Serum-free process development: improving the yield and consistency of human mesenchymal stem cell production

Background: The cost effective production of hMSCs for off-the-shelf and patient specific therapies will require an increasing focus on improving product yield and driving manufacturing consistency. Methods: Bone-marrow derived hMSCs from two donors were expanded for 36 days in monolayer with medium supplemented with either fetal bovine serum (FBS) or PRIME-XV® Serum-free Medium (SFM). Cells were assessed throughout culture for proliferation, mean cell diameter, colony forming potential, osteogenic potential, gene expression and metabolites. Results: Expansion of BM-hMSCs in PRIME-XV® SFM resulted in a significantly higher growth rate (p < 0.001) and increased consistency between donors compared with FBS-based culture. FBS-based culture showed an inter batch production range of 0.9 and 5 days per dose compared with 0.5 and 0.6 days in SFM for each BM-hMSC donor line. The consistency between donors was also improved by the use of PRIME-XV® SFM, with a production range of 0.9 days compared with 19.4 days in FBS-based culture. Mean cell diameter has also been demonstrated as a process metric for BM-hMSC growth rate and senescence via a correlation (R2 = 0.8705) across all conditions. PRIME-XV® SFM has also shown increased consistency in BM-hMSC characteristics such as per cell metabolite utilisation, in vitro colony forming potential and osteogenic potential despite the higher number of population doublings. Conclusions: We have increased the yield and consistency of BM-hMSC expansion between donors, demonstrating a level of control over the product, which has the potential to increase the cost effectiveness and reduce the risk in these manufacturing processes

Supplementary figures for "Process development of human multipotent stromal cell microcarrier culture using an automated high-throughput microbioreactor"

Supplementary information files for "Process development of human multipotent stromal cell microcarrier culture using an automated high-throughput microbioreactor"<div><br></div><div><p><b>Figure S1</b>. Growth kinetics of hMSCs donor 2 cells using serum-free (SFM) and fetal bovine serum (FBS)-based media in both the ambr15 and spinner flasks with data showing the viable cell density.</p><p><br></p><p><b>Figure S2</b>. Nutrient and metabolite flux for hMSC donor 1 cells expanded on microcarriers in the serum-based and serum-free cultures in both the ambr and spinner flasks.</p><p><br></p><p><b>Figure S3</b>. Functional characterisation of hMSCs from donor 1 harvested from the serum-free ambr15 bioprocess.</p><p><br></p><h2>ABSTRACT</h2><p>Microbioreactors play a critical role in process development as they reduce reagent requirements and can facilitate high-throughput screening of process parameters and culture conditions. Here, we have demonstrated and explained in detail, for the first time, the amenability of the automated ambr15 cell culture microbioreactor system for the development of scalable adherent human mesenchymal multipotent stromal/stem cell (hMSC) microcarrier culture processes. This was achieved by first improving suspension and mixing of the microcarriers and then improving cell attachment thereby reducing the initial growth lag phase. The latter was achieved by using only 50% of the final working volume of medium for the first 24 h and using an intermittent agitation strategy. These changes resulted in >150% increase in viable cell density after 24 h compared to the original process (no agitation for 24 h and 100% working volume). Using the same methodology as in the ambr15, similar improvements were obtained with larger scale spinner flask studies. Finally, this improved bioprocess methodology based on a serum-based medium was applied to a serum-free process in the ambr15, resulting in >250% increase in yield compared to the serum-based process. At both scales, the agitation used during culture was the minimum required for microcarrier suspension, N_JS. The use of the ambr15, with its improved control compared to the spinner flask, reduced the coefficient of variation on viable cell density in the serum containing medium from 7.65% to 4.08%, and the switch to serum free further reduced these to 1.06–0.54%, respectively. The combination of both serum-free and automated processing improved the reproducibility more than 10-fold compared to the serum-based, manual spinner flask process. The findings of this study demonstrate that the ambr15 microbioreactor is an effective tool for bioprocess development of hMSC microcarrier cultures and that a combination of serum-free medium, control, and automation improves both process yield and consistency.</p></div