Description:
<jats:p><jats:bold>BACKGROUND:</jats:bold> Regenerative stem cell therapy (SCT) is currently being tested in clinical trials. The ideal type and source of cells have not yet been defined. Lineage (Lin) depletion is an experimental procedure capable of enriching all recently recognized SC types with regenerative potency. This study was performed to define a practicable monoclonal antibody (MoAb) cocktail for Lin depletion and to test whether clinical‐scale Lin depletion is possible.</jats:p><jats:p><jats:bold>STUDY DESIGN AND METHODS:</jats:bold> MoAbs (CD2/14/15/19/41/56/glycophorin A) were selected to mark seven mature hematopoietic lineages. Lin7‐negative (Lin7<jats:sup>NEG</jats:sup>) cells were analyzed in peripheral blood (PB, n = 9), mobilized PB (MPB, n = 5), umbilical cord blood (UCB, n = 5), and marrow aspirates (BM, n = 4) by flow cytometry. Preclinical Lin depletion was tested with leukapheresis products from PB following good manufacturing practice (GMP) principles.</jats:p><jats:p><jats:bold>RESULTS:</jats:bold> Lin7<jats:sup>NEG</jats:sup> cells comprised 0.23 ± 0.04, 0.27 ± 0.03, 0.53 ± 0.07, and 0.49 ± 0.03 percent of PB, MPB, UCB, and BM, respectively. Basophils, CD34+, and dendritic cells constituted the major Lin7<jats:sup>NEG</jats:sup> subpopulations (84 ± 2, 90 ± 3, 40 ± 3, and 80 ± 3% in PB, MPB, UCB, and BM, respectively). Minor populations included CD7– and CD45– cells. Preclinical CD2/14/15/19/56 (Lin5) depletion after automated red blood cell and platelet reduction resulted in up to a 16.7‐fold enrichment of CD34+ and CD34–/Lin5<jats:sup>NEG</jats:sup> cells.</jats:p><jats:p><jats:bold>CONCLUSIONS:</jats:bold> A seven‐MoAb cocktail is sufficient to label more than 99 percent of nucleated cells in PB, MPB, UCB, and BM. Preclinical Lin depletion can be performed under GMP conditions from PB apheresis procedures.</jats:p>