Dexamethasone and lenalidomide have distinct functional effects on erythropoiesis

We explored the effects of dexamethasone and lenalidomide, individually and in combination, on the differentiation of primary human bone marrow progenitor cells in vitro. Both agents promote erythropoiesis, increasing the absolute number of erythroid cells produced from normal CD34+ cells and from CD34+ cells with the types of ribosome dysfunction found in DBA and del(5q) MDS. However, the drugs had distinct effects on the production of erythroid progenitor colonies; dexamethasone selectively increased the number burst-forming units-erythroid (BFU-E), while lenalidomide specifically increased colony-forming units-erythroid (CFU-E). Use of the drugs in combination demonstrates that their effects are not redundant. Human CD34+ cells were cultured for 48 hours in the erythroid differentiation media described above with the addition of 40 ng/mL of FMS-like tyrosine kinase 3 (flt-3; Miltenyi Biotech) and 15 ng/mL of Granulocyte colony-stimulating factor (G-CSF; Amgen). Cells were cultured in the presence of the drugs of interest for 24 hours. RNA was purified using Trizol (Invitrogen). RNA was amplified and labeled by in vitro transcription and hybridized to the Affymetrix HT Human Genome U133A Array. Three replicates per condition.