Hepatocyte growth factor mediates mesenchymal stem cell–induced recovery in multiple sclerosis models. Nat Neurosci. 2012;15:862-870. [PMID: 22610068 PMCID: PMC3427471 DOI: 10.1038/nn.3109]

Transcriptomic Analysis of Human Mesenchymal Stem Cell Therapy in Incontinent Rat Injured Urethra

Periurethral human mesenchymal stem cell (hMSC) injections are associated with functional improvement in animal models of postpartum stress urinary incontinence (SUI). However, limited data exist on the role of hMSCs in modulating gene expression in tissue repair after urethral injury. To this end, we quantified temporal gene expression modulation in hMSCs, and in injured rat urethral tissue, using RNA-seq in an animal model of SUI, over a 3-day period following urethral injury, and local hMSC injection. We injected PKH fluorescent-labeled hMSC into the periurethral space of rats following a 4 h vaginal distention (VD) (three rats per time point). Control rats underwent VD injury only, and all animals were euthanized at 12, 24, 36, 72 h postinjury. Rat urethral and vaginal tissues were frozen and sectioned. Fluorescent labeled hMSCs were distinguished from adjacent, unlabeled rat urethral tissue. RNA was prepared from hMSCs and urethral tissue obtained by laser dissection of frozen tissue sections and sequenced on an Illumina HiSeq 2500. Differentially expressed genes (DEGs) over 72 h were evaluated using a two-group t-test (p < 0.05). Our transcriptional analyses identified candidate genes involved in tissue injury that were broadly sorted by injury and exposure to hMSC throughout the first 72 h of acute phase of injury. DEGs in treated urethra, compared with untreated urethra, were functionally associated with tissue repair, angiogenesis, neurogenesis, and oxidative stress suppression. DEGs included a variety of cytokines, extracellular matrix stabilization and regeneration genes, cytokine signaling modification, cell cycle regulation, muscle differentiation, and stabilization. Moreover, our results revealed DEG changes in hMSCs (PKH-labeled) harvested from injured urethra. The expressions are related to DNA damage repair, transcription activation, stem cell regulation, cell survival, apoptosis, self-renewal, cell proliferation, migration, and injury response. Impact statement Stress urinary incontinence (SUI) affects nearly half of women over 40, resulting in reduced quality of life and increased health care cost. Development of SUI is multifactorial and strongly associated with vaginal delivery. While stem cell therapy in animal models of SUI and limited preliminary clinical trials demonstrate functional improvement of SUI, the role of stem cell therapy in modulating tissue repair is unclear impeding advanced clinical trials. Our work provides a new understanding of the transcriptional mechanisms with which human mesenchymal stem cells improve acute injury repair thus guiding the development of cell-based therapies for women with nonacute established SUI.

Mesenchymal Stem Cells Attenuated Blood-Brain Barrier Disruption via Downregulation of Aquaporin-4 Expression in EAE Mice

Blood-brain barrier disruption is one of the hallmarks of multiple sclerosis. Mesenchymal stem cells showed great potential for the multiple sclerosis therapy. However, the effect of mesenchymal stem cells on blood-brain barrier in multiple sclerosis remains unclear. Here, we investigated whether mesenchymal stem cells transplantation protected blood-brain barrier integrity and further explored possible underlying mechanisms. Adult female C57BL/6 mice were immunized with myelin oligodendrocyte glycoprotein peptide33-55 (MOG33-55) to induce experimental autoimmune encephalomyelitis (EAE). Mesenchymal stem cells (5 × 10⁵) were transplanted via tail vein at disease onset. In the cell culture, we examined lipopolysaccharide-induced AQP4 upregulation in astrocytes. Results indicated that mesenchymal stem cells therapy improved neurobehavioral outcomes in EAE mice, reduced inflammatory cell infiltration, IgG protein leakage, and demyelination in spinal cord. Mesenchymal stem cells therapy also increased tight junction protein expression. In addition, mesenchymal stem cells downregulated AQP4 and A_2B adenosine receptor (A_2BAR) expression in EAE mice in spinal cord. We found that MSCs-conditioned medium (MCM) reduced the expression of inflammatory cytokines, AQP4 and A_2BAR in lipopolysaccharide-activated astrocytes. BAY-60-6583 (a selective A_2BAR agonist) reversed the MCM-induced AQP4 downregulation and increased p38 MAPK phosphorylation. Furthermore, the upregulation effects of A_2BAR agonist were eliminated when treated with p38 MAPK inhibitor SB203580. Thus, we concluded that mesenchymal stem cells alleviated blood-brain barrier disruption by downregulating AQP4 in multiple sclerosis, possibly through inhibiting the A_2BAR/p38 MAPK signaling pathway. Our work suggests that mesenchymal stem cells exert beneficial effect through maintaining blood-brain barrier integrity in EAE mice.

Mesenchymal stromal cells (MSCs) for neurodegenerative disease: A promising frontier

Neurodegenerative disorders are a variety of diseases including Alzheimer's (AD), Parkinson's (PD), and Huntington's diseases (HD), multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS) along with some other less common diseases generally described by the advanced deterioration of central or peripheral nervous system, structurally or functionally. In the last two decades, mesenchymal stromal cells (MSCs) due to their unique assets encompassing self-renewal, multipotency and accessibility in association with low ethical concern open new frontiers in the context of neurodegenerative diseases therapy. Interestingly, MSCs can be differentiated into endodermal and ectodermal lineages (e.g., neurons, oligodendrocyte, and astrocyte), and thus could be employed to advance cell-based therapeutic strategy. Additionally, as inflammation ordinarily ensues as a local response provoked by microglia in the neurodegenerative diseases, MSCs therapy because of their pronounced immunomodulatory properties is noticed as a rational approach for their treatment. Recently, varied types of studies have been mostly carried out in vitro and rodent models using MSCs upon their procurement from various sources and expansion. The promising results of the studies in rodent models have motivated researchers to design and perform several clinical trials, with a speedily rising number. In the current review, we aim to deliver a brief overview of MSCs sources, expansion strategies, and their immunosuppressive characteristics and discuss credible functional mechanisms exerted by MSCs to treat neurodegenerative disorders, covering AD, PD, ALS, MS, and HD.

Changes of immune parameters of T lymphocytes and macrophages in EAE mice after BM-MSCs transplantation

Multiple sclerosis (MS) is an autoimmune disease characterized by inflammatory infiltration, demyelination and axonal injury. Mesenchymal stem cells (MSCs) are pluripotent which can not only differentiate into many types of cells, but also have immunomodulatory effects. We show here that the transplantation of bone marrow MSCs (BM-MSCs) prevents the development of experimental autoimmune encephalomyelitis (EAE), the most common animal model of MS. Furthermore, we demonstrate that the immunologic mechanism by which BM-MSC transplantation ameliorates EAE involves inhibiting the proliferation and activation of T cells, reducing the production of inflammatory cytokines, and regulating macrophage responses, especially the macrophage polarization. The findings broaden our understanding about the regulation of T cell and macrophage immune responses by MSC transplantation.

DNA methylation and demethylation link the properties of mesenchymal stem cells: Regeneration and immunomodulation

Mesenchymal stem cells (MSCs) are a heterogeneous population that can be isolated from various tissues, including bone marrow, adipose tissue, umbilical cord blood, and craniofacial tissue. MSCs have attracted increasingly more attention over the years due to their regenerative capacity and function in immunomodulation. The foundation of tissue regeneration is the potential of cells to differentiate into multiple cell lineages and give rise to multiple tissue types. In addition,the immunoregulatory function of MSCs has provided insights into therapeutic treatments for immune-mediated diseases. DNA methylation and demethylation are important epigenetic mechanisms that have been shown to modulate embryonic stem cell maintenance, proliferation, differentiation and apoptosis by activating or suppressing a number of genes. In most studies, DNA hypermethylation is associated with gene suppression, while hypomethylation or demethylation is associated with gene activation. The dynamic balance of DNA methylation and demethylation is required for normal mammalian development and inhibits the onset of abnormal phenotypes. However, the exact role of DNA methylation and demethylation in MSC-based tissue regeneration and immunomodulation requires further investigation. In this review, we discuss how DNA methylation and demethylation function in multi-lineage cell differentiation and immunomodulation of MSCs based on previously published work. Furthermore, we discuss the implications of the role of DNA methylation and demethylation in MSCs for the treatment of metabolic or immune-related diseases.

