Cellular Models for Studying Alexander Disease: Functional Analysis of Primary Rat Astrocytes

Summary

We develop a primary rat astrocyte model that provides a physiologically relevant system for studying Alexander disease (AxD), enabling investigation of GFAP aggregation, pathological modification, and astrocyte dysfunction. This system bridges in vitro and in vivo studies, offering a robust platform to explore AxD pathology and identify therapeutic targets for neurodegenerative diseases.

Abstract

Astrocytes play a vital role in maintaining central nervous system homeostasis, supporting neuronal function, and responding to injury or disease. Dysfunction in astrocyte activity is increasingly recognized as a key contributor to neurodegenerative disorders, including Alexander disease (AxD), a rare and fatal condition caused by mutations in glial fibrillary acidic protein (GFAP). These mutations result in GFAP aggregation, Rosenthal fiber formation, and progressive astrocyte dysfunction. While in vivo animal models offer a complex cellular environment, both current in vitro and in vivo models face limitations in accurately replicating the intricate cellular context and functions of astrocytes. To address this, we developed a cellular model using primary rat astrocytes derived from wild-type (WT) and AxD model rats to study the functional effects of GFAP mutations. This physiologically relevant system enables detailed investigation of astrocyte-specific mechanisms, including GFAP aggregation, oxidative stress responses, and pathological modifications. For researchers without access to AxD model rats, lentiviral transduction offers an alternative method to introduce AxD-associated GFAP mutations into astrocytes derived from normal rats, thereby broadening the applicability of this approach. Compared with immortalized astrocyte cell lines or in vitro studies using recombinant protein, primary astrocytes better preserve native cellular architecture and molecular profiles, offering a robust platform for studying GFAP dynamics, solubility, and astrocytic responses to stressors such as oxidative damage and pathological modifications. This cellular model bridges the gap between molecular and systemic studies, providing a controlled experimental framework to explore astrocyte dysfunction in AxD. By complementing existing methodologies, primary astrocyte cultures enhance our understanding of AxD pathology and represent a valuable tool for identifying potential therapeutic targets for neurodegenerative diseases.

Introduction

Astrocytes are specialized glial cells that span the entire central nervous system (CNS), playing critical roles in maintaining brain homeostasis, regulating neuronal activity, and responding to injury or disease¹. Their functions include neurotransmitter clearance and recycling, extracellular ion and water homeostasis, and support for neural circuit function. Astrocyte-secreted molecules are essential for synapse development and synaptic plasticity in the adult brain². In response to CNS injury or disease, astrocytes undergo reactive changes that can mediate either pro- or anti-inflammatory signaling, enabling neuroprot....

Protocol

Animals used in this protocol were approved by the Institutional Animal Care and Use Committee of the College of Life Sciences and Medicine at the National Tsing Hua University (NTHU IACUC Approval No. 109088 and 111060) and in accordance with the guidelines of the Agriculture Guidebook for the Care and Use of Laboratory Animals.

1. Preparation of media, coverslips, dishes, and plates 

1. Before starting, ensure the following solutions (Table 1) are prepared and ready for use.
2. Sterilize scissors and forceps by autoclaving before use to ensure sterility.
3. Prepare poly-L-lysin....

Results

A morphological overview of primary astrocyte cultures at various time points after isolation is presented in Figure 3. Following the plating of the cortical cell suspension, some astrocytes adhere to the surface of the culture dish within the first 24 h (Figure 3A). During the initial 3 to 5 days, the cultures contain cell debris and dying neurons (Figure 3B), as the culture medium is optimized to support the survival and growth of.......

Discussion

Primary astrocyte cultures have significantly advanced our understanding of astrocytes' roles in health and disease. Building on foundational work by McCarthy and de Vellis²¹, these cultures are critical for studying AxD as they allow for detailed exploration of astrocyte-specific processes, particularly the effects of AxD mutations on GFAP assembly and aggregate formation.

The successful isolation and culture of primary astrocytes depend on several key steps that i.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
1 M HEPES , pH 7.4	Gibco	15630-080
100× penicillin-streptomycin	Gibco	15140-122
10× Hank's Balanced Salt Solution (HBSS)	Gibco	14180-046
2.5% Trypsin	Gibco	15090046
30% Acrylamide/Bis solution 37.5:1	Biorad	1610158
anti-GFAP antibody	Cell Signaling Technology	12389
anti-human GFAP antibody	Biolegend	837202	Clone SMI21
anti-panGFAP antibody	Agilent	GA524
anti-ubiquitin antibody	Millipore	ST 1200	Clone FK2
anti-vimentin antibody	Sigma-Aldrich	V6389	Clone V9
anti-β III tubulin antibody	Biolegend	801201
B27 supplement	Gibco	17504044
Cacium chloride (CaCl2)	Arcos	34961
Cell culture-related reagents
ChemiDoc Imaging System	BioRad	NA
Coomassie blue dye	USB	32826
Cysteine	Sigma-Aldrich	C1276
Dithiothreitol (DTT)	UR	DTT
DNase I	Sigma-Aldrich	D5025
Dounce homogenizer	Wheaton
Dulbecco's modified Eagle Medium (DMEM)	Corning	10-013-CM
Endotoxin-free plasmid DNA preparation kit	Qiagen	12943
Enhanced chemiluminescent (ECL) reagent	PerkinElmer	NEL 105001
Ethylenediaminetetraacetic acid (EDTA)	USB	15699
Fetal bovine serum	Gibco	A5209401
Glucose	Sigma-Aldrich	G8270
GlutaMax	Gibco	35050-061
Minimal essential medium (MEM)	Corning	10-010-CVR
NaCl	Honeywell	31434S
Neurobasal medium	Gibco	21103049
Optima XE-90 Ultracentrifuge	Beckman	NA
Papain	Worthington	LS003126
Pnenylmethylsulfonyl fluoride (PMSF)	ACROS ORGANICS	215740050
Polyehtyleneimine	Sigma-Aldrich	P3143
Poly-L-lysine	Sigma-Aldrich	P6516
Potassium chloride (KCl)	Honeywell	12636
Rhodamine anti-actin antibody	BioRad	12004164
Sodium dodecyl sulfate (SDS)	USB	75819
Sodium pyruvate	Gibco	11360070
StarBright Blue 520 goat anti-mouse IgG	Biorad	12005867
StarBright Blue 700 goat anti-rabbit IgG	BioRad	12004161
Sucrose	Sigma-Aldrich	S5391
SW-28 Rotor	Beckman	NA
TansIT-LT1 Transfection reagent	Mirus	MR-MIR-2300
TEMED	USB	76320
Tris(hydroxymrthyl)aminomethane (Tris)	USB	75825
Triton X-100	Sigma-Aldrich	T9284
β-mercaptoethanol	Sigma-Aldrich	M3148