Umbilical cord-derived mesenchymal stem cells instruct dendritic cells to acquire tolerogenic phenotypes through the IL-6-mediated upregulation of SOCS1

Regulation of inflammation during wound healing: the function of mesenchymal stem cells and strategies for therapeutic enhancement

A wound takes a long time to heal and involves several steps. Following tissue injury, inflammation is the primary cause of tissue regeneration and repair processes. As a result, the pathophysiological processes involving skin damage, healing, and remodeling depend critically on the control of inflammation. The fact that it is a feasible target for improving the prognosis of wound healing has lately become clear. Mesenchymal stem cells (MSCs) are an innovative and effective therapeutic option for wound healing due to their immunomodulatory and paracrine properties. By controlling the inflammatory milieu of wounds through immunomodulation, transplanted MSCs have been shown to speed up the healing process. In addition to other immunomodulatory mechanisms, including handling neutrophil activity and modifying macrophage polarization, there may be modifications to the activation of T cells, natural killer (NK) cells, and dendritic cells (DCs). Furthermore, several studies have shown that pretreating MSCs improves their ability to modulate immunity. In this review, we summarize the existing knowledge about how MSCs influence local inflammation in wounds by influencing immunity to facilitate the healing process. We also provide an overview of MSCs optimizing techniques when used to treat wounds.

Interaction between Mesenchymal Stem Cells and Immune Cells during Bone Injury Repair

Fractures are the most common large organ trauma in humans. The initial inflammatory response promotes bone healing during the initial post-fracture phase, but chronic and persistent inflammation due to infection or other factors does not contribute to the healing process. The precise mechanisms by which immune cells and their cytokines are regulated in bone healing remain unclear. The use of mesenchymal stem cells (MSCs) for cellular therapy of bone injuries is a novel clinical treatment approach. Bone progenitor MSCs not only differentiate into bone, but also interact with the immune system to promote the healing process. We review in vitro and in vivo studies on the role of the immune system and bone marrow MSCs in bone healing and their interactions. A deeper understanding of this paradigm may provide clues to potential therapeutic targets in the healing process, thereby improving the reliability and safety of clinical applications of MSCs to promote bone healing.

Clinical Trials Targeting Secondary Damage after Traumatic Spinal Cord Injury

Spinal cord injury (SCI) often causes loss of sensory and motor function resulting in a significant reduction in quality of life for patients. Currently, no therapies are available that can repair spinal cord tissue. After the primary SCI, an acute inflammatory response induces further tissue damage in a process known as secondary injury. Targeting secondary injury to prevent additional tissue damage during the acute and subacute phases of SCI represents a promising strategy to improve patient outcomes. Here, we review clinical trials of neuroprotective therapeutics expected to mitigate secondary injury, focusing primarily on those in the last decade. The strategies discussed are broadly categorized as acute-phase procedural/surgical interventions, systemically delivered pharmacological agents, and cell-based therapies. In addition, we summarize the potential for combinatorial therapies and considerations.

Mesenchymal stem cell-based therapy as a new therapeutic approach for acute inflammation

Acute inflammatory diseases such as acute colitis, kidney injury, liver failure, lung injury, myocardial infarction, pancreatitis, septic shock, and spinal cord injury are significant causes of death worldwide. Despite advances in the understanding of its pathophysiology, there are many restrictions in the treatment of these diseases, and new therapeutic approaches are required. Mesenchymal stem cell-based therapy due to immunomodulatory and regenerative properties is a promising candidate for acute inflammatory disease management. Based on preclinical results, mesenchymal stem cells and their-derived secretome improved immunological and clinical parameters. Furthermore, many clinical trials of acute kidney, liver, lung, myocardial, and spinal cord injury have yielded promising results. In this review, we try to provide a comprehensive view of mesenchymal stem cell-based therapy in acute inflammatory diseases as a new treatment approach.

Promotion of right ventricular outflow tract reconstruction using a novel cardiac patch incorporated with hypoxia-pretreated urine-derived stem cells

Approximately 25% of patients with congenital heart disease require implantation of patches to repair. However, most of the currently available patches are made of inert materials with unmatched electrical conductivity and mechanical properties, which may lead to an increased risk for arrhythmia and heart failure. In this study, we have developed a novel Polyurethane/Small intestinal submucosa patch (PSP) with mechanical and electrical properties similar to those of the native myocardial tissue, and assessed its feasibility for the reconstruction of right ventricular outflow tract. A right ventricular outflow tract reconstruction model was constructed in 40 rabbits. Compared with commercially available bovine pericardium patch, the PSP patch has shown better histocompatibility and biodegradability, in addition with significantly improved cardiac function. To tackle the significant fibrosis and relatively poor vascularization during tissue remodeling, we have further developed a bioactive patch by incorporating the PSP composites with urine-derived stem cells (USCs) which were pretreated with hypoxia. The results showed that the hypoxia-pretreated bioactive patch could significantly inhibit fibrosis and promote vascularization and muscularization, resulting in better right heart function. Our findings suggested that the PSP patch combined with hypoxia-pretreated USCs may provide a better strategy for the treatment of congenital heart disease.

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A novel cardiac patch (PSP) with mechanical and electrical properties similar to native myocardium.

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PSP patch improved cardiac function in right ventricular outflow tract reconstruction model.

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Hypoxia pretreated USCs combined PSP patch promoted vascularization and inhibited fibrosis.

Mesenchymal Stem Cells Overexpressing ACE2 Favorably Ameliorate LPS-Induced Inflammatory Injury in Mammary Epithelial Cells

Mesenchymal stem cells (MSCs) are capable of homing injury sites to exert anti-inflammatory as well as anti-damage effects and can be used as a vehicle for gene therapy. Angiotensin-converting enzyme 2 (ACE2) plays an important role in numerous inflammatory diseases, but fewer studies have been reported in animal mastitis. We hypothesized that MSCs overexpressing ACE2 is more effective in ameliorating lipopolysaccharide (LPS)-induced inflammatory injury in mammary epithelial cells compared to MSCs alone. The results showed that MSC-ACE2 inhibited the LPS induction by upregulation of TNF-α, IL-Iβ, IL-6, and iNOS mRNA expression levels in EpH4-Ev cells compared with MSCs. Furthermore, results showed that both MSC and MSC-ACE2 were significantly activated IL-10/STAT3/SOCS3 signaling pathway as well as inhibited TLR4/NF-κB and MAPK signaling pathways, but MSC-ACE2 had more significant effects. Meanwhile, MSC-ACE2 promoted the expression of proliferation-associated proteins and inhibited the expression of the apoptosis-associated proteins in EpH4-Ev cells. In addition, MSC and MSC-ACE2 reversed the LPS-induced downregulation expression levels of the tight junction proteins in mammary epithelial cells, indicating that both MSC as well as MSC-ACE2 could promote blood-milk barrier repair, and MSC-ACE2 was more effective. These results suggested that MSCs overexpressing ACE2 were more anti-inflammatory as well as anti-injurious action into LPS-induced inflammatory injury in the EpH4-Ev cells. Thus, MSCs overexpressing ACE2 is expected to serve as a potential strategy for mastitis treatment.