Inflammation-related plasma and CSF biomarkers for multiple sclerosis

Effective biomarkers for multiple sclerosis diagnosis, assessment of prognosis, and treatment responses, in particular those measurable in blood, are largely lacking. We have investigated a broad set of protein biomarkers in cerebrospinal fluid (CSF) and plasma using a highly sensitive proteomic immunoassay. Cases from two independent cohorts were compared with healthy controls and patients with other neurological diseases. We identified and replicated 10 cerebrospinal fluid proteins including IL-12B, CD5, MIP-1a, and CXCL9 which had a combined diagnostic efficacy similar to immunoglobulin G (IgG) index and neurofilament light chain (area under the curve [AUC] = 0.95). Two plasma proteins, OSM and HGF, were also associated with multiple sclerosis in comparison to healthy controls. Sensitivity and specificity of combined CSF and plasma markers for multiple sclerosis were 85.7% and 73.5%, respectively. In the discovery cohort, eotaxin-1 (CCL11) was associated with disease duration particularly in patients who had secondary progressive disease (P _CSF < 4 × 10^-5, P _plasma < 4 × 10^-5), and plasma CCL20 was associated with disease severity (P = 4 × 10^-5), although both require further validation. Treatment with natalizumab and fingolimod showed different compartmental changes in protein levels of CSF and peripheral blood, respectively, including many disease-associated markers (e.g., IL12B, CD5) showing potential application for both diagnosing disease and monitoring treatment efficacy. We report a number of multiple sclerosis biomarkers in CSF and plasma for early disease detection and potential indicators for disease activity. Of particular importance is the set of markers discovered in blood, where validated biomarkers are lacking.

Tetramethylpyrazine enhanced the therapeutic effects of human umbilical cord mesenchymal stem cells in experimental autoimmune encephalomyelitis mice through Nrf2/HO-1 signaling pathway

INTRODUCTION

The therapeutic effects of mesenchymal stem cells (MSCs) have been limited by their apoptosis induced by oxidative stress after delivery into the injured sites. Therefore, strategies designed to improve the MSC therapeutic efficacy need to be explored. Tetramethylpyrazine (TMP) can promote the proliferation and differentiation of neural stem cells. In this study, we first evaluated the effects and mechanism of TMP on H₂O₂-stimulated human umbilical cord MSCs (hUCMSCs) and then further investigated the therapeutic effects of TMP-stimulated hUCMSCs on experimental autoimmune encephalomyelitis (EAE) mice.

METHODS

The toxicity of hUCMSCs against of TMP was determined by cell count kit-8 (CCK-8) assay. The effects of TMP on the hUCMSC cell cycle, the reactive oxygen species (ROS) production, and the apoptosis of H₂O₂-stimulated hUCMSCs were determined by flow cytometry. The expression of malondialdehyde (MDA) and superoxide dismutase (SOD) were also measured by colorimetry. The signaling pathway of TMP induced on H₂O₂-stimulated hUCMSCs was investigated by western blot. EAE was induced using immunization with MOG35-55 in C57BL/6 mice. The inflammatory cell infiltration and demyelination were detected by immunofluorescence staining. The blood-brain barrier (BBB) disruption was detected by Evans blue (EB) stain and the expression of tight junction protein (ZO-1) by western blot.

RESULTS

TMP significantly increased cell viability and changed the cell cycle of hUCMSCs. In addition, TMP (100 μM) significantly reduced intracellular ROS production, expression of MDA, and apoptosis, but increased expression of SOD through nuclear factor-erythroid 2-related factor-2 (Nrf2)/heme oxygenase 1 (HO-1) signaling pathway in H₂O₂-stimulated hUCMSCs. Most importantly, compared with wild hUCMSCs, TMP-stimulated hUCMSCs significantly ameliorated EAE, by attenuation of inflammation, demyelination, and BBB disruption.

CONCLUSION

The TMP-stimulated hUCMSCs provide a potential therapeutical protocol to enhance the therapeutic effects of hUCMSCs in multiple sclerosis.

Intra-Amniotic Delivery of CRMP4 siRNA Improves Mesenchymal Stem Cell Therapy in a Rat Spina Bifida Model

Neural tube defects (NTDs) result in prenatal mortality and lifelong morbidity, and available treatments have limited efficacy. We previously suggested that prenatal bone marrow-derived mesenchymal stem cell (BMSC) transplantation could treat neuron deficiency in NTD rats; however, BMSC-based therapy is limited by the low survival rate of BMSCs when used to treat severe NTDs. Herein, a new therapy using combined BMSC transplantation and small interfering RNA of collapsin response mediator protein 4 (CRMP4 siRNA), which was identified as a novel potential target for the NTD treatment, is proposed. The intra-amniotic CRMP4 siRNA, BMSC, and CRMP4 siRNA + BMSC injections repaired skin lesions, improved motor neural function, reduced neuronal apoptosis, and promoted expression of neural differentiation-related molecules and neurotrophic factors in the spinal cord of spina bifida rat fetuses. Therapeutic effects in the CRMP4 siRNA + BMSC injection group were superior to those of the CRMP4 siRNA only or BMSC only injection groups. CRMP4 siRNA + BMSC injection resulted in a 45.38% reduction in the skin lesion area and significantly shorter latency and higher amplitude of motor-evoked potentials (MEPs) in spina bifida fetuses. Our results suggest that intrauterine Ad-CRMP4 siRNA delivery with BMSCs is an innovative platform for developing fetal therapeutics to safely and efficaciously treat NTDs.

Inhalation of lung spheroid cell secretome and exosomes promotes lung repair in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal and incurable form of interstitial lung disease in which persistent injury results in scar tissue formation. As fibrosis thickens, the lung tissue loses the ability to facilitate gas exchange and provide cells with needed oxygen. Currently, IPF has few treatment options and no effective therapies, aside from lung transplant. Here we present a series of studies utilizing lung spheroid cell-secretome (LSC-Sec) and exosomes (LSC-Exo) by inhalation to treat different models of lung injury and fibrosis. Analysis reveals that LSC-Sec and LSC-Exo treatments could attenuate and resolve bleomycin- and silica-induced fibrosis by reestablishing normal alveolar structure and decreasing both collagen accumulation and myofibroblast proliferation. Additionally, LSC-Sec and LSC-Exo exhibit superior therapeutic benefits than their counterparts derived from mesenchymal stem cells in some measures. We showed that an inhalation treatment of secretome and exosome exhibited therapeutic potential for lung regeneration in two experimental models of pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease and adult lung spheroid cells have been shown to promote regeneration in animal models of IPF. Here the authors show that the secretome and exosomes of lung spheroid cells is effective as inhalation treatment in rodent models of lung injury and fibrosis and superior to the counterparts derived from mesenchymal stem cells.

c-Met is expressed by highly autoreactive encephalitogenic CD8+ cells

Background

CD8⁺ T lymphocytes are critical mediators of neuroinflammatory diseases. Understanding the mechanisms that govern the function of this T cell population is crucial to better understanding central nervous system autoimmune disease pathology. We recently identified a novel population of highly cytotoxic c-Met-expressing CD8⁺ T lymphocytes and found that hepatocyte growth factor (HGF) limits effective murine cytotoxic T cell responses in cancer models. Here, we examined the role of c-Met-expressing CD8⁺ T cells by using a MOG_35–55 T cell-mediated EAE model.

Methods

Mice were subcutaneously immunized with myelin oligodendrocyte glycoprotein peptide (MOG)_35–55 in complete Freund’s adjuvant (CFA). Peripheral and CNS inflammation was evaluated at peak disease and chronic phase, and c-Met expression by CD8 was evaluated by flow cytometry and immunofluorescence. Molecular, cellular, and killing function analysis were performed by real-time PCR, ELISA, flow cytometry, and killing assay.

