Expansion of umbilical cord blood derived haematopoietic stem cells under constant dynamic conditions

Abstract

Background & Aim Umbilical cord blood (UCB) offers a source of haematopoietic stem and progenitor cells (HSPCs) with a proven clinical rack record. However, one major drawback is the relatively low number of HSPCs within one unit, limiting its clinical potential. Due to this, strategies to expand UCB-HSPCs have been developed and involve the use of additional molecules to support expansion, such as SR-1, UM-171, immobilised Notch ligand Delta-like 1 and nicotinamide. As these potential therapeutics reach late stage clinical trials, considerations for manufacturing in order to meet clinical demand are required. In this study we have investigated the impact that constant shaking, at differing magnitudes, during the expansion of UBC-HSPCs has on the overall total nucleated cell expansion, Lin-CD34+ and Lin-CD34+CD38-CD90+ cell expansion, cell viability and colony forming unit (CFU) potential. Methods, Results & Conclusion Method UCB CD34+ cells were seeded at 1 × 104 cells/mL in IMDM+10% FBS supplemented with 100ng/mL SCF, TPO and Flt3-L and 20ng/mL IL-6 and maintained under static (T-flasks) or shaken (125mL Erlenmeyer flasks, with a 10mm shaking diameter) conditions for nine days. Daily cell counts were completed and immunophenotyping, apoptosis detection and CFU potential were performed on day 0 and day 9. Results UCB-HSPCs were successfully expanded for all donors under both conditions, the final viable cell densities achieved were significantly higher in the shaken conditions compared to the static controls, in addition the final viable cell densities increased with an increasing agitation rate, 3.1±0.3 × 104, 6.2±0.1 × 104, 10.2±0.2 × 104 and 12.4±0.4 × 104 cells mL−1 (mean value ± SD) for static, 30rpm, 70rpm and 110rpm respectively. Immunophenotyping of the expanded cells demonstrated an increase in both Lin-CD34+ HSPCs and Lin-CD34+CD38-CD90+ haematopoietic stem cells, this increase was significantly higher in the shaken conditions compared to the static controls. Finally, the fold change in CFU potential was significantly higher for both granulocyte, monocyte colonies and granulocyte, erythrocyte, monocyte, megakaryocyte colonies compared to static controls and with an increasing agitation rate. Conclusion In this study we have shown that expansion of UCB-HSPCs under shaken conditions improves the overall cellular yield that can be achieved, maintains both Lin-CD34+ and the more primitive Lin-CD34+CD38-CD90+ cell populations and enhances CFU potential.