Isolation and Intravenous Injection of Murine Bone Marrow Derived Monocytes

Summary

Here we present a protocol that generates large amounts of murine monocytes from heterogeneous bone marrow for translational applications. In comparison to others, this new method helps reduce the number of sacrificed animals and lowers costs by avoiding expensive methods such as high gradient magnetic cell separation (MACS).

Abstract

As a subtype of leukocytes and progenitors of macrophages, monocytes are involved in many important processes of organisms and are often the subject of various fields in biomedical science. The method described below is a simple and effective way to isolate murine monocytes from heterogeneous bone marrow.

Bone marrow from the femur and tibia of Balb/c mice is harvested by flushing with phosphate buffered saline (PBS). Cell suspension is supplemented with macrophage-colony stimulating factor (M-CSF) and cultured on ultra-low attachment surfaces to avoid adhesion-triggered differentiation of monocytes. The properties and differentiation of monocytes are characterized at various intervals. Fluorescence activated cell sorting (FACS), with markers like CD11b, CD115, and F4/80, is used for phenotyping. At the end of cultivation, the suspension consists of 45%± 12% monocytes. By removing adhesive macrophages, the purity can be raised up to 86%± 6%. After the isolation, monocytes can be utilized in various ways, and one of the most effective and common methods for in vivo delivery is intravenous tail vein injection.

This technique of isolation and application is important for mouse model studies, especially in the fields of inflammation or immunology. Monocytes can also be used therapeutically in mouse disease models.

Introduction

The isolation of monocytes is important and critical for many in vitro and in vivo studies. These cells are targets for diseases such as peripheral arterial disease, coronary heart disease, or other ischemic diseases, since collateral vessel growth is strongly driven by local inflammation. Inflammatory responses include endothelial activation and local recruitment of leukocytes, mainly monocytes, which then mature to macrophages and create a highly arteriogenic environment by secreting multiple growth factors to induce the remodeling of an arteriole into a functional collateral artery^1-3. Monocytes also mature to dendritic cells, which are....

Protocol

This study was performed with permission of the State of Saxony and Saxony-Anhalt, Regierungspraesidium Dresden/Halle, according to Section 8 of the German Law for animal protection (24D-9168.11-1/2008-24).

1 Cell Isolation

1.1 Preparation of Femur and Tibia

1. Anesthetize the mouse using a 5% isoflurane concentration by vaporizing isoflurane in a closed bin. After the mouse has stopped moving for 3 sec, perform the cervical dislocation.
2. Disinfect the hind limbs with ethanol (96%). Remove skin and muscles and separate the bones with a sterile scalpel.
   1. Start with an inguinal skin incisi....

Results

The cell solution extracted from the murine bone marrow consists of various cell types. The major cell types are lymphocytes, granulocytes and monocytes. Cell types can be estimated by size and granularity, which is shown in Figure 1 for both native suspensions and cells harvested after 5 days of differentiation. Note the shifting cellular composition during cultivation. However, accurate classification of populations must rely on distinctive expression of cellular markers.

Th.......

Discussion

We describe a simple and cost-effective method to isolate large amounts of murine monocytes from bone marrow. In comparison to other protocols using peripheral blood, which obtain monocyte yields⁵ of 1.4 x10⁶, we are able to obtain higher yields of 11 x 10⁶ ± 3 x 10⁶ monocytes from a single donor mouse.

