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

Xin Zhang,Yan-Ni Ma,Jun-Wu Zhang

doi:10.4067/s0716-97602007000100005

Abstract

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.

Highlights

The expression of human globin genes is stringently erythroid development specific
We found that the kinetics of globin gene expression in cord blood (CB)-derived CHS+ erythroid cultures differed from those in two kinds of adult bone marrow (BM)-derived erythroid cultures but they were very similar to the neonatal and adult kinetics of globin gene expression in vivo respectively, suggesting that the globin gene expression in neonatal and adult erythroid progenitors cultured in our optimized liquid culture systems recapitulated the expression patterns of their corresponding ontogenic stage in vivo
The mechanisms of hemoglobin switching have become the focus of study in globin field because the understanding of these mechanisms is of biological significance and relevant to the development of rational design of therapies for a variety of hemoglobinopathies, but the precise mechanisms of hemoglobin switching are still far from being demonstrated

Summary

Introduction

The expression of human globin genes is stringently erythroid development specific. During ontogeny, the expression of α-like globin gene displays an embryonic (ζ-) to adult (α-) globin switch, whereas the β-like globin gene expression displays two switches: the embryonic (ε-) to fetal globin (γ-) switch coinciding with the transition from embryonic (yolk sac) to definitive (fetal liver) hematopoiesis, and the fetal to adult (β-) globin switch, occurring near the perinatal period concomitantly with the establishment of the bone marrow as the main site of hematopoiesis (Stamatoyannopoulos and Grosveld, 2001).It was found that the fetal hemoglobin expression can be reactivated during adult erythropoiesis under several inherited and acquired conditions and the increased production of fetal hemoglobin can ameliorate the clinical severity of sickle cell anemia SCD and β-thalassemia (Stamatoyannopoulos and Grosveld, 2001; Rodgers and Rachmilewitz, 1995). The expression of human globin genes is stringently erythroid development specific. The expression of α-like globin gene displays an embryonic (ζ-) to adult (α-) globin switch, whereas the β-like globin gene expression displays two switches: the embryonic (ε-) to fetal globin (γ-) switch coinciding with the transition from embryonic (yolk sac) to definitive (fetal liver) hematopoiesis, and the fetal to adult (β-) globin switch, occurring near the perinatal period concomitantly with the establishment of the bone marrow as the main site of hematopoiesis (Stamatoyannopoulos and Grosveld, 2001). It was found that the fetal hemoglobin expression can be reactivated during adult erythropoiesis under several inherited and acquired conditions and the increased production of fetal hemoglobin can ameliorate the clinical severity of sickle cell anemia SCD and β-thalassemia (Stamatoyannopoulos and Grosveld, 2001; Rodgers and Rachmilewitz, 1995).

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Conclusion