Results

In the present study, we observed that a fraction of murine effector CD8⁺ T cells expressed c-Met receptor (c-Met⁺CD8⁺) in an experimental autoimmune encephalitis (EAE) model. Phenotypic and functional analysis of c-Met⁺CD8⁺ T cells revealed that they recognize the encephalitogenic epitope myelin oligodendrocyte glycoprotein_37–50. We demonstrated that this T cell population produces higher levels of interferon-γ and granzyme B ex vivo and that HGF directly restrains the cytolytic function of c-Met⁺CD8⁺ T cells in cell-mediated cytotoxicity reactions

Conclusions

Altogether, our findings suggest that the HGF/c-Met pathway could be exploited to modulate CD8⁺ T cell-mediated neuroinflammation.

Mesenchymal stromal cell based therapies for the treatment of immune disorders: recent milestones and future challenges

Introduction: Mesenchymal stromal cells (MSCs) present unique immunomodulatory properties that make them promising candidates for the treatment of inflammatory and immune disorders. MSC-mediated immunomodulation is a complex combination of mechanisms, in which the secretome plays a fundamental role. The plethora of bioactive molecules MSCs produce, such as indoleamine 2,3-dioxygenase (IDO) or prostaglandin E2 (PGE2), efficiently regulates innate and adaptive immunity. As a result, MSCs have been extensively employed in preclinical studies, leading to the conduction of multiple clinical trials.Areas covered: This review summarizes the effects of some of the key biomolecules in the MSC secretome and the advances in preclinical studies exploring the treatment of disorders including graft-versus-host disease (GvHD) or inflammatory bowel disease (IBD). Further, late-stage clinical trials and the first MSC-based therapies that recently obtained regulatory approval are discussed.Expert opinion: Extensive research supports the potential of MSC-based immunomodulatory therapies. However, to establish the bases for clinical translation, the future of study lies in the standardization of protocols and in the development of strategies that boost the therapeutic properties of MSCs.

Mesenchymal stem cell perspective: cell biology to clinical progress

The terms MSC and MSCs have become the preferred acronym to describe a cell and a cell population of multipotential stem/progenitor cells commonly referred to as mesenchymal stem cells, multipotential stromal cells, mesenchymal stromal cells, and mesenchymal progenitor cells. The MSCs can differentiate to important lineages under defined conditions in vitro and in limited situations after implantation in vivo. MSCs were isolated and described about 30 years ago and now there are over 55,000 publications on MSCs readily available. Here, we have focused on human MSCs whenever possible. The MSCs have broad anti-inflammatory and immune-modulatory properties. At present, these provide the greatest focus of human MSCs in clinical testing; however, the properties of cultured MSCs in vitro suggest they can have broader applications. The medical utility of MSCs continues to be investigated in over 950 clinical trials. There has been much progress in understanding MSCs over the years, and there is a strong foundation for future scientific research and clinical applications, but also some important questions remain to be answered. Developing further methods to understand and unlock MSC potential through intracellular and intercellular signaling, biomedical engineering, delivery methods and patient selection should all provide substantial advancements in the coming years and greater clinical opportunities. The expansive and growing field of MSC research is teaching us basic human cell biology as well as how to use this type of cell for cellular therapy in a variety of clinical settings, and while much promise is evident, careful new work is still needed.

Characteristic differences of cell sheets composed of mesenchymal stem cells with different tissue origins

INTRODUCTION

Stem cell therapy with mesenchymal stem cells (MSCs) has been widely used in many clinical trials, and therapy with MSC sheets shows promise for patients. However, there are few reports characterizing MSC sheets. In the present study, the properties of MSC sheets derived from bone marrow, adipose tissue, and umbilical cord were evaluated.

METHODS

Cell sheets were fabricated with MSCs from different tissue origins in temperature-responsive cell culture dishes with and without pre-coating of fetal bovine serum (FBS). MSC adhesion behavior in the culture dish was observed. Secretion of cytokines related to cell proliferation and immune regulation from MSC sheets was investigated by ELISA. The adhesion properties of the MSC sheets were investigated by time-lapse microscopy.

RESULTS

Different cell adhesion and proliferation rates in temperature-responsive cell culture dishes were observed among the three types of MSCs. FBS pre-coating of the dishes enhanced cell attachment and proliferation in all cell types. Harvested cell sheets showed high attachment capacity to tissue culture polystyrene dish surfaces.

CONCLUSIONS

MSC sheets can be fabricated from MSCs from different tissue origins using temperature-responsive cell culture dishes. The fabricated MSC sheets could be useful in cell transplantation therapies by choosing appropriate types of MSCs that secrete therapeutic cytokines for the targeted diseases.

Conditioned Medium of Mesenchymal Stromal Cells: A New Class of Therapeutics

Mesenchymal stromal cell (MSCs) represent a class of biologics with the prospects for employment as immunomodulatory, tissue-protective, and regenerative therapeutics. In parallel with cellular therapy, cell-free therapy based on MSC-secreted bioactive factors is being actively developed. MSCs secrete a variety of protein, peptide, RNA, and lipid mediators which can be concentrated, frozen, or even lyophilized without loss of activity, which gives them a certain advantage over cellular products requiring liquid nitrogen storage and infrastructure to revive frozen cells. This review (i) describes currently conducted clinical trials of cell-free products containing MSC secretome; (ii) summarizes main approaches to the generation and characterization of conditioned media concentrates and extracellular vesicle isolates; (iii) analyzes a variety of preclinical studies where effectiveness of secretome products has been shown; and (iv) summarizes current knowledge about secretome bioactive components obtained by analysis of in vivo models testing the therapeutic potential of the MSC secretome.

Placental Mesenchymal Stem Cell-Derived Extracellular Vesicles Promote Myelin Regeneration in an Animal Model of Multiple Sclerosis

Mesenchymal stem/stromal cells (MSCs) display potent immunomodulatory and regenerative capabilities through the secretion of bioactive factors, such as proteins, cytokines, chemokines as well as the release of extracellular vesicles (EVs). These functional properties of MSCs make them ideal candidates for the treatment of degenerative and inflammatory diseases, including multiple sclerosis (MS). MS is a heterogenous disease that is typically characterized by inflammation, demyelination, gliosis and axonal loss. In the current study, an induced experimental autoimmune encephalomyelitis (EAE) murine model of MS was utilized. At peak disease onset, animals were treated with saline, placenta-derived MSCs (PMSCs), as well as low and high doses of PMSC-EVs. Animals treated with PMSCs and high-dose PMSC-EVs displayed improved motor function outcomes as compared to animals treated with saline. Symptom improvement by PMSCs and PMSC-EVs led to reduced DNA damage in oligodendroglia populations and increased myelination within the spinal cord of treated mice. In vitro data demonstrate that PMSC-EVs promote myelin regeneration by inducing endogenous oligodendrocyte precursor cells to differentiate into mature myelinating oligodendrocytes. These findings support that PMSCs’ mechanism of action is mediated by the secretion of EVs. Therefore, PMSC-derived EVs are a feasible alternative to cellular based therapies for MS, as demonstrated in an animal model of the disease.

The combination of mannitol and temozolomide increases the effectiveness of stem cell treatment in a chronic stroke model

BACKGROUND

The blood-brain barrier (BBB) presents a significant challenge to the therapeutic efficacy of stem cells in chronic stroke. Various methods have been developed to increase BBB permeability, but these are associated with adverse effects and are, therefore, not clinically applicable. We recently identified that combination drug treatment of mannitol and temozolomide improved BBB permeability in vitro. Here, we investigated whether this combination could increase the effectiveness of stem cell treatment in an animal model of chronic ischemic stroke.

METHODS

Chronic stroke was induced in rats by middle cerebral artery occlusion (MCAo). After then, rats were administered human umbilical cord-derived mesenchymal stromal cells (hUC-MSCs) by intravenous injection with or without combination drug treatment of mannitol and temozolomide. To evaluate the therapeutic efficacy, behavioral and immunohistochemical tests were performed, and the differences among control, stem cell only, combination drug only and stem cell with combination drug treatment were analyzed.

