Rapid and Specific Immunomagnetic Isolation of Mouse Primary Oligodendrocytes

Summary

We describe the immunomagnetic isolation of primary mouse oligodendrocytes, which allows the rapid and specific isolation of the cells for in vitro culture.

Abstract

The efficient and robust isolation and culture of primary oligodendrocytes (OLs) is a valuable tool for the in vitro study of the development of oligodendroglia as well as the biology of demyelinating diseases such as multiple sclerosis and Pelizaeus-Merzbacher-like disease (PMLD). Here, we present a simple and efficient selection method for the immunomagnetic isolation of stage three O4⁺ preoligodendrocytes cells from neonatal mice pups. Since immature OL constitute more than 80% of the rodent-brain white matter at postnatal day 7 (P7) this isolation method not only ensures high cellular yield, but also the specific isolation of OLs already committed to the oligodendroglial lineage, decreasing the possibility of isolating contaminating cells such as astrocytes and other cells from the mouse brain. This method is a modification of the techniques reported previously, and provides oligodendrocyte preparation purity above 80% in about 4 h.

Introduction

Oligodendrocytes (OLs) are the myelinating cells of the central nervous system (CNS)¹. The isolation and culture of primary oligodendrocytes in a tightly regulated environment is a valuable tool for the in vitro study of the development of oligodendroglia as well as the biology of demyelinating diseases such as multiple sclerosis². This requires an efficient and robust oligodendrocyte isolation and culture method³. In this study, we took advantage of the expression of a distinctive oligodendrocyte cell surface marker to implement a modified isolation technique that is rapid and specific.<....

Protocol

The mice used in this study were cared for according to the guidelines of the SUNY Downstate Medical Center Division of Laboratory Animal Resources (DLAR) protocol number 15-10492.

NOTE: Primary oligodendrocytes were isolated from neonatal (P5-P7 wild-type C57Bl/6N) mice. At this stage, immature OLs constitute more than 80% of the rodent white matter ensuring high cellular yield. All buffer and reagent compositions are available at the end of the Table of Materials.

1. Coverslips Preparation

NOTE: Poly-D-lysine (PDL)/laminin coated coverslips should be prepared prior to ....

Results

The purpose of this study was to establish an improved isolation method for O4⁺ primary mouse oligodendrocytes requiring the least possible manipulation of the target cells. The entire procedure from euthanasia of the pups to plating of the cells in coverslips takes about 4 h and data shown here represent three independent experiments. After tissue dissociation, an average of 4.3 ± 0.46 x 10⁷ cells were isolated for each independent experiment, with a viability of 91.......

