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Updated: Jul 21, 2025
Preparation and Immunostaining of Myelinating Organotypic Cerebellar Slice Cultures
Published on: March 20, 2019
Polysialic acid promotes remyelination in cerebellar slice cultures by Siglec-E-dependent modulation of microglia
Lara-Jasmin Schröder1,2, Hauke Thiesler3, Lina Gretenkort3
1Clinic for Neurology, Hannover Medical School, Hannover, Germany.
Abstract:
Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system. Spontaneous restoration of myelin after demyelination occurs, but its efficiency declines during disease progression. Efficient myelin repair requires fine-tuning inflammatory responses by brain-resident microglia and infiltrating macrophages. Accordingly, promising therapeutic strategies aim at controlling inflammation to promote remyelination. Polysialic acid (polySia) is a polymeric glycan with variable chain lengths, presented as a posttranslational modification on select protein carriers. PolySia emerges as a negative regulator of inflammatory microglia and macrophage activation and has been detected on oligodendrocyte precursors and reactive astrocytes in multiple sclerosis lesions. As shown recently, polySia-modified proteins can also be released by activated microglia, and the intrinsically released protein-bound and exogenously applied free polySia were equally able to attenuate proinflammatory microglia activation via the inhibitory immune receptor Siglec-E. In this study, we explore polySia as a candidate substance for promoting myelin regeneration by immunomodulation. Lysophosphatidylcholine-induced demyelination of organotypic cerebellar slice cultures was used as an experimental model to analyze the impact of polySia with different degrees of polymerization (DP) on remyelination and inflammation. In lysophosphatidylcholine-treated cerebellar slice cultures, polySia-positive cells were abundant during demyelination but largely reduced during remyelination. Based on the determination of DP24 as the minimal polySia chain length required for the inhibition of inflammatory BV2 microglia activation, pools with short and long polySia chains (DP8-14 and DP24-30) were generated and applied to slice cultures during remyelination. Unlike DP8-14, treatment with DP24-30 significantly improved remyelination, increased arginase-1-positive microglia ratios, and reduced the production of nitric oxide in wildtype, but not in Siglec-E-deficient slice cultures. In vitro differentiation of oligodendrocytes was not affected by DP24-30. Collectively, these results suggest a beneficial effect of exogenously applied polySia DP24-30 on remyelination by Siglec-E-dependent microglia regulation.
Insights
Polysialic acid (polySia) with longer chains (DP24-30) promotes myelin repair in multiple sclerosis models by regulating microglia via the Siglec-E receptor. This finding suggests polySia as a potential therapeutic for enhancing myelin regeneration.
Area of Science:
- Neuroscience
- Immunology
- Biochemistry
Background:
- Multiple sclerosis (MS) involves inflammatory demyelination, where myelin repair efficiency decreases with disease progression.
- Microglia and macrophages modulate inflammation and myelin repair, making them therapeutic targets.
- Polysialic acid (polySia) regulates inflammatory responses and is found in MS lesions, suggesting a role in myelin repair.
Purpose of the Study:
- To investigate polysialic acid (polySia) as a therapeutic agent for promoting myelin regeneration through immunomodulation.
- To determine the optimal chain length of polySia for enhancing remyelination and regulating microglial activity.
Main Methods:
- Organotypic cerebellar slice cultures were subjected to lysophosphatidylcholine-induced demyelination.
- Cultures were treated with polySia of varying chain lengths (DP8-14 and DP24-30) during the remyelination phase.
- Remyelination, microglial activation (arginase-1 expression), nitric oxide production, and Siglec-E dependency were assessed.
Main Results:
- PolySia DP24-30 significantly enhanced remyelination in wildtype slice cultures.
- Treatment with polySia DP24-30 increased arginase-1-positive microglia and reduced nitric oxide production.
- These beneficial effects were dependent on the Siglec-E receptor and were not observed in Siglec-E-deficient cultures.
- PolySia DP24-30 did not affect oligodendrocyte differentiation in vitro.
Conclusions:
- Exogenously applied polysialic acid (polySia) with longer chain lengths (DP24-30) promotes myelin regeneration in a demyelination model.
- PolySia DP24-30 exerts its beneficial effects by modulating microglia via the Siglec-E receptor, reducing inflammation and enhancing repair.
- These findings highlight polySia as a promising therapeutic candidate for promoting remyelination in multiple sclerosis.
