Concise Review: Advanced Cell Culture Models for Diamond Blackfan Anemia and Other Erythroid Disorders

Abstract

In vitro surrogate models of human erythropoiesis made many contributions to our understanding of the extrinsic and intrinsic regulation of this process in vivo and how they are altered in erythroid disorders. In the past, variability among the levels of hemoglobin F produced by adult erythroblasts generated in vitro by different laboratories identified stage of maturation, fetal bovine serum, and accessory cells as "confounding factors," that is, parameters intrinsically wired in the experimental approach that bias the results observed. The discovery of these factors facilitated the identification of drugs that accelerate terminal maturation or activate specific signaling pathways for the treatment of hemoglobinopathies. It also inspired studies to understand how erythropoiesis is regulated by macrophages present in the erythroid islands. Recent cell culture advances have greatly increased the number of human erythroid cells that can be generated in vitro and are used as experimental models to study diseases, such as Diamond Blackfan Anemia, which were previously poorly amenable to investigation. However, in addition to the confounding factors already identified, improvement in the culture models has introduced novel confounding factors, such as possible interactions between signaling from cKIT, the receptor for stem cell factor, and from the glucocorticoid receptor, the cell proliferation potential and the clinical state of the patients. This review will illustrate these new confounding factors and discuss their clinical translation potential to improve our understanding of Diamond Blackfan Anemia and other erythroid disorders. Stem Cells 2018;36:172-179.

Keywords: Anemia; Cell culture advances; Clinical translation; Erythropoiesis; Experimental models.

Figure 1. Examples of clinical applications of in vitro modeling of erythroid cells

Left Panel: Representative confocal microscopy image of erythroid cells expanded in vitro from adult blood stained with antibodies against calreticulin (red signal) and the glucocorticoid receptor (GR). These studies may elucidate mechanisms which regulate the stress response in human erythroid cells and how their alterations may determine the pathobiology of myeloproliferative neoplasms [90]. Right panel: Representative confocal microscopy analyses for EKLF (also known as KLF1, green signal) in erythroid cells expanded in vitro from adult blood. Human erythroid cells expanded in vitro may elucidate the cross-regulation between EKLF and BCL11A in the regulation of hemoglobin F production as well identify the effects exerted by EKLF mutations in human erythropoiesis [91]. Nuclei were counterstained with DAPI. Original magnification 1500×. Scale bars are not presented.