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Published online before print January 17, 2007
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*Hematology Department, Children’s Hospital,
Laboratory of Mechanobiology and Engineering of Cells and Tissues, CNRS UMR 7563, and Unit of Cellular and Tissue Therapy and ¶Department of Electron Microscopy, Faculty of Medicine, and ||Laboratory of Hematology, CHU Nancy, France;
Department of Pediatrics, University of Michigan Cancer Center, Ann Arbor, Michigan, USA;
Department of Pathology and Pathophysiology, Wuhan University, China; and #Immunogenomics Mixed Unit, HCL-BioMerieux, Lyon, France
@ To whom correspondence should be addressed. E-mail: sophiep{at}umich.edu.
| Abstract |
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As a result of their potent antigen-presentation function, dendritic cells (DC) are important tools for cell therapy programs. In vitro-generated DC from enriched CD34+ hematopoietic stem cells (HSC; enriched CD34 DC) have already proven their efficiency in Phase I/II clinical trials. Here, we investigated whether enrichment of CD34+ HSC before the onset of culture was absolutely required for their differentiation into DC. With this aim, we developed a new two-step culture method. PBMC harvested from G-CSF-mobilized, healthy patients were expanded for 7 days during the first step, with early acting cytokines, such as stem cell factor, fetal liver tyrosine kinase 3 ligand (Flt-3L), and thrombopoietin. During the second step, expanded cells were then induced to differentiate into mature DC in the presence of GM-CSF, Flt-3L, and TNF-
for 8 days, followed by LPS exposure for 2 additional days. Our results showed that the rate of CD34+/CD38+/lineageneg cells increased 19.5 ± 10-fold (mean±SD) during the first step, and the expression of CD14, CD1a, CD86, CD80, and CD83 molecules was up-regulated markedly following the second step. When compared with DC generated from enriched CD34+ cells, which were expanded for 7 days before differentiation, DC derived from nonenriched peripheral blood stem cells showed a similar phenotye but higher yields of production. Accordingly, the allogeneic, stimulatory capacity of the two-step, cultured DC was as at least as efficient as that of enriched CD34 DC. In conclusion, we report herein a new two-step culture method that leads to high yields of mature DC without any need of CD34+ HSC enrichment.
Key Words: ex vivo expansion immunotherapy cell vaccine lipopolysaccharide
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