To facilitate comparative genomic analyses of human fetal and adult cells undergoing erythropoiesis, we employed a serum-free two-phase liquid culture system to expand and differentiate primary human CD34+ hematopoietic stem/progenitor cells (HSPCs) ex vivo. In this experimental context, highly enriched populations of stage-matched, differentiating, primary proerythroblasts (ProEs) were generated. We selected four time points (day 0, CD34+ HSPCs; day 3, 5, and 7, differentiating ProEs) that represented similar stages differentiation for gene expression profiling using microarrays.

Primary maturing fetal or adult erythroblasts were generated ex vivo from CD34+ hematopoietic stem/progenitor cells (HSPCs) using a serum-free two-phase liquid culture system. Total RNA from primary fetal and adult HSPCs (day 0) and differentiating proerythroblasts (ProEs; day 3, 5, and 7) were extracted and used to hybridize to Affymetrix expression arrays using the HG-U133 Plus 2.0 platform.