected.

Immunomodulatory Properties of Cytokine-preconditioned Compact-bone Derived Mesenchymal Stem Cells Cultured in 2D and 3D Culture Conditions

Mesenchymal stem cells (MSCs) possess potent immunomodulatory properties and therefore represent a promising therapeutic tool for the treatment of immune-related diseases. Recently, preconditioning has been proposed as a strategy to improve the immunomodulatory activity of MSCs. In this study, we focused to investigate the effects of preconditioning with pro-inflammatory cytokines (TNF-α and IFN-γ) on immunomodulatory activity of mouse compact bone-derived MSCs (CB MSCs) in 2D and 3D culture conditions. Mouse CB MSCs for the 2D condition were cultured in a standard tissue culture plate. 3D spheroid MSCs were formed by enforced composing in Nunclon Sphera 96-well U-bottom plate. MSCs in 2D and 3D spheroid cultures were preconditioned with TNF-α and IFN-γ alone and in combination for 24 hours. The levels of immunomodulatory factors (PGE2, IL-6, IL-10, TNF-α, IFN-γ) were measured by ELISA. The immunomodulatory properties of MSCs were examined by macrophage inflammation and lymphocyte co-culture assays. Our results showed that TNF-α and IFN-γ more effectively increased the secretion of PGE2 and IL-6 by 3D spheroid MSCs compared with 2D MSCs culture.Сytokine-preconditioned 3D spheroid MSCs significantly decreased the production of TNF-α, IFN-γ, IL-10 in splenic lymphocytes and TNF-α and IL-6 in macrophages. Сytokine-preconditioned 3D spheroid MSCs increased IL-6 and IL-10 levels in lymphocytes and macrophages respectively. It was found that 3D spheroid MSCs more effectively suppressed the proliferation of T cells compared with 2D MSCs culture. Moreover, preconditioning of 3D spheroid MSCs using TNF-α suppressed more effectively in vitro immune response than preconditioning with IFN-γ or with the combination of two cytokines. Thus, our data suggest that preconditioning with pro-inflammatory cytokines more effectively increases the immunomodulatory activity of 3D MSC spheroids compared to 2D MSC culture.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

Regulation of pathophysiological and tissue regenerative functions of MSCs mediated via the WNT signaling pathway (Review).

Tissues have remarkable natural capabilities to regenerate for the purpose of physiological turnover and repair of damage. Adult mesenchymal stem cells (MSCs) are well known for their unique self-renewal ability, pluripotency, homing potential, paracrine effects and immunomodulation. Advanced research of the unique properties of MSCs have opened up new horizons for tissue regenerative therapies. However, certain drawbacks of the application of MSCs, such as the low survival rate of transplanted MSCs, unsatisfactory efficiency and even failure to regenerate under an unbalanced microenvironment, are concerning with regards to their wider therapeutic applications. The activity of stem cells is mainly regulated by the anatomical niche; where they are placed during their clinical and therapeutic applications. Crosstalk between various niche signals maintains MSCs in homeostasis, in which the WNT signaling pathway plays vital roles. Several external or internal stimuli have been reported to interrupt the normal bioactivity of stem cells. The irreversible tissue loss that occurs during infection at the site of tissue grafting suggests an inhibitory effect mediated by microbial infections within MSC niches. In addition, MSC-seeded tissue engineering success is difficult in various tissues, when sites of injury are under the effects of a severe infection despite the immunomodulatory properties of MSCs. In the present review, the current understanding of the way in which WNT signaling regulates MSC activity modification under physiological and pathological conditions was summarized. An effort was also made to illustrate parts of the underlying mechanism, including the inflammatory factors and their interactions with the regulatory WNT signaling pathway, aiming to promote the clinical translation of MSC-based therapy.

Mesenchymal stem cell- mediated immunomodulation and the potential therapeutic application in Crohn’s Disease

Mesenchymal stem cells (MSCs) are self-renewing stromal cells that possess a multipotent differentiation capacity as they can differentiate into numerous cell types such as adipose, bone and cartilage cells. MSCs have generated considerable interest for their remarkable tissue-reparative and immunomodulatory properties whereby MSCs can develop into functional cells at the injury site and control the body’s response to tissue damage respectively. Consequently, MSCs have vast therapeutic potential in treating Crohn’s disease (CD) which is a lifelong inflammatory bowel disease where tissue damage to a section of the gastrointestinaltract occurs. The review aims to discuss the properties of MSCs and explore their potential application in treating CD. This review highlights the tissue-reparative properties of MSCs and specifically focuses on the immunomodulatory properties of MSCs. Results from clinical trials regarding the efficacy and safety of MSCs have been promising, proving that MSCs could potentially be used to treat CD.

