Intranasal administration of small extracellular vesicles derived from mesenchymal stem cells ameliorated the experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is a mouse model for the human multiple sclerosis, which is characterized by inflammation in the central nervous system (CNS), de-myelination of axonal neurons, and loss of motor coordination. The aim of the current study was to evaluate the effect of intranasal administration of mesenchymal stem cells (MSCs) and small extracellular vesicle (SEV) derived from the MSC (MSC-SEV) on disease activity and antigen-specific responses in the EAE mouse model. MSCs (5 × 105) were administered intranasally to EAE mice (n = 5) on the 15th and 24th days after immunization. In addition, the intranasal administration of MSC-SEV (10 µg) was used to treat EAE mice (n = 5) on a daily basis from the 15th to the 27th day after induction of the disease. The outcomes of therapies were evaluated using studying clinical symptoms and histological analysis of CNS lesions. Moreover, T cell proliferation, the frequency of regulatory T cells, the expression of transcription factors of T-helper subsets, and the levels of their corresponded cytokines were evaluated in splenocytes culture that was stimulated with specific-antigen. The results of treatment of EAE mice with MSC- SEV and MSC showed a significant decrease in the clinical scores, and it was found that treatment with MSC-SEV was more effective in alleviating clinical scores than MSC. In addition, the decrease in clinical symptoms was associated with an increase in immunomodulatory responses, including an increase in the frequency of Foxp3+ CD25+ regulatory T cells. Moreover, the level of TGF-ß was increased by both treatments; however, interleukin-10 was increased only by MSC treatment. Ultimately, it was achieved that the intranasal administration of MSC-SEV to EAE mice was more effective than the administration of MSC to reduce clinical scores and histological lesions of the CNS tissue.

Predicting Carbon Spectrum in Heteronuclear Single Quantum Coherence Spectroscopy for Online Feedback During Surgery.

1H High-Resolution Magic Angle Spinning (HRMAS) Nuclear Magnetic Resonance (NMR) is a reliable technology used for detecting metabolites in solid tissues. Fast response time enables guiding surgeons in real time, for detecting tumor cells that are left over in the excision cavity. However, severe overlap of spectral resonances in 1D signal often render distinguishing metabolites impossible. In that case, Heteronuclear Single Quantum Coherence Spectroscopy (HSQC) NMR is applied which can distinguish metabolites by generating 2D spectra ( 1H- 13C). Unfortunately, this analysis requires much longer time and prohibits real time analysis. Thus, obtaining 2D spectrum fast has major implications in medicine. In this study, we show that using multiple multivariate regression and statistical total correlation spectroscopy, we can learn the relation between the 1H and 13C dimensions. Learning is possible with small sample sizes and without the need for performing the HSQC analysis, we can predict the 13C dimension by just performing 1H HRMAS NMR experiment. We show on a rat model of central nervous system tissues (80 samples, 5 tissues) that our methods achieve 0.971 and 0.957 mean R2 values, respectively. Our tests on 15 human brain tumor samples show that we can predict 104 groups of 39 metabolites with 97 percent accuracy. Finally, we show that we can predict the presence of a drug resistant tumor biomarker (creatine) despite obstructed signal in 1H dimension. In practice, this information can provide valuable feedback to the surgeon to further resect the cavity to avoid potential recurrence.

A role for cathepsin Z in neuroinflammation provides mechanistic support for an epigenetic risk factor in multiple sclerosis.

