A clinical‐scale expansion of mobilized CD34+ hematopoietic stem and progenitor cells by use of a new serum‐free medium

Abstract

The autologous transplantation of CD 34+ cells expanded ex vivo in serum-free conditions dramatically reduces post-myeloablative neutropenia in myeloma patients. In our cell therapy unit, cells for this clinical assay have been expanded under GMP with serum-free Irvine Scientific (IS) medium with stem cell factor (SCF), granulocyte-colony-stimulating factor (G-CSF), and megakaryocyte growth and development factor (MGDF; 100 ng/mL, respectively). Because this clinical-grade IS medium is no longer available, a new serum-free medium, Maco Biotech HP 01 (Macopharma), was evaluated. Purified CD 34+ cells (Isolex 300i, Baxter) from mobilized peripheral blood samples of myeloma patients were thawed, washed, and cultured, as for previous clinical assays. Twenty million CD 34+ cells were resuspended per 1 L of SCF-, G-CSF-, and MGDF-supplemented medium (HP 01 or IS), introduced into 3-L culture bags (AFC), and cultured for 10 days in 5 percent CO(2), at 37 degrees C, and at 100 percent humidity. A higher amplification of total nucleated cells (NCs) and colony-forming cells (CFCs) was obtained with HP 01 medium than with IS medium (42+/-16.6-fold vs. 20.5+/-5.9-fold for NCs and 26.7+/-7.4-fold vs. 15.5+/-2.5-fold for CFCs, respectively), whereas an increase in CD 34+ cells (3.5+/- 1.2-fold for HP 01 vs. 2.7+/- 1.5-fold for IS) was not significant. IS medium partially maintained SCID-repopulating cells (SRC), whereas the culture in HP 01 medium fully maintained the stem cell activity for 10 days. A higher frequency of CD 41+ cells after expansion in HP 01 than in IS medium was also observed. Maco Biotech HP 01 medium is suitable for clinical-scale expansion of CD 34+ cells with the SCF, G-CSF, and MGDF cytokine cocktail, permitting an intensive amplification of CFCs and maintenance of SRCs.