Achievements and Challenges in Transplantation of Mesenchymal Stem Cells in Otorhinolaryngology.

Otorhinolaryngology enrolls head and neck surgery in various tissues such as ear, nose, and throat (ENT) that govern different activities such as hearing, breathing, smelling, production of vocal sounds, the balance, deglutition, facial animation, air filtration and humidification, and articulation during speech, while absence of these functions can lead to high morbidity and even mortality. Conventional therapies for head and neck damaged tissues include grafts, transplants, and artificial materials, but grafts have limited availability and cause morbidity in the donor site. To improve these limitations, regenerative medicine, as a novel and rapidly growing field, has opened a new therapeutic window in otorhinolaryngology by using cell transplantation to target the healing and replacement of injured tissues. There is a high risk of rejection and tumor formation for transplantation of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs); mesenchymal stem cells (MSCs) lack these drawbacks. They have easy expansion and antiapoptotic properties with a wide range of healing and aesthetic functions that make them a novel candidate in otorhinolaryngology for craniofacial defects and diseases and hold immense promise for bone tissue healing; even the tissue sources and types of MSCs, the method of cell introduction and their preparation quality can influence the final outcome in the injured tissue. In this review, we demonstrated the anti-inflammatory and immunomodulatory properties of MSCs, from different sources, to be safely used for cell-based therapies in otorhinolaryngology, while their achievements and challenges have been described too.

Are mesenchymal stem cells able to manage cytokine storm in COVID-19 patients? A review of recent studies.

The Covid-19 disease has recently become one of the biggest challenges globally, and there is still no specific medication. Findings showed the immune system in severe Covid-19 patients loses regulatory control of pro-inflammatory cytokines, especially IL-6 production, called the “Cytokine storm” process. This process can cause injury to vital organs, including lungs, kidneys, liver, and ultimately death if not inhibited. While many treatments have been proposed to reduce cytokine storm, but the safety and effectiveness of each of them are still in doubt. Mesenchymal stem cells (MSCs) are multipotent cells with self-renewal potential capable of suppressing overactive immune responses and leading to tissue restoration and repair. These immuno-modulatory properties of MSCs and their derivatives (like exosomes) can improve the condition of Covid-19 patients with serious infectious symptoms caused by adaptive immune system dysfunction. Many clinical trials have been conducted in this field using various MSCs around the world. Some of these have been published and summarized in the present article, while many have not yet been completed. Based on these available data, MSCs can reduce inflammatory cytokines, increase oxygen saturation, regenerate lung tissue and improve clinical symptoms in Covid-19 patients. The review article aims to collect available clinical data in more detail and investigate the role of MSCs in reducing cytokine storms as well as improving clinical parameters of Covid-19 patients for use in future clinical studies.

Mesenchymal stem cells in the treatment of osteonecrosis of the jaw.

Medication-related osteonecrosis of the jaw (MRONJ) has recently associated to the increase in antiresorptive and anti-angiogenic drugs prescriptions in the treatment of oncologic and osteoporotic patients. The physiopathogenesis of MRONJ remains unclear and available treatments are unsatisfactory. Newer pharmacological treatments have shown good results, but are not curative and could have major side effects. At the same time as pharmacological treatments, mesenchymal stem cells (MSCs) have emerged as a promising therapeutic modality for tissue regeneration and repair. MSCs are multipotential non-hematopoietic progenitor cells capable to differentiating into multiple lineages of the mesenchyme. Bone marrow MSCs can differentiate into osteogenic cells and display immunological properties and secrete paracrine anti-inflammatory factors in damaged tissues. The immunomodulatory, reparative, and anti-inflammatory properties of bone marrow MSCs have been tested in a variety of animal models of MRONJ and applied in specific clinical settings. The aim of this review is to discuss critically the immunogenicity and immunomodulatory properties of MSCs, both in vitro and in vivo, the possible underlying mechanisms of their effects, and their potential clinical use as modulators of immune responses in MRONJ, and to identify clinical safety and recommendations for future research.

