Ex vivo expansion of hematopoietic cells from CD34+ cord blood cells in various culture conditions

Abstract

This study compared the cell expansion and colony-forming ability of human cord blood stem cells cultured ex vivo with 2 types of cytokine combinations, and 2 types of media characterized by the presence or absence of fetal bovine serum (FBS) in 2 or 3 dimensional (2D or 3D) culture environments. Purified CD34+ cells derived from different donors were cultured in Iscove’s Modified Dulbecco’s Medium (IMDM) and Ultraculture serum-free medium (SFM) containing the cytokine cocktail-I (coc-I) (EPO, GM-CSF, SCF, and IL-3) or cytokine cocktail-II (coc-II) (TPO, G-CSF, SCF, IL-6, and Flt3/Flk-2 ligand) with or without FBS. Generally, higher CFU-GM values were observed in the IMDM compared to the SFM. In the coc-I conditions, the ‘IMDM + coc-I’ and ‘IMDM + coc-I + FBS’ conditions gave the greatest cell (1,667 ± 274 and 1,600 ± 140-fold, respectively) and colony-forming units (CFU) expansions (BFU-E: 21 ± 3, 36 ± 5; CFU-GM: 95 ± 19, 81 ± 17; and CFU-GEMM: 2 ± 1, 3 ± 1-fold, respectively) in 26 day culture, respectively. In the coc-II conditions, the ‘SFM + coc-II’ condition gave the greatest cell expansion (2,143 ± 134-fold), but the ‘IMDM + coc-II’ condition gave the best CFU-GM expansion (924 ± 110-fold) in 26 day culture. In conclusion, ‘IMDM + coc-I’ and ‘IMDM + coc-II’ were the most accessible conditions for CFU expansion for all culture cases. The 2D stationary culture had affirmative effect on CFU expansion compared to the 3D culture using semisolid Methocult™. These results are believed to be significant in the ex vivo expansion of hematopoietic stem cells.