(P-BT-3) Can Hematopoietic Stem Cell Expansion Be More Cost Effective?

Background/Case Studies: Ex vivo expansion of hematopoietic stem cells (HSC) is receiving more attention as the potential patient benefits are recognized, including cell dose augmentation for umbilical cord blood (UCB) and increase of CD34+ cell dose for allogeneic and autologous donors who fail to collect a sufficient yield. Cost continues to be a significant hurdle to accessing these technologies however, especially when using premade cytokine cocktails for expansion supplementation. To mitigate costs, expansion cultures were undertaken using a premade CD34+ HSC promoting cytokine cocktail at concentrations from 0.1 to 1.0 times the manufacturers recommendation in conjunction with a small molecule purine derivative to limit CD34+ HSC differentiation.

Study

Design/Methods: Vented tissue culture flasks were coated overnight with fibronectin and human stem cell factor. The next morning, additional fluid was aspirated off. A total of 10mL base media supplemented with a purine derivate and increasing concentrations of cytokine cocktail was seeded on day 0 with thawed CD34+ enriched HSCs derived from mobilized peripheral blood at 1x10^6 cells per flask. Cells were cultured for a total of 5 days. Samples were taken at baseline and on days 3, 4 and 5 to assess media lactate concentrations and cell viability, WBC counts and CD34+ cell frequency analyzed by flow cytometry.

Results/Findings: At the time of abstract submission, 4 replicates were performed. Flask study 4 was excluded from the data due to donor factors identified after seeding. Means and range for datapoints are shown in Table 1 for each concentration (n = 2 for 0.5, n = 3 for all other concentrations). Percent viability of baseline cells at time of thaw was 98.7 (98 – 99). The percentage of CD34+CD133+ cells was 85%.

Conclusions: Successful ex vivo culture expansion of HSCs can be achieved using as little as 0.4X concentration of a premade cytokine cocktail with comparable growth to the 1X concentration. Our center plans to continue exploring expansion of peripheral blood CD34+ isolated cells with upcoming trials using other small molecules including UM171 and phosphoinositide e-kinases (PI3K) inhibitors.

Importance of research: Ex vivo hematopoietic stem cell expansion is rapidly being recognized as a means to expand potential graft sources to recipients. The process however is both expensive and time consuming. Identifying cost effective approaches for expansion will allow for increased access of this technology and may improve access for those in underserved areas or minority groups who frequently have more limited graft options.