Scalability and the role of expertise: an interview with Lisa-Mareike Scheid and Kübra Özer

When thinking about regenerative medicine, often mesenchymal stem cells (MSCs) come to mind immediately. They can self-renew and, due to their multipotency, differentiate into a large variety of different cell types. This makes them an awesome workhorse for regenerative medicine. But there’s a drawback: their percentage in the original tissues is small. Thus, to exploit their huge potential, we need to expand MSCs in vitro after their isolation. Especially when it comes to treating diseases or injuries using cell-based therapies, we often need a large number of cells to be effective. Cell expansion refers to the process of growing and multiplying cells in the laboratory, allowing us to generate a sufficient quantity of cells for therapeutic purposes. This is particularly important in cases where the patient’s own cells are not sufficient or suitable for transplantation.

However, it’s worth noting that cell expansion is a complex process that requires careful control and optimization.

There are several challenges that need to be addressed in cell expansion. Continuous research and development efforts are needed to optimize respective techniques, improve quality control measures and ensure the safety and efficacy of expanded cells for therapeutic applications.

To name just a few challenges:

Maintaining cell identity: During expansion there is a risk of cells losing their original characteristics and functionality. It is crucial to ensure that the expanded cells retain their desired properties and do not differentiate into unwanted cell types. When talking about, for example, MSCs, their self-renewal capacities, as well as their stemness, need to be kept intact.

Contamination: Cell cultures are susceptible to contamination by bacteria, fungi, viruses or other microorganisms. Maintaining sterile conditions throughout the expansion process is essential.

Scalability: Developing scalable and cost-effective methods for large-scale cell expansion is crucial to meet the demand for cell-based therapies. For example, expanding primary adherent cells adds another challenge to the upscaling process. One needs to offer the cells a surface to attach to, e.g., microcarriers can be an option here when moving into a bioreactor during upscaling.

Reproducibility: Consistency in cell expansion is vital for reproducibility across different batches or manufacturing sites. Variability in culture conditions, media composition or handling techniques can impact the quality and functionality of expanded cells. Thus, standardization of the established expansion and upscaling processes is vital.

Senescence and limited lifespan: Many primary cells have a limited capacity for proliferation due to replicative senescence. Finding ways to overcome this limitation and extend the lifespan of cells without compromising their functionality is a significant challenge in cell expansion.

When transferring from the small scale, e.g., using a few cell culture flasks, to the large scale, e.g., in a bioreactor, the culture conditions will change significantly. Not only will one have to evaluate the substrate for adherent cells, as mentioned above, working in a bioreactor means handling large volumes of cell culture media. One has to ensure a sufficient supply of nutrients and, at the same time, avoid the accumulation of toxic metabolites. Temperature, pH and gas exchange have to be monitored. Also, the established protocols for subculturing, especially when working with adherent cells, need amendment. Overall, moving from a small-scale 2D into a large-scale 3D culture environment, you will have to re-evaluate the full process and parameter settings to ensure reproducibility.

Further, the challenges include equipment and infrastructure, contamination control, process optimization, cost considerations and regulatory compliance.

Overcoming these challenges requires a combination of scientific expertise, engineering solutions, process optimization and adherence to regulatory guidelines to successfully transition from small-scale to large-scale cell expansion.

The process of cell expansion can impact the quality and functionality of therapeutic cells in several ways. Some of the common effects include changes in cell phenotype, loss of differentiation potential and reduced functionality. To maintain the desired characteristics of therapeutic cells during expansion, various strategies are employed:

Culture condition optimization: The culture conditions, including media composition, growth factors and supplements, are optimized to provide an environment that supports cell growth while maintaining their desired characteristics.

Passaging techniques: The frequency and method of passaging (splitting) cells during expansion can impact their quality. Careful consideration needs to be given to minimize cellular senescence or phenotypic changes.

Quality control measures: Implementing rigorous quality control measures throughout the expansion process helps ensure that cells meet predefined criteria for identity, purity, viability, potency and safety.

