A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. The protocol utilizes cryopreservation of monocytes coupled with their bulk differentiation into macrophages. Then harvested macrophages can then be seeded into culture wells at required cell densities for carrying out experiments.
A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. For initiation of experiments, fresh or frozen monocytes are cultured in flasks for 1 week with M-CSF to induce their differentiation into macrophages. Then, the macrophages can be harvested and seeded into culture wells at required cell densities for carrying out experiments. The use of defined numbers of macrophages rather than defined numbers of monocytes to initiate macrophage cultures for experiments yields macrophage cultures in which the desired cell density can be more consistently attained. Use of cryopreserved monocytes reduces dependency on donor availability and produces more homogeneous macrophage cultures.
Study of cultured macrophages is a useful model to understand the function of these cells in inflammation such as occurs in atherosclerotic plaques. When the research focus is on human diseases involving macrophages, it is useful to study primary human macrophages rather than non-human macrophages to avoid species differences. Also, the effects of cell transformation can be avoided by using primary macrophages rather than macrophage cell lines. For this purpose, macrophages differentiated from monocytes isolated from human blood serve as a means of obtaining primary human macrophages.
Tissue macrophages may be either resident within tissues or may be derived from monocytes that migrate into the tissue and differentiate into macrophages 1. Two types of human monocyte-derived macrophages have been defined that differ not only in morphology but also gene expression and cell function 2. These two types are obtained from monocytes that are differentiated into macrophages in the presence of M-CSF + fetal bovine serum (FBS) and monocytes that are differentiated into macrophages in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) + FBS 2-6. In our experience (unpublished observation), use of human serum rather than FBS generates the GM-CSF type regardless of whether M-CSF or GM-CSF is included in the differentiation medium. M-CSF type macrophages tend to be more elongated than GM-CSF type macrophages, which resemble fried eggs in their morphology. Investigators should recognize that human M-CSF and GM-CSF monocyte-derived macrophages are not the same as so called M1 and M2 mouse bone marrow-derived macrophages 6.
During research using human monocyte-derived M-CSF differentiated macrophages, we experienced difficulty related to the availability of monocytes to initiate experiments and variation in the obtained cell densities of macrophages during differentiation of monocytes into macrophages. To overcome these problems, we have developed the following protocol in which monocytes are frozen until required for use, and monocytes are differentiated in bulk into macrophages that can then be removed from culture flasks and plated at desired cell densities to obtain more uniform cultures from experiment to experiment.
Génération types de macrophage définis peut clarifier certains des résultats contradictoires obtenus par les enquêteurs lors de l'étude de la biologie macrophage. L'utilisation de différentes conditions de culture et des facteurs de différenciation pour générer des macrophages humains primaires peuvent conduire à des types très différents macrophage, un fait qui ne peut être apprécié par le chercheur. Par exemple, les macrophages sont parfois produites à partir de monocytes humains en utilisant …
The authors have nothing to disclose.
The Department of Transfusion Medicine, Clinical Center, National Institutes of Health, provided elutriated monocytes. This work was supported by the Intramural Research Program, National Heart, Lung, and Blood Institute, National Institutes of Health.
Cellbind 12-well culture plate | Corning | 3336 | |
CELLSTAR, T-75 flask, tissue culture treated | Greiner Bio-One North America | 658157 | |
RPMI 1640 culture medium | Cellgro Mediatech | 15-040-CM | warmed to 37 °C |
L-Glutamine | Cellgro Mediatech | 25-005-CI | |
Fetal bovine serum | Gibco | 16000-036 | |
M-CSF | PeproTech | 300-25 | |
GM-CSF | PeproTech | 300-03 | |
IL-10 | PeproTech | 200-10 | |
DMSO | Sigma | D2650 | |
Cryovial | Thermo Scientific | 375418 | |
DPBS without Ca2+ and Mg2+ | Corning cellgro | 21-031-CV | |
0.25% Trypsin-EDTA | Gibco | 25200-056 | |
50 ml polypropylene conical tube | Falcon | 352070 | |
Trypan Blue | Lonza | 17-942E | |
Neubauer-improved bright light hemocytometer | Paul Marienfeld GmbH & Co. KG | 610031 | http://www.marienfeld-superior.com/index.php/counting-chambers/articles/counting-chambers.html |
CoolCell LX cell freezing container | BioCision | BCS-405 | other freezing containers also should be adequate for this step |
Liquid Nitrogen Storage System, CryoPlus 1 | Thermo Scientific | 7400 | any liquid nitrogen tank should be adequate |