RESULTS

Although no hUC-MSCs were detected in any group, treatment with stem cells and combination drug of mannitol and temozolomide increased the intracerebral delivery of hCD63-positive microvesicles compared with stem cell only treatment. Furthermore, treatment with stem cells and drug combination ameliorated behavioral deficits and increased bromodeoxyuridine-, doublecortin- and Reca-1-positive cells in the perilesional area as compared with other groups.

DISCUSSION

The combination drug treatment of mannitol and temozolomide allowed for the efficient delivery of hUC-MSC-derived microvesicles into the brain in a chronic stroke rat model. This attenuated behavioral deficits, likely by improving neural regeneration and angiogenesis. Thus, combination drug treatment of mannitol and temozolomide could be a novel therapeutic option for patients with chronic ischemic stroke.

Autophagy inhibition via Becn1 downregulation improves the mesenchymal stem cells antifibrotic potential in experimental liver fibrosis

Liver fibrosis (LF) is the result of a vicious cycle between inflammation-induced chronic hepatocyte injury and persistent activation of hepatic stellate cells (HSCs). Mesenchymal stem cell (MSC)-based therapy may represent a potential remedy for treatment of LF. However, the fate of transplanted MSCs in LF remains largely unknown. In the present study, the fate and antifibrotic effect of MSCs were explored in a LF model induced by CCl₄ in mouse. Additionally, MSCs were stimulated in vitro with LF-associated factors, tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and transforming growth factor-β1 (TGF-β1), to mimic the LF microenvironment. We unveiled that MSCs exhibited autophagy in response to the LF microenvironment through Becn1 upregulation both in vivo and in vitro. However, autophagy suppression induced by Becn1 knockdown in MSCs resulted in enhanced antifibrotic effects on LF. The improved antifibrotic potential of MSCs may be attributable to their inhibitory effects on T lymphocyte infiltration, HSCs proliferation, as well as production of TNF-α, IFN-γ, and TGF-β1, which may be partially mediated by elevated paracrine secretion of PTGS2/PGE₂ . Thus, autophagy manipulation in MSCs may be a novel strategy to promote their antifibrotic efficacy.

The potential use of mesenchymal stem cells for the treatment of multiple sclerosis

Multiple sclerosis (MS) is a chronic autoimmune inflammatory disease of the central nervous system (CNS). In attempt to identify an appropriate treatment for improving the neurological symptoms and remyelination process, autologous and allogenic transplantation of mesenchymal stem cells (MSCs) have been introduced as an effective therapeutic strategy in MS. MSCs are a heterogeneous subset of pluripotent non-hematopoietic stromal cells that are isolated from bone marrow, adipose tissue, placenta and other sources. MSCs have considerable therapeutic effects due to their ability in differentiation, migration, immune-modulation and neuroregeneration. To date, numerous experimental and clinical studies demonstrated that MSCs therapy improves the CNS repair and modulates functional neurological symptoms. Here, we provided an overview of the current knowledge about the clinical applications of MSCs in MS. Furthermore, the major challenges and risks of MSCs therapy in MS patients have been elucidated.

Immunoregulatory mechanisms of mesenchymal stem and stromal cells in inflammatory diseases

Mesenchymal stem cells (MSCs; also referred to as mesenchymal stromal cells) have attracted much attention for their ability to regulate inflammatory processes. Their therapeutic potential is currently being investigated in various degenerative and inflammatory disorders such as Crohn's disease, graft-versus-host disease, diabetic nephropathy and organ fibrosis. The mechanisms by which MSCs exert their therapeutic effects are multifaceted, but in general, these cells are thought to enable damaged tissues to form a balanced inflammatory and regenerative microenvironment in the presence of vigorous inflammation. Studies over the past few years have demonstrated that when exposed to an inflammatory environment, MSCs can orchestrate local and systemic innate and adaptive immune responses through the release of various mediators, including immunosuppressive molecules, growth factors, exosomes, chemokines, complement components and various metabolites. Interestingly, even nonviable MSCs can exert beneficial effects, with apoptotic MSCs showing immunosuppressive functions in vivo. Because the immunomodulatory capabilities of MSCs are not constitutive but rather are licensed by inflammatory cytokines, the net outcomes of MSC activation might vary depending on the levels and the types of inflammation within the residing tissues. Here, we review current understanding of the immunomodulatory mechanisms of MSCs and the issues related to their therapeutic applications.

Aging restricts the ability of mesenchymal stem cells to promote the generation of oligodendrocytes during remyelination

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS) that leads to severe neurological deficits. Due to their immunomodulatory and neuroprotective activities and their ability to promote the generation of oligodendrocytes, mesenchymal stem cells (MSCs) are currently being developed for autologous cell therapy in MS. As aging reduces the regenerative capacity of all tissues, it is of relevance to investigate whether MSCs retain their pro-oligodendrogenic activity with increasing age. We demonstrate that MSCs derived from aged rats have a reduced capacity to induce oligodendrocyte differentiation of adult CNS stem/progenitor cells. Aging also abolished the ability of MSCs to enhance the generation of myelin-like sheaths in demyelinated cerebellar slice cultures. Finally, in a rat model for CNS demyelination, aging suppressed the capability of systemically transplanted MSCs to boost oligodendrocyte progenitor cell (OPC) differentiation during remyelination. Thus, aging restricts the ability of MSCs to support the generation of oligodendrocytes and consequently inhibits their capacity to enhance the generation of myelin-like sheaths. These findings may impact on the design of therapies using autologous MSCs in older MS patients.

Effect of mesenchymal stem cells on glial cells population in cuprizone induced demyelination model

Mesenchymal stem cells (MSCs) have a notable potential to modulate immune responses and protect the central nervous system (CNS), mostly by secreting factors that affect inflammation. MSCs have the ability to improve several autoimmune diseases in animal models including multiple sclerosis (MS). MS is a disease of the CNS among adult humans and it is characterized by demyelination, neuroinflammation and gliosis. In this study, we first induced chronic demyelination by cuprizone, followed by intraventricular injection of MSC. Our results showed that MSC significantly decreased microgliosis and astrocytosis by secreting cytokines that have neuroprotective activity including TGF-β and CX3CL1. Also, downregulation of IL-1β and TNF-α as inflammatory chemokines was seen along with decreased astrocytes and microglia activation. Finally, these results showed that trophic factors secreted by MSC can increase oligodendrocyte population and remyelination rate by reducing pro-inflammatory factors. These findings demonstrate that MSC could decrease inflammation, gliosis and demyelination with neuroprotective and immunomodulating properties in chronic cuprizone demyelination model. Therefore MSC transplantation can be considered as a suitable approach for enhancing myelination and reducing inflammation in diseases such as MS.

Engineered delivery strategies for enhanced control of growth factor activities in wound healing

Growth factors (GFs) are versatile signalling molecules that orchestrate the dynamic, multi-stage process of wound healing. Delivery of exogenous GFs to the wound milieu to mediate healing in an active, physiologically-relevant manner has shown great promise in laboratories; however, the inherent instability of GFs, accompanied with numerous safety, efficacy and cost concerns, has hindered the clinical success of GF delivery. In this article, we highlight that the key to overcoming these challenges is to enhance the control of the activities of GFs throughout the delivering process. We summarise the recent strategies based on biomaterials matrices and molecular engineering, which aim to improve the conditions of GFs for delivery (at the 'supply' end of the delivery), increase the stability and functions of GFs in extracellular matrix (in transportation to target cells), as well as enhance the GFs/receptor interaction on the cell membrane (at the 'destination' end of the delivery). Many of these investigations have led to encouraging outcomes in various in vitro and in vivo regenerative models with considerable translational potential.