Application of Wharton jelly-derived mesenchymal stem cells in patients with pulmonary fibrosis

Pulmonary fibrosis is a devastating disease that eventually leads to death and respiratory failure. Despite the wide range of drugs, including corticosteroids, endothelin antagonist, and pirfenidone, there is no effective treatment, and the only main goal of treatment is to alleviate the symptoms as much as possible to slow down the progression of the disease and improve the quality of life. Lung transplantation may be a treatment option for a few people if pulmonary fibrosis develops and there is no established treatment. Pulmonary fibrosis caused by the COVID19 virus is another problem that we face in most patients despite the efforts of the international medical communities. Therefore, achieving alternative treatment for patients is a great success. Today, basic research using stem cells on pulmonary fibrosis has published promising results. New stem cell-based therapies can be helpful in patients with pulmonary fibrosis. Wharton jelly-derived mesenchymal stem cells are easily isolated in large quantities and made available for clinical trials without causing ethical problems. These cells have higher flexibility and proliferation potential than other cells isolated from different sources and differentiated into various cells in laboratory environments. More clinical trials are needed to determine the safety and efficacy of these cells. This study will investigate the cellular and molecular mechanisms and possible effects of Wharton jelly-derived mesenchymal stem cells in pulmonary fibrosis.

Effects of immune cells on mesenchymal stem cells during fracture healing

In vertebrates, bone is considered an osteoimmune system which encompasses functions of a locomotive organ, a mineral reservoir, a hormonal organ, a stem cell pool and a cradle for immune cells. This osteoimmune system is based on cooperatively acting bone and immune cells, cohabitating within the bone marrow. They are highly interdependent, a fact that is confounded by shared progenitors, mediators, and signaling pathways. Successful fracture healing requires the participation of all the precursors, immune and bone cells found in the osteoimmune system. Recent evidence demonstrated that changes of the immune cell composition and function may negatively influence bone healing. In this review, first the interplay between different immune cell types and osteoprogenitor cells will be elaborated more closely. The separate paragraphs focus on the specific cell types, starting with the cells of the innate immune response followed by cells of the adaptive immune response, and the complement system as mediator between them. Finally, a brief overview on the challenges of preclinical testing of immune-based therapeutic strategies to support fracture healing will be given.

Effects of indoleamine 2, 3-dioxygenase (IDO) silencing on immunomodulatory function and cancer-promoting characteristic of adipose-derived mesenchymal stem cells (ASCs)

Indoleamine 2, 3-dioxygenase (IDO) catabolizes tryptophan, mediates immunomodulatory functions, and is released by stromal cells such as mesenchymal stem cells. The aims of this study were to investigate the effects of IDO silencing on immunosuppressive function of adipose-derived mesenchymal stem cells (ASCs), T cells phenotype, and the proliferation/migration of tumor cells. ASCs isolated from adipose tissues of healthy women were transfected with IDO-siRNA. Galectin-3, transforming growth factor-β1, hepatocyte growth factor, and interleukin-10 as immunomodulators were measured in ASCs using qRT-PCR. T cells phenotype, interferon-γ, and interleukin-17 expression were evaluated in peripheral blood lymphocytes (PBLs) cocultured with IDO silenced-ASCs by flow cytometry and qRT-PCR, respectively. Scratch assay was applied to assess the proliferation/migration of MDA-MB-231 cell line. Galectin-3 was upregulated (p ˂ 0.05) while hepatocyte growth factor was downregulated (p ˂ 0.05) in IDO-silenced ASCs compared to control groups. Regulatory T cells were inhibited in PBLs cocultured with IDO-silenced ASCs; also T helper2 was decreased in PBLs cocultured with IDO-silenced ASCs relative to the scramble group. IDO-silenced ASCs caused interferon-γ overexpression but interleukin-17 downregulation in PBLs. The proliferation/migration of MDA-MB-231 was suppressed after exposing to condition media of IDO-silenced ASCs compared with condition media of untransfected (p < 0.01) and scramble-transfected ASCs (p < 0.05). The results exhibited the weakened capacity of IDO-silenced ASCs for suppressing the immune cells and promoting the tumor cells' proliferation/migration. IDO suppression may be utilized as a strategy for cancer treatment. Simultaneous blocking of immunomodulators along with IDO inhibitors may show more effects on boosting the efficiency of immune-based cancer therapies.

Local Immunomodulatory Strategies to Prevent Allo-Rejection in Transplantation of Insulin-Producing Cells

Islet transplantation has shown promise as a curative therapy for type 1 diabetes (T1D). However, the side effects of systemic immunosuppression and limited long-term viability of engrafted islets, together with the scarcity of donor organs, highlight an urgent need for the development of new, improved, and safer cell-replacement strategies. Induction of local immunotolerance to prevent allo-rejection against islets and stem cell derived β cells has the potential to improve graft function and broaden the applicability of cellular therapy while minimizing adverse effects of systemic immunosuppression. In this mini review, recent developments in non-encapsulation, local immunomodulatory approaches for T1D cell replacement therapies, including islet/β cell modification, immunomodulatory biomaterial platforms, and co-transplantation of immunomodulatory cells are discussed. Key advantages and remaining challenges in translating such technologies to clinical settings are identified. Although many of the studies discussed are preliminary, the growing interest in the field has led to the exploration of new combinatorial strategies involving cellular engineering, immunotherapy, and novel biomaterials. Such interdisciplinary research will undoubtedly accelerate the development of therapies that can benefit the whole T1D population.

The impact of recipient age on the effects of umbilical cord mesenchymal stem cells on HBV-related acute-on-chronic liver failure and liver cirrhosis

Background

The results of a previous study verified that umbilical cord mesenchymal stem cells (UCMSCs) have good therapeutic effects for the treatment of HBV-related acute-on-chronic liver failure (ACLF) and liver cirrhosis (LC). Nevertheless, it is still unknown whether the effects of UCMSCs are affected by recipient age.

Methods

Patients treated with UCMSCs who met the criteria of HBV-related ACLF and liver cirrhosis were identified in this retrospective observational study. Patients were divided into subgroups according to the World Health Organization (WHO) age criteria (< 45 vs. ≥ 45 years). Group A included young ACLF patients (< 45 y), and group B included older ACLF patients (≥ 45 y). Young LC patients (< 45 y) were assigned to group C, and group D included older LC patients (≥ 45 y). Patients’ clinical characteristics, demographics, biochemical factors, and model for end-stage liver disease (MELD) scores were compared for 24 weeks.

Results

Sixty-four ACLF patients and 59 LC patients were enrolled in this study. Compared with patients in groups B and C, patients in group A did not show significant superiority in terms of the levels of ALT, AST, TBIL, AFP, and PTA and MELD scores. However, the median decrease and cumulative decrease in the TBIL and ALT levels of patients in group C were larger than those of patients in group D after four weeks of UCMSC transfusions. For older patients (≥ 45 y), the cumulative decrease and the median decrease in the TBIL of ACLF patients were significantly greater than those of LC patients after UCMSC treatment. However, the median decrease in ALT levels of ACLF patients was significantly greater than that of LC patients during UCMSC treatment, and the cumulative decrease in ALT levels of ACLF patients was significantly greater than that of LC patients at all time points.

Conclusion

The therapeutic effects of UCMSCs for HBV-related acute-on-chronic liver failure and liver cirrhosis varied partly by patient age. Assessing patient age is necessary prior to UCMSC clinical use.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02544-x.

