Human erythroid progenitors from adult bone marrow and cord blood in optimized liquid culture systems respectively maintained adult and neonatal characteristics of globin gene expression

In vitro suspension culture procedures for erythroid progenitor cells make it possible for us to obtain large cultures of erythrocyte populations for the investigation of globin gene switching. In this study we aimed to establish optimized culture systems for neonatal and adult erythroblasts and to explore the globin expression patterns in these culture systems. To culture CD34(+) cells purified from human umbilical cord blood (CB) and adult bone marrow (BM), we respectively replaced the fetal bovine serum (FBS) with human cord serum and human adult serum. These CD34(+) cells were then induced to erythroid differentiation. All the globin mRNA (including alpha-, zeta-, beta-, gamma-and epsilon-globin), the hemoglobin (Hb)-producing erythroid cells and the cellular distribution of fetal hemoglobin (Hb F) were identified during the culture process. The results showed that the globin expression pattern during erythroid differentiation in our culture systems closely recapitulated neonatal and adult patterns of globin expression in vivo, suggesting that our specially optimized culture systems not only overcame the higher Hb F levels in the BM-derived CD34(+) culture in FBS-containing medium but also eliminated the disadvantages of low cell proliferation rate and low globin mRNA levels in serum-free medium.