Bioprocess Development for Large-Scale Production of Skin Derived Precursor Schwann Cells

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Peripheral nerve and spinal cord injuries are debilitating, leading to lifelong complications and reduced quality of life. Cellular therapies have demonstrated beneficial outcomes when treating these injuries especially when using Schwann cells. However, there is currently no robust and reproducible method for producing Schwann cells at clinical scale. Bioprocesses that use bioreactors have significant advantages when scaling-up cellular therapies. Therefore, the research in this thesis was done to address this gap and develop methods, tools, and protocols to create a bioprocess for the large-scale expansion of Schwann cells. The hydrodynamics of the bioreactor were investigated by using CFD modeling, comparing velocity, shear rate, and energy dissipation rate at different agitation rates and their effect on cell expansion. The model that was generated can be used to scale up processes to larger, clinical and manufacturing scale, bioreactors. Upstream and downstream unit operations were then developed. Commercially available microcarriers were evaluated and tested in bioreactors to find the microcarrier that supported both inoculation and expansion of SKP-SCs. Different bioreactor platforms were evaluated, showing that controlling the process parameters increased cell densities. An in-depth DOE was conducted to find the best inoculation conditions, investigating which parameters had significant effects on cell attachment, distribution, and expansion. Detachment of SKP-SCs from microcarriers was investigated with different enzymes and agitation rates to develop an in-vessel passaging protocol that can easily be scale-up. After harvest, cryopreservation medium and cell density were investigated to ensure a quality product can be frozen and delivered to the patient. After the process was developed, 3 rat lines and 1 human line were tested. The process was reproducible and robust and easily adapted to human cells. Additional development is needed to use this process for nerve derived Schwann cells. This process was then integrated together and 150 x106 cells were produced from 3x106 in 7 days. Lastly, the expansion design space was investigated to determine the effects of pH, DO, and agitation on the expansion of SKP-SCs. All the tools and methods developed in this thesis can easily be adapted to nearly any bioprocess that utilize bioreactors for cellular therapies.
Bioreactor, Bioprocess Development, Scale-Up, Cell Culture, Schwann Cells, Cell Therapy, Nerve Repair
Walsh, T. D. (2018). Bioprocess Development for Large-Scale Production of Skin Derived Precursor Schwann Cells (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from doi:10.11575/PRISM/32890