Discussion

In this communication, we present a method for the efficient isolation of highly purified immature mouse oligodendrocyte cultures. Compared to previously published protocols^39,40, this method yielded a higher purity with a much lower level of GFAP-positive astrocytes and a very low percentage of other non-characterized cells. It is important to point out that these are immature OLs already committed to the oligodendroglial lineage. Thus, these cells would not be .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
10ml serological pipets	Fisher Scientific	13-676-10J
10ml syringe Luer-Loc tip	BD, Becton Dickinson	309604
15ml conical tubes	Falcon	352097
24-well tissue culture plates	Falcon	353935
40µm cell strainer	Fisher Scientific	22368547
50ml conical tubes	Falcon	352098
5ml serological pipets	Fisher Scientific	13-676-10H
60mm tissue culture plates	Falcon	353002
70µm cell strainer	Fisher Scientific	22363548
Alexa Fluor 488 goat anti-mouse IgG (H+L) secondary antibody	Invitrogen	A11001
Alexa Fluor 488 goat anti-rabbit IgM (H+L) secondary antibody	Invitrogen	A21042
Alexa Fluor 488 goat anti-rabbit IgM (H+L) secondary antibody	Invitrogen	A11008
Alexa Fluor 594 goat anti-chicken IgG (H+L) secondary antibody	Invitrogen	A11042
Anti-O4 beads- Anti-O4MicroBeads	Miltenyi Biotec	130-094-543
Apo-Transferrin human	Sigma	T1147
Autofil complete bottle top filter assembly, 0.22um filter, 250ml	USA Scientific	6032-1101
Autofil complete bottle top filter assembly, 0.22um filter, 250ml	USA Scientific	6032-1102
B27 Supplement	Invitrogen	17504-044
Boric acid	Sigma	B7660
Bovine Growth Serum (BGS)	GE Healthcare Life Sciences	SH30541.03
BSA	Fisher Scientific	BP-1600-100
CNTF	Peprotech	450-50
d-Biotin	Sigma	B4639
Desoxyribonuclease I (DNAse I)	Worthington	LS002007
EDTA	Fisher Scientific	S311
Epifluorescence microscope with an Olympus DP70 camera	Olympus	Bx51
Feather disposable scalpels	Andwin Scientific	EF7281C
Forskolin	Sigma	F6886
German glass coverslips, #1 thickness, 12mm diameter round	NeuVitro	GG-12-oz
GFAP antibody	Aves	GFAP
Glucose	Fisher Scientific	D16-1
GlutaMAX	Invitrogen	35050-61
Insulin	Invitrogen	12585-014
Magnetic separator stand - MACS multistand	Miltenyi Biotec	130-042-303
Magnetic separator-MiniMACS separator	Miltenyi Biotec	130-042-302
Millex PES 0.22µm filter unit	Millipore	SLG033RS
Mounting media- Prolong Gold with DAPI	Thermo Fisher	P36930
N-acetyl-cysteine (NAC)	Sigma	A8199
Natural mouse laminin	Invitrogen	23017-015
Neurobasal Medium A	Invitrogen	10888-022
Neurotrophin-3 (NT-3)	Peprotech	450-03
NG2 antibody	Millipore	AB5320
Papain	Worthington	LS003126
PBS without Ca2+ and Mg2+	Sigma	D5652
PDGF	Peprotech	100-13A
Petri dishes	Falcon	351029
Poly-D-Lysine	Sigma	P6407
Primocin	Invivogen	ant-pm-2
Progesterone	Sigma	P8783
Putrescine	Sigma	P5780
Selection column-LS columns	Miltenyi Biotec	130-042-401
Sodium Selenite	Sigma	S5261
Trace elements B	Corning	25-000-CI
Triiodothyronine (T3)	Sigma	T6397
Triton-X	Sigma	T8787
Trypan Blue Solution	Corning	25-900-CI
Tween 20	Sigma	P1379
B27NBMA			487.75 mL Neurobasal Medium A; 10 mL B27 Supplement; 1 mL Primocin; 1.25 mL Glutamax; Filter sterilize and store at 4 °C until use.
B27NBMA + 10% BGS			27 mL B27NBMA; 3 mL Bovine growth serum
CNTF solution stock (10 µg/ml; 1000X)			Order from Peprotech (450-50). Make up at 0.1 to 1 mg/ml according to Manufacturer’s instruction (may vary from lot to lot) in buffer (e.g. DPBS + 0.2% BSA). Store at -80 °C. Working solution (10 µg/ml, 1000X) 1. Make on 0.2% BSA (Fisher scientific BP-1600-100) in DPBS solution and filter sterilize. 2. Dilute master stock aliquot to 10µg/ml in sterile, chilled 0.2% BSA/DPBS. 3. Aliquot (20µl/tube) and snap freeze in liquid nitrogen. 4. Store aliquots at -80 °C.
d-Biotin stock solution (50 µg/ml; 5000X)			Resuspend d-Biotin (Sigma-B4639) in double-distilled H2O at 50 µg/ml (e.g. 2.5 mg in 50 ml of ddH2O). Resuspension might take fair amount of agitation/vortexing, or mild warming briefly at 37°C. If the d-Biotin still will not solubilize, it is fine to make up a less concentrated (e.g. 10µg/ml), and to add a higher volume to the B27NBMA (1/1000), instead of 1/5000). Store at 4°C.