Early Developmental Zebrafish Embryo Extract to Modulate Senescence in Multisource Human Mesenchymal Stem Cells

Stem cells undergo senescence both in vivo, contributing to the progressive decline in self-healing mechanisms, and in vitro during prolonged expansion. Here, we show that an early developmental zebrafish embryo extract (ZF1) could act as a modulator of senescence in human mesenchymal stem cells (hMSCs) isolated from both adult tissues, including adipose tissue (hASCs), bone marrow (hBM-MSCs), dental pulp (hDP-MSCs), and a perinatal tissue such as the Wharton’s Jelly (hWJ-MSCs). In all the investigated hMSCs, ZF1 decreased senescence-associated β-galactosidase (SA β-gal) activity and enhanced the transcription of TERT, encoding the catalytic telomerase core. In addition, it was associated, only in hASCs, with a transcriptional induction of BMI1, a pleiotropic repressor of senescence. In hBM-MSCs, hDP-MSCs, and hWJ-MSCs, TERT over-expression was concomitant with a down-regulation of two repressors of TERT, TP53 (p53), and CDKN1A (p21). Furthermore, ZF1 increased the natural ability of hASCs to perform adipogenesis. These results indicate the chance of using ZF1 to modulate stem cell senescence in a source-related manner, to be potentially used as a tool to affect stem cell senescence in vitro. In addition, its anti-senescence action could also set the basis for future in vivo approaches promoting tissue rejuvenation bypassing stem cell transplantation.

Mussel-Inspired Nanostructures Potentiate the Immunomodulatory Properties and Angiogenesis of Mesenchymal Stem Cells

The therapeutic effects of mesenchymal stem cells (MSCs)-material constructs mainly come from the secretion of trophic factors from MSCs, especially the immunomodulatory and angiogenic cytokines. Recent findings indicate the significance of topographical cues from these materials in modulating paracrine functions of MSCs. Here, we developed functionalized three-dimensional-printed bioceramic (BC) scaffolds with a mussel-inspired surface coating in order to regulate the paracrine function of adipose-derived MSCs (Ad-MSCs). We found that Ad-MSCs cultured on polydopamine-modified BC scaffolds (DOPA-BC) significantly produced more immunomodulatory and pro-angiogenic factors when compared with those cultured on BC scaffolds or microplates. Functional assays, such as endothelial progenitor cells migration, tube formation, and macrophage polarization, were performed to confirm the enhanced paracrine functions of the secreted trophic factors from Ad-MSCs cultured on DOPA-BC scaffolds. Further investigation identified that both focal adhesion kinase- and extracellular signal-related kinase signaling were the required mechano-transduction pathways through which the mussel-inspired surface stimulated the paracrine effect of Ad-MSCs. In a diabetic skin-defect-healing model in rats, conditioned medium received from the Ad-MSCs cultured on DOPA-BC sped wound closure, enhanced vascularization, and promoted macrophage switching from a proinflammatory M1 to a pro-healing and anti-inflammatory M2 phenotype in the wound bed. These results demonstrate that a bio-inspired coating with polydopamine represents an effective method to enhance the paracrine function of MSCs. Our findings illustrate a novel strategy to accelerate tissue regeneration by guiding the paracrine-signaling network.

The Potential of Stem Cell Therapy to Repair White Matter Injury in Preterm Infants: Lessons Learned From Experimental Models

Diffuse white matter injury (dWMI) is a major cause of morbidity in the extremely preterm born infant leading to life-long neurological impairments, including deficits in cognitive, motor, sensory, psychological, and behavioral functioning. At present, no treatment options are clinically available to combat dWMI and therefore exploration of novel strategies is urgently needed. In recent years, the pathophysiology underlying dWMI has slowly started to be unraveled, pointing towards the disturbed maturation of oligodendrocytes (OLs) as a key mechanism. Immature OL precursor cells in the developing brain are believed to be highly sensitive to perinatal inflammation and cerebral oxygen fluctuations, leading to impaired OL differentiation and eventually myelination failure. OL lineage development under normal and pathological circumstances and the process of (re)myelination have been studied extensively over the years, often in the context of other adult and pediatric white matter pathologies such as stroke and multiple sclerosis (MS). Various studies have proposed stem cell-based therapeutic strategies to boost white matter regeneration as a potential strategy against a wide range of neurological diseases. In this review we will discuss experimental studies focusing on mesenchymal stem cell (MSC) therapy to reduce white matter injury (WMI) in multiple adult and neonatal neurological diseases. What lessons have been learned from these previous studies and how can we translate this knowledge to application of MSCs for the injured white matter in the preterm infant? A perspective on the current state of stem cell therapy will be given and we will discuss different important considerations of MSCs including cellular sources, timing of treatment and administration routes. Furthermore, we reflect on optimization strategies that could potentially reinforce stem cell therapy, including preconditioning and genetic engineering of stem cells or using cell-free stem cell products, to optimize cell-based strategy for vulnerable preterm infants in the near future.

MEsenchymal StEm cells for Multiple Sclerosis (MESEMS): a randomized, double blind, cross-over phase I/II clinical trial with autologous mesenchymal stem cells for the therapy of multiple sclerosis

Background

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system with a degenerative component, leading to irreversible disability. Mesenchymal stem cells (MSC) have been shown to prevent inflammation and neurodegeneration in animal models of MS, but no large phase II clinical trials have yet assessed the exploratory efficacy of MSC for MS.

Methods/design

This is an academic, investigator-initiated, randomized, double-blind, placebo-compared phase I/II clinical trial with autologous, bone-marrow derived MSC in MS. Enrolled subjects will receive autologous MSC at either baseline or at week 24, through a cross-over design. Primary co-objectives are to test safety and efficacy of MSC treatment compared to placebo at 6 months. Secondary objectives will evaluate the efficacy of MSC at clinical and MRI levels. In order to overcome funding constraints, the MEsenchymal StEm cells for Multiple Sclerosis (MESEMS) study has been designed to merge partially independent clinical trials, following harmonized protocols and sharing some key centralized procedures, including data collection and analyses.

Discussion

Results will provide patients and the scientific community with data on the safety and efficacy of MSC for MS. The innovative approach utilized to obtain funds to support the MESEMS trial could represent a new model to circumvent limitation of funds encountered by academic trials.

Trial registration

Andalusia: NCT01745783, registered on Dec 10, 2012.

Badalona: NCT02035514 EudraCT, 2010–024081–21. Registered on 2012.

Canada: ClinicalTrials.gov, NCT02239393. Registered on September 12, 2014.

Copenhagen: EudraCT, 2012–000518-13. Registered on June 21, 2012.

Italy: EudraCT, 2011–001295-19, and ClinicalTrials.gov, NCT01854957. Retrospectively registered on May 16, 2013.

London: Eudra CT 2012–002357-35, and ClinicalTrials.gov, NCT01606215. Registered on May 25, 2012.

Salzburg: EudraCT, 2015–000137-78. Registered on September 15, 2015.

Stockholm: ClinicalTrials.gov, NCT01730547. Registered on November 21, 2012.

Toulouse: ClinicalTrials.gov, NCT02403947. Registered on March 31, 2015.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3346-z) contains supplementary material, which is available to authorized users.

Novel 18F-Labeled Radioligands for Positron Emission Tomography Imaging of Myelination in the Central Nervous System

Myelin is the protective sheath that surrounds nerves in vertebrates to protect axons, which thereby facilitates impulse conduction. Damage to myelin is associated with many neurodegenerative diseases such as multiple sclerosis and also includes spinal cord injury (SCI). The small size of the spinal cord poses formidable challenges to in vivo monitoring of myelination, which we investigated via conducting a structure-activity relationship study to determine the optimum positron-emitting agent to use for imaging myelin using positron emission tomography (PET). From these studies, [¹⁸F]PENDAS was identified as the lead agent to use in conjunction with PET imaging to delineate the integrity of spinal cord myelin. A subsequent in vivo PET imaging study of [¹⁸F]PENDAS in rats with SCI showed promising pharmacokinetic results that justify further development of imaging markers for diagnosing myelin-related diseases. Additionally, [¹⁸F]PENDAS could be valuable in determining the efficacy of therapies that are currently under development.

