Development of a fixed bed bioreactor for the expansion of human hematopoietic progenitor cells

The ex vivo expansion of hematopoietic progenitor cells is of great interes t for a variety of clinical applications, e.g. bone marrow transplantation or gene therapy. Therefore it is of general interest to develop a culture s ystem, able to mimic the in vivo hematopoesis, which is a prerequisite for long-term hematopoietic culture. Our approach was to modify a continuously perfused bioreactor for cultivation and expansion of human hematopoietic st em cells. Therefore we immobilized stromal cells (human primary stromal cel ls or the murine cell line M2-10B4) in porous glass carriers in a fixed bed reactor and cocultivated human hematopoietic progenitor cells for several weeks. After inoculation of mononuclear cells derived from umbilical cord b lood or peripheral blood stem cells both adherent and non adherent cells we re harvested and analyzed by flow cytometry and short-term colony assays. D uring cultivation there was a permanent production of progenitor cells and mature blood cells derived from the immobilized cells in the carriers. We c ould demonstrate the immobilization of hematopoietic progenitor cells of th e myeloid system detectable in short-term colony assays. Additionally we co uld observe the expansion of very early progenitor cells (CFU-GEMM) up to 4 .2-fold and later progenitor cells (CFU-GM and BFU-E) up to 7-fold and 1.8- fold, respectively.