Role of IL-6 in dendritic cell functions

Dendritic cells (DCs) are efficient antigen-presenting cells that serve as a link between the innate and adaptive immune systems. These cells are broadly involved in cellular and humoral immune responses by presenting antigens to initiate T cell reactions, cytokine and chemokine secretion, T cell differentiation and expansion, B cell activation and regulation, and the mediation of immune tolerance. The functions of DCs depend on their activation status, which is defined by the stages of maturation, phenotype differentiation, and migration ability, among other factors. IL-6 is a soluble mediator mainly produced by a variety of immune cells, including DCs, that exerts pleiotropic effects on immune and inflammatory responses through interaction with specific receptors expressed on the surface of target cells. Here, we review the role of IL-6, when generated in an inflammatory context or as derived from DCs, in modulating the biologic function and activation status of DCs and emphasize the importance of searching for novel strategies to target the IL-6/IL-6 signaling pathway as a means to diminish the inflammatory activity of DCs in immune response or to prime the immunogenic activity of DCs in immunosuppressive conditions.

Biological Characteristics of Umbilical Cord Mesenchymal Stem Cells and Its Therapeutic Potential for Hematological Disorders

Umbilical cord mesenchymal stem cells (UC-MSCs) are a class of multifunctional stem cells isolated and cultured from umbilical cord. They possessed the characteristics of highly self-renewal, multi-directional differentiation potential and low immunogenicity. Its application in the field of tissue engineering and gene therapy has achieved a series of results. Recent studies have confirmed their characteristics of inhibiting tumor cell proliferation and migration to nest of cancer. The ability of UC-MSCs to support hematopoietic microenvironment and suppress immune system suggests that they can improve engraftment after hematopoietic stem cell transplantation, which shows great potential in treatment of hematologic diseases. This review will focus on the latest advances in biological characteristics and mechanism of UC-MSCs in treatment of hematological diseases.

Novel cell-based therapies in inflammatory bowel diseases: the established concept, promising results

Inflammatory bowel diseases (IBDs) are chronic and relapsing disorders that affect the quality of life in many individuals around the world. Over the past few years, the prevalence of IBDs is substantially rising which might pose a considerable social and economic burden on health systems. Progresses in the management of chronic inflammatory diseases lead to prolonged remission phase and decreased hospitalization rate. However, during treatment, many patients become refractory to conventional therapies. Recently, advanced approaches using somatic cell therapy medicinal products (SCTMPs) including immune and stem cell-based therapies have drawn many researchers' attentions. Promising results from recent trials, alongside with the emerging market indicated that these therapeutic approaches could be an alternative and promising treatment to conventional therapies. In this review, we will discuss recent advances in cell-based therapies, which have been developed for treatment of IBDs. In addition, the global emerging market and the novel products in this field are highlighted.

Synergistic therapeutic effect of mesenchymal stem cells and tolerogenic dendritic cells in an acute colitis mouse model

Cell-based therapy with tolerizing cells has been applied for the treatment of inflammatory bowel disease (IBD) in previous experimental and clinical studies with promising results. In the current study, we utilized the dextran sulfate sodium (DSS)-induced colitis model, to investigate if tolerogenic dendritic cell-mesenchymal stem cell (tDC-MSC) combination therapy can augment the therapeutic effects of single transplantation of each cell type. The effect of MSC and tDC co-transplantation on the severity of colitis was assessed by daily monitoring of body weight, stool consistency, and rectal bleeding, and compared with control groups. Moreover, the colon length, colon weight, myeloperoxidase (MPO) activity were measured and evaluated with histological analysis of colon tissues. The Treg cell percentage and cytokine levels in spleens and mesenteric lymph nodes (MLNs) were measured by flow cytometry and ELISA, respectively. The results showed co-transplantation of MSCs and tDCs was more effective in alleviating the clinical and histological manifestations of colitis than monotherapy, especially when compared with MSC alone. The protective effects of tDC-MSC were accompanied by the induction of Treg cells and increased the production of anti-inflammatory cytokines in spleens and mesenteric lymph nodes. Together, co-transplantation of MSCs and tDCs could be a promising and effective therapeutic approach in the treatment of IBD.

Human Umbilical Cord Mesenchymal Stem Cells Attenuate Abdominal Aortic Aneurysm Progression in Sprague-Dawley Rats: Implication of Vascular Smooth Muscle Cell Phenotypic Modulation

Abdominal aortic aneurysm (AAA) is life-threatening, for which efficient nonsurgical treatment strategy has not been available so far. Several previous studies investigating the therapeutic effect of mesenchymal stem cells (MSCs) in AAA indicated that MSCs could inhibit aneurysmal inflammatory responses and extracellular matrix destruction, and suppress aneurysm occurrence and expansion. Vascular smooth muscle cell (VSMC) phenotypic plasticity is reported to be predisposed in AAA initiation and progression. However, little is known about the effect of MSCs on VSMC phenotypic modulation in AAA. In this study, we investigate the therapeutic efficacy of umbilical cord mesenchymal stem cells (UC-MSCs) in elastase-induced AAA model and evaluate the effect of UC-MSC on VSMC phenotypic regulation. We demonstrate that the intravenous injection of UC-MSC attenuates elastase-induced aneurysmal expansion, reduces elastin degradation and fragmentation, inhibits MMPs and TNF-α expression, and preserves and/or restores VSMC contractile phenotype in AAA. Taken together, these results highlight the therapeutic and VSMC phenotypic modulation effects of UC-MSC in AAA progression, which further indicates the potential of applying UC-MSC as an alternative treatment candidate for AAA.

Enhanced therapeutic effects of umbilical cord mesenchymal stem cells after prolonged treatment for HBV-related liver failure and liver cirrhosis

Background

Umbilical cord mesenchymal stem cells (UCMSCs) have been demonstrated to have good therapeutic effects in the treatment of HBV-related liver diseases. However, the therapeutic effect of UCMSCs on HBV-related liver failure and liver cirrhosis and the variations in the efficacy of UCMSCs after different treatment courses remain poorly understood. Therefore, this study was designed to answer these two questions.

Methods

This was an observational study that retrospectively considered a 3-year period during which 513 patients who received stem cell infusion and met the criteria of hepatic failure and liver cirrhosis were identified from the databases of the Third Affiliated Hospital of Sun Yat-sen University. The eligible patients were categorized into the liver failure group and liver cirrhosis group. The two groups were divided into different subgroups according to the duration of stem cell therapy. In the liver failure group, group A received more than 4 weeks and group B received less than 4 weeks of stem cell therapy. In the liver cirrhosis group, patients who received more than 4 weeks of stem cell therapy belonged to group C, and the patients in group D received less than 4 weeks of stem cell therapy. The patients were followed up for 24 weeks. The demographics, clinical characteristics, biochemical factors, and model for end-stage liver disease (MELD) scores were recorded and compared among different groups.

Results

A total of 64 patients met the criteria for liver failure, and 59 patients met the criteria for liver cirrhosis. After UCMSC treatment, the levels of alanine aminotransferase (ALT), glutamic-oxaloacetic transaminase (AST), and total bilirubin (TBIL) at all postbaseline time points were significantly lower than those at baseline in the liver failure group and liver cirrhosis group; the prothrombin activity (PTA) and MELD scores gradually improved in only the liver failure group. Four weeks after UCMSC treatment, patients who received prolonged treatment with UCMSCs had a larger decrease in TBIL levels than patients who terminated treatment with UCMSCs. After more than 4 weeks of UCMSC treatment, there were no statistically significant differences in the changes in ALT, AST, TBIL, and PTA values and MELD scores between patients with liver failure who received prolonged treatment with UCMSCs and patients with liver cirrhosis who received prolonged treatment with UCMSCs at any time point. However, the median decrease and cumulative decrease in the TBIL level of patients with liver failure with a standard 4-week treatment course were larger than those of patients with liver cirrhosis with a standard 4-week treatment course.

