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Cytomatrix 
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Development of a Cytokine-Free Animal Protein-Free Clinical System for the Expansion of Human CD34+ Cells |
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Kristen Biber, Kathleen Pigeon, Mark Pykett, Michael Rosezweig
Cytomatrix, Woburn, MA, 01801 |
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CD34 continues to serve as the sole indicator of hematopoietic stem cell content in bone marrow and/or mobilized peripheral blood products. There is a direct correlation between increased CD34+ cell dose/kilogram body weight and successful hematopoietic reconstitution. Due to the limited number of CD34+ cells in the body, it has been necessary to design a system that allows for expansion of CD34+ cells ex vivo without compromising the developmental capacity of the cells in the end product. Cell Science Therapeutics Inc. has pioneered the use of a 3-dimensional, biocompatible material Cytomatrix™ for the growth and expansion of human CD34+ cells in vitro. We report here, the successful integration of the Cytomatrix™ into a clinical-grade system (TranStem™) for the expansion of CD34+ cells. The TranStem™ system provides an environment conducive to the expansion of human CD34+ cells in the absence of exogenous cytokines and animal-derived protein products. In initial studies, mobilized peripheral blood-derived CD34+ cells were cultured in the TranStem™ system with QBSF-60 media for one week without any further manipulation. Flow cytometric analysis of the cultured cells revealed an approximate 7-fold increase in the number of CD34+CD38- cells. While myeloid and megakaryocyte progenitors also expanded in number, there was no expansion of B lineage or T lineage cells. To directly examine the function of cells cultured in the TranStem™ system, 1 x 106 cultured cells were injected into the tail vein of sublethally irradiated NOD/SCID mice. Seven weeks post-transplantation all mice showed successful multi-lineage engraftment as demonstrated by the presence of human B lineage and T lineage cells, with the maintenance of CD34+ CD38- hematopoietic progenitors in the bone marrow. These data demonstrate that the TranStem™ system allows for a substantial increase in hematopoietic progenitors in the absence of animal protein or cytokines. The TranStem™ system requires minimal handling and requires a one-week duration making this system an efficient and cost-effective clinical alternative for expansion of CD34+ cells. |
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