Search

Transplantation of mesenchymal stem cells (MSCs) into injured or diseased tissue-for the in situ delivery of a wide variety of MSC-secreted therapeutic proteins-is an emerging approach for the modulation of the clinical course of several diseases and traumata. From an emergency point-of-view, allogeneic MSCs have numerous advantages over patient-specific autologous MSCs since "off-the-shelf" cell preparations could be readily available for instant therapeutic intervention following acute injury. Although we confirmed the in vitro immunomodulatory capacity of allogeneic MSCs on antigen-presenting cells with standard coculture experiments, allogeneic MSC grafts were irrevocably rejected by the host's immune system upon either intramuscular or intracerebral transplantation. In an attempt to modulate MSC allograft rejection in vivo, we transduced MSCs with an interleukin-13 (IL13)-expressing lentiviral vector. Our data clearly indicate that prolonged survival of IL13-expressing allogeneic MSC grafts in muscle tissue coincided with the induction of an alternatively activated macrophage phenotype in vivo and a reduced number of alloantigen-reactive IFNγ- and/or IL2-producing CD8(+) T cells compared to nonmodified allografts. Similarly, intracerebral IL13-expressing MSC allografts also exhibited prolonged survival and induction of an alternatively activated macrophage phenotype, although a peripheral T cell component was absent. In summary, this study demonstrates that both innate and adaptive immune responses are effectively modulated in vivo by locally secreted IL13, ultimately resulting in prolonged MSC allograft survival in both muscle and brain tissue. Stem Cells 2016;34:1971-1984., (© 2016 The Authors Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.) more...

In this study, the interaction between cells and micron-sized paramagnetic iron oxide (MPIO) particles was investigated by characterizing MPIO in their original state, and after cellular uptake in vitro as well as in vivo. Moreover, MPIO in the olfactory bulb were studied 9 months after injection. Using various imaging techniques, cell-MPIO interactions were investigated with increasing spatial resolution. Live cell confocal microscopy demonstrated that MPIO co-localize with lysosomes after in vitro cellular uptake. In more detail, a membrane surrounding the MPIO was observed by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Following MPIO uptake in vivo, the same cell-MPIO interaction was observed by HAADF-STEM in the subventricular zone at 1 week and in the olfactory bulb at 9 months after MPIO injection. These findings provide proof for the current hypothesis that MPIO are internalized by the cell through endocytosis. The results also show MPIO are not biodegradable, even after 9 months in the brain. Moreover, they show the possibility of HAADF-STEM generating information on the labeled cell as well as on the MPIO. In summary, the methodology presented here provides a systematic route to investigate the interaction between cells and nanoparticles from the micrometer level down to the nanometer level and beyond., (Copyright © 2014 John Wiley & Sons, Ltd.) more...

Over the past decade a lot of research has been performed towards the therapeutic use of mesenchymal stem cells (MSCs) in neurodegenerative and neuroinflammatory diseases. MSCs have shown to be beneficial in different preclinical studies of central nervous system (CNS) disorders due to their immunomodulatory properties and their capacity to secrete various growth factors. Nevertheless, most of the transplanted cells die within the first hours after transplantation and induce a neuroinflammatory response. In order to increase the efficacy of MSC transplantation, it is thus imperative to completely characterise the mechanisms mediating neuroinflammation and cell death following MSC transplantation into the CNS. Consequently, different components of these cell death- and neuroinflammation-inducing pathways can be targeted in an attempt to improve the therapeutic potential of MSCs for CNS disorders. more...

Although cell transplantation is increasingly suggested to be beneficial for the treatment of various neurodegenerative diseases, the therapeutic application of such intervention is currently hindered by the limited knowledge regarding central nervous system (CNS) transplantation immunology. In this study, we aimed to investigate the early post transplantation innate immune events following grafting of autologous mesenchymal stromal cells (MSC) in the CNS of immune competent mice. First, the survival of grafted Luciferase/eGFP-expressing MSC (MSC-Luc/eGFP) was demonstrated to be stable from on day 3 post implantation using in vivo bioluminescence imaging (BLI), which was further confirmed by quantitative histological analysis of MSC-Luc/eGFP graft survival. Additional histological analyses at week 1 and week 2 post grafting revealed the appearance of (i) graft-surrounding/-invading Iba1+ microglia and (ii) graft-surrounding GFAP+ astrocytes, as compared to day 0 post grafting. While the density of graft-surrounding astrocytes and microglia did not change between week 1 and week 2 post grafting, the density of graft-invading microglia significantly decreased between week 1 and week 2 post implantation. However, despite the observed decrease in microglial density within the graft site, additional phenotypic analysis of graft-invading microglia, based on CD11b- and MHCII-expression, revealed >50% of graft-invading microglia at week 2 post implantation to display an activated status. Although microglial expression of CD11b and MHCII is already suggestive for a pro-inflammatory M1-oriented phenotype, the latter was further confirmed by: (i) the expression of NOS2 by microglia within the graft site, and (ii) the absence of arginase 1-expression, an enzyme known to suppress NO activity in M2-oriented microglia, on graft-surrounding and -invading microglia. In summary, we here provide a detailed phenotypic analysis of post transplantation innate immune events in the CNS of mice, and warrant that such intervention is associated with an M1-oriented microglia response and severe astrogliosis., (Copyright © 2012 Elsevier GmbH. All rights reserved.) more...