Process validation: Validating the cell expansion process involves demonstrating that it consistently produces cells with the desired characteristics.

By employing these strategies, researchers and manufacturers aim to maintain the desired characteristics of therapeutic cells during expansion, ensuring their safety, efficacy and functionality for applications. Continuous monitoring, optimization and adherence to quality control measures are essential throughout the expansion process to achieve consistent and reliable results.

Expansion services often have specialized expertise and experience in cell culture techniques, process optimization and regulatory compliance. They bring valuable knowledge and skills to the table, helping to overcome challenges and streamline the expansion process. They are also equipped with the necessary infrastructure, equipment and resources to scale up cell expansion processes efficiently. They can handle larger volumes of cells, enabling the production of relevant quantities required.

Thus, using a cell expansion service is cost-effective compared to establishing and maintaining in-house facilities for large-scale expansion. It eliminates the need for significant capital investment in costly equipment, facility setup and ongoing maintenance costs. Besides money, using an expansion service saves time by leveraging their established protocols, optimized processes and experienced personnel. This allows researchers or manufacturers to focus on other aspects of their work, such as research, development or downstream processing. Expansion services often have robust quality control measures in place to ensure consistent and reliable cell expansion. This includes, besides other advantages, a reduced risk of contamination during the expansion process, as often stringent quality control measures are in place to mitigate these risks.

Besides the actual cell expansion, the service provider should be an effective communicator and clear agreements have to be set in place between the service provider and the client to ensure alignment of goals, timelines and expectations.

PromoCell is a well-established company specializing in the production and distribution of primary human cells and specialized cell culture media. Our team consists of experts with extensive expertise and qualifications in the field of cell culture, including dealing with various cell types. The knowledge on specific cellular characteristics inside PromoCell has grown over more than 30 years – working together between different departments and sharing this knowledge allows us to design and optimize culture conditions specific to different cell types. And it allows us to support our customers, providing guidance on cell culture protocols, troubleshooting and experimental design.

Our team of experts is skilled in isolating primary human cells from various tissues, such as skin, blood, kidney and many others. We employ rigorous protocols for cell isolation to ensure high purity and viability. Additionally, we perform thorough characterization of isolated cells to confirm their identity and functionality. We are proficient in a wide range of cell culture techniques, including adherent cultures, suspension cultures, 3D cultures, co-cultures and more. We are experienced in working with different culture vessels, bioreactors and scaffolds to support the growth and expansion of various cell types. We understand the specific requirements of each cell type regarding media composition, growth factors, supplements, substrate coatings and other parameters. Taken together, there is a broad expertise in optimizing culture conditions for different cell types to promote their growth, maintain their phenotype and preserve their functionality, with an extraordinary focus on product quality.

When one is considering outsourcing their cell expansion to a service provider, one should ensure that the provider not only is an expert in expanding the cell type in question but also brings a deep understanding of the regulatory landscape for cell-based therapies. Respective certifications of the quality management system in place are highly beneficial, as they ensure compliance with regulations. Whereas it is ultimately the responsibility of the client to ensure that their therapeutic cells meet all applicable regulatory requirements, having a capable partner at one’s side is invaluable.

Expansion service providers ensure consistent production, control and documentation of products. Their facilities adhere to strict protocols for cleanliness, equipment calibration, personnel training, record-keeping and other critical aspects. They also implement robust quality control measures to ensure the safety, purity, potency and identity of cells.

The expansion service provider of choice should maintain comprehensive documentation throughout the expansion process. This includes batch records, standard operating procedures, protocols, validation reports and other relevant documents required for regulatory compliance. The traceability of each step in the expansion process helps demonstrate adherence to regulatory guidelines. Ideally, there are regulatory experts on their team who can provide guidance and support in navigating the regulatory requirements for different cell types and intended uses.

Overall, close collaboration between the client and the expansion service provider is crucial to align goals, expectations and responsibilities regarding regulatory compliance.