Erythroblast island macrophages: recent discovery and future perspectives

Wei Li; Yaomei Wang; Lixiang Chen; Xiuli An

doi:10.1097/BS9.0000000000000017

Erythroblast island macrophages: recent discovery and future perspectives

Blood Sci. 2019 Sep 17;1(1):61-64. doi: 10.1097/BS9.0000000000000017. eCollection 2019 Aug.

Authors

Wei Li^{1

2}, Yaomei Wang^{1

3}, Lixiang Chen¹, Xiuli An^{1

2}

Affiliations

¹ School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China.
² Laboratory of Membrane Biology, New York Blood Center, New York, NY 10065, USA.
³ Department of Hematology, the Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital, Zhengzhou 450008, China.

Abstract

Erythroblastic island (EBI), composed of a central macrophage surrounded by developing erythroid cells, is a structure found in hematopoietic tissues such as fetal liver and bone marrow. It is the first described hematopoietic niche that predominantly supports erythropoiesis. Although it is well accepted that EBIs and EBI macrophage play important roles during erythropoiesis, the mechanisms by which they support erythropoiesis remain largely unclear due to our inability to identify and isolate EBI macrophages. Earlier efforts to identify surface markers for EBI macrophages have focused on the adhesion molecules which are involved in macrophage's interaction with erythroblasts. These include EMP, Vcam1, CD169, CD163, and αV integrin. Findings from these earlier studies suggested that combination of Vcam1, CD169, and mouse macrophage surface marker F4/80 can be used to define mouse EBI macrophage. We found that not all F4/80⁺Vcam1⁺CD169⁺ macrophages are EBI macrophages. Instead, we discovered that EBI macrophages are characterized by the expression of Epor in both mouse and man. RNA-seq analyses of the newly identified EBI macrophages revealed that EBI macrophages have involved specialized function in supporting erythropoiesis. Our findings provide foundation for future studies. Here we will review current knowledge of EBI macrophages and discuss future perspectives.

Keywords: Epor; Erythroblast islands; Erythroblastic island macrophages; Erythropoiesis.