Dynamic human erythropoiesis in a three-dimensional perfusion bone marrow biomimicry

Traditional culture systems for human erythropoiesis lack microenvironmental niches, spatial marrow gradients and dense cellularity rendering them incapable of effectively translating marrow physiology ex vivo. Herein, a bio-inspired three-dimensional (3D) perfusion bioreactor was engineered and inoculated with unselected single donor umbilical cord blood mononuclear cells (CBMNCs). Functional stromal and hematopoietic environments supporting long-term erythropoiesis were generated using defined medium supplemented only with stem cell factor (SCF) and erythropoietin (EPO) at near physiological concentrations. Quantitative 3D image analyses spatiotemporally mapped 21 multi-lineal cell distributions and interactions within multiple microenvironments that secreted extracellular matrix proteins and at least 16 endogenous hematopoietic and stromal growth factors. Tissue-like culture densities (≥2∙10⁹ cells/mL), 1000-fold above flask cultures, were attained with continuous erythropoiesis and erythrocyte harvest. We propose this physiologically-relevant system for understanding normal and abnormal erythropoiesis, as well as for drug testing and/or discovery aimed at clinical translation.