Organotypic Slice Cultures to Study Oligodendrocyte Dynamics and Myelination

Summary

A technique to study NG2 cells and oligodendrocytes using a slice culture system of the forebrain and cerebellum is described. This method allows examination of the dynamics of proliferation and differentiation of cells within the oligodendrocyte lineage where the extracellular environment can be easily manipulated while maintaining tissue cytoarchitecture.

Abstract

NG2 expressing cells (polydendrocytes, oligodendrocyte precursor cells) are the fourth major glial cell population in the central nervous system. During embryonic and postnatal development they actively proliferate and generate myelinating oligodendrocytes. These cells have commonly been studied in primary dissociated cultures, neuron cocultures, and in fixed tissue. Using newly available transgenic mouse lines slice culture systems can be used to investigate proliferation and differentiation of oligodendrocyte lineage cells in both gray and white matter regions of the forebrain and cerebellum. Slice cultures are prepared from early postnatal mice and are kept in culture for up to 1 month. These slices can be imaged multiple times over the culture period to investigate cellular behavior and interactions. This method allows visualization of NG2 cell division and the steps leading to oligodendrocyte differentiation while enabling detailed analysis of region-dependent NG2 cell and oligodendrocyte functional heterogeneity. This is a powerful technique that can be used to investigate the intrinsic and extrinsic signals influencing these cells over time in a cellular environment that closely resembles that found in vivo.

Introduction

Organoytpic slice cultures of the central nervous system have proven to be extremely useful for studying neuron and glial cell biology in a semiintact system^1–4. These cultures are relatively simple to adopt and retain many benefits of primary dissociated cell cultures such as manipulation of the extracellular environment and easy access for repeated long-term live cell imaging and electrophysiological recordings^5–9. In addition, slice cultures maintain 3-dimensional tissue cytoarchitecture, regional neural connectivity, and most major cell types are present in the system. These properties m....

Protocol

NOTE: All animal procedures are following the guidelines and have been approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Connecticut.

NOTE: For these experiments constitutive NG2cre¹⁸ (JAX#008533) and inducible NG2creER¹⁶ (JAX#008538) transgenic mice crossed to Z/EG¹⁹ (JAX#003920) or gtRosa26:YFP reporter²⁰ (JAX#006148) lines respectively were used to image NG2 cells and their progeny. To image mature oligodendrocytes, PLPDsRed transgenic mice²¹ were used. For consistent survival, slices can be isolated from mice up to postnatal day 10 from both the forebrain and cerebellum.

Results

Examples of representative data are given below that have been obtained using slice cultures from both the forebrain and cerebellum of P8 NG2cre:ZEG, NG2creER:YFP and PLPDsRed transgenic mouse lines. NG2 cells can be imaged over days in forebrain and cerebellum slices (Figure 1B-D, Video 1) and the phenotype of these cells can be determined after fixation and immunostaining with NG2 and CC1 antibodies (Figure 1E). In addition to live imaging, cell proliferation can also be assessed using.......

Discussion

Myelination in the central nervous system is essential for efficient neuronal communication and axonal survival²². NG2 cells continuously generate myelinating oligodendrocytes into adulthood while maintaining a resident population in most brain regions^16,23–25. Some genetic and molecular mechanisms regulating the differentiation of these cells have been described but much remains to be discovered. Organotypic slice cultures are a convenient tool to investigate these mecha.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Slice Culture Medium
Minimum Essential Medium	Invitrogen	11090	50%
Hank’s Balanced Salt Solution	Invitrogen	14175	25%
HEPES	Sigma-Aldrich	H-4034	25mM
L-Glutamine	Invitrogen	25030	1mM
Insulin	Sigma-Aldrich	I6634	1mg/L
Ascorbic Acid	Sigma-Aldrich	A-0278	0.4mM
Horse Serum	Hyclone	SH30074.03	25%
Titrate to pH 7.22 with NaOH, filter with bottle top filter, and store at 4 degrees Celsius
Dissection Buffer
NaCl	Sigma-Aldrich	S3014	124mM
KCl	Sigma-Aldrich	P5405	3.004mM
KH2PO4	Sigma-Aldrich	P5655	1.25mM
MgSO4 (anhydrous)	Sigma-Aldrich	M7506	4.004mM
CaCl2 2H2O	Sigma-Aldrich	C7902	2mM
NaHCO3	Sigma-Aldrich	S5761	26mM
D-(+)-Glucose	Sigma-Aldrich	G7021	10mM
Ascorbic Acid	Sigma-Aldrich	A-0278	2.0mM
Adenosine	Sigma-Aldrich	A4036	0.075mM
Filter with bottle top filter and store at 4 degrees Celsius, oxygenate with 95%O2 5%CO2 before use
Other Reagents and Supplies
4-hydroxy tamoxifen (4OHT)	Sigma-Aldrich	H7904	100nM
Paraformaldehyde (PFA)	EM Sciences	19200	4%
L-Lysine	Sigma-Aldrich	L-6027	0.1M
Sodium Metaperiodate	Sigma-Aldrich	S-1878	0.01M
Rabbit anti NG2 antibody	Chemicon (Millipore)	AB5320	1:500
Mouse anti CC1 antibody	Calbiochem (Millipore)	OP80	1:200
Mouse anti Ki67 antibody	Vision Biosystems	NCL-Ki67-MM1	1:300
Mouse anti NeuN antibody	Chemicon (Millipore)	MAB377	1:500
Species specific secondary antibodies	Jackson Immunoresearch
Normal Goat Serum (NGS)			5%
Triton X-100			0.10%
Mounting medium with DAPI	Vector Labs	H-1200
Millicell culture membrane inserts 0.45μm pore size	Fisher Scientific	PICM03050
Bottle top filters	Fisher Scientific	09-740-25E
Ethanol
95% O2 5% CO2 gas mix
Phosphate Buffered Saline (PBS)
Sterile six well plates
Dissecting (hippocampal) or weighing spatulas
Manual or automatic tissue chopper
Razor blades
Disposable transfer pipettes
35mm and 60mm sterile Petri dishes
Stereomicroscope
Inverted Phase Microscope
Laminar Flow Hood
Tissue Culture Incubator
Inverted Fluorescence Microcope