Mesenchymal stem cell therapy for the treatment of inflammatory diseases: Challenges, opportunities, and future perspectives

Mesenchymal stem cells (MSCs) are promising alternative agents for the treatment of inflammatory disorders due to their immunomodulatory functions, and several clinical trials on MSC-based products are currently being conducted. In this review, we discuss recent progress made on the use of MSCs as immunomodulatory agents, developmental challenges posed by MSC-based therapy, and the strategies being used to overcome these challenges. In this context, current understanding of the mechanisms responsible for MSC interactions with the immune system and the molecular responses of MSCs to inflammatory signals are discussed. The immunosuppressive activities of MSCs are initiated by cell-to-cell contact and the release of immuno-regulatory molecules. By doing so, MSCs can inhibit the proliferation and function of T cells, natural killer cells, B cells, and dendritic cells, and can also increase the proliferation of regulatory T cells. However, various problems, such as low transplanted cell viability, poor homing and engraftment into injured tissues, MSC heterogeneity, and lack of adequate information on optimum MSC doses impede clinical applications. On the other hand, it has been shown that the immunomodulatory activities and viabilities of MSCs might be enhanced by 3D-cultured systems, genetic modifications, preconditioning, and targeted-delivery.

Stem Cell-Based Therapies for Multiple Sclerosis: Current Perspectives

Multiple sclerosis (MS) is an inflammatory and neurodegenerative autoimmune disease of the central nervous system (CNS). Disease-modifying therapies (DMT) targeting inflammation have been shown to reduce disease activity in patients with relapsing–remitting MS (RRMS). The current therapeutic challenge is to find an effective treatment to halt disease progression and reverse established neural damage. Stem cell-based therapies have emerged to address this dilemma. Several types of stem cells have been considered for clinical use, such as autologous hematopoietic (aHSC), mesenchymal (MSC), neuronal (NSC), human embryonic (hESC), and induced pluripotent (iPSC) stem cells. There is convincing evidence that immunoablation followed by hematopoietic therapy (aHSCT) has a high efficacy for suppressing inflammatory MS activity and improving neurological disability in patients with RRMS. In addition, MSC therapy may be a safe and tolerable treatment, but its clinical value is still under evaluation. Various studies have shown early promising results with other cellular therapies for CNS repair and decreasing inflammation. In this review, we discuss the current knowledge and limitations of different stem cell-based therapies for the treatment of patients with MS.

Skin tissue engineering: wound healing based on stem-cell-based therapeutic strategies

Normal wound healing is a dynamic and complex multiple phase process involving coordinated interactions between growth factors, cytokines, chemokines, and various cells. Any failure in these phases may lead wounds to become chronic and have abnormal scar formation. Chronic wounds affect patients' quality of life, since they require repetitive treatments and incur considerable medical costs. Thus, much effort has been focused on developing novel therapeutic approaches for wound treatment. Stem-cell-based therapeutic strategies have been proposed to treat these wounds. They have shown considerable potential for improving the rate and quality of wound healing and regenerating the skin. However, there are many challenges for using stem cells in skin regeneration. In this review, we present some sets of the data published on using embryonic stem cells, induced pluripotent stem cells, and adult stem cells in healing wounds. Additionally, we will discuss the different angles whereby these cells can contribute to their unique features and show the current drawbacks.

Hepatocyte growth factor plays a dual role in tendon-derived stem cell proliferation, migration, and differentiation

Heterotopic ossification is common in tendon healing after trauma, but the detailed mechanisms remain unknown. Tendon-derived stem cells (TDSCs) are a type of progenitor cell found in the tendon niche, and their incorrect differentiation after trauma may lead to tendon calcification. The expression of hepatocyte growth factor (HGF) presents drastic fluctuations in serum/tissue after trauma and was found to activate quiescent stellate cells and contribute to wound healing; however, its potential role in TDSCs remains elusive. In this study, TDSCs isolated from rats were cultured in media containing HGF with or without a signaling inhibitor, and the proliferation, migration, and differentiation ability of TDSCs were measured to determine the role and mechanism of HGF in TDSCs. We showed that HGF promotes TDSC proliferation and migration but inhibits TDSC osteogenic differentiation ability. HGF activated-HGF/c-Met, mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling, which was positively correlated with TDSCs proliferation and migration but negatively related to TDSC osteogenic differentiation ability. The phosphorylation of Smad1/5/8 was also negatively related to HGF/c-Met, MAPK/ERK1/2, and PI3K/AKT signaling, which demonstrated that the inhibition of osteogenic differentiation was dependent on BMP/Smad1/5/8 signaling. Overall, we showed that HGF could promote TDSCs proliferation and migration and inhibit osteogenic differentiation in vitro, suggesting a potential role for HGF as a cytokine treatment of tendon trauma.

IFNβ enhances mesenchymal stromal (Stem) cells immunomodulatory function through STAT1-3 activation and mTOR-associated promotion of glucose metabolism

Administration of mesenchymal stem cells (MSC) ameliorate experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis (MS), at both clinical and neuropathological levels. The therapeutic properties of MSC in EAE are mainly mediated by the modulation of pathogenic immune response, but other neurotropic effects, including decreased demyelination and axonal loss as well as promotion of tissue repair, play also a role. Properly controlled phase II clinical trials to explore the potential of MSC transplantation as a treatment for MS are underway. Interferon beta (IFNβ) is an approved treatment for relapsing-remitting and secondary progressive MS. Here, we explored the possibility that IFNβ might influence the therapeutic potential of MSC, in view of possible synergistic effects as add-on therapy. IFNβ enhanced the immunomodulatory functions of MSC and induced the expression of secretory leukocyte protease inhibitor (Slpi) and hepatocyte growth factor (Hgf), two soluble mediators involved in immune and regenerative functions of MSC. At molecular level, IFNβ induced a rapid and transient phosphorylation of STAT1 and STAT3, the transcription factors responsible for Slpi and Hgf induction. Concomitantly, IFNβ dynamically affected the activity of mTOR, a key checkpoint in the control of metabolic pathways. Indeed, the impairment of mTOR activity observed early upon exposure to IFNβ, was followed by a long-lasting induction of mTOR signaling, that was associated with an increased glycolytic capacity in MSC. When induced to switch their energetic metabolism towards glycolysis, MSC showed an improved ability to control T-cell proliferation. These results suggest that modifications of MSC energetic metabolism induced by IFNβ may contribute to promote MSC immunomodulatory function and support a role for metabolic pathways in the therapeutic function of MSC. Altogether, these findings support the idea of a combined treatment for MS, in which the immunomodulatory and possibly regenerative activity of MSC could be enhanced by the administration of IFNβ.

Clinical Application of Stem/Stromal Cells in COPD

Chronic obstructive pulmonary disease (COPD) is a progressive life-threatening disease that is significantly increasing in prevalence and is predicted to become the third leading cause of death worldwide by 2030. At present, there are no true curative treatments that can stop the progression of the disease, and new therapeutic strategies are desperately needed. Advances in cell-based therapies provide a platform for the development of new therapeutic approaches in severe lung diseases such as COPD. At present, a lot of focus is on mesenchymal stem (stromal) cell (MSC)-based therapies, mainly due to their immunomodulatory properties. Despite increasing number of preclinical studies demonstrating that systemic MSC administration can prevent or treat experimental COPD and emphysema, clinical studies have not been able to reproduce the preclinical results and to date no efficacy or significantly improved lung function or quality of life has been observed in COPD patients. Importantly, the completed appropriately conducted clinical trials uniformly demonstrate that MSC treatment in COPD patients is well tolerated and no toxicities have been observed. All clinical trials performed so far, have been phase I/II studies, underpowered for the detection of potential efficacy. There are several challenges ahead for this field such as standardized isolation and culture procedures to obtain a cell product with high quality and reproducibility, administration strategies, improvement of methods to measure outcomes, and development of potency assays. Moreover, COPD is a complex pathology with a diverse spectrum of clinical phenotypes, and therefore it is essential to develop methods to select the subpopulation of patients that is most likely to potentially respond to MSC administration. In this chapter, we will discuss the current state of the art of MSC-based cell therapy for COPD and the hurdles that need to be overcome.

