Cell and Gene Therapy (CGT) represents an emerging frontier in transformative medicine, offering the potential to cure a variety of genetic and acquired diseases through the restoration or reconditioning of cells and genes. Unlike traditional medicine and surgery, which can moderate diseases but often fall short of curing them, CGT approaches aim to provide lasting solutions by employing cells—especially genetically engineered ones—that can act as “living drugs” to heal or replace damaged tissues or organs. Although CGT applications remain in their infancy, the rapid development of these therapies is paving the way for significant advancements in disease treatment and prevention.

Eppendorf recently published an ebook, Optimizing Cell and Gene Therapy Workflows – A Bioprocessing Resource Guide which provides an in-depth exploration of cellular therapies, particularly focusing on stem cell-based regenerative medicine and the critical role of bioprocessing in scaling these therapies. It emphasizes the promise of stem cells, including human pluripotent stem cells (hPSCs) and induced pluripotent stem cells (hiPSCs), in treating complex diseases and advancing regenerative medicine. The ebook also highlights the challenges and innovations in bioreactor technology, such as stirred-tank bioreactors, and their application in optimizing the production of therapeutic cells. Case studies, like the work of Dr. Robert Zweigerdt’s team in cultivating hiPSCs, demonstrate the potential of bioreactor-based cultivation to improve cell yield and quality. The ebook underscores the need for further technological advancements to make stem cell-based therapies more scalable, cost-effective, and accessible, pointing to the continued progress in bioreactor design and cell culture optimization as key drivers of success in the field. Below, we’ve highlighted key insights, but we highly recommend downloading the full ebook for comprehensive details and in-depth data.

Cellular Therapy and Regenerative Medicine: Stem Cells

One of the most promising areas within CGT is cellular therapy (CT), which involves the transplantation of human cells to replace or repair damaged tissue. These cells may be sourced either from the patient (autologous) or a healthy donor (allogeneic). Stem cells, in particular, are a vital component of regenerative medicine due to their remarkable ability to differentiate into a variety of specialized cell types. Among the most widely studied are human pluripotent stem cells (hPSCs), which include human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs). These stem cells are key to treating diseases such as blood cancers, autoimmune disorders, and neurological conditions that are otherwise challenging to address with conventional treatments.

Stem cells can also play a significant role in the development of in vitro disease models and in drug discovery, providing valuable insights into disease mechanisms and enabling the development of predictive safety assays. However, the research and production of these therapies require large quantities of high-quality cells, often billions of them, which presents a significant challenge for scale-up and consistency. Traditional two-dimensional (2D) cell culture systems, such as T-flasks or bags, are limited in their ability to provide scalable, controlled, and efficient environments for growing large numbers of cells. Therefore, there is a growing need for more advanced culture systems capable of supporting the high-demand production of stem cells at the necessary scale.

Stem Cell Bioprocessing: Stirred-Tank Bioreactors

A critical component in the scale-up and optimization of stem cell therapies is bioprocessing, with bioreactors playing a central role in this effort. Bioreactors are used to cultivate cells in controlled environments that can be scaled from laboratory research to full-scale production. Stirred-tank bioreactors are particularly well-suited for suspension cell cultures and can be adapted to support both research and production scales. These bioreactors are often paired with microcarriers to facilitate the growth of cells that are not naturally suspended. In recent years, single-use plastic bioreactors have gained popularity for culturing specialized cells, such as chimeric antigen receptor T-cells (CAR-T cells), because they eliminate the need for time-consuming cleaning and sterilization processes, resulting in faster turnaround times.

The Eppendorf BioBLU® c Single-Use Bioreactors, in combination with their DASbox® Mini Bioreactor System, are designed to help streamline the cell expansion process and provide reliable results even in small-scale parallel bioreactor setups. These bioreactors offer various benefits, including the ability to monitor and control key process parameters such as oxygen levels, pH, and temperature in real time. This level of precision is crucial for the successful cultivation and expansion of stem cells and other therapeutic cells.

Case Study: Optimizing Stem Cell Cultivation in Bioreactors

A notable example of bioreactor optimization comes from the work of Dr. Robert Zweigerdt and his team at Hannover Medical School, Germany, who successfully increased the yield of human induced pluripotent stem cells (hiPSCs) using stirred-tank bioreactors. Their work demonstrated how bioreactor-based cultivation of hiPSCs could be optimized to achieve high-density cell cultures necessary for regenerative medicine applications. By employing a modified stirring impeller and a retention-filter system for enhanced cell aggregation, the team improved the homogeneity and survival of hiPSCs, significantly increasing the overall yield.

In a recent study, they achieved a remarkable 35 million hiPSCs per mL using a perfusion feeding strategy, which ensures continuous media replenishment while maintaining optimal cell growth conditions. This approach proved to be much more effective than traditional batch feeding, particularly for high-density cultures where issues such as nutrient depletion and lactate accumulation can limit cell growth. By overcoming these growth-limiting factors, Dr. Zweigerdt’s team significantly improved both the viability and proliferation of hiPSCs, facilitating the scaling up of their production.

Challenges and Opportunities in Scaling Stem Cell Production

Despite these successes, challenges remain in scaling stem cell production for therapeutic purposes. For example, when differentiating hiPSCs into functional cells such as cardiomyocytes for heart repair, the yield of differentiated cells is still relatively low, and further improvements are necessary to meet the demand for clinical applications. However, as bioreactor technologies continue to advance, researchers are confident that scalability and efficiency will improve, enabling the generation of large numbers of therapeutic cells for patient treatments.

In terms of differentiation, the transition from 2D monolayer cultures to 3D suspension cultures in bioreactors is not without its hurdles. Factors such as cell aggregate size, heterogeneity, and overall cell density must be carefully controlled to ensure successful differentiation. However, the latest research indicates that, with advanced bioreactor designs, the transition to 3D cultures can be streamlined, making it a promising approach for scaling up stem cell-based therapies.

Looking to the Future

As stem cell-based therapies move closer to widespread clinical application, the need for further bioprocess optimization, including improvements in differentiation and culture systems, will only increase. The ability to scale up production without compromising cell quality is crucial for the successful commercialization of these therapies. Bioreactor technologies, like those being developed by Eppendorf, are at the forefront of this effort, helping researchers to optimize cultivation and differentiation processes while reducing costs and increasing throughput.

In the coming years, as stem cell bioprocessing continues to evolve, researchers will likely see even greater improvements in cell density, viability, and differentiation efficiency. These advancements will be essential for making stem cell-based therapies more accessible and effective for patients worldwide, with applications ranging from tissue repair to disease prevention and even cure. The future of regenerative medicine looks bright, as CGT and bioreactor technology continue to push the boundaries of what is possible in medical science.

To download the full ebook, please see Optimizing Cell and Gene Therapy Workflows