It has been reported that monocytes entered the injured brain, and differentiate into microglia, resident brain macrophages. In this study, I found that slice culture conditioned media (SCM) induced expression of Tmem119, a microglia specific marker, in bone marrow-derived monocytes (BMDM). In addition, SCM also increased phagocytic activity of monocytes. However, Tmem119 expression was not changed in the presence of a TLR4 agonist (LPS), or culture conditioned media from astrocytes (ACM) and neurons (NCM) treated with or without insults such as glutamate and ATP. These results suggest that factors from several types of cells in damaged brain tissues may cooperate to induce differentiation of monocytes into microglia.