TNF\u03b1/TNFR2 signaling pathway: an active immune checkpoint for mesenchymal stem cell immunoregulatory function

BackgroundIn addition to their multilineage potential, mesenchymal stem cells (MSCs) have a broad range of functions from tissue regeneration to immunomodulation. MSCs have the ability to modulate the immune response and change the progression of different inflammatory and autoimmune disorders. However, there are still many challenges to overcome before their widespread clinical administration including the mechanisms behind their immunoregulatory function. MSCs inhibit effector T cells and other immune cells, while inducing regulatory T cells (T regs), thus, reducing directly and indirectly the production of pro-inflammatory cytokines. TNF/TNFR signaling plays a dual role: while the interaction of TNFα with TNFR1 mediates pro-inflammatory effects and cell death, its interaction with TNFR2 mediates anti-inflammatory effects and cell survival. Many immunosuppressive cells like T regs, regulatory B cells (B regs), endothelial progenitor cells (EPCs), and myeloid-derived suppressor cells (MDSCs) express TNFR2, and this is directly related to their immunosuppression efficiency. In this article, we investigated the role of the TNFα/TNFR2 immune checkpoint signaling pathway in the immunomodulatory capacities of MSCs.MethodsCo-cultures of MSCs from wild-type (WT) and TNFR2 knocked-out (TNFR2 KO) mice with T cells (WT and TNFα KO) were performed under various experimental conditions.ResultsWe demonstrate that TNFR2 is a key regulatory molecule which is strongly involved in the immunomodulatory properties of MSCs. This includes their ability to suppress T cell proliferation, activation, and pro-inflammatory cytokine production, in addition to their capacity to induce active T regs.ConclusionsOur results reveal for the first time the importance of the TNFα/TNFR2 axis as an active immune checkpoint regulating MSC immunological functions.

P0145MESENCHYMAL STEM CELLS PROTECT RENAL TUBULAR CELLS VIA TSG-6 REGULATED MACROPHAGE FUNCTION AND PHENOTYPE SWITCHING

Abstract Background and Aims Tumor necrosis factor-α-induced gene/protein (TSG)-6 is a key factor influencing mesenchymal stem cells (MSCs) immunomodulatory properties, but its renoprotective efficacy is unknown. Using a novel swine model of renal artery stenosis (RAS) complicated by metabolic syndrome (Mets), we assessed the therapeutic effects of adipose tissue-derived MSCs-produced TSG-6 and mechanisms underlying the immunomodulatory properties of MSCs. Method Five groups of pigs (n=6 each) were studied after 16 weeks of diet-induced Mets and unilateral RAS (Mets+RAS), either untreated or treated 4 weeks earlier with a single intra-renal delivery of autologous posrcine adipose tissue-derived MSCs (pMSC). Lean, Mets, and RAS shams served as controls. We studied renal function in vivo (using CT imaging) and kidney histopathology and macrophage phenotype ex vivo. In vitro, TSG-6 levels were measured in conditioned media of human MSCs (hMSCs) incubated with or without TNF-α. Additionally, levels of the tubular injury marker LDH were measured in conditioned media after co-culturing macrophages with injured HK-2 cells (achieved by TNF-α and antimycin-A, AMA) with or without addition of TSG-6. The effects of TSG-6 on macrophage phenotype (M1/M2), adhesion, and migration capability were determined. Results Mets+RAS pigs showed increased renal M1 macrophages and renal vein TNF-α levels. After p-MSCs delivery, renal vein TSG-6 increased and TNF-α decreased, M1 macrophage switched to M2 (Fig. A),, renal function improved, and fibrosis alleviated. In vitro, TNF-α increased TSG-6 secretion by h-MSCs. TSG-6 decreased LDH release from injured HK-2, induced a macrophage phenotypic switch from M1 to M2 (Fig. B), and reduced M1 macrophage adhesion and migration (Fig. C). Conclusion TNF-α-induced TSG-6 release from MSCs in vivo and in vitro may decrease renal tubular cells injury, which is associated with and may be at least in part mediated by regulating macrophage function and phenotype.

