title: The influence of patient-related factors on ex vivo retroviral-mediated gene transfer into mobilized peripheral blood myeloid progenitors.
abstract: Mobilized human peripheral blood progenitor cells are potential alternatives to bone marrow cells as targets for ex vivo gene transfer. We report the transduction efficiency of retroviral-mediated gene transfer into myeloid progenitors of peripheral blood progenitor cell (PBPC) harvests, mobilized by high-dose cyclophosphamide and GM-CSF, compared with nonmobilized bone marrow (BM). Eleven PBPC samples were enriched for CD34+ cells, preincubated with IL-3 (10 ng/ml), IL-6 (50 ng/ml), and 10% autologous plasma for 42 hr, and transduced over a 6-hr incubation with IL-3 + IL-6 and a retroviral vector carrying the NeoR gene. NeoR-specific sequences were detected by polymerase chain reaction in 10 cell pellets (91%). Gene expression in CFU-GM colonies was found in nine transduced samples (82%), with a mean transduction efficiency of 5.2% (95% CI, 1.3-11.8%) CFU-GM per PBPC sample. In univariate analysis, a higher transduction efficiency into CFU-GM correlated significantly with a higher CFU-GM concentration in the CD34+-enriched sample (p = 0.009), a shorter interval from diagnosis (p < 0.001), and fewer months of prior cytotoxic treatment (p = 0.001); correlation with younger age was of borderline statistical significance (p = 0.077). In multivariate analysis a shorter interval from diagnosis and, to a lesser degree, a higher CFU-GM concentration in the CD34+-enriched sample were independent predictors of higher transduction efficiency. Twelve BM samples were similarly transduced; 11 pellets were PCR positive. CFU-GM NeoR gene expression was 4.2% (95% CI, 2.0-7.2%) CFU-GM per BM sample, which was not significantly different from the transduction efficiency into PBPC cells. No correlation was found between the transduction efficiency of CFU-GM in BM samples and CFU-GM concentration in the CD34+-enriched sample, time from diagnosis, months of prior cytotoxic treatment, and/or patient age. Our data suggest that the transduction efficiency ex vivo may be influenced by time from diagnosis, CFU-GM concentration in the sample, and possibly by the extent of prior cytotoxic administration.
authors.affiliation: Department of Preventive Medicine, University of Southern California/Norris Comprehensive Cancer Center, Los Angeles 90033, USA.
authors.forename: D
authors.initials: D
authors.lastname: Douer
authors.forename: L
authors.initials: L
authors.lastname: Ramezani
authors.forename: A F
authors.initials: AF
authors.lastname: Mohrbacher
authors.forename: A
authors.initials: A
authors.lastname: Khan
authors.forename: S
authors.initials: S
authors.lastname: Groshen
authors.forename: A M
authors.initials: AM
authors.lastname: Levine
authors.forename: W F
authors.initials: WF
authors.lastname: Anderson
mesh_terms: D000328:Adult; D000368:Aged; D001854:Bone Marrow Cells / Q000378:metabolism*; D015870:Gene Expression; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D008875:Middle Aged; D012190:Retroviridae; D014162:Transfection