Conclusion

Peripheral infusion of UCMSCs showed good therapeutic effects for HBV-related liver failure and liver cirrhosis. Prolonging the treatment course can increase the curative effect of UCMSCs for end-stage liver disease, especially for patients with cirrhosis.

Mesenchymal stem cell derived extracellular vesicles: promising immunomodulators against autoimmune, autoinflammatory disorders and SARS-CoV-2 infection

Discovery of novel and broad-acting immunomodulators is of critical importance for the prevention and treatment of disorders occurring due to overexuberant immune responseincluding SARS-CoV-2 triggered cytokine storm leading to lung pathology and mortality during the ongoing viral pandemic. Mesenchymal stem/stromal cells (MSCs), highly regarded for their regenerative capacities, also possessesremarkable immunoregulatory functions affecting all types of innate and adaptive immune cells. Owing to that, MSCs have been heavily investigated in clinic for the treatment of autoimmune and inflammatory diseases along with transplant rejection. Extensive research in the last decaderevealed that MSCs carry out most of their functions through paracrine factors which are soluble mediators and extracellular vesicles (EVs). EVs, including exosomes and microvesicles, are an efficient way of intercellular communication due to their unique ability to carry biological messages such as transcription factors, growth factors, cytokines, mRNAs and miRNAs over long distances. EVs originate through direct budding of the cell membrane or the endosomal secretion pathway and they consist of the cytosolic and membrane components of their parent cell. Therefore, they are able to mimic the characteristics of the parent cell, affecting the target cells upon binding or internalization. EVs secreted by MSCs are emerging as a cell-free alternative to MSC-based therapies. MSC EVs are being tested in preclinical and clinical settings where they exhibit exceptional immunosuppressivecapacity. They regulate the migration, proliferation, activation and polarization of various immune cells, promoting a tolerogenic immune response while inhibiting inflammatory response. Being as effective immunomodulators as their parent cells, MSC EVs are also preferable over MSC-based therapies due to their lower risk of immunogenicity, tumorigenicity and overall superior safety. In this review, we present the outcomes of preclinical and clinical studies utilizing MSC EVs as therapeutic agents for the treatment of a wide variety of immunological disorders.

Mesenchymal stem cells activate Notch signaling to induce regulatory dendritic cells in LPS-induced acute lung injury

Background

Mesenchymal stem cells (MSCs) have been shown to alleviate acute lung injury (ALI) and induce the production of regulatory dendritic cells (DCregs), but the potential link between these two cell types remains unclear. The goal of this study was to investigate the effect and mechanism of MSC-induced regulatory dendritic cells in ALI mice.

Material/methods

In vivo experiments, C57BL/6 wild-type male mice were sacrificed at different times after intratracheal injection of LPS to observe changes in lung DC maturation and pathological damage. MSCs, DCregs or/and carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled DCs were administered to the mice by tail vein, and flow cytometry was performed to measure the phenotype of lung DCs and T cells. Lung injury was estimated by the lung wet weight/body weight ratio and histopathological analysis. In vitro, Western blotting or flow cytometry was used to detect the expression of Notch ligand or receptor in MSCs or DCs after coculture or LPS stimulation. Finally, in vivo and in vitro, we used the Notch signaling inhibitor DAPT to verify the effect of the Notch pathway on MSC-induced DCregs and their pulmonary protection.

Results

We showed significant accumulation and maturation of lung DCs 2 h after intratracheal injection of LPS, which were positively correlated with the lung pathological injury score. MSC treatment alleviated ALI lung injury, accompanied by a decrease in the number and maturity of classical DCs in the lungs. CFSE-labeled DCs migrated to the lungs of ALI mice more than those of the normal group, and the elimination of CFSE-labeled DCs in the blood was slower. MSCs inhibited the migration of CFSE-labeled DCs to the lung and promoted their elimination in the blood. DCregs, which are obtained by contact coculture of mDCs with MSCs, expressed reduced levels of MHCII, CD86, CD40 and increased levels of PD-L1, and had a reduced ability to stimulate lymphocyte proliferation and activation (expression of CD44 and CD69). mDCs expressing Notch2 significantly increased after coculture with MSCs or rhJagged1, and MSCs expressed more Jagged1 after LPS stimulation. After stimulation of mDCs with recombinant Jagged1, DCs with low expression of MHCII, CD86 and CD40 were also induced, and the effects of both rhJagged1 and MSCs on DCs were blocked by the Notch inhibitor DAPT. Intra-airway DAPT reversed the inhibitory effect of mesenchymal stem cells on DC recruitment to the lungs and its maturation.

Conclusions

Our results suggested that the recruitment and maturation of lung DCs is an important process in early ALI, MSCs attenuate LPS-induced ALI by inducing the production of DCregs by activating Notch signaling.

Human Wharton's Jelly-Cellular Specificity, Stemness Potency, Animal Models, and Current Application in Human Clinical Trials

Stem cell therapies offer a great promise for regenerative and reconstructive medicine, due to their self-renewal and differentiation capacity. Although embryonic stem cells are pluripotent, their utilization involves embryo destruction and is ethically controversial. Therefore, adult tissues that have emerged as an alternative source of stem cells and perinatal tissues, such as the umbilical cord, appear to be particularly attractive. Wharton's jelly, a gelatinous connective tissue contained in the umbilical cord, is abundant in mesenchymal stem cells (MSCs) that express CD105, CD73, CD90, Oct-4, Sox-2, and Nanog among others, and have the ability to differentiate into osteogenic, adipogenic, chondrogenic, and other lineages. Moreover, Wharton's jelly-derived MSCs (WJ-MSCs) do not express MHC-II and exhibit immunomodulatory properties, which makes them a good alternative for allogeneic and xenogeneic transplantations in cellular therapies. Therefore, umbilical cord, especially Wharton's jelly, is a promising source of mesenchymal stem cells.

Mesenchymal stem cells induce dendritic cell immune tolerance via paracrine hepatocyte growth factor to alleviate acute lung injury

BACKGROUND

Mesenchymal stem cells (MSCs) have been shown to alleviate acute lung injury (ALI) via paracrine hepatocyte growth factor (HGF) and to induce the differentiation of dendritic cells (DCs) into tolerogenic dendritic cells (DCregs) and participate in the immune response. However, whether MSCs induce the production of DCregs by secreting HGF to alleviate early ALI remains unclear. We observed that the protective effect of mouse bone marrow-derived MSCs against lipopolysaccharide (LPS)-induced ALI was achieved by inducing mature DCs (mDCs) to differentiate into DCregs, and its mechanism is related to the activation of the HGF/Akt pathway.

METHODS

MSCs or MSCs with overexpression or knockdown of HGF were cocultured with DCs derived from mouse bone marrow using a Transwell system for 3 days. Moreover, we used MSCs or MSCs with overexpression or knockdown of HGF to treat LPS-induced ALI mice for 24 h. Flow cytometry was performed to measure the phagocytosis, accumulation, and maturation of DCs, as well as proliferation of T cells. Lung injury was estimated by lung wet weight to body weight ratio (LWW/BW) and histopathological analysis. Furthermore, we used the Akt inhibitor MK-2206 in a coculture system to elucidate the role of the HGF/Akt pathway in regulating the differentiation of DCs into regulatory DCs and relieving lung injury in early ALI mice.

