Why optimizing insulin supplementation is crucial
Stem cells represent one of the most powerful tools in modern biomedical science. Their unique ability to both self-renew and differentiate into specialized cell types makes them invaluable for research, disease modeling, and the development of regenerative therapies. Realizing this potential, however, requires more than the cells themselves—it depends on carefully controlled culture conditions that allow stem cells to proliferate without losing their differentiation potential.
Among the critical components of stem cell culture media is insulin. Traditionally known for its role in regulating glucose metabolism in the human body, insulin also exerts profound effects on cell signaling pathways that influence growth, survival, and differentiation. In stem cell systems, these functions are essential: insulin helps maintain pluripotency while supporting robust proliferation, making it indispensable for both research-scale and therapeutic-scale applications.
Most commercially available stem cell media include insulin as part of a pre-mixed formulation. While these ready-to-use solutions are convenient, they are not always transparent about the concentration or source of insulin, and they offer limited room for optimization. For applications where reproducibility, efficiency, and scalability are paramount—such as clinical-grade induced pluripotent stem cells (iPSCs)—such limitations can pose challenges.
This article explores the role of insulin in stem cell culture, highlighting its biological functions, its use in commercial media, and why optimizing insulin supplementation is crucial for advancing stem cell research and therapy.
Biological role of insulin in stem cells
Insulin is widely recognized as a hormone that regulates blood glucose levels in the human body. However, beyond its metabolic role, insulin functions as a potent growth factor that activates key intracellular signaling pathways. When insulin binds to its receptor on the surface of a cell, it triggers cascades such as the PI3K/Akt and MAPK/ERK pathways. These pathways are central to processes including cell proliferation, survival, differentiation, and metabolism.
In the context of stem cells, these signaling effects are particularly important. Stem cells require a delicate balance between self-renewal and the potential to differentiate into specialized cell types. Insulin contributes to maintaining this balance by:
- Promoting proliferation: Insulin stimulates DNA synthesis and protein translation, allowing stem cells to expand efficiently in culture.
- Supporting survival: By reducing apoptosis (programmed cell death), insulin helps maintain viable and stable cell populations during long-term culture.
- Preserving pluripotency: Insulin signaling has been shown to work alongside other growth factors to sustain the undifferentiated state of pluripotent stem cells.
These functions are essential both in small-scale research experiments and in large-scale production of stem cells for clinical use. Without sufficient insulin, stem cells may proliferate poorly or undergo spontaneous differentiation, leading to inconsistent results and reduced yields. On the other hand, an excess of insulin may alter the differentiation profile of the cells, emphasizing the importance of careful regulation.
Thus, insulin is not simply an additive in culture media—it is a central regulator of stem cell physiology. Its presence ensures that cultures remain healthy, expandable, and capable of fulfilling their therapeutic potential.
Commercial pre-mixed media and their limitations
Many laboratories use commercial pre-mixed stem cell media to simplify the complex task of maintaining stem cells. These formulations include essential nutrients and growth factors such as insulin, offering researchers a convenient and consistent solution for routine culture work. While this approach saves time and reduces variability, it also introduces several important limitations:
- Lack of transparency: The concentration, purity, and origin of insulin in pre-mixed media are often undisclosed, preventing researchers from knowing the precise composition of their culture environment.
- Inflexibility: Different stem cell types and applications may require different insulin levels. Standard formulations do not allow for adjustments, which can lead to suboptimal growth or premature differentiation.
- Variability across products: Commercial media can vary in formulation between suppliers, making it difficult to compare results across studies or scale experiments consistently.
- Regulatory challenges: For clinical applications, regulatory agencies require strict documentation and reproducibility. Media without defined insulin concentrations—or those containing animal-derived components—may not meet compliance standards.
These limitations underline the need for researchers to move beyond reliance on pre-mixed solutions. Developing defined and optimized media formulations allows precise control of insulin supplementation, improving both scientific reproducibility and the potential for therapeutic translation.
Why optimization matters
Stem cell culture is highly sensitive to the composition of its media, and insulin plays a central role in determining cell health and performance. While pre-mixed formulations provide a baseline, they rarely reflect the optimal concentration of insulin needed for specific cell types or experimental goals. Optimizing insulin supplementation is therefore critical for several reasons:
- Proliferation efficiency: Too little or excess insulin limits cell division and slows the expansion of cultures. In research contexts, this reduces experimental throughput, while in therapeutic manufacturing it can constrain scalability.
- Maintenance of pluripotency: Stem cells must retain their ability to differentiate into multiple lineages. Excess insulin can disrupt this balance, pushing cells toward unwanted fates or altering differentiation kinetics.
- Yield and quality: Properly optimized insulin concentrations improve both the number and quality of stem cells produced, which is particularly important for downstream applications such as disease modeling, drug testing, and regenerative medicine.
In practice, this means that insulin should not be treated as a fixed background component of culture media. Instead, it must be considered a variable to fine-tune based on the stem cell type, stage of culture, and intended use of the cells. For example, induced pluripotent stem cells (iPSCs) used in clinical applications require careful optimization to ensure both expansion efficiency and the preservation of pluripotency markers.
By taking control of insulin supplementation rather than relying exclusively on pre-mixed formulations, researchers can achieve greater reproducibility, scalability, and consistency—all essential for translating stem cell research into therapeutic success.
Case study: Enhancing iPSC culture with Recombinant Insulin
A study conducted by Novo Nordisk Pharmatech demonstrated the essential role of Recombinant Insulin in iPSC culture. Adding optimized concentrations of insulin to chemically defined media improved cell morphology, proliferation, and attachment, while maintaining pluripotency markers unchanged over multiple passages.
The findings highlight that insulin optimization is a prerequisite for scalable, high-quality iPSC cultures. Click the button below to read the full case study.
Recombinant Insulin from Novo Nordisk Pharmatech
Novo Nordisk Pharmatech supplies high-quality, animal-free Recombinant Insulin (Insulin Human AF) produced through recombinant yeast expression. With over 100 years of insulin expertise, we ensure purity, consistency, and global regulatory compliance.
Our insulin supports serum-free and chemically defined media, making it ideal for stem cell culture as well as the production of monoclonal antibodies, vaccines, and gene therapies. Its proven reliability and batch-to-batch consistency help researchers and manufacturers achieve reproducible, scalable results.
