Background: Patients receiving recombinant human erythropoietin (rHuEPO) may experience side effects arising from the vascular system. The underlying mechanisms, however, are largely unknown.

Methods: To elucidate downstream events following erythropoietin receptor triggering, a differential display analysis of human vascular endothelial cell mRNA was performed.

Results: We identified eight genes that were upregulated by rHuEPO as confirmed in two further independent cell culture experiments using a semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) protocol. The genes coded for proteins that may be assigned to four different groups: 1) proteins implicated in the regulation of vascular functions (thrombospondin-1, 20 kDa myosin regulatory light chain; relative increase of rHuEPO induced mRNA levels: 155.2%, P = 0.043; 137.6%, P = 0.046, respectively); 2) gene products involved in gene transcription and/or translation (c-myc purine-binding transcription factor PuF, tryptophanyl-tRNA synthetase, S19 ribosomal protein; increase of mRNA levels: 126.4%, P = 0.032; 150.9%, P = 0.012; 134.9%, P = 0.038); 3) subunits of mitochondrial enzymes related to energy transfer (NADH dehydrogenase subunit 6, cytochrome C oxidase subunit 1; increase of mRNA concentrations: 141.7%, P = 0.007; 140.3%, P = 0.01); and 4) regulators of signal transduction (protein tyrosine phosphatase G1, increase of transcript level: 160.3%, P = 0.016).

Conclusions: We report on novel molecular downstream events following rHuEPO receptor triggering of human vascular endothelial cells. We identified EPO-responsive immediate-early genes, coding for proteins involved in vascular functions, gene transcription, and/or translation, energy transfer, and signal transduction. Thus, our data provide new insights into the molecular changes induced by EPO in human vascular endothelial cells.