Control of dissolved oxygen significantly increases the yield of skin‐derived Schwann cells during expansion in stirred suspension bioreactors

Abstract

Peripheral nerve and spinal cord injuries affect millions of people worldwide often leading to lifelong disability and pain. Cell therapy using autologous Schwann cells are currently being investigated for the treatment of these injuries and are showing great potential. In particular, skin-derived Schwann cells offer a non-invasive option for highly therapeutic cells that have been shown to regenerate tissue and restore function. However, it is estimated that for an effective therapy, hundreds of millions of Schwann cells are needed, and current static and spinner flask methods cannot generate these clinical numbers. Therefore, this study utilizes control systems facilitated by stirred suspension bioreactors to monitor and maintain the pH and dissolved oxygen at levels that promote cell proliferation and survival. By adapting the current culture practices to scalable bioreactor platforms, we were able to control the dissolved oxygen creating new expansion protocols that enabled the bioreactor process to grow to clinical scale, producing 667 × 10 6 cells in a single 500 mL bioreactor in 7 days. Since individual injury is different in terms of complexity and severity, and therefore cell needs, by changing the available surface area in the bioreactor, this developed process is highly adjustable to meet the cell quantity needs for each individual treatment. Following the bioprocess, cells that were harvested from the microcarriers continue to express typical Schwann cell markers suggesting that they retain phenotypic stability. By increasing the production potential of skin-derived Schwann cells, this therapy is one step closer to the clinic with the hope for ultimately restoring function and improving quality of life to patients with neural injuries.

A Multi-Stage Bioprocess for the Expansion of Rodent Skin-Derived Schwann Cells in Computer-Controlled Bioreactors

“…The efficient and reproducible inoculation results achieved lead to high overall reproducibility in the expansion of skin-SCs between both bioreactor runs. By using bioreactors with computer-controlled set points, and maintaining each bioreactor at the same values, not only are higher growth kinetics and cell densities achieved, but there is less variability between runs compared to expansion in uncontrolled spinner flasks [ 34 ]. The culture parameters were maintained within a tight window around each set point allowing for the best conditions to expand the skin-SCs.…”

“…If a greater number of cells are needed, a static or small-scale bioreactor seed train can be developed to increase the number of starting cells, and the surface area in the reactor can be increased by adding more microcarriers. We have previously shown that by starting with 12 million cells with a microcarrier density of 2 g/L, about 667 million cells can be generated before harvest [ 34 ]. Using the overall harvesting efficiency determined in this study, by increasing the starting cell number by 4-fold we can generate an estimated 500 million cells.…”

Identification of optimal flow rate for culture media, cell density, and oxygen toward maximization of virus production in a fed‐batch baculovirus‐insect cell system

“…The results also showed that both these schemes of fed‐batch operation resulted in better performance as compared to the batch operation. Further comparison of case and case by considering one more control variable as oxygen was also made as oxygen significantly affects cell growth (Hu & Bentley, 1999; Oliveira et al, 2005; Walsh et al, 2021). Here, the result shows that though the IGD value for was higher that case, the performance was similar in both cases in terms of the final virus and cell density obtained.…”