Effects of recombinant human erythropoietin on hematopoietic progenitors of chronic hemodialysis patients in vitro and in vivo

Perturbation of autocrine/paracrine loops of burst-forming units of erythroid-derived cells in rHuEPO-hyporesponsive hemodialysis patients

BACKGROUND

Quantitative or qualitative abnormalities of erythroid progenitors in patients with chronic renal failure (CRF) could be the major factor for recombinant human erythropoietin (rHuEPO) hyporesponsiveness and severe anemia in hemodialysis (HD) patients receiving rHuEPO therapy.

METHODS

Purified 1 x 10(4) circulating CD34+ cells isolated from rHuEPO-hyporesponsive HD patients (EPO-H; n = 10), rHuEPO-responsive non-HD patients with CRF (EPO-R; n = 8), nonanemic HD patients without rHuEPO therapy (EPO-W/O; n = 10), and healthy volunteer controls (CON; n = 10) were subjected to a methylcellulose culture system supplemented with rHuEPO, recombinant human interleukin-3 (IL-3), recombinant human stem cell factor (SCF), and recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) for 14 days.

RESULTS

The average number of burst-forming units of erythroids (BFU-Es) was significantly less in the EPO-H group compared with the CON and EPO-W/O groups. Furthermore, colony size also was significantly smaller in the EPO-H group. Total RNAs were extracted from approximately 100 colonies/patient and subjected to complementary DNA expression array studies of 268 growth factors, cytokines, chemokines, and their receptors. A characteristic cluster upregulated in the EPO-R and EPO-W/O groups and downregulated in the EPO-H group was identified that contained various cytokines and growth factors, including IL-6, GM-CSF, vascular endothelial growth factor B, IL-9, IL-3, leukemia inhibitory factor, and interferon alpha-2, and such receptors as thrombopoietin receptor, IL-9 receptor, and colony-stimulating factor 1 receptor.

CONCLUSION

These data suggest that the cross-talk network or autocrine/paracrine regulatory loop is critically impaired in BFU-E-derived cells in EPO-H patients, and investigation of these cluster genes would facilitate the development of novel therapeutic strategies for such patients.

Haematological toxicities associated with dose-intensive chemotherapy, the role for and use of recombinant growth factors

High-dose chemotherapy is increasingly accepted as a treatment approach in a number of tumour types. However, there are controversies surrounding its efficacy and there is a need to consider its safety. In view of this, much effort has been directed towards the provision of adequate supportive care strategies to prevent toxicities and to ameliorate myelosuppression. Severe anaemia and its associated symptoms, for example, fatigue can have a debilitating effect on a patient's quality of life and often necessitates red blood cell transfusions. Erythropoietin, a glycoprotein hormone which stimulates red blood cell production, has been established for the treatment of anaemia in patients with chronic renal insufficiency. It is currently approved in most countries for treating anaemia associated with cancer, and its role is emerging especially in patients undergoing high-dose chemotherapy. This paper gives an overview of the studies conducted to date with epoetin alfa (recombinant human erythropoietin) in patients receiving allogeneic and autologous bone marrow transplants or peripheral blood stem cells in conjunction with high-dose chemotherapy. In addition, there are some novel clinical applications for epoetin alfa: for example, in delayed anaemia, as a supportive strategy prior to high-dose chemotherapy and as a synergistic enhancer of blood progenitor cell mobilisation in combination with granulocyte-colony-stimulating factor (G-CSF).