DNase I stock solution			1. Dissolve at 12,500 U Deoxyribonuclease I / ml in HBSS chilled on ice. 2. Filter sterilize on ice 3. Aliquot at 200 µl and freeze overnight at -20°C. 4. Store aliquots at -20 to -30°C.
Dulbecco’s Phosphate Buffered Saline (w/o Ca2+ and Mg2+)			Dissolve pouch in 1 Liter of water to yield 1 liter of medium at 9.6 grams of powder per liter of medium. Store at 2-8 °C.
Forskolin stock solution (4.2 mg/ml; 1000X)			Add 1 ml of sterile DMSO to 50 mg Forskolin in bottle (Sigma-F6886) and pipette until resuspended. Transfer to a 15 ml centrifuge tube and add 11 ml of sterile DMSO to bring to 4.2 mg/ml. Aliquot (e.g. 20 µl) and store at -20°C.
Hank’s balanced salts (HBSS) (Sigma			1. Measure 900 ml of water (temperature 15-20 °C) in a cylinder and stir gently. 2. Add the power and stir until dissolved. 3. Rinse original package with a small amount of water to remove all traces of the powder. 4. Add to the solution in step 2. 5. Add 0.35 gr of sodium bicarbonate (7.5% w/v) for each liter of final volume. 6. Keep stirring until dissolved. 7. Adjust the pH of the buffer while stirring to 0.1-0.3 units below pH= 7.4 since it may rise during filtration. The use of 1N HCl or 1N NaOH is recommended to adjust the pH. 8. Add additional water to bring the final volume to 1L. 9. Sterilize by filtration using a membrane with a porosity of 0.22 microns. 10. Store at 2-8 °C.
Insulin stock solution (4000 µg/ml)			Thaw the bottle and aliquot 25 µl per microcentrifuge tube and store at -20°C.
Laminin solution			Slowly thaw laminin in the cold (2°C to 8°C) to avoid gel formation. Then, aliquot into polypropylene tubes. Store at 5° C to -20° C in aliquots (e.g. 20 µl) and do not freeze/thaw repeatedly. Laminin may be stored at these temperatures for up to six months.
Magnetic Cell Sorting (MCS) Buffer			Prepare the solution containing phosphate-buffered saline (PBS), pH 7.2, and 0.5% bovine serum albumin (BSA), 0.5 mM EDTA, 5µg/ml Insulin, 1 g/L Glucose. Sterilize and degas by filtration the buffer by passing it through a 0.22 µm Millex filter. Store the buffer at 4°C until use
N-Acetyl-L-cysteine (NAC) stock solution (5mg/ml; 1000X)			Dissolve N-Acetyl-L-cysteine (Sigma-A8199) at 5 mg/ml in DMEM (e.g. 50 mg NAC in 10 ml B27NBMA). Filter sterilize and aliquot (e.g. 20 µl). Store at -20°C.
NT3 stock solution (1 µg/ml; 1000X)			Master stock: Order from Peprotech (450-03). Make up at 0.1 to 1 mg/ml according to manufacturer’s instructions (may vary from lot to lot), in buffer (e.g. DPBS + 0.2% BSA). Store at -80°C. Working stock (1µg/ml; 1000X): 1. Make on 0.2% BSA in DPBS solution and filter sterilize. 2. Dilute master stock aliquot to 1 µg/ml in sterile, chilled 0.2% BSA/DPBS. 3. Aliquot (e.g. 20µl/tube) and snap freeze in liquid nitrogen. 4. Store aliquots at -80°C.
PDGF stock solution (10 µg/ml; 1000X)			Master stock: Order from Peprotech (100-13A). Make up at 0.1 to 1 mg/ml according to manufacturer’s instructions (may vary from lot to lot) in buffer (e.g. DPBS) + 0.2% BSA). Store at -80°C. Working stock (1µg/ml; 1000X): 1. Make on 0.2% BSA in DPBS solution and filter sterilize. 2. Dilute master stock aliquot to 1µg/ml in sterile, chilled 0.2% BSA/DPBS. 3. Aliquot (e.g. 20µl/tube) and snap freeze in liquid nitrogen. 4. Store aliquots at -80°C.
Poly-D-lysine (1mg/ml; 100X)			Resuspend poly-D-lysine, molecular weight 70-150 kD (Sigma P6407) at 0.5mg/ml in 0.15M boric acid pH 8.4 (e.g. 50mg in 50ml borate buffer). Filter sterilize and aliquot (e.g. 100µl/tube). Store at -20°C. Prior to use, dilute the 100X stock (1mg/ml) to 50 µg/ml in sterile water.
Oligodendrocyte proliferation media			see Supplementary Table 1
Oligodendrocyte differentiation media			see Supplementary Table 1
Sato supplement (100X)			see Supplementary Table 1
References: the list of reagents and recipes were adopted from the protocols previously described by Emery et. al. 2013 (Emery, B. & Dugas, J. C. Purification of oligodendrocyte lineage cells from mouse cortices by immunopanning. Cold Spring Harb Protoc. 2013 (9), 854-868, doi:10.1101/pdb.prot073973, (2013)) and Dincman et. al. (Dincman, T. A., Beare, J. E., Ohri, S. S. & Whittemore, S. R. Isolation of cortical mouse oligodendrocyte precursor cells. J Neurosci Methods. 209 (1), 219-226, doi:10.1016/j.jneumeth.2012.06.017, (2012))