RESULTS

Immature DCs (imDCs) were induced to mature after 24 h of LPS (50 ng/ml) stimulation. MSCs or HGF induced the differentiation of mDCs into regulatory DCs characterized by low expression of MHCII, CD86, and CD40 molecules, strong phagocytic function, and the ability to inhibit T cell proliferation. The effect of MSCs on DCregs was enhanced with the increase in HGF secretion and was weakened with the decrease in HGF secretion. DCregs induced by recombinant HGF were attenuated by the Akt inhibitor MK-2206. Lung DC aggregation and mDC ratio increased in LPS-induced ALI mice, while treatment with MSCs decreased lung DC aggregation and maturation and alleviated lung pathological injury. High expression of the HGF gene enhanced the above effect of MSCs, while decreased expression of HGF weakened the above effect of MSCs.

CONCLUSIONS

MSCs alleviate early ALI via paracrine HGF by inducing mDCs to differentiate into regulatory DCs. Furthermore, the mechanism of HGF-induced differentiation of mDCs into DCregs is related to the activation of the Akt pathway.

Immune modulation by mesenchymal stem cells

Mesenchymal stem cells (MSCs) can be derived from various adult tissues with multipotent and self‐renewal abilities. The characteristics of presenting no major ethical concerns, having low immunogenicity and possessing immune modulation functions make MSCs promising candidates for stem cell therapies. MSCs could promote inflammation when the immune system is underactivated and restrain inflammation when the immune system is overactivated to avoid self‐overattack. These cells express many immune suppressors to switch them from a pro‐inflammatory phenotype to an anti‐inflammatory phenotype, resulting in immune effector cell suppression and immune suppressor cell activation. We would discuss the mechanisms governing the immune modulation function of these cells in this review, especially the immune‐suppressive effects of MSCs.

Perinatal Mesenchymal Stromal Cells and Their Possible Contribution to Fetal-Maternal Tolerance

During pregnancy, a successful coexistence between the mother and the semi-allogenic fetus occurs which requires a dynamic immune system to guarantee an efficient immune protection against possible infections and tolerance toward fetal antigens. The mechanism of fetal-maternal tolerance is still an open question. There is growing in vitro and in vivo evidence that mesenchymal stromal cells (MSC) which are present in perinatal tissues have a prominent role in generating a functional microenvironment critical to a successful pregnancy. This review highlights the immunomodulatory properties of perinatal MSC and their impact on the major immune cell subsets present in the uterus during pregnancy, such as natural killer cells, antigen-presenting cells (macrophages and dendritic cells), and T cells. Here, we discuss the current understanding and the possible contribution of perinatal MSC in the establishment of fetal-maternal tolerance, providing a new perspective on the physiology of gestation.

Umbilical cord-derived mesenchymal stromal cells in cardiovascular disease: review of preclinical and clinical data

The human umbilical cord has recently emerged as an attractive potential source of mesenchymal stromal cells (MSCs) to be adopted for use in regenerative medicine. Umbilical cord MSCs (UC-MSCs) not only share the same features of all MSCs such as multi-lineage differentiation, paracrine functions and immunomodulatory properties, they also have additional advantages, such as no need for bone marrow aspiration and higher self-renewal capacities. They can be isolated from various compartments of the umbilical cord (UC) and can be used for autologous or allogeneic purposes. In the past decade, they have been adopted in cardiovascular disease and have shown promising results mainly due to their pro-angiogenic and anti-inflammatory properties. This review offers an overview of the biological properties of UC-MSCs describing available pre-clinical and clinical data with respect to their potential therapeutic use in cardiovascular regeneration, with current challenges and future directions discussed.

Stem-Cell Therapy Advances in China

Stem-cell therapy is a promising method for treating patients with a wide range of diseases and injuries. Increasing government funding of scientific research has promoted rapid developments in stem-cell research in China, as evidenced by the substantial increase in the number and quality of publications in the past 5 years. Multiple high-quality studies have been performed in China that concern cell reprogramming, stem-cell homeostasis, gene modifications, and immunomodulation. The number of translation studies, including basic and preclinical investigations, has also increased. Around 100 stem-cell banks have been established in China, 10 stem-cell drugs are currently in the approval process, and >400 stem cell-based clinical trials are currently registered in China. With continued state funding, advanced biotechnical support, and the development of regulatory standards for the clinical application of stem cells, further innovations are expected that will lead to a boom in stem-cell therapies. This review highlights recent achievements in stem-cell research in China and discusses future prospects.

Genetic contribution to mesenchymal stem cell dysfunction in systemic lupus erythematosus

Allogeneic mesenchymal stem cell (MSC) transplantation has recently become a promising therapy for patients with systemic lupus erythematosus (SLE). MSCs are a kind of multipotent stem cell than can efficiently modulate both innate and adaptive immune responses, yet those from SLE patients themselves fail to maintain the balance of immune cells, which is partly due to the abnormal genetic background. Clarifying genetic factors associated with MSC dysfunction may be helpful to delineate SLE pathogenesis and provide new therapeutic targets. In this review, the scientific evidence on the genetic contribution to MSC dysfunction in SLE is summarized.

Allogeneic mesenchymal stem cells as induction therapy are safe and feasible in renal allografts: pilot results of a multicenter randomized controlled trial

BACKGROUND

Kidneys from deceased donors are being used to meet the growing need for grafts. However, delayed graft function (DGF) and acute rejection incidences are high, leading to adverse effects on graft outcomes. Optimal induction intervention should include both renal structure injury repair and immune response suppression. Mesenchymal stem cells (MSCs) with potent anti-inflammatory, regenerative, and immune-modulatory properties are considered a candidate to prevent DGF and acute rejection in renal transplantation. Thus, this prospective multicenter paired study aimed to assess the clinical value of allogeneic MSCs as induction therapy to prevent both DGF and acute rejection in deceased donor renal transplantation.

METHODS

Forty-two renal allograft recipients were recruited and divided into trial and control groups. The trial group (21 cases) received 2 × 10⁶/kg human umbilical-cord-derived MSCs (UC-MSCs) via the peripheral vein before renal transplantation, and 5 × 10⁶ cells via the renal artery during the surgical procedure. All recipients received standard induction therapy. Incidences of DGF and biopsy-proven acute rejection were recorded postoperatively and severe postoperative complications were assessed. Graft and recipient survivals were also evaluated.

RESULTS

Treatment with UC-MSCs achieved comparable graft and recipient survivals with non-MSC treatment (P = 0.97 and 0.15, respectively). No increase in postoperative complications, including DGF and acute rejection, were observed (incidence of DGF: 9.5% in the MSC group versus 33.3% in the non-MSC group, P = 0.13; Incidence of acute rejection: 14.3% versus 4.8%, P = 0.61). Equal postoperative estimated glomerular filtration rates were found between the two groups (P = 0.88). All patients tolerated the MSCs infusion without adverse clinical effects. Additionally, a multiprobe fluorescence in situ hybridization assay revealed that UC-MSCs administered via the renal artery were absent from the recipient's biopsy sample.

CONCLUSIONS

Umbilical-cord-derived MSCs can be used as clinically feasible and safe induction therapy. Adequate timing and frequency of UC-MSCs administration may have a significant effect on graft and recipient outcomes. Trial registration NCT02490020 . Registered on June 29 2015.

