Brain-Derived Neurotrophic Factor (BDNF) Preserves the Functional Integrity of Neural Networks in the β-Amyloidopathy Model in vitro.

Elena V Mitroshina,Tatiana A Mishchenko,Maria V Vedunova,Ekaterina A Epifanova,Victoria G Krut’,Maria S Gavrish,Alexey A Babaev,Roman S Yarkov

doi:10.3389/fcell.2020.00582

Abstract

Alzheimer’s disease (AD) is a widespread chronic neurodegenerative pathology characterized by synaptic dysfunction, partial neuronal death, cognitive decline and memory impairments. The major hallmarks of AD are extracellular senile amyloid plaques formed by various types of amyloid proteins (Aβ) and the formation and accumulation of intracellular neurofibrillary tangles. However, there is a lack of relevant experimental models for studying changes in neural network activity, the features of intercellular signaling or the effects of drugs on the functional activity of nervous cells during AD development. In this work, we examined two experimental models of amyloidopathy using primary hippocampal cultures. The first model involves the embryonic brains of 5xFAD mice; the second uses chronic application of amyloid beta 1-42 (Aβ1-42). The model based on primary hippocampal cells obtained from 5xFAD mice demonstrated changes in spontaneous network calcium activity characterized by a decrease in the number of cells exhibiting Ca2+ activity, a decrease in the number of Ca2+ oscillations and an increase in the duration of Ca2+ events from day 21 of culture development in vitro. Chronic application of Aβ1-42 resulted in the rapid establishment of significant neurodegenerative changes in primary hippocampal cultures, leading to marked impairments in neural network calcium activity and increased cell death. Using this model and multielectrode arrays, we studied the influence of amyloidopathy on spontaneous bioelectrical neural network activity in primary hippocampal cultures. It was shown that chronic Aβ application decreased the number of network bursts and spikes in a burst. The spatial structure of neural networks was also disturbed that characterized by reduction in both the number of key network elements (hubs) and connections between network elements. Moreover, application of brain-derived neurotrophic factor (BDNF) recombinant protein and BDNF hyperexpression by an adeno-associated virus vector partially prevented these amyloidopathy-induced neurodegenerative phenomena. BDNF maintained cell viability and spontaneous bioelectrical and calcium network activity in primary hippocampal cultures.

Highlights

Alzheimer’s disease (AD) studies are becoming more relevant each year due to the increase in the life expectancy of the population and the accumulation of information regarding AD polyetiology (Dubois et al, 2014; Hampel et al, 2015)
To obtain a valid model, we conducted a single and chronic application of Aβ1-42 to primary hippocampal cultures obtained from C57BL/6 murine embryos and investigated the features of longterm cultivation of primary hippocampal cultures obtained from 5xFAD murine embryos
Comparative morphological assessment did not reveal significant changes between primary hippocampal cultures obtained from wild-type and 5xFAD murine embryos over 28 DIV (Figure 2, Supplementary Figure S1)

Summary

Introduction

Alzheimer’s disease (AD) studies are becoming more relevant each year due to the increase in the life expectancy of the population and the accumulation of information regarding AD polyetiology (Dubois et al, 2014; Hampel et al, 2015). The features of AD pathological processes and the development of new strategies to prevent neurodegeneration are actively pursued worldwide (Hadar and Gurwitz, 2018; Cao et al, 2018; Wang N. et al, 2018). Investigations of AD processes have raised questions about the possibility of using endogenous regulatory molecules, such as neurotrophic factors, to correct neurodegeneration at different stages of pathology development. Viral constructs carrying the BDNF gene are a promising therapeutic strategy to restore BDNF levels in the brain. Several studies have indicated the efficacy of viral vectors carrying neurotrophic factor genes in the treatment of Parkinson’s disease (Lim et al, 2010; Cheng et al, 2018; Tereshchenko et al, 2014). The establishment of approaches to use viral constructs carrying the BDNF gene in AD has been carrying out for the past 10 years (Nagahara et al, 2009; Nagahara et al, 2013; Jiao et al, 2016)

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Results

Conclusion