Analysis of circulating hematopoietic progenitors in patients with chronic renal failure under hemodialysis

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.

[The effect of erythropoietin (rh-EPO) om in vitro proliferation of granulocyte/monocyte-determined stem cells in bone marrow and peripheral blood]

AIM

The aim of the investigation was to determine the effect of recombinant human erythropoietin (rh-EPO) therapy on in-vitro proliferation of granulocyte/monocyte(gm)-determined stem cells in bone marrow and peripheral blood.

PATIENTS AND METHODS

The study comprised 28 dialysis patients (15 female, 13 male, aged between 22 and 78 years, dialysis sessions 3 times weekly 4 to 5 hours, mean duration time of dialysis treatment 4 to 99 months). Stem cell parameters were estimated before and after reaching the target hematocrit and the absolute number of leukocytes in peripheral blood was measured.

RESULTS

No alteration in total leukocyte number (PMN, monocytes, lymphocytes) of peripheral blood was found. Dialysis patients had a diminished proliferation capacity of colony forming unit-granulocyte/monocyte (CFU-GM) in bone marrow and an increased one in peripheral blood. The CFU-GM proliferation capacity in bone marrow improved during rh-EPO (34.3 +/- 5.8 x 10(5)/ml vs 120.5 +/- 37.8 x 10(5)/ml), whereas no changes in peripheral blood could be observed (46.7 +/- 7.15 x 10(5)/ml vs 37.6 +/- 12.05 x 10(5)/ml).