Inflammation, mesenchymal stem cells and bone regeneration

Achieving satisfactory reconstruction of bone remains an important goal in orthopedic and dental conditions such as bone trauma, osteoporosis, arthritis, osteonecrosis, and periodontitis. Appropriate temporal and spatial differentiation of mesenchymal stem cells (MSCs) is essential for postnatal bone regeneration. Additionally, an acute inflammatory response is crucial at the onset of bone repair, while an adaptive immune response has important implications during late bone remodeling. Various reports have indicated bidirectional interactions between MSCs and inflammatory cells or molecules. For example, inflammatory cells can recruit MSCs, direct their migration and differentiation, so as to exert anabolic effects on bone repair. Furthermore, both pro-inflammatory and anti-inflammatory cytokines can regulate MSCs properties and subsequent bone regeneration. MSCs have demonstrated highly immunosuppressive functions, such as inhibiting the differentiation of monocytes/hematopoietic precursors and suppressing the secretion of pro-inflammatory cytokines. This review emphasizes the important interactions between inflammatory stimuli, MSCs, and bone regeneration as well as the underlying regulatory mechanisms. Better understanding of these principles will provide new opportunities for promoting bone regeneration and the treatment of bone loss associated with immunological diseases.

Perineurium-like sheath derived from long-term surviving mesenchymal stem cells confers nerve protection to the injured spinal cord

The functional multipotency enables mesenchymal stem cells (MSCs) promising translational potentials in treating spinal cord injury (SCI). Yet the fate of MSCs grafted into the injured spinal cord has not been fully elucidated even in preclinical studies, rendering concerns of their safety and genuine efficacy. Here we used a rat spinal cord transection model to evaluate the cell fate of allograft bone marrow derived MSCs. With the application of immunosuppressant, donor cells, delivered by biocompatible scaffold, survived up to 8 weeks post-grafting. Discernible tubes formed by MSCs were observed beginning 2 weeks after transplantation and they dominated the morphological features of implanted MSCs at 8 weeks post-grafting. The results of immunocytochemistry and transmission electron microscopy displayed the formation of perineurium-like sheath by donor cells, which, in a manner comparable to the perineurium in peripheral nerve, enwrapped host myelins and axons. The MSC-derived perineurium-like sheath secreted a group of trophic factors and permissive extracellular matrix, and served as a physical and chemical barrier to insulate the inner nerve fibers from ambient oxidative insults by the secretion of soluble antioxidant, superoxide dismutase-3 (SOD3). As a result, many intact regenerating axons were preserved in the injury/graft site following the forming of perineurium-like sheath. A parallel study utilizing a good manufacturing practice (GMP) grade human umbilical cord-derived MSCs or allogenic MSCs in an acute contusive/compressive SCI model exhibited a similar perineurium-like sheath formed by surviving donor cells in rat spinal cord at 3 weeks post-grafting. The present study for the first time provides an unambiguous morphological evidence of perineurium-like sheath formed by transplanted MSCs and a novel therapeutic mechanism of MSCs in treating SCI.

Tissue regeneration: The crosstalk between mesenchymal stem cells and immune response

Mesenchymal stem cells (MSCs) exist in almost all tissues with the capability to differentiate into several different cell types and hold great promise in tissue repairs in a cell replacement manner. The study of the bidirectional regulation between MSCs and immune response has ushered an age of rethinking of tissue regeneration in the process of stem cell-based tissue repairs. By sensing damaged signals, both endogenous and exogenous MSCs migrate to the damaged site where they involve in the reconstitution of the immune microenvironment and empower tissue stem/progenitor cells and other resident cells, whereby facilitate tissue repairs. This MSC-based therapeutic manner is conferred as cell empowerment. In this process, MSCs have been found to exert extensive immunosuppression on both innate and adaptive immune response, while such regulation needs to be licensed by inflammation. More importantly, the immunoregulation of MSCs is highly plastic, especially in the context of pathological microenvironment. Understanding the immunoregulatory properties of MSCs is necessary for appropriate application of MSCs. Here we review the current studies on the crosstalk of MSCs and immune response in disease pathogenesis and therapy.

Allogeneic mesenchymal stem cell as induction therapy to prevent both delayed graft function and acute rejection in deceased donor renal transplantation: study protocol for a randomized controlled trial

Background

Using kidneys from deceased donors is an available strategy to meet the growing need of grafts. However, higher incidences of delayed graft function (DGF) and acute rejection exert adverse effects on graft outcomes. Since ischemia-reperfusion injury (IRI) and ongoing process of immune response to grafts are the major causes of DGF and acute rejection, the optimal induction intervention should possess capacities of both repairing renal structure injury and suppressing immune response simultaneously. Mesenchymal stem cells (MSCs) with potent anti-inflammatory, regenerative and immune-modulatory properties are considered as a candidate to prevent both DGF and acute rejection in renal transplantation. Previous studies just focused on the safety of autologous MSCs on living-related donor renal transplants, and lack of concomitant controls and the sufficient sample size and source of MSCs. Here, we propose a prospective multicenter controlled study to assess the clinical value of allogeneic MSCs in preventing both DGF and acute rejection simultaneously as induction therapy in deceased-donor renal transplantation.

Methods/design

Renal allograft recipients (n = 100) will be recruited and divided into trial and control groups, and 50 patients in the trial group will be administered with a dose of 2 × 10⁶ per kilogram human umbilical-cord-derived MSCs (UC-MSCs) via peripheral vein injection preoperatively, and a dose of 5 × 10⁶ cells via renal arterial injection during surgery, with standard induction therapy. Incidences of postoperative DGF and biopsy-proved acute rejection (BPAR) will be recorded and analyzed. Additionally, other clinical parameters such as baseline demographics, graft and recipient survival and other severe postoperative complications, including complicated urinary tract infection, severe pneumonia, and severe bleeding, will be also assessed.

Discussion

This study will clarify the clinical value of UC-MSCs in preventing DGF and acute rejection simultaneously in deceased-donor renal transplantation, and provide evidence as to whether allogeneic MSCs can be used as clinically feasible and safe induction therapy.

Trial registration

ClinicalTrials.gov, NCT02490020. Registered on 29 June 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2291-y) contains supplementary material, which is available to authorized users.

Interactions between mesenchymal stem cells and the immune system

In addition to being multi-potent, mesenchymal stem cells (MSCs) possess immunomodulatory functions that have been investigated as potential treatments in various immune disorders. MSCs can robustly interact with cells of the innate and adaptive immune systems, either through direct cell-cell contact or through their secretome. In this review, we discuss current findings regarding the interplay between MSCs and different immune cell subsets. We also draw attention to the mechanisms involved.

Adipose Tissue-Derived Mesenchymal Stem Cells Have a Heterogenic Cytokine Secretion Profile

Mesenchymal stem cells derived from adipose tissue (ASC) have immune regulatory function, which makes them interesting candidates for cellular therapy. ASC cultures are however heterogeneous in phenotype. It is unclear whether all ASC contribute equally to immunomodulatory processes. ASC are also responsive to cytokine stimulation, which may affect the ratio between more and less potent ASC populations. In the present study, we determined IL-6 receptor (CD126 and CD130 subunits) and IFN-γ receptor (CD119) expression on ASC by flow cytometry. The production of IL-6 and IFN-γ was measured by ELISA and the frequency of IL-6 and IFN-γ secreting cells by ELISPOT. The results showed that ASC did not express CD126, and only 10–20% of ASC expressed CD130 on their surface, whereas 18–31% of ASC expressed CD119. ASC produced high levels of IL-6 and 100% of ASC were capable of secreting IL-6. Stimulation by IFN-γ or TGF-β had no effect on IL-6 secretion by ASC. IFN-γ was produced by only 1.4% of ASC, and TGF-β significantly increased the frequency to 2.7%. These results demonstrate that ASC cultures are heterogeneous in their cytokine secretion and receptor expression profiles. This knowledge can be employed for selection of potent, cytokine-producing, or responsive ASC subsets for cellular immunotherapy.

