Intracerebral transplantation of interleukin 13-producing mesenchymal stem cells limits microgliosis, oligodendrocyte loss and demyelination in the cuprizone mouse model

Abstract

BackgroundPromoting 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).MethodsIn 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 graft-infiltrating 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 T 2-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.ResultsIn 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.ConclusionsControlled 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.

Combination of cuprizone and experimental autoimmune encephalomyelitis to study inflammatory brain lesion formation and progression

“…An additional cohort of Cup/EAE animals was used to investigate inflammatory brain lesions during chronic disease, 47 days after immunization. A second study utilized female CX 3 CR1 +/eGFP /CCR2 +/RFP reporter gene transgenic mice [C57BL/6 background; (Dooley et al, ; Le Blon et al, )] with green fluorescent microglia and red fluorescent infiltrating macrophages/monocytes under the same experimental conditions to discriminate brain‐resident microglia from infiltrating peripheral monocytes/macrophages.…”

“…All immunofluorescence analyses were performed according to previously described procedures (Dooley et al, ; Le Blon et al, ). Briefly, mice were transcardially perfused with a 0.9% NaCl solution followed by 4.0% PFA.…”

Hyperpolarized 13 C MR metabolic imaging can detect neuroinflammation in vivo in a multiple sclerosis murine model

“…In this model, the vast majority of activated MPs are endogenous microglia, not peripheral macrophages (49)(50)(51)(52). At W4 of CPZ, proinflammatory MPs in the corpus callosum express the phagocytic marker CD11b and are responsible for the phagocytosis of myelin debris (53,54).…”

“…This supportive action of MPs is an essential step for subsequent remyelination at W6 and W6 + W6 recovery (49,55). Indeed, directing MPs toward an antiinflammatory phenotype before and during the first weeks of CPZ diet prevents in part oligodendrocyte cell death, demyelination, and astrogliosis (52,56). We chose to monitor CPZ mice at W4 and W6 of CPZ diet and after a subsequent period of 6 wk without CPZ because these three time points are characterized by different cellular events.…”

Intracerebral delivery of the M2 polarizing cytokine interleukin 13 using mesenchymal stem cell implants in a model of temporal lobe epilepsy in mice

“…Recent studies used intracerebral grafting of mesenchymal stem cells (MSCs) for in situ delivery of the M2 polarizing cytokine interleukin 13 (IL‐13). These studies found reduced microglia/macrophage immune response upon grafting IL‐13 MSCs, during cuprizone‐mediated central nervous system (CNS) inflammation and demyelination, as well as following spinal cord injury . In these specific models, a major inflammatory component precedes primary or secondary cellular injury, and the induction of M2 alternative activation of microglia/macrophages may thus be directly linked to reduced downstream microglia/macrophage cytotoxicity.…”