Navigating the technical landscape of stem cell therapy production

In this interview, Alyssa Clearwood, Platform Development Specialist at Sartorius (Göttingen, Germany), gives her insight into how cell therapy developers and manufacturers can navigate the technical and regulatory challenges that arise when working with iPSCs and MSCs. Alyssa explores how automation and bioreactor technologies enhance manufacturing efficiency, strategies for optimizing differentiation protocols and best practices for developing robust processes across variable cell sources.

This interview is part of the RegMedNet In Focus on iPSCs and MSCs, in association with Sartorius. Discover expert opinions on this topic by visiting our feature homepage.

What are the most significant challenges when translating promising laboratory results with iPSCs or MSCs into successful clinical outcomes?

There are many challenges, but standardization and quality control are the most significant. This is inclusive of variability in cell lines, protocols and differentiation processes leading to inconsistent results. 

Scalability is also crucial, being able to produce enough iPSCS or MSCS for clinical use while maintaining critical cell quality attributes. Another difficult step is demonstrating the efficacy in a clinical setting to treat specific conditions.  

A huge challenge in today’s cell therapy landscape is cost. The high cost of developing and producing stem cell therapies can be a barrier to widespread clinical applications. Within cell therapies right now, one of the biggest limitations is the ability to produce clinical material in a cost-effective manner. 

How can automation and bioreactor technology be integrated into iPSC or MSC culture to enhance scalability?

When developing a stem cell process, it is essential to keep the end in mind and to develop a process that’s scalable, robust and cost effective. Start from the beginning by implementing small-scale automated bioreactor systems and using a DOE-based approach to optimize and develop cell culture conditions. 

Automated systems that handle tasks such as media exchange, passaging and monitoring cell growth will help to build a robust system. Using scalable bioreactor platforms is key. Use bioreactor platforms that accommodate the expansion of iPSCs and MSCs from small to large scale. One way to do that is to ensure that the impeller design, the stir speed and the geometry of the vessels scale properly. A working example of that is what Sartorius offers with our bioreactor platforms. There is ease of scalability with our Ambr® 250, Univessel® and Biostat STR®. These platforms adapt to different cell types and allow for easier scale-up without compromising cell quality as their geometries are very similar. Utilizing data analytics tools that Sartorius offers in MODDE® (DOE software) and SIMCA® (MVDA software) will allow you to integrate and analyze data from automated systems to optimize culture conditions and improve decision-making processes. 

How can differentiation protocols be optimized for large-scale iPSC cultures to ensure efficient and consistent cell-type production?

The key is to standardize protocols. When cells are derived from different sources or donors it is necessary to ensure the process and protocols are robust enough to be applied to each batch. This includes small runs such as PD scale to large GMP scales. Always have the end in mind. The goal is to scale as seamlessly as possible. 

Use xeno-free and serum-free media, such as the NutriStem® hPSC XF Medium, which reduces variability and improves reproducibility. Minimize the use of serum, which can introduce inconsistencies due to batch-to-batch variability. 

Optimizing the concentrations and timings of adding cytokines or growth factors to promote efficient differentiation is important. Use cytokines with consistent lot-to-lot performance and ensure pre-clinical-grade cytokines perform the same as GMP-grade. Prevent the need to restart process development when scaling up to GMP. 

Regularly assessing the genetic integrity of these cells can prevent unwanted variations during differentiation processes. Monitor differentiation efficiency and cell purity through flow cytometry which regularly assesses cell markers and functional assays to ensure the process is producing the desired cell type. 

How do you go about determining the optimal culture conditions for scaling up MSC production while maintaining their therapeutic properties?

The key to MSC expansion is thoroughly characterizing growth patterns of multiple MSC donors that perform differently. For example, a donor with less expansion potential, a middle performing donor, and a very robust donor. You want to make sure that you are characterizing the expression of key markers via flow cytometry and other functional assays such as trilineage differentiation. Once multiple donors are well characterized, you can then optimize cell culture conditions that support robust expansion in bioreactor culture. Consider factors such as pH and dissolved oxygen control and ensure that your media exchange regimen is optimized to work well with multiple donors.  

If you’re scaling up in a bioreactor system, determine the best-suited microcarrier concentration and identify what an optimal viable cell density is in these conditions. Remember that just because you are producing the largest number of cells, that does not necessarily equate to the most clinically effective product, so assess critical quality attributes and nutrient-metabolite consumption/production at multiple viable cell densities. 

Another important factor is the stir profile. Do these cells perform best at higher or lower stir speeds or a combination. Conduct DOE studies to test different culture conditions and scale-up strategies to identify the most effective approaches for maintaining therapeutic properties. 

What are some best practices to develop robust culture conditions that work well independent of variable cell sources for MSCs?

Similar to iPSCs, use xeno-free and serum-free media such as MSC NutriStem® XF Medium to eliminate or reduce serum or platelet lysate use. Ensure effective attachment to surfaces such as microcarriers within the first 24 hours of culture and verify that attachment remains reproducible with multiple donors and cell sources. Test and optimize protocols that work well regardless of cell source or donor. 

What standardized tests are required to assess the safety and efficacy of iPSC and MSC products?

Yes, this is a constant revolving door, so to say, and involves multiple steps and multiple different types of testing: 

• Identity testing: Assess specific markers and gene expression profiles to ensure cells are correctly characterized after differentiation. 
• Purity testing: Evaluate cell populations to ensure minimal contamination of unwanted cell types using flow cytometry or immunochemistry. 
• Potency testing: Assess functional capabilities to ensure therapeutic function. For MSCs, this might include mixed lymphocyte reaction tests; for iPSCs, trilineage differentiation assessment and cytokine secretion profiles. 
• Viability testing: Measure cell viability to ensure cells are alive and functional. 
• Genetic stability testing: Evaluate stability both at batch end and over passages to ensure no harmful mutations or chromosomal abnormalities. 
• Immunogenicity testing: Evaluate potential immune responses, especially for allogeneic applications, by co-culturing with immune cells. 
• Sterility testing: Work in closed systems and test for bacteria, fungi and viruses to ensure product safety. 
• Endotoxin testing: Measure levels to ensure they’re within acceptable limits to prevent adverse patient reactions. 
• Preclinical testing: Test cells both in vitro and in vivo to assess safety before proceeding to human trials. 

Learn how Sartorius is setting the standard in cell therapy here!

The opinions expressed in this interview are those of the interviewee and do not necessarily reflect the views of RegMedNet or Taylor & Francis Group.

This interview was created in association with Sartorius.