Effective erythropoiesis and HbF reactivation induced by kit ligand in beta-thalassemia.
In human beta-thalassemia, the imbalance between alpha- and non-alpha-globin chains causes ineffective erythropoiesis, hemolysis, and anemia: this condition is effectively treated by an enhanced level of fetal hemoglobin (HbF). In spite of extensive studies on pharmacologic induction of HbF synthesis, clinical trials based on HbF reactivation in beta-thalassemia produced inconsistent results. Here, we investigated the in vitro response of beta-thalassemic erythroid progenitors to kit ligand (KL) in terms of HbF reactivation, stimulation of effective erythropoiesis, and inhibition of apoptosis. In unilineage erythroid cultures of 20 patients with intermedia or major beta-thalassemia, addition of KL, alone or combined with dexamethasone (Dex), remarkably stimulated cell proliferation (3-4 logs more than control cultures), while decreasing the percentage of apoptotic and dyserythropoietic cells (<5%). More important, in both thalassemic groups, addition of KL or KL plus Dex induced a marked increase of gamma-globin synthesis, thus reaching HbF levels 3-fold higher than in con-trol cultures (eg, from 27% to 75% or 81%, respectively, in beta-thalassemia major). These studies indicate that in beta-thalassemia, KL, alone or combined with Dex, induces an expansion of effective erythropoiesis and the reactivation of gamma-globin genes up to fetal levels and may hence be considered as a potential therapeutic agent for this disease.
Gabbianelli
Marco
M
Department of Hematology, Oncology, and Molecular Medicine, Istituto Superiore di Sanità, Viale Regina Elena, 299-00161 Rome, Italy. marco.gabbianelli@iss.it
Morsilli
Ornella
O
Massa
Adriana
A
Pasquini
Luca
L
Cianciulli
Paolo
P
Testa
Ugo
U
Peschle
Cesare
C
D017209:Apoptosis / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D004359:Drug Therapy, Combination; D004912:Erythrocytes / Q000166:cytology / Q000502:physiology; D004920:Erythropoiesis / Q000187:drug effects*; D005319:Fetal Hemoglobin / Q000502:physiology*; D005938:Glucocorticoids / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology; D006801:Humans; D019089:Stem Cell Factor / Q000494:pharmacology*; D017086:beta-Thalassemia / Q000097:blood* / Q000188:drug therapy*
D005938:Glucocorticoids; D019089:Stem Cell Factor; D003907:Dexamethasone; D005319:Fetal Hemoglobin