Harvesting, characterization, and culture of CD34+ cells from human bone marrow, peripheral blood, and cord blood.

Abstract

Stem and progenitor cells from a variety of sources including bone marrow, cord blood, and peripheral blood have been used for transplantation. This study compares CD34 cells from all three sources. Flow cytometry analysis of CD34 cells in multiple samples of normal peripheral blood and patient peripheral blood mobilized with chemotherapy (cyclophosphamide/VP16), chemotherapy plus granulocyte colony stimulating factor (G-CSF), and G-CSF alone were compared to bone marrow and cord blood. Although the relative distribution of CD34 percentages in each preparation of cells varied widely, on average the percentage of CD34 cells in these different preparations was 0.15%, 0.6%, 2%, 0.45%, 1.68%, and 0.83% respectively. CD34 subset analysis was performed on these cell preparations using multicolor flow cytometry and antibodies to CD33, CD13, CD45RA, CD19, CD71, and CD38. The major differences observed were that bone marrow CD34 cells contain high percentages of CD19+ cells not found in significant quantity in the other cell preparations and cord blood CD34 cells contained a higher percentage of CD38-cells than the other cell preparations. A magnetic bead system was used with anti-CD34 antibody to purify CD34 cells from mobilized peripheral blood apheresis products, cord blood, and bone marrow. Efficient selection with high purities of CD34 cells was achieved with each of the cell preparations. Comparison of colony-forming activity of each of the cell preparations showed cord blood and mobilized peripheral blood to have slightly higher cloning efficiencies than bone marrow with higher numbers of erythroid blast-forming units (BFU-E) also observed in cord blood CD34 cells. Culture of isolated CD34 cells in liquid culture with interleukin-3, stem cell factor, G-CSF, and granulocyte-macrophage GM-CSF showed over a 100-fold expansion in cell numbers after 25 days, with the peak expansion of colony-forming cells occurring between days 11 and 16. Analysis of day-10 cells from these cultures showed them to be predominantly promyelocytes, myelocytes, and metamyelocytes, with cord blood CD34 cultures showing more promyelocytes than peripheral blood or bone marrow and bone marrow showing more metamyelocytes. Comparison of the proliferation of CD34 cells from these different cell preparations showed that cord blood CD34 cells cultured for 10 days averaged an 85-fold increase in cell numbers followed by mobilized peripheral blood CD34 cells, with an average 56-fold increase, and bone marrow CD34 cells, with an average 49-fold increase.