BACKGROUND: Hypomethylation of the cathepsin Z locus has been proposed as an epigenetic risk factor for multiple sclerosis (MS). Cathepsin Z is a unique lysosomal cysteine cathepsin expressed primarily by antigen presenting cells. While cathepsin Z expression has been associated with neuroinflammatory disorders, a role for cathepsin Z in mediating neuroinflammation has not been previously established. METHODS: Experimental autoimmune encephalomyelitis (EAE) was induced in both wildtype mice and mice deficient in cathepsin Z. The effects of cathepsin Z-deficiency on the processing and presentation of the autoantigen myelin oligodendrocyte glycoprotein, and on the production of IL-1ß and IL-18 were determined in vitro from cells derived from wildtype and cathepsin Z-deficient mice. The effects of cathepsin Z-deficiency on CD4+ T cell activation, migration, and infiltration to the CNS were determined in vivo. Statistical analyses of parametric data were performed by one-way ANOVA followed by Tukey post-hoc tests, or by an unpaired Student's t test. EAE clinical scoring was analyzed using the Mann-Whitney U test. RESULTS: We showed that mice deficient in cathepsin Z have reduced neuroinflammation and dramatically lowered circulating levels of IL-1ß during EAE. Deficiency in cathepsin Z did not impact either the processing or the presentation of MOG, or MOG- specific CD4+ T cell activation and trafficking. Consistently, we found that cathepsin Z-deficiency reduced the efficiency of antigen presenting cells to secrete IL-1ß, which in turn reduced the ability of mice to generate Th17 responses-critical steps in the pathogenesis of EAE and MS. CONCLUSION: Together, these data support a novel role for cathepsin Z in the propagation of IL-1ß-driven neuroinflammation.

Regulation of effector function of CNS autoreactive CD4 T cells through inhibitory receptors and IL-7Rα.

BACKGROUND: Multiple sclerosis (MS) is a chronic CNS autoimmune disease characterized by inflammation, demyelination, and neuronal degeneration, where myelin-specific CD4 T cells play critical roles in the formation of acute MS lesions and disease progression. The suppression of IL-7Rα expression and the upregulation of inhibitory receptors (PD-1, etc.) are essential parts of the cell-intrinsic immunosuppressive program regulating T effector functions to prevent autoimmunity. However, little is known on the factors regulating IL-7Rα/PD-1 balance in myelin-specific CD4 T effector/memory cells during the development of CNS autoimmunity. METHODS: We analyzed the roles of the transcription factor T-bet in regulating the expression of IL-7Rα and inhibitory receptors in myelin-specific CD4 T cells. Furthermore, we compared the effects of different inflammatory cytokines that are crucial for Th1 and Th17 development in regulating the IL-7Rα/PD-1 balance. RESULTS: We discovered that T-bet suppresses the expression of inhibitory receptors (PD-1 and LAG-3) and promotes IL-7Rα expression in myelin-specific CD4 T cells in vitro and in vivo. As a result, T-bet skews IL-7Rα/PD-1 balance towards IL-7Rα and promotes enhanced effector function. Furthermore, IL-12 enhances IL-7Rα expression in a T-bet independent manner in myelin-specific Th1 cells. Meanwhile, IL-6, the cytokine inducing highly encephalitogenic Th17 differentiation, suppresses PD-1 while upregulating IL-7Rα, skewing IL-7Rα/PD-1 balance towards IL-7Rα, and promoting enhanced effector function. Moreover, blocking IL-7 signaling in myelin-specific CD4 T cells by αIL-7Rα significantly delays experimental autoimmune encephalomyelitis (EAE) onset and reduces disease severity. CONCLUSIONS: T-bet is a major transcription factor regulating IL-7Rα/PD-1 balance in myelin-specific CD4 T cells during EAE development, and there is a positive correlation between several major determinants promoting T cell encephalitogenicity (T-bet, IL-6, IL-12) and an IL-7Rα/PD-1 balance skewed towards IL-7Rα. Furthermore, IL-7 signaling inhibits PD-1 expression in myelin-specific CD4 T cells and blocking IL-7 signaling suppresses T cell encephalitogenicity. Therefore, interference with inhibitory pathways and IL-7Rα expression may suppress the encephalitogenic potential of myelin-specific CD4 T cells and have therapeutic benefits for MS patients.