When considering challenges with this method, it is important to mention the potential for contamination when working under non-sterile conditio.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
6-well-ultra-low-attachment plate	Corning Incorporated, NY, USA		6-well-ultra-low-attachment plate, with cap, sterile
8- 12 week old, male, balb/c mice	Charles River, Sulzfeld, Germany
96-well-plate	Greiner bio one GmbH, Frickenhausen, Germany
Blue dead cell stain	Life technologies GmbH, Darmstadt, Germany
Bovine serum albumine	GE Healthcare, Freiburg, Germany		Fraction V, pH 7.0
Canules	B. Braun, Melsungen AG, Melsungen, Germany		28G, 30G
CD115	eBioscience, San Diego, USA	12-1152
CD11b	eBioscience, San Diego, USA	53-0112
Cell culture dish	Greiner Bio-One GmbH, Frickenhausen, Germany		With cap, steril
Centrifuge	Beckman Coulter GmbH, Krefeld, Germany		Allegra® X-15R centrifuge
Depilatory cream	Veet, Mannheim, Germany
Disinfection agent	Schülke&Mayr GmbH, Norderstedt, Germany		Kodan Tinktur forte
Disposable scalpel No.10	Feather safety razor Co.Ltd, Osaka, Japan
EDTA	Sigma Aldrich, Hamburg, Germany
Ethanol 96%	Otto Fischar GmbH und Co KG, Saarbrücken, Germany
Extraction unit Pipetus	Hirschmann Laborgeräte GmbH & Co.KG, Eberstadt, Germany
F4/80	AbD Serotec, Düsseldorf, Germany	MCA497APC
FACS buffer	Manufactured by our group with single components		PBS, 0.5% BSA, 0.1% NaN3
FACS device	Becton, Dickinson and Company, Franklyn Lakes, New Jersey, USA		BD FACS Canto II
FACS tubes	Becton, Dickinson and Company, Franklyn Lakes, New Jersey, USA
Falcon® pipette	Becton Dickenson Labware, NY, USA
Fetal calf serum	Sigma Aldrich, Hamburg, Germany
Fine forceps	Rubis, Stabio, Switzerland
Gloves	Rösner-Matby Meditrade GmbH, Kiefersfelden, Germany
Gr1	eBioscience, San Diego, USA	53-5931
Heating plate	Labotect GmbH, Göttingen, Germany		Hot Plate 062
Incubator	Ewald Innovationstechnik GmbH, Bad Nenndorf, Germany		Incu safe
Isofluran	Baxter Deutschland GmbH, Unterschleißheim, Germany
Light microscope	Carl Zeiss SMT GmbH, Oberkochen, Germany		Axiovert 40 °C
Macrophage-Colony Stimulating Factor	Sigma Aldrich, Hamburg, Germany	SRP3110
Mechanical shaker	IKA, Staufen, Germany		ms2 minishaker
Medium 199	PAA Laboratories GmbH, Pasching, Austria		Warm in 37 °C water bath before use
Micro test tubes	Eppendorf AG, Hamburg, Germany
Microbiological work bench	Thermo Electron, LED GmbH, Langenselbold, Germany		Hera safe
Monocyte wash buffer	Manufactured by our group with single components		PBS, 0.5% BSA, 2 mM EDTA
Mouse restrainer	Various
NaCl	Berlin Chemie AG, Berlin, Germany
NaN3 (sodium acide)	Sigma Aldrich, Hamburg, Germany
Neubauer counting chamber	Paul Marienfeld GmbH und Co.KG, Lauda-Königshofen, Germany
Nylon cellsieve	Becton, Dickinson and Company, Franklyn Lakes, New Jersey, USA		Cell strainer, 70 µm mesh size
Penicillin/Streptomycin	Sigma Aldrich, Hamburg, Germany
Phosphate buffered saline	Life technologies GmbH, Darmstadt, Germany		pH 7.4, sterile
Pipettes	Eppendorf AG, Hamburg, Germany		10µl/100µl/200µl/1,000µl
Pipetting heads	Eppendorf AG, Hamburg, Germany
Serological pipette	Greiner Bio-One GmbH, Frickenhausen, Germany		Cellstar 5 ml, 10 ml
Suction unit	Integra bioscience, Fernwald, Germany		Vacusafe comfort
Surgical scissors	Word Precision Instruments, Inc., Sarasota, USA
Syringe	B. Braun, Melsungen AG, Melsungen, Germany		1 ml Omnifix® -F insuline syringe
Tubes with cap	Greiner bio one GmbH, Frickenhausen, Germany		15 ml/50 ml Cellstar tubes
Warm water bath	Julabo Labortechnik GmbH, Seelbach, Germany		Julabo SW22