title: Autonomous control of terminal erythropoiesis via physical interactions among erythroid cells.
abstract: In vitro erythropoiesis has been studied extensively for its application in the manufacture of transfusable erythrocytes. Unfortunately, culture conditions have not been as effective as in vivo growth conditions, where bone marrow macrophages are known to be a key regulator of erythropoiesis. This study focused on the fact that some erythroblasts are detached from macrophages and only contact other erythroblasts. We hypothesized that additional factors regulate erythroblasts, likely through either physical contact or secreted factors. To further elucidate these critical factors, human erythroblasts derived from cord blood were cultured at high density to mimic marrow conditions. This growth condition resulted in a significantly increased erythroid enucleation rate and viability. We found several novel contact-related signals in erythroblasts: intercellular adhesion molecule-4 (ICAM-4) and deleted in liver cancer-1 (DLC-1). DLC-1, a Rho-GTPase-activating protein, has not previously been reported in erythroid cells, but its interaction with ICAM-4 was demonstrated here. We further confirmed the presence of a secreted form of human ICAM-4 for the first time. When soluble ICAM-4 was added to media, cell viability and enucleation increased with decreased nuclear dysplasia, suggesting that ICAM-4 is a key factor in contact between cells. These results highlight potential new mechanisms for autonomous control of erythropoiesis. The application of these procedures to erythrocyte manufacturing could enhance in vitro erythrocyte production for clinical use.
authors.affiliation: Department of Laboratory Medicine, School of Medicine, Hanyang University, Seoul, Republic of Korea.
authors.forename: Hye Sook
authors.initials: HS
authors.lastname: Choi
authors.forename: Eun Mi
authors.initials: EM
authors.lastname: Lee
authors.forename: Hyun Ok
authors.initials: HO
authors.lastname: Kim
authors.forename: Moon-Il
authors.initials: MI
authors.lastname: Park
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Baek
mesh_terms: D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D002450:Cell Communication; D019070:Cell Lineage; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D048749:Cytokinesis; D004900:Erythroblasts / Q000166:cytology* / Q000378:metabolism; D004920:Erythropoiesis / Q000187:drug effects; D005312:Fetal Blood / Q000166:cytology; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006801:Humans; D020014:K562 Cells; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D015815:Cell Adhesion Molecules; D017077:Culture Media, Conditioned; C112352:DLC1 protein, human; D020690:GTPase-Activating Proteins; C095100:ICAM4 protein, human; D011994:Recombinant Proteins; D025521:Tumor Suppressor Proteins