Resveratrol augments therapeutic efficiency of mouse bone marrow mesenchymal stem cell-based therapy in experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalitis (EAE) is an inflammatory demyelinating disease, which served as a useful model providing considerable insights into the pathogenesis of multiple sclerosis (MS). Mouse bone marrow mesenchymal stem cells (mBM-MSC) were shown to have neuroprotection capabilities in EAE. Resveratrol is a small polyphenolic compound and possess therapeutic activity in various immune-mediated diseases. The sensitivity of mBM-MSCs to resveratrol was determined by an established cell-viability assay. Resveratrol-treated mBM-MSCs were also characterized with flow cytometry using MSC-specific surface markers and analyzed for their multiple differentiation capacities. EAE was induced in C57BL/6 mice by immunization with MOG35-55. Interferon gamma (IFN-γ)/tumor necrosis factor alpha (TNF-α) and interleukin-4 (IL-4)/interleukin-10 (IL-10), the hallmark cytokines that direct T helper type 1 (Th1) and Th2 development, were detected with enzyme-linked immunosorbent assay (ELISA). In vivo efficacy experiments showed that mBM-MSCs or resveratrol alone led to a significant reduction in clinical scores, and combined treatment resulted in even more prominent reduction. The combined treatment with mBM-MSCs and resveratrol enhanced the immunomodulatory effects, showing suppressed proinflammatory cytokines (IFN-γ, TNF-α) and increased anti-inflammatory cytokines (IL-4, IL-10). The combination of mBM-MSCs and resveratrol provides a novel potential experimental protocol for alleviating EAE symptoms.

Transplantation of olfactory ensheathing cells promotes partial recovery in rats with experimental autoimmune encephalomyelitis.

OBJECTIVE: This study was to investigate the efficacy of olfactory ensheathing cell (OEC) transplantation on experimental autoimmune encephalomyelitis (EAE). METHODS: EAE models were established by guinea pig spinal cord homogenate (GPSCH) immunization in Lewis rats. OECs were purified and cultured from the olfactory nerve layer of SD rats, and then transplanted to the EAE models through the vena caudalis (Group A) or into the lateral cerebral ventricle (Group B). Neurological function scores and body weights were daily recorded following transplantation, and histological analysis was performed to assess the pathological changes in EAE rats. RESULTS: Cultured cells mainly exhibited bipolar or tripolar morphology, and the majority of these cells were positive for NGFR p75 staining. Neurological function scoring and the body weight measurement showed that, OEC transplantation could significantly improve the performance of EAE rats, and similar results were observed for the transplantation through the vena caudalis and into the lateral cerebral ventricle. Moreover, the transplanted OECs accumulated to the lesions in the brains of EAE rats, in spite of the different transplantation approaches. However, no significant differences in histopathology (HE and LFB staining) were observed between the OEC-transplanted groups and the control group. CONCLUSION: OEC transplantation could exert beneficial effects in the treatment of EAE, no matter which the cells were transplanted through the vena caudalis or into the lateral cerebral ventricle. Our findings might provide evidence for the clinical treatment of multiple sclerosis with cell transplantation.

Connexin43 and connexin47 alterations after neural precursor cells transplantation in experimental autoimmune encephalomyelitis.

Exogenous transplanted neural precursor cells (NPCs) exhibit miscellaneous immune-modulatory effects in models of autoimmune demyelination. However, the regional interactions of NPCs with the host brain tissue in remissive inflammatory events have not been adequately studied. In this study we used the chronic MOG-induced Experimental Autoimmune Encephalomyelitis (EAE) model in C57BL/six mice. Based on previous data, we focused on neuropathology at Day 50 post-induction (D50) and studied the expression of connexin43 (Cx43) and Cx47, two of the main glial gap junction (GJ) proteins, in relation to the intraventricular transplantation of GFP(+) NPCs and their integration with the host tissue. By D50, NPCs had migrated intraparenchymally and were found in the corpus callosum at the level of the lateral ventricles and hippocampus. The majority of GFP(+) cells differentiated with simple or ramified processes expressing mainly markers of mature GLIA (GFAP and NogoA) and significantly less of precursor glial cells. GFP(+) NPCs expressed connexins and formed GJs around the hippocampus more than lateral ventricles. The presence of NPCs did not alter the increase in Cx43 GJ plaques at D50 EAE, but prevented the reduction of oligodendrocytic Cx47, increased the number of oligodendrocytes, local Cx47 levels and Cx47 GJ plaques per cell. These findings suggest that transplanted NPCs may have multiple effects in demyelinating pathology, including differentiation and direct integration into the panglial syncytium, as well as amelioration of oligodendrocyte GJ loss, increasing the supply of potent myelinating cells to the demyelinated tissue.

