Abstract
Background aims. CD34 + enrichment from cord blood units (CBU) is used increasingly in clinical applications involving ex vivo expansion. The CliniMACS instrument from Miltenyi Biotec is a current good manufacturing practice (cGMP) immunomagnetic selection system primarily designed for processing larger numbers of cells: a standard tubing set (TS) can process a maximum of 60 billion cells, while the larger capacity tubing set (LS) will handle 120 billion cells. In comparison, most CBU contain only 1–2 billion cells, raising a question regarding the optimal tubing set for CBU CD34 + enrichment. We compared CD34 + cell recovery and overall viability after CliniMACS processing of fresh CBU with either TS or LS. Methods. Forty-six freshly collected CBU (≤ 36 h) were processed for CD34 + enrichment; 22 consecutive units were selected using TS and a subsequent 24 processed with LS. Cell counts and immunophenotyping were performed pre- and post-selection to assess total nucleated cells (TNC), viability and CD34 + cell content. Results. Two-sample t-tests of mean CD34 + recovery and viability revealed significant differences in favor of LS (CD34 + recovery, LS = 56%, TS = 45%, P = 0.003; viability, LS = 74%, TS = 59%, P = 0.011). Stepwise linear regression, considering pre-processing unit age, viability, TNC and CD34 + purity, demonstrated statistically significant correlations only with the tubing set used and age of unit. Conclusions. For CD34 + enrichment from fresh CBU, LS provided higher post-selection viability and more efficient recovery. In this case, a lower maximum TNC specification of TS was not predictive of better performance. The same may hold for smaller scale enrichment of other cell types with the CliniMACS instrument.
Acknowledgments
The authors thank Ted Gooley for his expert review of the statistical methods and results.
This project has been funded in part with Federal funds from the Biomedical Advanced Research and Development Authority, Office of the Assistant Secretary for Preparedness and Response, Office of the Secretary, Department of Health and Human Services, under Contract No. HHSO100200800064C. Other funding was provided by National Institutes of Health grants DK56465, CA18029 and CA15704.
Declaration of interest: The authors report no conflicts of interest in connection with this manuscript.