Isolation of Human CD34⁺Peripheral Blood Stem Cells Using an Immunomagnetic Positive Selection System: Prior Monocyte Depletion Using a Nylon-Wool Column

CD34+ Cell Positive Selection from Mobilized Peripheral Blood by an Indirect Immunomagnetic Method: Effect of the Type of Mobilization and Assessment of Tumor Depletion Ability

“…In this study, we describe a suitable method to enrich CD344-progenitors from mobilized peripheral blood with purity and yield similar to the highest reported using other methods (9,10,(17)(18)(19)(20)(21). We were consistently able to obtain very highly enriched fractions from samples with a preselection CD344-purity higher than 0.65%, which were derived from mobilized peripheral blood collections from a heterogeneous group of patients primed with chemotherapy alone or plus rhG-CSF therapy (median final purity 94.7%).…”

“…According to Nakamura et al (9), even when 0.5% human immunoglobulin was added to block nonspecific binding of anti-CD34 antibody to the monocyte Fc receptor, the purity did not exceed 60%. Several systems have been described for monocyte predepletion, including the use of nylon-wool or preincubation with magnetic beads (9,10), which should remove those cell populations likely to interfere with the resetting and release processes.…”

“…Several systems have been described for monocyte predepletion, including the use of nylon-wool or preincubation with magnetic beads (9,10), which should remove those cell populations likely to interfere with the resetting and release processes. Nakamura et al (9) presented results from four positive selections from peripheral blood after priming with chemotherapy plus G-CSF with a mean starting CD344-cell percentage of around 1.9%. After monocyte predepletion and CD344-cell immunomagnetic selection, they achieved a mean purity of around 95%.…”

“…Immunomagnetic systems have been used for positive selection in bone marrow in preclinical and clinical settings, with satisfactory results (2,7,8). However, when used with mobilized peripheral blood, these systems have achieved lower final purities than obtained with bone marrow or cord blood and, therefore, a lower tumor depletion efficiency (2,(7)(8)(9). The reasons for this are unclear, but different groups have proposed an additional predepletion step to try to improve the tumor depletion ability of positive selections from mobilized peripheral blood (9)(10)(11).…”

Comparison of monocyte-dependent T cell inhibitory activity in GM-CSF vs G-CSF mobilized PSC products

“…Further, it has been shown that the efficacy of CD34 + stem cell purification from mobilized PSC is inversely proportional to the number of monocytes in the initial cell population. Nakamura et al 60 also reported an increased purification of CD34 + cells from mobilized PSC products followed depletion of adherent cells. Similarly, Yamaguchi et al 61 reported an inverse correlation between the frequency of CD14 + cells in the initial cell population and the efficacy of CD34 + cell purification using immunomagnetic microspheres.…”