Signaling through three chemokine receptors triggers the migration of transplanted neural precursor cells in a model of multiple sclerosis.

Multiple sclerosis (MS) is a multifocal disease, and precursor cells need to migrate into the multiple lesions in order to exert their therapeutic effects. Therefore, cell migration is a crucial element in regenerative processes in MS, dictating the route of delivery, when cell transplantation is considered. We have previously shown that inflammation triggers migration of multi-potential neural precursor cells (NPCs) into the white matter of experimental autoimmune encephalomyelitis (EAE) rodents, a widely used model of MS. Here we investigated the molecular basis of this attraction. NPCs were grown from E13 embryonic mouse brains and transplanted into the lateral cerebral ventricles of EAE mice. Transplanted NPC migration was directed by three tissue-derived chemokines. Stromal cell-derived factor-1α, monocyte chemo-attractant protein-1 and hepatocyte growth factor were expressed in the EAE brain and specifically in microglia and astrocytes. Their cognate receptors, CXCR4, CCR2 or c-Met were constitutively expressed on NPCs. Selective blockage of CXCR4, CCR2 or c-Met partially inhibited NPC migration in EAE brains. Blocking all three receptors had an additive effect and resulted in profound inhibition of NPC migration, as compared to extensive migration of control NPCs. The inflammation-triggered NPC migration into white matter tracts was dependent on a motile NPC phenotype. Specifically, depriving NPCs from epidermal growth factor (EGF) prevented the induction of glial commitment and a motile phenotype (as indicated by an in vitro motility assay), hampering their response to neuroinflammation. In conclusion, signaling via three chemokine systems accounts for most of the inflammation-induced, tissue-derived attraction of transplanted NPCs into white matter tracts during EAE.

Therapeutic effect of transplanted human Wharton's jelly stem cell-derived oligodendrocyte progenitor cells (hWJ-MSC-derived OPCs) in an animal model of multiple sclerosis.

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system (CNS). A potential new therapeutic approach for MS is cell transplantation which may promote remyelination. We transplanted human Wharton's jelly stem cell-derived oligodendrocyte progenitor cells (hWJ-MSC-derived OPCs) into the brain ventricles of mice induced with experimental autoimmune encephalomyelitis (EAE), the animal model of MS. We studied the effect of the transplanted OPCs on the functional and pathological manifestations of the disease. Transplanted hWJ-MSC-derived OPCs significantly reduced the clinical signs of EAE. Histological examinations showed that remyelination was significantly increased after transplantation. These results suggest that hWJ-MSC-derived OPCs promote the regeneration of myelin sheaths in the brain.

[Therapeutic effect of allogenic bone marrow mesenchymal stem cell transplantation on EAE mouse].

OBJECTIVE: To investigate the therapeutic effect of allogenic bone marrow stem cells (BMSCs) transplantation on experimental autoimmune encephalomyelitis (EAE) and the underlying immunoregulatory mechanism. METHODS: EAE models were established by myelin oligodendrocyte glycoprotein (MOG) peptide immunization in C57BL/6J mice; BMSCs were purified and cultured from bone marrow of BALB/c mice, then transplanted to the EAE models. The scores of neurological function defect were assessed before and after BMSCs transplantation. The frequencies of CD4(+);CD25(+);Foxp3(+); T cells (Tregs) in mice lymph organs were measured by flow cytometry and the expressions of IL-2, IL-4, IL-17 and IL-23 mRNA in mouse spleen samples were detected by real-time quantitative RT-PCR after BMSCs transplantation. RESULTS: Transplantation of allogenic BMSCs improved the clinical score of the EAE mice. Compared with EAE control group, the frequencies of Tregs in spleen, lymph node and thymus of EAE mice transplanted with BMSCs increased significantly, and the levels of IL-2 and IL-17 mRNA significantly decreased, while IL-4 and IL-23 mRNA increased. CONCLUSION: Transplantation of allogenic BMSCs can prevent the development of EAE by regulating the frequency of Tregs and the levels of the cytokines secreted by CD4(+);T cells.