Umbilical Cord-derived Mesenchymal Stem Cells Instruct Monocytes Towards an IL10-producing Phenotype by Secreting IL6 and HGF

Human UC-MSCs are regarded as an attractive alternative to BM-MSCs for clinical applications due to their easy preparation, higher proliferation and lower immunogenicity. However, the mechanisms underlying immune suppression by UC-MSCs are still unclear. We studied the mechanism of inhibition by UC-MSCs during the differentiation of monocytes into DCs and focused on the specific source and the role of the involved cytokines. We found that UC-MSCs suppressed monocyte differentiation into DCs and instructed monocytes towards other cell types, with clear decreases in the expression of co-stimulatory molecules, in the secretion of inflammatory factors and in allostimulatory capacity. IL6, HGF and IL10 might be involved in this process because they were detected at higher levels in a coculture system. UC-MSCs produce IL-6 and HGF, and neutralization of IL-6 and HGF reversed the suppressive effect of UC-MSCs. IL10 was not produced by UC-MSCs but was exclusively produced by monocytes after exposure to UC-MSCs, IL-6 or HGF. In summary, we found that the UC-MSC-mediated inhibitory effect was dependent on IL6 and HGF secreted by UC-MSCs and that this effect induced monocyte-derived cells to produce IL10, which might indirectly strengthen the suppressive effect of UC-MSCs.

Systemic Delivery of Bone Marrow Mesenchymal Stem Cells for In Situ Intervertebral Disc Regeneration

Cell therapies for intervertebral disc (IVD) regeneration presently rely on transplantation of IVD cells or stem cells directly to the lesion site. Still, the harsh IVD environment, with low irrigation and high mechanical stress, challenges cell administration and survival. In this study, we addressed systemic transplantation of allogeneic bone marrow mesenchymal stem cells (MSCs) intravenously into a rat IVD lesion model, exploring tissue regeneration via cell signaling to the lesion site. MSC transplantation was performed 24 hours after injury, in parallel with dermal fibroblasts as a control; 2 weeks after transplantation, animals were killed. Disc height index and histological grading score indicated less degeneration for the MSC‐transplanted group, with no significant changes in extracellular matrix composition. Remarkably, MSC transplantation resulted in local downregulation of the hypoxia responsive GLUT‐1 and in significantly less herniation, with higher amounts of Pax5+ B lymphocytes and no alterations in CD68+ macrophages within the hernia. The systemic immune response was analyzed in the blood, draining lymph nodes, and spleen by flow cytometry and in the plasma by cytokine array. Results suggest an immunoregulatory effect in the MSC‐transplanted animals compared with control groups, with an increase in MHC class II+ and CD4+ cells, and also upregulation of the cytokines IL‐2, IL‐4, IL‐6, and IL‐10, and downregulation of the cytokines IL‐13 and TNF‐α. Overall, our results indicate a beneficial effect of systemically transplanted MSCs on in situ IVD regeneration and highlight the complex interplay between stromal cells and cells of the immune system in achieving successful tissue regeneration. Stem Cells Translational Medicine2017;6:1029–1039

Mesenchymal stromal cells and immunomodulation: A gathering of regulatory immune cells

Because of their well-recognized immunomodulatory properties, mesenchymal stromal cells (MSCs) represent an attractive cell population for therapeutic purposes. In particular, there is growing interest in the use of MSCs as cellular immunotherapeutics for tolerance induction in allogeneic transplantations and the treatment of autoimmune diseases. However, multiple mechanisms have been identified to mediate the immunomodulatory effects of MSCs, sometimes with several ambiguities and inconsistencies. Although published studies have mainly reported the role of soluble factors, we believe that a sizeable cellular component plays a critical role in MSC immunomodulation. We refer to these cells as regulatory immune cells, which are generated from both the innate and adaptive responses after co-culture with MSCs. In this review, we discuss the nature and role of these immune regulatory cells as well as the role of different mediators, and, in particular, regulatory immune cell induction by MSCs through interleukin-10. Once induced, immune regulatory cells accumulate and converge their regulatory pathways to create a tolerogenic environment conducive for immunomodulation. Thus, a better understanding of these regulatory immune cells, in terms of how they can be optimally manipulated and induced, would be suitable for improving MSC-based immunomodulatory therapeutic strategies.

Type 1 Diabetes Mellitus Donor Mesenchymal Stromal Cells Exhibit Comparable Potency to Healthy Controls In Vitro

: Bone marrow mesenchymal stromal cells (BM-MSCs) have been characterized and used in many clinical studies based on their immunomodulatory and regenerative properties. We have recently reported the benefit of autologous MSC systemic therapy in the treatment of type 1 diabetes mellitus (T1D). Compared with allogeneic cells, use of autologous products reduces the risk of eliciting undesired complications in the recipient, including rejection, immunization, and transmission of viruses and prions; however, comparable potency of autologous cells is required for this treatment approach to remain feasible. To date, no analysis has been reported that phenotypically and functionally characterizes MSCs derived from newly diagnosed and late-stage T1D donors in vitro with respect to their suitability for systemic immunotherapy. In this study, we used gene array in combination with functional in vitro assays to address these questions. MSCs from T1D donors and healthy controls were expanded from BM aspirates. BM mononuclear cell counts and growth kinetics were comparable between the groups, with equivalent colony-forming unit-fibroblast capacity. Gene microarrays demonstrated differential gene expression between healthy and late-stage T1D donors in relation to cytokine secretion, immunomodulatory activity, and wound healing potential. Despite transcriptional differences, T1D MSCs did not demonstrate a significant difference from healthy controls in immunosuppressive activity, migratory capacity, or hemocompatibility. We conclude that despite differential gene expression, expanded MSCs from T1D donors are phenotypically and functionally similar to healthy control MSCs with regard to their immunomodulatory and migratory potential, indicating their suitability for use in autologous systemic therapy.

SIGNIFICANCE

The potential for mesenchymal stromal cells (MSCs) as a cell-based therapy in the treatment of immunologic disorders has been well established. Recent studies reported the clinical potential for autologous MSCs as a systemic therapy in the treatment of type I diabetes mellitus (T1D). The current study compared the genotypic and phenotypic profiles of bone marrow-derived MSCs from T1D and healthy donors as autologous (compared with allogeneic) therapy provides distinct advantages, such as reduced risk of immune reaction and transmission of infectious agents. The findings of the current study demonstrate that despite moderate differences in T1D MSCs at the gene level, these cells can be expanded in culture to an extent corresponding to that of MSCs derived from healthy donors. No functional difference in terms of immunosuppressive activity, blood compatibility, or migratory capacity was evident between the groups. The study findings also show that autologous MSC therapy holds promise as a T1D treatment and should be evaluated further in clinical trials.

Mesenchymal Stem and Progenitor Cells in Normal and Dysplastic Hematopoiesis-Masters of Survival and Clonality?

