Selection of CD34-positive blood cells for allogeneic transplantation: Approaches to optimize CD34-cell recovery, purity, viability, and T-cell depletion

Background: Methods for clinical-scale selection of CD34-positive hematopoi etic stem and progenitor cells have facilitated allogeneic transplants usin g HLA-mismatched healthy donors. We examined different approaches to purify mobilized CD34+ cells, focusing on yield, purity, and viability of the sel ected cells and T-cell depletion levels. Methods: Sixty-seven CD34-positive selections were performed for a total of 37 allogeneic transplantations, 2 3 of which from HLA-haploidentical donors. The selection devices were the l solex(R) 300i (v. 1.12) used alone (n=13) or with the SuperMACS (n = 29); t he CliniMACS (n = 3); and the Isolex 300i (v. 2.0b1). The latter was used f or CD34-positive selection (n=7) and combined CD34+/CD4 8 19-negative selec tions (n=15). DNAse was included to reduce cell clumping. Results:With the Isolex 300i (v. 1.12), the median CD34+-cell recovery increased from 51% (w ithout DNAse) to 61% (15 mg DNAse) and 70% (7.5 mg). DNAse (5 mg) was used for 22 selections with the Isolex (v, 2.0b1) without cell clumping. CD34-po sitive cell purity, yield, and viability, as well as the degree of CD3 depl etion varied with the selection device and procedure used. Conclusion:With regard to all of the above-mentioned parameters, the best results were obta ined with the Isolex 300i (v. 2.0b1). Values achieved for CD34-positive cel ls were 98% for purity, 50-60% for yield, and >96% for cell viability; T-ce ll depletion was 4.5 to >5 log. The automated and closed system provides ta rget cells that are free of both magnetic particles and murine monoclonal a ntibody.