In vitro proliferation and differentiation of erythroid progenitors from patients with myelodysplastic syndromes: evidence for Fas-dependent apoptosis.
Erythropoiesis results from the proliferation and differentiation of pluripotent stem cells into immature erythroid progenitors (ie, erythroid burst-forming units (BFU-Es), whose growth, survival, and terminal differentiation depends on erythropoietin (Epo). Ineffective erythropoiesis is a common feature of myelodysplastic syndromes (MDS). We used a 2-step liquid-culture procedure to study erythropoiesis in MDS. CD34(+) cells from the marrow of patients with MDS were cultured for 10 days in serum-containing medium with Epo, stem cell factor, insulin-like growth factor 1, and steroid hormones until they reached the proerythroblast stage. The cells were then placed in medium containing Epo and insulin for terminal erythroid differentiation. Numbers of both MDS and normal control cells increased 10(3) fold by day 15. However, in semisolid culture, cells from patients with refractory anemia (RA) with ringed sideroblasts and RA or RA with excess of blasts produced significantly fewer BFU-Es than cells from controls. Fluorescence in situ hybridization analysis of interphase nuclei from patients with chromosomal defects indicated that abnormal clones were expanded in vitro. Epo-signaling pathways (STAT5, Akt, and ERK 1/2) were normally activated in MDS erythroid progenitors. In contrast, apoptosis was significantly increased in MDS cells once they differentiated, whereas it remained low in normal cells. Fas was overexpressed on freshly isolated MDS CD34(+) cells and on MDS erythroid cells throughout the culture. Apoptosis coincided with overproduction of Fas ligand during the differentiation stage and was inhibited by Fas-Fc chimeric protein. Thus, MDS CD34(+)-derived erythroid progenitors proliferated normally in our 2-step liquid culture with Epo but underwent abnormal Fas-dependent apoptosis during differentiation that could be responsible for the impaired erythropoiesis.
Claessens
Yann-Erick
YE
Department of Hematology, AP-HP, Hôpital Cochin, Paris, France.
Bouscary
Didier
D
Dupont
Jean-Michel
JM
Picard
Françoise
F
Melle
Josiane
J
Gisselbrecht
Sylvie
S
Lacombe
Catherine
C
Dreyfus
François
F
Mayeux
Patrick
P
Fontenay-Roupie
Michaëla
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018952:Antigens, CD34; D017209:Apoptosis / Q000187:drug effects; D001854:Bone Marrow Cells / Q000473:pathology; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D015672:Erythroid Precursor Cells / Q000473:pathology*; D004920:Erythropoiesis / Q000187:drug effects*; D004921:Erythropoietin / Q000494:pharmacology / Q000502:physiology; D053222:Fas Ligand Protein; D005260:Female; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008875:Middle Aged; D009190:Myelodysplastic Syndromes / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D014411:Neoplastic Stem Cells / Q000473:pathology; D019014:fas Receptor / Q000378:metabolism / Q000494:pharmacology
D018952:Antigens, CD34; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D019014:fas Receptor; D004921:Erythropoietin