Producing pluripotent stem cells on an industrial scale

MHH researchers aim to achieve a higher cell yield in stirred-tank bioreactors while using less material and reducing costs.

Pluripotent stem cells (PSCs) are among the most promising starting materials in regenerative medicine. Therapies derived from PSCs are already being investigated in more than 100 clinical trials for a range of diseases-from Parkinson's disease to heart failure to type 1 diabetes. However, all potential applications face the same challenge: How can these cells be produced reliably and cost-effectively on an industrial scale so that the therapies will be affordable for healthcare systems in the future, especially when a large number of cells are required for a single treatment? The "INDUZELL" project, led by Prof. Dr. Robert Zweigerdt-a cell biologist and research group leader at the Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO) within the Clinical Department of Cardiac, Thoracic, Transplant, and Vascular Surgery at Hannover Medical School (MHH)-is addressing this problem. Also participating in the consortium are Leibniz University Hannover, Hannover University of Applied Sciences and Arts, and Emden/Leer University of Applied Sciences. The project is receiving approximately 1.4 million euros in funding over three years from the European Regional Development Fund (ERDF).

From 2D to 3D Production

"Pluripotent stem cells, as an unlimited, renewable raw material, can be transformed into virtually any cell type," explains Professor Zweigerdt. "They therefore offer numerous new applications-from therapeutic cell products in medicine to the development of better active ingredients in the pharmaceutical industry or the production of meat for alternative food sources." To date, these cells are still being cultured in cell culture dishes in many laboratories. This two-dimensional cultivation results in a relatively low yield while requiring a large amount of space and energy, as well as generating a significant amount of plastic waste. It is not suitable for industrial-scale production. The researchers, however, are focusing on 3D cultivation in glass stirred-tank bioreactors typical of industrial settings. The Zweigerdt research group is a global leader in the development of such processes. In their project, they are developing a production platform that, within a closed system, ensures a high cell yield with consistent quality in an automated, reliable, and reproducible manner. "We want to optimize cell production in suspension culture and increase the volume of the bioreactors from the current two liters to up to ten liters," says the cell biologist.

Cultivation with cryopreserved cells

For cultivation, the 3D culture is to be seeded directly with frozen cell stocks. This process, known in technical terms as cryopreservation, offers several advantages: The frozen cells retain their properties for years without undergoing uncontrolled changes. "In our case, this means that the PSCs are guaranteed to retain their pluripotency-that is, their ability to be reprogrammed into other cell types," says Dr. Kevin Cyrys, co-applicant for the project and research associate in the working group. The cryopreserved cells are transferred to the stirred-tank bioreactor in a sterile manner via so-called cryobags. This minimizes the risk of contamination with bacteria or fungi. Another advantage of cryopreserved cells is that they do not need to be precultured and are therefore available exactly when they are needed to inoculate the suspension.

Using AI to create a "Smart" production platform

One challenge of cell production in stirred-tank bioreactors is that the cells aggregate into multicellular clusters. Whereas in culture dishes only the number of individual cells increases over time, here the size of the cell aggregates also changes. Single cells form clumps consisting of hundreds or even thousands of cells, which collectively influence the properties of the entire cell production. Using multimodal microscopy-which simultaneously employs various measurement methods and imaging techniques-the researchers aim to precisely quantify these influences.

With the help of AI and machine learning, the entire production process will be continuously monitored and optimized. The researchers then aim to use all the collected data to develop a "smart" production platform that can respond to unforeseen process deviations, suggest improvements on its own, and thus increase cell yield. "The platform is designed to ensure that PSC production will function reliably on a large scale in the future, while keeping costs low and minimizing material consumption," emphasizes Professor Zweigerdt.

Text: Kirsten Pötzke

SERVICE:

Further information can be found here.

Information about the Zweigerdt research group can be found here.