title: Improved immunomagnetic enrichment of CD34(+) cells from umbilical cord blood using the CliniMACS cell separation system.
abstract: OBJECTIVE
  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.
authors.affiliation: Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA. jblake@fhcrc.org
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Blake
authors.forename: Ian B
authors.initials: IB
authors.lastname: Nicoud
authors.forename: Daniel
authors.initials: D
authors.lastname: Weber
authors.forename: Howard
authors.initials: H
authors.lastname: Voorhies
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Guthrie
authors.forename: Shelly
authors.initials: S
authors.lastname: Heimfeld
authors.forename: Colleen
authors.initials: C
authors.lastname: Delaney
mesh_terms: D018952:Antigens, CD34 / Q000276:immunology; D002452:Cell Count; D002469:Cell Separation / Q000295:instrumentation*; D005312:Fetal Blood / Q000166:cytology* / Q000276:immunology; D005434:Flow Cytometry; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods; D006801:Humans; D018189:Immunomagnetic Separation / Q000295:instrumentation / Q000379:methods; D016130:Immunophenotyping
chemical_list: D018952:Antigens, CD34