Background: Despite positive reports on the efficacy of stem cell therapy for the treatment of cardiovascular disease, the nature of stem cell homing to ischemic tissues remains elusive., Results: We used a mouse model of peripheral tissue ischemia to study the survival and homing capacity of dual reporter gene (eGFP/Luciferase) expressing bone marrow-derived stromal cells (BMSC). Cell homing and survival were studied in the presence and absence of ciclosporin A (CsA) immunosuppression using bioluminescence imaging (BLI) together with confocal endomicroscopy. Different injection strategies were applied: central venous (CV), intra-arterial (IA) and intramuscular (IM). BLI and confocal endomicroscopy evidenced complete rejection of the IM injected allogeneic BMSC transplant within 5 to 10 days. Immunosuppression with CsA could only marginally prolong graft survival. IM injected BMSC did not migrate to the site of the arterial ligation. CV injection of BMSC resulted in massive pulmonary infarction, leading to respiratory failure and death. Intrapulmonary cell trapping was evidenced by confocal endomicroscopy, BLI and fluorescence microscopy. IA injection of BMSC proved to be a feasible and safe strategy to bypass the lung circulation. During the follow-up period, neither BLI nor confocal endomicroscopy revealed any convincing ischemia-directed homing of BMSC., Conclusions: BLI and confocal endomicroscopy are complementary imaging techniques for studying the in vivo biology of dual reporter gene-expressing BMSC. Allogeneic BMSC survival is limited in an immunocompetent host and cannot be preserved by CsA immunosuppression alone. We did not find substantial evidence for ischemia-directed BMSC homing and caution against CV injection of BMSC, which can lead to massive pulmonary infarction. more...

Purpose: Development of multimodal imaging strategies is currently of utmost importance for the validation of preclinical stem cell therapy studies.Procedures: We performed a combined labeling strategy for bone marrow-derived stromal cells (BMSC) based on genetic modification with the reporter genes Luciferase and eGFP (BMSC-Luc/eGFP) and physical labeling with blue fluorescent micron-sized iron oxide particles (MPIO) in order to unambiguously identify BMSC localization, survival, and differentiation following engraftment in the central nervous system of mice by in vivo bioluminescence (BLI) and magnetic resonance imaging and postmortem histological analysis.Results: Using this combination, a significant increase of in vivo BLI signal was observed for MPIO-labeled BMSC-Luc/eGFP. Moreover, MPIO labeling of BMSC-Luc/eGFP allows for the improved identification of implanted cells within host tissue during histological observation.Conclusions: This study describes an optimized labeling strategy for multimodal stem cell imaging resulting in improved quantitative and qualitative detection of cellular grafts. [ABSTRACT FROM AUTHOR] more...

Background: Promoting the neuroprotective and repair-inducing effector functions of microglia and macrophages, by means of M2 polarisation or alternative activation, is expected to become a new therapeutic approach for central nervous system (CNS) disorders in which detrimental pro-inflammatory microglia and/or macrophages display a major contribution to the neuropathology. In this study, we present a novel in vivo approach using intracerebral grafting of mesenchymal stem cells (MSC) genetically engineered to secrete interleukin 13 (IL13-MSC). Methods: In the first experimental setup, control MSC and IL13-MSC were grafted in the CNS of eGFP+ bone marrow chimaeric C57BL/6 mice to histologically evaluate IL13-mediated expression of several markers associated with alternative activation, including arginase1 and Ym1, on MSC graft-recognising microglia and MSC graftinfiltrating macrophages. In the second experimental setup, IL13-MSC were grafted on the right side (or on both the right and left sides) of the splenium of the corpus callosum in wild-type C57BL/6 mice and in C57BL/6 CX3CR1eGFP/+CCR2RFP/+ transgenic mice. Next, CNS inflammation and demyelination was induced by means of a cuprizone-supplemented diet. The influence of IL13-MSC grafting on neuropathological alterations was monitored by non-invasive T2-weighted magnetic resonance imaging (MRI) and quantitative histological analyses, as compared to cuprizone-treated mice with control MSC grafts and/or cuprizone-treated mice without MSC injection. Results: In the first part of this study, we demonstrate that MSC graft-associated microglia and MSC graft-infiltrating macrophages are forced into alternative activation upon grafting of IL13-MSC, but not upon grafting of control MSC. In the second part of this study, we demonstrate that grafting of IL13-MSC, in addition to the recruitment of M2 polarised macrophages, limits cuprizone-induced microgliosis, oligodendrocyte death and demyelination. Furthermore, we here demonstrate that injection of IL13-MSC at both sides of the splenium leads to a superior protective effect as compared to a single injection at one side of the splenium. Conclusions: Controlled and localised production of IL13 by means of intracerebral MSC grafting has the potential to modulate cell graft- and pathology-associated microglial/macrophage responses, and to interfere with oligodendrocyte death and demyelinating events in the cuprizone mouse model. [ABSTRACT FROM AUTHOR] more...