Determining the Effect of Cell Culture Methods on the Polarization and Phenotype of Macrophages

Abstract

Macrophages play an important role in the regulation of cancer tumor microenvironments (TME). The specific role they play depends on their polarization, which is divided into two general phenotypes: M1, a pro-inflammatory phenotype, and M2, an anti-inflammatory phenotype known to support tumor growth. As the field of cancer research develops, there is an increased focus on understanding the role of the macrophage in the TME and how it can be manipulated to limit the growth of the tumor. Thus, it is important for researchers who are studying the macrophage’s role in the TME to know the phenotype of the macrophages that they are culturing in their research. The goal of this study was to observe the differentiation and polarization of macrophages during the standard cell culture protocol. We expected the macrophages to be fully differentiated after 7 days of culture with M-CSF and that cell passaging would result in a higher abundance of M1 polarized macrophages in culture. However, we found that macrophages are fully polarized after only 5 days of exposure to M-CSF and that passaging has no significant effect on macrophage polarization. This implies that macrophage differentiation protocols can be shortened with no loss in macrophage yield and that passaging is a suitable cell culture method for macrophages.