Background & Aim

Cell therapies hold the promise to fundamentally change health care by curing previously uncurable diseases. Both autologous and allogeneic cell therapies rely on donor cells for expansion. The variety of disease, cell type, and inherent growth kinetic donor variability puts a high demand on the manufacturing process. This production process has to be robust, follow cGMP guidelines, and be scalable in order to reduce the cost for patient and society. To this end, we developed a perfusion process for the expansion of allogeneic human Mesenchymal Stromal cells (hMSCs) in controlled bioreactors.

Methodology

A perfusion system, where medium is continuously replenished inside the bioreactor, was developed for the expansion of one donor. We then cultured cells from 2 additional donors on microcarriers using the same perfusion process in 100 mL stirred-tank bioreactors. The process was then scaled 20x to a 2L process.

Results

After initial development, the process achieved an expansion factor of 14 within 8 days of culture with one donor. After further optimizations, three tested donors were cultured. They exhibited different growth characteristics, resulting in some variation in lag phase after inoculation. A similar growth rate was observed in two out of the three donors in the exponential phase, while the third was slower. All donors achieved an expansion factor of 12 or higher (20 highest). Following this confirmation of growth, the process was scaled 20x to 2 L. In the 2 L bioreactor process, an expansion factor of 19.2 was achieved, displaying good comparability to the downscaled model. The final process achieved a 4x higher volumetric productivity than planar culture at equivalent passage.

Conclusion

The perfusion process was successfully applied to three donors, despite differences in growth characteristics and could be scaled to 2L with great results. The reported results are an important step toward achieving an economically feasible scalable production process for hMSCs.