Quantification of HBG mRNA in primary erythroid cultures: prediction of the response to hydroxyurea in sickle cell and beta-thalassemia

Abstract

Background and objective: Increased expression of fetal hemoglobin (HbF) may ameliorate the clinical course of hemoglobinopathies like sickle cell disease (SCD) and β-thalassemia. Hydroxyurea (HU) can stimulate HbF production in these diseases but the response is highly variable indicating the utility of developing an in vitro test to predict the patient's response to HU. We assessed whether the HbF response of patients with SCD and thalassemia intermedia (TI) to HU correlates with HBG (both γ-globin genes) expression in their cultured erythroid progenitors following exposure to HU.

Patients and methods: We exposed primary erythroid cultures from peripheral blood mononuclear cells from 30 patients with SCD and 15 with TI to HU and measured HBG mRNA by real-time quantitative PCR. The same patients were then treated with HU and their HbF response after treatment with a stable dose of HU was compared with the mRNA results in cultured cells.

Results and conclusion: The fold increase in HBG mRNA in erythroid progenitors was similar to the fold increase in HbF in vivo. Quantification of HBG mRNA in erythroid progenitor cell cultures from patients with SCD and TI is predictive of their clinical response to HU.

Keywords: hydroxyurea; liquid erythroid cultures; real-time quantitative PCR; sickle cell disease; β-thalassemia.