Developing a mouse model of acute encephalopathy using low-dose lipopolysaccharide injection and hyperthermia treatment

Effects of Muse Cell on a Mouse Model With Acute Encephalopathy

INTRODUCTION

Acute encephalopathy (AE) in childhood due to a viral infection causes convulsions and altered consciousness, leading to severe sequelae and death. Among the four types of AE, cytokine storm-induced AE is the most severe and causes serious damage to the brain. Moreover, a fundamental treatment for AE has not been established yet. Recently, it has been shown that the administration of multilineage-differentiating stress-enduring (Muse) cells, a population of mesenchymal stem cells, improves symptoms in various types of brain injuries when administered in the subacute phase (1-7 days after brain damage). We aimed to examine the effects of Muse cells in a cytokine storm-induced AE animal model using immunocompromised nonobese diabetic/severe combined immunodeficiency (NOD/SCID) neonatal mice.

METHODS

We established a modified protocol to induce AE-like symptoms in NOD/SCID. Then, Muse cells were injected at an acute phase (2-4 h after hyperthermia treatment).

RESULTS

Injection of Muse cells significantly improved body weight gain 1 day after treatment and the survival ratio for 3 weeks.

CONCLUSION

These effects could be a result of the direct and/or indirect upregulation of IL-10, an anti-inflammatory cytokine, in the Muse cell-treated brain. Although non-Muse cells, a residual cell population in the bone marrow after isolating Muse cells, also improved some symptoms, their effects were weaker than those of Muse cells. Our results indicate that the injection of Muse cells in the acute phase has an effect on AE, suggesting that they exert their therapeutic effects not only in the subacute phase but also in the acute phase.

NORSE/FIRES: how can we advance our understanding of this devastating condition?

Introduction

New onset refractory status epilepticus (NORSE) is a rare and devastating condition characterised by the sudden onset of refractory status epilepticus (RSE) without an identifiable acute or active structural, toxic, or metabolic cause in an individual without a pre-existing diagnosis of epilepsy. Febrile infection-related epilepsy syndrome (FIRES) is considered a subcategory of NORSE and presents following a febrile illness prior to seizure onset. NORSE/FIRES is associated with high morbidity and mortality in children and adults.

Methods and results

In this review we first briefly summarise the reported clinical, paraclinical, treatment and outcome data in the literature. We then report on existing knowledge of the underlying pathophysiology in relation to in vitro and in vivo pre-clinical seizure and epilepsy models of potential relevance to NORSE/FIRES.

Discussion

We highlight how pre-clinical models can enhance our understanding of FIRES/NORSE and propose future directions for research.

Improvement in Double Staining With Fluoro-Jade C and Fluorescent Immunostaining: FJC Staining Is Not Specific to Degenerating Mature Neurons

Fluoro-Jade C (FJC) staining has been used to detect degenerating neurons in tissue sections. It is a simple and easy staining procedure and does not depend on the manner of cell death. In some experiments, double staining with FJC and fluorescent immunostaining (FI) is required to identify cell types. However, pretreatment for FJC staining contains some processes that are harsh to fluorophores, and the FI signal is greatly reduced. To overcome this issue, we improved the double staining protocol to acquire clear double-stained images by introducing the labeled streptavidin-biotin system. In addition, several studies indicate that FJC can label non-degenerating glial cells, including resting/reactive astrocytes and activated microglia. Moreover, our previous study indicated that degenerating mesenchymal cells were also labeled by FJC, but it is still unclear whether FJC can label degenerating glial cells. Acute encephalopathy model mice contained damaged astrocytes with clasmatodendrosis, and 6-aminonicotinamide-injected mice contained necrotic astrocytes and oligodendrocytes. Using our improved double staining protocol with FJC and FI, we detected FJC-labeled degenerating astrocytes and oligodendrocytes with pyknotic nuclei. These results indicate that FJC is not specific to degenerating neurons in some experimental conditions.