Methods and Strategies for Procurement, Isolation, Characterization, and Assessment of Senescence of Human Mesenchymal Stem Cells from Adipose Tissue

Human adipose-derived mesenchymal stem (stromal) cells (hADSC) represent an attractive source of the cells for numerous therapeutic applications in regenerative medicine. These cells are also an efficient model to study biological pathways of stem cell action, tissue injury and disease. Like any other primary somatic cells in culture, industrial-scale expansion of mesenchymal stromal cells (MSC) leads to the replicative exhaustion/senescence as defined by the "Hayflick limit." The senescence is not only greatly effecting in vivo potency of the stem cell cultures but also might be the cause and the source of clinical inconsistency arising from infused cell preparations. In this light, the characterization of hADSC replicative and stressor-induced senescence phenotypes is of great interest.This chapter summarizes some of the essential protocols and assays used at our laboratories and clinic for the human fat procurement, isolation, culture, differentiation, and characterization of mesenchymal stem cells from adipose tissue and the stromal vascular fraction. Additionally, we provide manuals for characterization of hADSC senescence in a culture based on stem cells immunophenotype, proliferation rate, migration potential, and numerous other well-accepted markers of cellular senescence. Such methodological framework will be immensely helpful to design standards and surrogate measures for hADSC-based therapeutic applications.

Adipose-Derived Mesenchymal Stem Cells Migrate and Rescue RPE in the Setting of Oxidative Stress

Oxidative stress leads to the degeneration of retinal pigment epithelial (RPE) and photoreceptor cells. We evaluated the potential of adipose-derived mesenchymal stem cells (ASCs) as a therapeutic tool by studying the migration capacity of ASCs in vitro and their protective effect against RPE cell death under oxidative stress in vitro and in vivo. ASCs exhibited enhanced migration when exposed to conditioned medium of oxidative stressed RPE cells obtained by hydrogen peroxide. Migration-related axis SDF-1/CXCR4 was studied, and upregulation of SDF-1 in stressed RPE and of CXCR4 in ASCs was detected. Moreover, ASCs' conditioned medium prevented H₂O₂-induced cell death of RPE cells. Early passage ASCs had high expression level of HGF, low VEGF levels, and unmodulated IL-1β levels, compared to late passage ASCs. Thus, early passage ASCs show the potential to migrate towards damaged RPE cells and protect them in a paracrine manner from cell death induced by oxidative stress. In vivo, mice received systemic injection of NaIO₃, and 72 h later, ASCs were transplanted in the subretinal space. Seven days after ASC transplantation, the eyes were enucleated fixed and frozen for immunohistochemical analysis. Under such conditions, ASC-treated mice showed preservation of nuclear layers in the outer nuclear layer and stronger staining of RPE and photoreceptor layer, compared to PBS-treated mice. Taken together, our results indicate that ASCs are able to home in on damaged RPE cells and protect against damage to the RPE and PR layers caused by oxidative stress. These data imply the potential that ASCs have in regenerating RPE under oxidative stress, providing the basis for a therapeutic approach to retinal degeneration diseases related to oxidative stress that could help save the eyesight of millions of people worldwide.

Transplantation of human mobilized mononuclear cells improved diabetic neuropathy

Rodent stem cells demonstrated regenerative effects in diabetic neuropathy via improvement in nerve perfusion. As a pre-clinical step, we explored if human mobilized mononuclear cells (hMNC) would have the same effects in rats. hMNC were injected into Rt. hind-limb muscles of streptozotocin-induced diabetic nude rats, and the grafts were monitored using with MRI. After 4 weeks, the effects were compared with those in the vehicle-injected Lt. hind limbs. Nerve conduction, muscle perfusion and gene expression of sciatic nerves were assessed. Induction of diabetes decreased nerve function and expression of Mpz and Met in the sciatic nerves, which are related with myelination. hMNC injection significantly improved the amplitude of compound muscle action potentials along with muscle perfusion and sciatic nerve Mpz expression. On MRI, hypointense signals were observed for 4 weeks at the graft site, but their correlation with the presence of hMNC was detectable for only 1 week. To evaluate paracrine effects of hMNC, IMS32 cells were tested with hepatocyte growth factor (HGF), which had been reported as a myelination-related factor from stem cells. We could observe that HGF enhanced Mpz expression in the IMS32 cells. Because hMNC secreted HGF, IMS32 cells were co-cultured with hMNC, and the expression of Mpz increased along with morphologic maturation. The hMNC-induced Mpz expression was abrogated by treatment of anti-HGF. These results suggest that hMNC could improve diabetic neuropathy, possibly through enhancement of myelination as well as perfusion. According to in vitro studies, HGF was involved in the hMNC-induced myelination activity, at least in part.

Tolerising cellular therapies: what is their promise for autoimmune disease?

The current management of autoimmunity involves the administration of immunosuppressive drugs coupled to symptomatic and functional interventions such as anti-inflammatory therapies and hormone replacement. Given the chronic nature of autoimmunity, however, the ideal therapeutic strategy would be to reinduce self-tolerance before significant tissue damage has accrued. Defects in, or defective regulation of, key immune cells such as regulatory T cells have been documented in several types of human autoimmunity. Consequently, it has been suggested that the administration of ex vivo generated, tolerogenic immune cell populations could provide a tractable therapeutic strategy. Several potentially tolerogenic cellular therapies have been developed in recent years; concurrent advances in cell manufacturing technologies promise scalable, affordable interventions if safety and efficacy can be demonstrated. These therapies include mesenchymal stromal cells, tolerogenic dendritic cells and regulatory T cells. Each has advantages and disadvantages, particularly in terms of the requirement for a bespoke versus an ‘off-the-shelf’ treatment but also their suitability in particular clinical scenarios. In this review, we examine the current evidence for these three types of cellular therapy, in the context of a broader discussion around potential development pathway(s) and their likely future role. A brief overview of preclinical data is followed by a comprehensive discussion of human data.

Bone Marrow Derived Mesenchymal Stem Cells in Addiction Related Hippocampal Damages

The brain is an important organ that controls all sensory and motor actions, memory, and emotions. Each anatomical and physiological modulation in various brain centers, results in psychological, behavioral, and sensory-motor changes. Alcohol and addictive drugs such as opioids and amphetamines have been shown to exert a great impact on brain, specifically on the hippocampus. Emerging evidence has indicated that altered hippocampal neurogenesis is associated with the pathophysiology of neuropsychological disorders including addiction. The addictive drugs impair neurogenesis and undermine the function of neural stem/progenitor cells in hippocampus. This feature was claimed to be one of the underlying mechanisms of behavioral changes in patients with addiction. As the impairment of stem cells’ function has been proven to be the underlying cause of pathologic neuroadaptations in the brain, the administration of stem cell populations has shown promising results for re-modulating of neuronal status in the brain and especially in the hippocampus. Among the different types of stem cells, bone marrow derived mesenchymal stem cells are the most proper candidates for stem cell therapies. In this review article, the recent studies on the effects of addictive drugs on brain neurogenesis, and also the promising potential effects of stem cells in curing addiction related hippocampal damages are discussed.

Stem Cells in Osteochondral Tissue Engineering

Mesenchymal stem cells (MSCs) are pluripotent stem cells with the ability to differentiate into a variety of other connective tissue cells, such as chondral, bony, muscular, and tendon tissue. Bone marrow-derived MSCs are pluripotent cells that can differentiate among others into osteoblasts, adipocytes and chondrocytes.Bone marrow-derived cells may represent the future in osteochondral repair. A one-step arthroscopic technique is developed for cartilage repair, using a device to concentrate bone marrow-derived cells and collagen powder or hyaluronic acid membrane as scaffolds for cell support and platelet gel.The rationale of the "one-step technique" is to transplant the entire bone-marrow cellular pool instead of isolated and expanded mesenchymal stem cells allowing cells to be processed directly in the operating room, without the need for a laboratory phase. For an entirely arthroscopic implantation are employed a scaffold and the instrumentation previously applied for ACI; in addition to these devices, autologous platelet-rich fibrin (PRF) is added in order to provide a supplement of growth factors. Results of this technique are encouraging at mid-term although long-term follow-up is still needed.

