Suchergebnisse

While multiple rodent preclinical studies, and to a lesser extent human clinical trials, claim the feasibility, safety, and potential clinical benefit of cell grafting in the central nervous system (CNS), currently only little convincing knowledge exists regarding the actual fate of the grafted cells and their effect on the surrounding environment (or vice versa). Our preceding studies already indicated that only a minor fraction of the initially grafted cell population survives the grafting process, while the surviving cell population becomes invaded by highly activated microglia/macrophages and surrounded by reactive astrogliosis. In the current study, we further elaborate on early cellular and inflammatory events following syngeneic grafting of eGFP(+) mouse embryonic fibroblasts (mEFs) in the CNS of immunocompetent mice. Based on obtained quantitative histological data, we here propose a detailed mathematically derived working model that sequentially comprises hypoxia-induced apoptosis of grafted mEFs, neutrophil invasion, neoangiogenesis, microglia/macrophage recruitment, astrogliosis, and eventually survival of a limited number of grafted mEFs. Simultaneously, we observed that the cellular events following mEF grafting activates the subventricular zone neural stem and progenitor cell compartment. This proposed model therefore further contributes to our understanding of cell graft-induced cellular responses and will eventually allow for successful manipulation of this intervention. ; This work was supported by research grants G.0136.11 and G.0130.11 (granted to Zwi Berneman, Annemie Van der Linden, and Peter Ponsaerts) of the Fund for Scientific Research-Flanders (FWO-Vlaanderen, Belgium), in part by a Methusalem research grant from the Flemish government (granted to Zwi Berneman and Herman Goossens) and in part by funding received from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 278850 (INMiND; granted to Annemie Van der Linden). Debbie Le Blon holds a Ph.D.-studentship from the Flemish Institute for Science and Technology (IWT-Vlaanderen). Chloe Hoornaert holds a Ph.D.-studentship from the FWO-Vlaanderen. The authors declare no conflict of interest.

Detrimental inflammatory responses in the central nervous system are a hallmark of various brain injuries and diseases. With this study we provide evidence that lentiviral vector-mediated expression of the immune-modulating cytokine interleukin 13 (IL-13) induces an alternative activation program in both microglia and macrophages conferring protection against severe oligodendrocyte loss and demyelination in the cuprizone mouse model for multiple sclerosis (MS). First, IL-13 mediated modulation of cuprizone induced lesions was monitored using T-2-weighted magnetic resonance imaging and magnetization transfer imaging, and further correlated with quantitative histological analyses for inflammatory cell influx, oligodendrocyte death, and demyelination. Second, following IL-13 immune gene therapy in cuprizone-treated eGFP(+) bone marrow chimeric mice, we provide evidence that IL-13 directs the polarization of both brain-resident microglia and infiltrating macrophages towards an alternatively activated phenotype, thereby promoting the conversion of a pro-inflammatory environment toward an anti-inflammatory environment, as further evidenced by gene expression analyses. Finally, we show that IL-13 immune gene therapy is also able to limit lesion severity in a pre-existing inflammatory environment. In conclusion, these results highlight the potential of IL-13 to modulate microglia/macrophage responses and to improve disease outcome in a mouse model for MS. ; This work was supported by research grants G.0136.11 (granted to PP, AVDL and ZB), G.0130.11 (granted to PP, AVDL and ZB) and G.0834.11 (granted to PP and SH) of the Fund for Scientific Research-Flanders (FWO-Vlaanderen, Belgium), in part by a Methusalem research grant from the Flemish government (granted to HG), in part by funding received from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement 278850 (INMiND) (granted to AVdL and AMP), in part by the Brainpath project (MSCA IAPP project granted to AVdL) and in part by funding received from the Belgian Charcot Foundation (granted to PP and AVdL). DLB, DS and CG hold a PhD-studentship from the Flemish Institute for Science and Technology (IWT-Vlaanderen). NDV and CH hold a PhD-studentship from the FWO-Vlaanderen. FK and JP hold a post-doctoral fellowship from the FWO-Vlaanderen.

Transplantation of mesenchymal stem cells (MSCs) into injured or diseased tissuefor the in situ delivery of a wide variety of MSC-secreted therapeutic proteinsis 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 IFN- 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. ; We thank A. Liston and S. Humblet-Baron (VIB Translational Immunology Lab, KU Leuven, Belgium) for sharing their optimized staining protocols for intracellular cytokine analysis by flow cytometry. This work was supported by research grants G.0130.11 and G.0136.11 (granted to A.V.d.L., Z.N.B. and P.P.), G.0131.11 (granted to Z.N.B. and P.P.), G.0834.11 (granted to S.H. and P.P.) and G.0851.11 (granted to C.V. and Z.N.B.) of the Research Foundation Flanders (FWO Vlaanderen, Belgium) and in part by a Methusalem research grant from the Flemish government (granted to H.G.). C.J.H. and E.Lu. hold a PhD studentship from the FWO Vlaanderen. C.G. and D.L.B. hold a PhD studentship from the Flemish Institute for Science and Technology (IWT Vlaanderen).