Adipose Tissue-Derived Mesenchymal Stem Cells’ Acellular Product Extracellular Vesicles as a Potential Therapy for Crohn Disease

Abstract The breakdown of gastrointestinal tract immune homeostasis leads to Crohn’s disease (CD). Mesenchymal stem cells (MSCs) have demonstrated clinical efficacy in treating CD in clinical trials, but there is little known about the mechanism of healing. Considering the critical roles of macrophage polarization and T cell activation in CD, and immunomodulatory properties of MSCs, we sought to decipher the interaction between adipose derived MSCs, macrophages and T cells including their cytokine production, regulation of differentiation and pro-/anti-inflammatory function. When MSC derived EVs from inflamed Crohn’s mesentery were added to monocyte culture, monocytes rapidly differentiated into M1 macrophages (CD68+) from myeloid progenitors. When MSC derived EVS from control patients, regardless of the adipose source of MSCs (subcutaneous fat, omentum, normal mesentery), monocytes selectively differentiated into M2 macrophages (Arg-1+). Adoptive transfer of these differentiated M2 macrophages, effectively reversed T cell activation, proliferation, and cytokine production. Control patient isolated MSC derived EVs significantly suppressed T cells function with significantly decreased levels of inflammatory cytokines, as compared to diseased mesentery MSC derived EVs. This T cells inhibition was a result of NO synthase, arginase, and reduced ERK induced inflammatory signaling. MSCs alter macrophage polarization and subsequent T cell activation. Healthy MSCs have the ability to drive monocytes to a M2 subset which then effectively reverses T cell function. This mechanism supports why MSCs are effective for regulating CD progression and offers pathways for the evaluation of various MSC sources for optimal efficacy.

The Potential of Mesenchymal Stem Cells to Treat Systemic Inflammation in Horses.

One hallmark of mesenchymal stem cells (MSCs) is the ability to differentiate into multiple tissue types which assists in tissue regeneration. Another hallmark of MSCs is their potent anti-inflammatory and immunomodulatory properties and the potential to treat inflammatory, immune-mediated, and ischemic conditions. In equine practice, MSCs have shown efficacy in the treatment of musculoskeletal disorders such as tendinopathy, meniscal tears and cartilage injury. However, there are many equine disease processes and conditions that may benefit from the immunomodulatory properties of MSCs. Examples include conditions associated with overwhelming acute inflammatory response such as systemic inflammatory response syndrome to chronic diseases characterized by a prolonged low level of inflammation such as equine asthma and recurrent uveitis. For the acute inflammatory response processes, there is often high morbidity and mortality with no effective immunomodulatory treatment to prevent the overwhelming synthesis of proinflammatory mediators. For chronic inflammatory disease processes, frequently long-term corticosteroid treatment is the therapeutic mainstay, with serious potential complications. Thus, there is an unmet need for alternative anti-inflammatory treatments for both acute and chronic illnesses in horses. While MSCs show promise for such conditions, much research is needed before a clinically safe and effective treatment will be available. Optimal MSC tissue source, patient vs. donor source (autologous vs. allogeneic) and cell growth conditions need to be determined for each problem. For immediate use, allogeneic MSC treatments is preferable, but immune tolerance and adequate safety require further study. MSC collection and cryopreservation from horses before they are injured or ill, whether from umbilical cord tissue, bone marrow or adipose might become more widespread. Once these fundamental approaches to treating specific diseases with MSCs are determined, the route of administration, dose and timing of administration also need to be studied. To provide a framework for development of MSC immunomodulatory treatments, this article reviews the current understanding of equine MSC anti-inflammatory and immunomodulatory properties and proposes how MSC therapy may be further developed to treat acute onset systemic inflammatory processes and chronic inflammatory diseases.