Myelodysplastic syndromes (MDS) are malignant hematopoietic stem cell disorders that have the capacity to progress to acute myeloid leukemia (AML). Accumulating evidence suggests that the altered bone marrow (BM) microenvironment in general, and in particular the components of the stem cell niche, including mesenchymal stem cells (MSCs) and their progeny, play a pivotal role in the evolution and propagation of MDS. We here present an overview of the role of MSCs in the pathogenesis of MDS, with emphasis on cellular interactions in the BM microenvironment and related stem cell niche concepts. MSCs have potent immunomodulatory capacities and communicate with diverse immune cells, but also interact with various other cellular components of the microenvironment as well as with normal and leukemic stem and progenitor cells. Moreover, compared to normal MSCs, MSCs in MDS and AML often exhibit altered gene expression profiles, an aberrant phenotype, and abnormal functional properties. These alterations supposedly contribute to the “reprogramming” of the stem cell niche into a disease-permissive microenvironment where an altered immune system, abnormal stem cell niche interactions, and an impaired growth control lead to disease progression. The current article also reviews molecular targets that play a role in such cellular interactions and possibilities to interfere with abnormal stem cell niche interactions by using specific targeted drugs.

Evaluation of Immunomodulatory Effects of Mesenchymal Stem Cells Soluble Factors on miR-155 and miR-23b Expression in Mice Dendritic Cells

Mesenchymal stem cells (MSCs) can modulate dendritic cells (DCs) activation and induce tolerogenic characteristics in DCs. All mechanisms involved in MSCs-induced tolerogenic DCs are not fully understood. MicroRNAs (miRs) play important role in maturation and function of DCs. In this study, we investigated the effects of MSCs culture supernatant (C.S.) on expression of miR-155 and miR-23b in mice DCs. BALB/c mice spleens were used for DCs isolation. MSCs were isolated from the mice bone marrow and cultured in DMEM media. When MSCs expanded to sixth passage, C.S. was collected after 12, 24 and 48 h. Quantitative polymerase chain reaction (QPCR) was used to determine the expression of miR-155 and miR-23b in DCs treated with C.S. after 6 and 12 h. Secretion of IL-23 and TGF- β were detected in DCs treated with C.S. by ELISA after 24 h. miR-23b expression was significantly increased in DCs treated with 12 h C.S. for 12 h compared to negative controls. miR-155 expression did not change in DCs treated with C.S. after 6 and 12 h. miR-23b expression was significantly increased in DCs treated with 12 h C.S. for 12 h, compared to those treated with C.S. for 6 h. Similarly, miR-23b expression was increased in DCs treated with 24 h C.S. for 12 h when compared to those treated for 6 h. Production of TGF-β and IL-23 were not influenced by C.S. In conclusion, miR-23b is considered to be one of the mechanisms involved in tolerogenic DCs induction by C.S. in a time-dependent manner.

The murine Pbx1-d lupus susceptibility allele accelerates mesenchymal stem cell differentiation and impairs their immunosuppressive function

Pre–B cell leukemia homeobox 1 (Pbx1)-d is a dominant-negative splice isoform of the gene Pbx1 that corresponds to the NZM2410 lupus susceptibility locus Sle1a1. Pbx1 is required to maintain stem cell self-renewal, including that of mesenchymal stem cells (MSCs). MSCs have immunosuppressive functions that require stem cell maintenance. We tested the hypothesis that the expression of Pbx1-d favors MSC differentiation and impairs their immunosuppressive functions. We demonstrate that Sle1a1 MSCs express high levels of Pbx1-d as compared with congenic C57BL/6J (B6) MSCs. Sle1a1 MSCs grew faster and differentiated significantly more rapidly into osteoblasts than did B6 MSCs. This corresponded to a significant decrease in the expression of genes associated with stemness and an increase in the expression of genes associated with differentiation. Additionally, Sle1a1 MSCs express a gene expression profile associated with an enhanced innate immunity and inflammation. Suppression of Ig production from TLR-activated B6 B cells and IL-2 secretion from activated B6 CD4+ T cells was significantly impaired in Sle1a1 MSCs as compared with B6 MSCs. B6.Sle1a1 MSCs showed intermediate activity in suppressing lupus immunophenotypes in three different mouse models. Taken together, these data suggest that the expression of the lupus susceptibility allele Pbx1-d isoform impairs MSC functions, which may contribute to lupus pathogenesis both through a defective immunosuppression and the promotion of a proinflammatory environment.

Hepatic carcinoma-associated fibroblasts induce IDO-producing regulatory dendritic cells through IL-6-mediated STAT3 activation

Although carcinoma-associated fibroblasts (CAFs) in tumor microenvironments have a critical role in immune cell modulation, their effects on the generation of regulatory dendritic cells (DCs) are still unclear. In this study, we initially show that CAFs derived from hepatocellular carcinoma (HCC) tumors facilitate the generation of regulatory DCs, which are characterized by low expression of costimulatory molecules, high suppressive cytokines production and enhanced regulation of immune responses, including T-cell proliferation impairment and promotion of regulatory T-cell (Treg) expansion via indoleamine 2,3-dioxygenase (IDO) upregulation. Our findings also indicate that STAT3 activation in DCs, as mediated by CAF-derived interleukin (IL)-6, is essential to IDO production. Moreover, IDO inhibitor, STAT3 and IL-6 blocking antibodies can reverse this hepatic CAF-DC regulatory function. Therefore, our results provide new insights into the mechanisms by which CAFs induce tumor immune escape as well as a novel cancer immunotherapeutic approach (for example, targeting CAFs, IDO or IL-6).

Hepatic carcinoma-associated fibroblasts induce IDO-producing regulatory dendritic cells through IL-6-mediated STAT3 activation

Although carcinoma-associated fibroblasts (CAFs) in tumor microenvironments have a critical role in immune cell modulation, their effects on the generation of regulatory dendritic cells (DCs) are still unclear. In this study, we initially show that CAFs derived from hepatocellular carcinoma (HCC) tumors facilitate the generation of regulatory DCs, which are characterized by low expression of costimulatory molecules, high suppressive cytokines production and enhanced regulation of immune responses, including T-cell proliferation impairment and promotion of regulatory T-cell (Treg) expansion via indoleamine 2,3-dioxygenase (IDO) upregulation. Our findings also indicate that STAT3 activation in DCs, as mediated by CAF-derived interleukin (IL)-6, is essential to IDO production. Moreover, IDO inhibitor, STAT3 and IL-6 blocking antibodies can reverse this hepatic CAF-DC regulatory function. Therefore, our results provide new insights into the mechanisms by which CAFs induce tumor immune escape as well as a novel cancer immunotherapeutic approach (for example, targeting CAFs, IDO or IL-6).

Immunogenicity of allogeneic mesenchymal stromal cells: what has been seen in vitro and in vivo?

Mesenchymal stromal cells (MSC) are promising candidates for supporting regeneration and suppressing undesired immune reactivity. Although autologous MSC have been most commonly used for clinical trials, data on application of allogeneic MHC-unmatched MSC were reported. The usage of MSC as an 'off-the-shelf' product would have several advantages; however, it is an immunological challenge. The preclinical studies on the (non)immunogenicity of MSC are contradictory and, unfortunately, solid data from clinical trials are missing. Induction of an alloresponse would be a major limitation for the application of allogeneic MSC. Here we discuss the key elements for the induction of an alloresponse and targets of immunomodulation by MSC as well as preclinical and clinical hints on allo(non)response to MSC.

Umbilical Cord as Prospective Source for Mesenchymal Stem Cell-Based Therapy

The paper presents current evidence on the properties of human umbilical cord-derived mesenchymal stem cells, including origin, proliferative potential, plasticity, stability of karyotype and phenotype, transcriptome, secretome, and immunomodulatory activity. A review of preclinical studies and clinical trials using this cell type is performed. Prospects for the use of mesenchymal stem cells, derived from the umbilical cord, in cell transplantation are associated with the need for specialized biobanking and transplant standardization criteria.