Identification, Isolation and Transcriptome Analyses of Mouse, Rat and Man Erythroblastic Island Central Macrophages

Erythroblastic island (EBI), composed of a central macrophage and surrounding erythroid cells, is the first hematopoietic niche discovered for erythropoiesis. Yet, the identity of the central macrophage has so far remained elusive. Based on the previous findings that F4/80, VCAM1 and CD169 are potential mouse central macrophage markers, we first calculated the number of F4/80+VCAM1+CD169+ mouse macrophages in the mouse bone marrow and compared it to the number of Ter119+ erythroblasts. We found that the ratio of F4/80+VCAM1+CD169+ macrophage and erythroblasts is about 1:2. Given the fact that one central macrophage is surrounded by multiple erythroblasts, the above finding suggests that it is unlikely that all the F4/80+VCAM1+CD169+ macrophages are central macrophages.