Human mesenchymal stem cells upregulate CD1dCD5(+) regulatory B cells in experimental autoimmune encephalomyelitis.

BACKGROUND/AIMS: Multiple sclerosis (MS) causes significant neurological disability. Experimental autoimmune encephalomyelitis (EAE) is an animal model of MS. Human bone marrow mesenchymal stem cells (hMSCs) possess anti-inflammatory and immunosuppressive effects. We studied whether hMSCs affect CD1d(high)CD5(+) regulatory B-cell activity in EAE. METHODS: EAE was induced in C57BL/6N mice by immunization with MOG35-55 peptide. hMSCs were injected intravenously into EAE mice on day 3 and day 12 after first immunization. Mice were sacrificed on day 26. Immunohistochemistry of the spinal cord, serum cytokines levels, production of cytokines by cultured splenic cells, and flow cytometry for splenic Th17 and CD1d(high)CD5(+) regulatory B cells were studied. RESULTS: EAE mice with hMSC treatment on day 3 and day 12 had reduced EAE scores from day 14 to day 26 compared to EAE mice without hMSC treatment, and reduced infiltration of inflammatory cells and demyelination in the spinal cord. EAE mice with hMSC treatment on day 3 and day 12 had: (1) lower serum levels of IL-6, TNF-α (p < 0.0005), and IL-17 (p < 0.005 for day 3, p < 0.0005 for day 12); (2) reduced splenic cell production and secretion of IL-6, TNF-α (p < 0.05), and IL-17 (p < 0.05), and increased splenic production of IL-10; (3) reduced splenic Th17 cells (p < 0.05 for day 3, p < 0.005 for day 12), and (4) increased CD1d(high)CD5(+) regulatory B cells (p < 0.005) compared to EAE mice without hMSC treatment. CONCLUSION: hMSC treatment on day 3 and day 12 suppresses EAE severity. The underlying mechanisms involve downregulation of Th17 cells and upregulation of CD1d(high)CD5(+) regulatory B-cell activity.

Time limited immunomodulatory functions of transplanted neural precursor cells.

Fetal neural stem/precursor cells (NPCs) possess powerful immunomodulatory properties which enable them to protect the brain from immune-mediated injury. A major issue in developing neural stem/precursor cell (NPC) therapy for chronic neuroinflammatory disorders such as multiple sclerosis is whether cells maintain their immune-regulatory properties for prolonged periods of time. Therefore, we studied time-associated changes in NPC immunomodulatory properties. We examined whether intracerebrally-transplanted NPCs are able to inhibit early versus delayed induction of autoimmune brain inflammation and whether allogeneic NPC grafts continuously inhibit host rejection responses. In two experimental designs, intraventricular fetal NPC grafts attenuated clinically and pathologically brain inflammation during early EAE relapse but failed to inhibit the disease relapse if induced at a delayed time point. In correlation, long-term cultured neural precursors lost their capacity to inhibit immune cell proliferation in vitro. Loss of NPC immune functions was associated with transition into a quiescent undifferentiated state. Also, allogeneic fetal NPC grafts elicited a strong immune reaction of T cell and microglial infiltration and were rejected from the host brain. We conclude that long-term functional changes in transplanted neural precursor cells lead to loss of their therapeutic immune-regulatory properties, and render allogeneic grafts vulnerable to immunologic rejection. Thus, the immunomodulatory effects of neural precursor cell transplantation are limited in time.