Stem Cells as Potential Targets of Polyphenols in Multiple Sclerosis and Alzheimer's Disease

Alzheimer's disease (AD) and multiple sclerosis are major neurodegenerative diseases, which are characterized by the accumulation of abnormal pathogenic proteins due to oxidative stress, mitochondrial dysfunction, impaired autophagy, and pathogens, leading to neurodegeneration and behavioral deficits. Herein, we reviewed the utility of plant polyphenols in regulating proliferation and differentiation of stem cells for inducing brain self-repair in AD and multiple sclerosis. Firstly, we discussed the genetic, physiological, and environmental factors involved in the pathophysiology of both the disorders. Next, we reviewed various stem cell therapies available and how they have proved useful in animal models of AD and multiple sclerosis. Lastly, we discussed how polyphenols utilize the potential of stem cells, either complementing their therapeutic effects or stimulating endogenous and exogenous neurogenesis, against these diseases. We suggest that polyphenols could be a potential candidate for stem cell therapy against neurodegenerative disorders.

Glial Cells Shape Pathology and Repair After Spinal Cord Injury

Glial cell types were classified less than 100 years ago by del Rio-Hortega. For instance, he correctly surmised that microglia in pathologic central nervous system (CNS) were "voracious monsters" that helped clean the tissue. Although these historical predictions were remarkably accurate, innovative technologies have revealed novel molecular, cellular, and dynamic physiologic aspects of CNS glia. In this review, we integrate recent findings regarding the roles of glia and glial interactions in healthy and injured spinal cord. The three major glial cell types are considered in healthy CNS and after spinal cord injury (SCI). Astrocytes, which in the healthy CNS regulate neurotransmitter and neurovascular dynamics, respond to SCI by becoming reactive and forming a glial scar that limits pathology and plasticity. Microglia, which in the healthy CNS scan for infection/damage, respond to SCI by promoting axon growth and remyelination-but also with hyperactivation and cytotoxic effects. Oligodendrocytes and their precursors, which in healthy tissue speed axon conduction and support axonal function, respond to SCI by differentiating and producing myelin, but are susceptible to death. Thus, post-SCI responses of each glial cell can simultaneously stimulate and stifle repair. Interestingly, potential therapies could also target interactions between these cells. Astrocyte-microglia cross-talk creates a feed-forward loop, so shifting the response of either cell could amplify repair. Astrocytes, microglia, and oligodendrocytes/precursors also influence post-SCI cell survival, differentiation, and remyelination, as well as axon sparing. Therefore, optimizing post-SCI responses of glial cells-and interactions between these CNS cells-could benefit neuroprotection, axon plasticity, and functional recovery.

Mesenchymal Stem Cell-Based Immunomodulation: Properties and Clinical Application

Mesenchymal stem cells (MSCs) are multipotent stem cells characterized by self-renewal, production of clonal cell populations, and multilineage differentiation. They exist in nearly all tissues and play a significant role in tissue repair and regeneration. Additionally, MSCs possess wide immunoregulatory properties via interaction with immune cells in both innate and adaptive immune systems, leading to immunosuppression of various effector functions. Numerous bioactive molecules secreted by MSCs, particularly cytokines, growth factors, and chemokines, exert autocrine/paracrine effects that modulate the physiological processes of MSCs. These invaluable virtues of MSCs provide new insight into potential treatments for tissue damage and inflammation. In particular, their extensive immunosuppressive properties are being explored for promising therapeutic application in immune disorders. Recently, clinical trials for MSC-mediated therapies have rapidly developed for immune-related diseases following reports from preclinical studies declaring their therapeutic safety and efficacy. Though immunotherapy of MSCs remains controversial, these clinical trials pave the way for their widespread therapeutic application in immune-based diseases. In this review, we will summarize and update the latest research findings and clinical trials on MSC-based immunomodulation.

Transcriptional Profiling of Mesenchymal Stem Cells Identifies Distinct Neuroimmune Pathways Altered by CNS Disease

Background and Objectives

Bone marrow mesenchymal stem cells (BM-MSCs) are an attractive cell based therapy in the treatment of CNS demyelinating diseases such as multiple sclerosis (MS). Preclinical studies demonstrate that BM-MSCs can effectively reduce clinical burden and enhance recovery in experimental autoimmune encephalomyelitis (EAE), a commonly used animal model of MS. However, a number of recent clinical trials have not shown significant functional benefit following BM-MSC infusion into MS patients. One possibility for the discrepancy between animal and human studies is the source of the cells, as recent studies suggest BM-MSCs from MS patients or animals with EAE lack reparative efficacy compared to naïve cells. We sought to define important transcriptional and functional differences between diseased and naïve MSCs.

Methods and Results

We utilized RNA Sequencing (RNA-Seq) to assess changes in gene expression between BM-MSCs derived from EAE animals and those derived from healthy controls. We show that EAE alters the expression of a large number of genes in BM-MSCs and changes in gene expression are more pronounced in chronic versus acute disease. Bioinformatic analysis revealed extensive perturbations in BM-MSCs in pathways related to inflammation and the regulation of neural cell development. These changes suggest that signals from EAE derived BM-MSCs inhibit rather than enhance remyelination, and in-vitro studies showed that conditioned medium from EAE MSCs fails to support the development of mature oligodendrocytes, the myelinating cells of the CNS.

Conclusions

These data provide insight into the failure of autologous BM-MSCs to promote recovery in MS and support the concept of utilizing non-autologous MSCs in future clinical trials.

Interleukin-1 receptor antagonist-mediated neuroprotection by umbilical cord-derived mesenchymal stromal cells following transplantation into a rodent stroke model

The human umbilical cord is a promising source of mesenchymal stromal cells (MSCs). Intravenous administration of human umbilical cord-derived MSCs (IV-hUMSCs) showed a favorable effect in a rodent stroke model by a paracrine mechanism. However, its underlying therapeutic mechanisms must be determined for clinical application. We investigated the therapeutic effects and mechanisms of our good manufacturing practice (GMP)-manufactured hUMSCs using various cell doses and delivery time points in a rodent model of stroke. IV-hUMSCs at a dose of 1 × 10⁶ cells at 24 h after stroke improved functional deficits and reduced neuronal damage by attenuation of post-ischemic inflammation. Transcriptome and immunohistochemical analyses showed that interleukin-1 receptor antagonist (IL-1ra) was highly upregulated in ED-1-positive inflammatory cells in rats treated with IV-hUMSCs. Treatment with conditioned medium of hUMSCs increased the expression of IL-1ra in a macrophage cell line via activation of cAMP-response element-binding protein (CREB). These results strongly suggest that the attenuation of neuroinflammation mediated by endogenous IL-1ra is an important therapeutic mechanism of IV-hUMSCs for the treatment of stroke.

Endothelial Progenitor Cell Secretome and Oligovascular Repair in a Mouse Model of Prolonged Cerebral Hypoperfusion

BACKGROUND AND PURPOSE

Endothelial progenitor cells (EPCs) have been extensively investigated as a therapeutic approach for repairing the vascular system in cerebrovascular diseases. Beyond vascular regeneration per se, EPCs may also release factors that affect the entire neurovascular unit. Here, we aim to study the effects of the EPC secretome on oligovascular remodeling in a mouse model of white matter injury after prolonged cerebral hypoperfusion.

METHODS

The secretome of mouse EPCs was analyzed with a proteome array. In vitro, the effects of the EPC secretome and its factor angiogenin were assessed on primary oligodendrocyte precursor cells and mature human cerebral microvascular endothelial cells (hCMED/D3). In vivo, mice were subjected to permanent bilateral common carotid artery stenosis, then treated with EPC secretome at 24 hours and at 1 week, and cognitive outcome was evaluated with the Y maze test together with oligodendrocyte precursor cell proliferation/differentiation and vascular density in white matter at 4 weeks.

RESULTS

Multiple growth factors, cytokines, and proteases were identified in the EPC secretome, including angiogenin. In vitro, the EPC secretome significantly enhanced endothelial and oligodendrocyte precursor cell proliferation and potentiated oligodendrocyte precursor cell maturation. Angiogenin was proved to be a key factor since pharmacological blockade of angiogenin signaling negated the positive effects of the EPC secretome. In vivo, treatment with the EPC secretome increased vascular density, myelin, and mature oligodendrocytes in white matter and rescued cognitive function in the mouse hypoperfusion model.

CONCLUSIONS

Factors secreted by EPCs may ameliorate white matter damage in the brain by boosting oligovascular remodeling.