In vivo and in vitro studies of fetal hemoglobin induction by hydroxyurea in β-thalassemia/hemoglobin E patients

• Published in: Experimental hematology Vol. 33; no. 12; pp. 1486 - 1492
• Main Authors: Watanapokasin, Yuwadee, Chuncharunee, Suporn, Sanmund, Duangmanee, Kongnium, Wantana, Winichagoon, Pranee, Rodgers, Griffin P., Fucharoen, Suthat
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01-12-2005
• Subjects: Adult; beta-Thalassemia - blood; beta-Thalassemia - diagnosis; beta-Thalassemia - drug therapy; Cells, Cultured; Drug Monitoring - methods; Erythroid Cells - drug effects; Female; Fetal Hemoglobin - analysis; Fetal Hemoglobin - genetics; Gene Expression Regulation - drug effects; Hemoglobin E; Hemoglobinuria - blood; Hemoglobinuria - diagnosis; Hemoglobinuria - drug therapy; Humans; Hydroxyurea - administration & dosage; Hydroxyurea - pharmacology; Male; Middle Aged; Predictive Value of Tests; Prognosis
• ISSN: 0301-472X; 1873-2399
• DOI: 10.1016/j.exphem.2005.09.006

Some, but not all, β-thalassemia/hemoglobin E (β-thal/HbE) patients respond to hydroxyurea treatment. It would be helpful if patient responses to hydroxyurea could be screened in vitro to identify responders and nonresponders before beginning in vivo treatment.
Thirteen β-Thal/HbE patients were treated with hydroxyurea orally for 2 years at a starting dose of 5 mg/kg/day for 5 days/week with escalation to a maximum of 10 mg/kg/day. For comparison, erythroid cells obtained from peripheral blood of the same patients 1 year after they had stopped hydroxyurea treatment were treated with hydroxyurea in vitro. The γ-globin mRNA was measured by real-time reverse-transcription polymerase chain reaction, fetal hemoglobin (HbF) by high-performance liquid chromatography,
Gγ- and
Aγ-globin chains by Triton X-100 acid urea polyacrylamide gel electrophoresis.
Treatment of cells in primary culture with 30 μM hydroxyurea for 96 hours significantly increased the fractional HbF content in β-Thal/HbE patients. The
Gγ:
Aγ-globin mRNA was induced 0.30- to 8-fold in vitro and 0.30- to 6-fold in vivo (r
2 = 0.51,
p = 0.16 by paired
t-test); the fractional HbF content was induced 0.50- to 19-fold in vitro and 0.30- to 12-fold in vivo (r
2 = 0.61,
p = 0.20) and the
Gγ:
Aγ-globin chain ratio was increased 0.80- to 1.40-fold in vitro and 1- to 1.20-fold in vivo (r
2 = 0.62,
p = 0.13).
The correlation of in vivo and in vitro results of HbF synthesis and globin mRNA suggest that in vitro testing may predict the in vivo response.