Influence of Donor's Age on Immunomodulatory Properties of Canine Adipose Tissue-Derived Mesenchymal Stem Cells

Osteoarthritis challenges traditional therapies and remains a leading cause of lameness in older dogs. Regenerative medicine offers new strategies, typically involving the injection of autologous adipose-derived mesenchymal stem cells (MSCs). Conversely, allogenic MSCs are appealing candidates to palliate patient morbidity and cell preparation time. Regardless of the source of cells, identifying critical donor characteristics, such as age, is essential to obtain the most competent MSCs. The objectives of this study were to determine the influence of donor's age on proliferation, gene expression, and immunomodulatory properties of MSCs in dogs. Canine adipose tissue-derived MSCs (cAD-MSCs) were isolated from the falciform-ligament adipose tissues of nine pairs of gender-matched young (<2 years) or old (>7 years) client-owned dogs undergoing abdominal surgery. Growth kinetics, transcriptome before and after stimulation by tumor necrosis factor alpha and interferon gamma, MSC-induced lymphocyte suppression assay, and secretion of prostaglandin E2 (PGE2) and indoleamine 2,3-dioxygenase (IDO) were compared between cells obtained from young or old dogs. The doubling times at passages 2 and 3 were shorter when MSCs were isolated from young (34.8 ± 1.8 h and 46.3 ± 2.3 h) rather than old dogs (56.5 ± 8.0 h and 123.8 ± 46.7 h, P < 0.05). The MSC transcriptomes from both populations were similar without stimulation, while stimulation resulted in a 3-fold greater expression of osteogenic gene, fibroblast growth factor 10, in cells from old dogs. cAD-MSCs from young dogs suppressed proliferation of activated T cells more strongly (P < 0.05), although secretion of PGE2 and IDO did not differ between groups. In conclusion, donors' age affected proliferation, immunomodulatory properties of cAD-MSCs, and increased expression of osteogenic gene under proinflammatory conditions in our population of dogs. Collectively, our results provide evidence to support further evaluation of allogenic MSC therapies derived from young donors as alternatives to autologous MSC therapy in older dogs.

Mesenchymal stem cells enhance microglia M2 polarization and attenuate neuroinflammation through TSG-6

Microglia are the primary cells that exert immune function in the central nervous system (CNS), and they play an important role in the pathogenesis and progression of neuroinflammation-related diseases. Mesenchymal stem cells (MSCs) have been demonstrated to promote functional recovery in many neurological diseases. The mechanisms underlying this may be that MSCs can reduce inflammatory responses through various soluble factors. Among these factors, tumor necrosis factor-α-induced gene/protein 6 (TSG-6) is a key factor influencing MSCs immunomodulatory properties; however, the precise mechanisms underlying the anti-inflammatory effects are not fully understood. Here, we aim to investigate the potential effects of MSCs on neuroinflammation and to reveal the underlying mechanisms. First, we confirmed that administration of MSCs could inhibit the lipopolysaccharide (LPS)-induced neuroinflammatory responses in a mouse model. Then, we found that MSCs promoted M2 polarization and inhibited M1 polarization both in vivo and in vitro. Moreover, we demonstrated that the effect of MSCs on microglial polarization was dependent on TSG-6. This study demonstrated that MSCs promoted M2 polarization of microglia via TSG-6, thus conferring anti-neuroinflammatory effects.

Low-Dose Pesticide Mixture Induces Accelerated Mesenchymal Stem Cell Aging In Vitro.

The general population is chronically exposed to multiple environmental contaminants such as pesticides. We have previously demonstrated that human mesenchymal stem cells (MSCs) exposed in vitro to low doses of a mixture of seven common pesticides showed a permanent phenotype modification with a specific induction of an oxidative stress‐related senescence. Pesticide mixture also induced a shift in MSC differentiation toward adipogenesis. Thus, we hypothesized that common combination of pesticides may induce a premature cellular aging of adult MSCs. Our goal was to evaluate if the prolonged exposure to pesticide mixture could accelerate aging‐related markers and in particular deteriorate the immunosuppressive properties of MSCs. MSCs exposed to pesticide mixture, under long‐term culture and obtained from aging donor, were compared by bulk RNA sequencing analysis. Aging, senescence, and immunomodulatory markers were compared. The protein expression of cellular aging‐associated metabolic markers and immune function of MSCs were analyzed. Functional analysis of the secretome impacts on immunomodulatory properties of MSCs was realized after 21 days' exposure to pesticide mixture. The RNA sequencing analysis of MSCs exposed to pesticide showed some similarities with cells from prolonged culture, but also with the MSCs of an aged donor. Changes in the metabolic markers MDH1, GOT and SIRT3, as well as an alteration in the modulation of active T cells and modifications in cytokine production are all associated with cellular aging. A modified functional profile was found with similarities to aging process. stem cells 2019;37:1083–1094