Peripheral Blood Progenitor Cell Apheresis Increases Circulating Stem Cells.

Peripheral blood hematopoietic stem cell transplantation has been replacing the bone marrow source stem cell transplantation for the treatment of hematological malignancies. Many efforts were made to enhance the stem cell number in peripheral blood and optimize the peripheral stem cell collection. Hematopoietic stem cell circles between bone marrow and peripheral blood during maturation. Thus the recruitment of hematopoietic stem cell in peripheral blood is a factor influencing the efficacy of peripheral blood stem cell apheresis. The aim of this study was to evaluate the effects of apheresis on the number of circulating stem cells. There were 41 consecutive cases involved. The mobilization regimen was chemotherapy + G-CSF. All patients underwent at least two apheresis. The volume of blood processed was calculated automatically by COBE Spectra cell separator. Blood samples were drawn just before each apheresis. CD₃₄⁺ cells both in blood samples and in apheresis products were analyzed by multicolour flowcytometry. CFU-GM was cultured at same time. Data from the 1st and 2nd collection was compared. CD₃₄⁺ /CD₃₈⁻ cells in peripheral blood increased from 48±12/ul to 133±40/ul (p<0.05) and CD₃₄⁺/HLA-DR⁻ cells from 45±12/ul to 97±29/ul (p<0.05) after apheresis. But CFU-GM was unchanged (154±35/10⁵ cells to101±20/10⁵ cells). CD₃₄⁺ /CD₃₈⁻ cells, CD₃₄⁺/HLA-DR⁻ cells and CFU-GM in apheresis products were slightly increased but not reached the statistical significance(2.10±2.31x10⁸ to 2.89±2.08x10⁸, 2.09±2.35x10⁸ to 2.32±1.61x10⁸, 1.28±1.53x10⁷ to1.93±3.11x10⁷ respectively).

Conclusions: Peripheral blood stem cell apheresis promotes stem cell recruitment in peripheral blood and increases circulating hematopoietic stem cells.