Implanting glass spinal cord windows in adult mice with experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) in adult rodents is the standard experimental model for studying autonomic demyelinating diseases such as multiple sclerosis. Here we present a low-cost and reproducible glass window implantation protocol that is suitable for intravital microscopy and studying the dynamics of spinal cord cytoarchitecture with subcellular resolution in live adult mice with EAE. Briefly, we surgically expose the vertebrae T12-L2 and construct a chamber around the exposed vertebrae using a combination of cyanoacrylate and dental cement. A laminectomy is performed from T13 to L1, and a thin layer of transparent silicone elastomer is applied to the dorsal surface of the exposed spinal cord. A modified glass cover slip is implanted over the exposed spinal cord taking care that the glass does not directly contact the spinal cord. To reduce the infiltration of inflammatory cells between the window and spinal cord, anti-inflammatory treatment is administered every 2 days (as recommended by ethics committee) for the first 10 days after implantation. EAE is induced only 2-3 weeks after the cessation of anti-inflammatory treatment. Using this approach we successfully induced EAE in 87% of animals with implanted windows and, using Thy1-CFP-23 mice (blue axons in dorsal spinal cord), quantified axonal loss throughout EAE progression. Taken together, this protocol may be useful for studying the recruitment of various cell populations as well as their interaction dynamics, with subcellular resolution and for extended periods of time. This intravital imaging modality represents a valuable tool for developing therapeutic strategies to treat autoimmune demyelinating diseases such as EAE.

Clinical and pathological effects of intrathecal injection of mesenchymal stem cell-derived neural progenitors in an experimental model of multiple sclerosis.

Multiple sclerosis (MS) is associated with irreversible disability in a significant proportion of patients. At present, there is no treatment to halt or reverse the progression of established disability. In an effort to develop cell therapy-based strategies for progressive MS, we investigated the pre-clinical efficacy of bone marrow mesenchymal stem cell-derived neural progenitors (MSC-NPs) as an autologous source of stem cells. MSC-NPs consist of a subpopulation of bone marrow MSCs with neural progenitor and immunoregulatory properties, and a reduced capacity for mesodermal differentiation, suggesting that this cell population may be appropriate for clinical application in the CNS. We investigated whether MSC-NPs could promote repair and recovery after intrathecal injection into mice with EAE. Multiple injections of MSC-NPs starting at the onset of the chronic phase of disease improved neurological function compared to controls, whereas a single injection had no effect on disease scores. Intrathecal injection of MSC-NPs correlated with reduced immune cell infiltration, reduced area of demyelination, and increased number of endogenous nestin-positive progenitor cells in EAE mice. These observations suggest that MSC-NPs may influence the rate of repair through effects on endogenous progenitors in the spinal cord. This study supports the use of autologous MSC-NPs in MS patients as a means of promoting CNS repair.

Infiltrating monocytes trigger EAE progression, but do not contribute to the resident microglia pool.

In multiple sclerosis and the experimental autoimmune encephalitis (EAE) mouse model, two pools of morphologically indistinguishable phagocytic cells, microglia and inflammatory macrophages, accrue from proliferating resident precursors and recruitment of blood-borne progenitors, respectively. Whether these cell types are functionally equivalent is hotly debated, but is challenging to address experimentally. Using a combination of parabiosis and myeloablation to replace circulating progenitors without affecting CNS-resident microglia, we found a strong correlation between monocyte infiltration and progression to the paralytic stage of EAE. Inhibition of chemokine receptor-dependent recruitment of monocytes to the CNS blocked EAE progression, suggesting that these infiltrating cells are essential for pathogenesis. Finally, we found that, although microglia can enter the cell cycle and return to quiescence following remission, recruited monocytes vanish, and therefore do not ultimately contribute to the resident microglial pool. In conclusion, we identified two distinct subsets of myelomonocytic cells with distinct roles in neuroinflammation and disease progression.

[Mesenchymal stromal cells: Biological properties and clinical prospects]. / Cellules stromales mésenchymateuses : propriétés biologiques et perspectives thérapeutiques.

