Isolation and Culture of Mouse Cortical Astrocytes

Summary

Astrocytes have been recognized to be versatile cells participating in fundamental biological processes that are essential for normal brain development and function, and central nervous system repair. Here we present a rapid procedure to obtain pure mouse astrocyte cultures to study the biology of this major class of central nervous system cells.

Abstract

Astrocytes are an abundant cell type in the mammalian brain, yet much remains to be learned about their molecular and functional characteristics. In vitro astrocyte cell culture systems can be used to study the biological functions of these glial cells in detail. This video protocol shows how to obtain pure astrocytes by isolation and culture of mixed cortical cells of mouse pups. The method is based on the absence of viable neurons and the separation of astrocytes, oligodendrocytes and microglia, the three main glial cell populations of the central nervous system, in culture. Representative images during the first days of culture demonstrate the presence of a mixed cell population and indicate the timepoint, when astrocytes become confluent and should be separated from microglia and oligodendrocytes. Moreover, we demonstrate purity and astrocytic morphology of cultured astrocytes using immunocytochemical stainings for well established and newly described astrocyte markers. This culture system can be easily used to obtain pure mouse astrocytes and astrocyte-conditioned medium for studying various aspects of astrocyte biology.

Introduction

Astrocytes are a very abundant cell type in the central nervous system (CNS). The ratio of astrocytes to neurons is 1:3 in the cortex of mice and rats, whereas there are 1.4 astrocytes per neuron in the human cortex ¹. Interest in astrocyte function has increased dramatically in recent years. A key function of astrocytes is their role in providing structural and metabolic support to neurons ^2,3. Newly discovered roles for astrocytes cover a broad spectrum of functions. These include guiding the migration of developing axons and certain neuroblasts during development^4-6, functions in synaptic transmission, synapse strength and informati....

Protocol

1. Isolation and Plating of Mixed Cortical Cells

Mixed cortical cell isolation for astrocyte cultures can be performed using P1 to P4 mouse pups. In order to achieve proper astrocyte density it is necessary to use 4 mouse pup cortices per T75 tissue culture flask. Therefore, volumes in the following protocol are calculated for a cell preparation using 4 mouse pups.

1. Before starting the dissection procedure, prewarm 30 ml of astrocyte culture media (DMEM, high glucose + 10% heat-inactivated fetal bovine serum + 1% Penicillin/Streptomycin; see table) to 37 °C. Coat one T75 flask with 20 ml of poly-D-lysine (PDL) at a concentrat....

Results

Upon isolation of the complete mouse brain (Figure 1A), the cerebellum and the olfactory bulbs have to be removed (Figure 1B). The cortices are peeled of the mouse brain stem (Figure 1C) and meninges of the individual cortex (Figure 1D') are carefully removed (Figure 1E). Meninges are obvious by the meningeal artery system and incomplete removal results in contamination of the final astrocyte culture by meningeal cells and fibroblasts.

Discussion

The method outlined here is based on the astrocyte culture preparation from rodent neonatal brains, originally described by McCarthy and de Vellis in 1980 ²⁷. The modified method of the isolation and culture of cortical astrocytes from postnatal P1 to P4 mouse brain presented here is fast, yields pure primary astrocytes and is highly reproducible. This technique can easily be transferred to isolate astrocytes from other species, such as from rat or pig and from other brain regions, such as the spinal cor.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Astrocyte culture media
DMEM, high glucose	Life Technologies	31966-021
FBS, heat-inactivated	Life Technologies	10082-147	Final Concentration: 10%
Penicillin-Streptomycin	Life Technologies	15140-122	Final Concentration: 1%
Solution for brain tissue digestion
HBSS	Life Technologies	14170-088
2.5% Trypsin	Life Technologies	15090-046	Final Concentration: 0.25%
Other
70% (vol/vol) ethanol	Roth	9065.2
Poly-D-Lysine	Millipore	A-003-E	50 μg/ml
Water	PAA	S15-012	cell culture grade
PBS	PAA	H15-002	cell culture grade
0.05% Trypsin-EDTA	Life Technologies	25300-062
0.45 μm Sterile filter	Sartorius	16555
3.5 cm petri dish	BD Falcon	353001
15 ml Falcon tube	BD Falcon	352096
50 ml Falcon tube	BD Falcon	352070
75 cm2 Tissue culture flask	BD Falcon	353136
Forceps, fine	Dumont	2-1032; 2-1033	# 3c; # 5
Forceps, flat tip	KLS Martin	12-120-11
13 cm surgical scissors	Aesculap	BC-140-R
Stereomicroscope	Leica		MZ7.5
Stereomicroscope + Camera	Leica		MZ16F; DFC320
Microscope + Camera	Zeiss; Canon		Primo Vert; PowerShot A650 IS
Centrifuge	Eppendorf	5805000.017	Centrifuge5804R
Orbital Shaker	Thermo Scientific	SHKE 4450-1CE	MaxQ 4450
Water bath	Julabo		SW20; 37 °C