Mesenchymal stromal cells are defined as non-hematopoietic progenitors characterised by their adherence to plastic in culture, their expression of non-specific markers and their differentiation potential into cells of mesodermic lineage. Resident in numerous tissues, mesenchymal stromal cells are now available from several sources, including both adult and foetal tissues. After their administration, mesenchymal stromal cells preferentially migrate to injured tissues. Mesenchymal stromal cells have therapeutic effects in numerous animal models of tissue injury by a mechanism not yet clearly understood. Mechanisms likely involved in repair can be the production of paracrine, anti-inflammatory and anti-apoptotic factors, as well as cell replacement by their differentiation potential. Mesenchymal stromal cells possess immunosuppressive properties on both innate and adaptative immunity in vitro and in animal models of autoimmunity. Currently their immunosuppressive properties allow testing of mesenchymal stromal cells in allogenic context, although this use requires further investigations. Mesenchymal stromal cells can be isolated and expanded in vitro in clinical grade conditions. They represent a promising candidate for the cellular therapy of diseases, such as acute myocardial infarction, diabetes, graft versus host disease or neurodegenerative diseases. Critical points including the standardization of production and long term toxicity have to be resolved before their large scale use in clinical conditions.

Variable behavior and complications of autologous bone marrow mesenchymal stem cells transplanted in experimental autoimmune encephalomyelitis.

Autologous bone marrow stromal cells (BMSCs) offer significant practical advantages for potential clinical applications in multiple sclerosis (MS). Based on recent experimental data, a number of clinical trials have been designed for the intravenous (IV) and/or intrathecal (ITH) administration of BMSCs in MS patients. Delivery of BMSCs in the cerebrospinal fluid via intracerebroventricular (ICV) transplantation is a useful tool to identify mechanisms underlying the migration and function of these cells. In the current study, BMSCs were ICV administered in severe and mild EAE, as well as naive animals; neural precursor cells (NPCs) served as cellular controls. Our data indicated that ICV-transplanted BMSCs significantly ameliorated mild though not severe EAE. Moreover, BMSCs exerted significant anti-inflammatory effect on spinal cord with concomitant reduced axonopathy only in the mild EAE model. BMSCs migrated into the brain parenchyma and, depending on their cellular density, within brain parenchyma formed cellular masses characterized by focal inflammation, demyelination, axonal loss and increased collagen-fibronectin deposition. These masses were present in 64% of ICV BMASC-transplanted severe EAE animals whereas neither BMSCs transplanted in mild EAE cases nor the NPCs exhibited similar behavior. BMSCs possibly exerted their fibrogenic effect via both paracrine and autocrine manner, at least partly due to up-regulation of connective tissue growth factor (CTGF) under the trigger of TGFb1. Our findings are of substantial relevance for clinical trials in MS, particularly regarding the possibility that ICV transplanted BMSCs entering the inflamed central nervous system may exhibit - under conditions - a local pathology of yet unknown consequences.

Time-dependent fate of transplanted neural precursor cells in experimental autoimmune encephalomyelitis mice.

Transplanted Neural Precursor Cells (NPCs) are capable of long-distance migration inside the inflamed CNS, but exhibit limited myelinating capacities in animal models of Multiple Sclerosis (MS). Inflammation seems to be both beneficial for the recruitment and migration of NPCs and restrictive for their terminal differentiation. In the present study, a set of transplantation experiments was applied in order to investigate the migratory potential, the differentiation pattern and long-term survival of NPCs in Experimental Autoimmune Encephalomyelitis (EAE) mice, the animal model of MS. The in vitro differentiation potential of NPCs in the presence of either pro- (TNFa, INFγ) or anti- (TGFb) inflammatory cytokines was also analyzed. According to the in vivo results obtained, at the acute phase of EAE only a small fraction of transplanted NPCs succeed to differentiate, whereas at chronic phase most of them followed a differentiation process to glial cell lineage along white matter tracts. However, this differentiation was not fully completed, since 8 months after their transplantation a number of NPCs remained as pre-oligodendrocytes. Glial differentiation of NPCs was also found to be inhibited or promoted following their treatment with TNFa or TGFb respectively, in vitro. Our findings suggest that inflammation triggers migration whereas the anti-inflammatory component is a prerequisite for NPCs to follow glial differentiation thereby providing myelinating oligodendrocytes. It is speculated that the fine balance between the pro- and anti-inflammatory determinants in the CNS may be a key factor for transplanted NPCs to exhibit a better therapeutic effect in EAE and MS. This article is part of a Special Issue entitled "Interaction between repair, disease, & inflammation."