Coatings for cell culture surfaces are important for the health of many cell types grown in the lab. But for scientists culturing stem cells, finding the right biological or synthetic coating is critical.
Benefits of coatings for bioproduction include structural support, attachment, biological relevance, and cell signaling. The choice of coating has a huge impact on stem cell quality and fate, whether grown at a small or large scale.
According to Corning Field Application Scientist Robert Padilla, coatings are essential for creating the ideal microenvironment that can help each type of stem cell maintain its health and pluripotent properties. Extracellular matrix (ECM) coatings help investigators recapitulate the in vivo environment as much as possible so stem cells can behave in biologically relevant ways.
"Not all cell types require an ECM for attachment," explains Whitney Wilson, a Field Application Scientist at Corning. "Historically, scientists have developed cell lines that will attach to plastic. When working on cell lines or fully differentiated cells, we're less concerned about them changing their form. We know they're going to stay a fibroblast or a cancer cell. Stem cells are much trickier to work with — they want to become another cell type. We have to constantly trick them into remaining stem cells."
The right coating provides attachment points and appropriate signaling to stem cells. For example, cell surface receptors called integrins bind to ECM proteins, such as collagen or fibronectin. This interaction between ECM and stem cells provides both adhesion and signaling that can affect cell function.
Pluripotent stem cells (PSCs) have the potential to become any cell type of the adult body and do not exist in the human body except for a brief period in early embryonic development. Investigators culturing these cells, which include human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), need to carefully manage the cells' microenvironment to help them maintain pluripotency.
According to Padilla, scientists can prevent unwanted differentiation of PSCs by growing them on Corning® Matrigel® matrix, a widely used ECM derived from mouse Engelbreth-Holm-Swarm sarcoma cells, along with managing other factors such as media composition. Corning offers a reduced-variability, hESC-qualified Matrigel matrix product that's pre-screened for stem cell applications.
Multipotent stem cells, also known as adult stem cells, exist in specific locations in the adult body and can differentiate into a limited number of cell types. Choosing the proper coating for bioproduction can help researchers and manufacturers mimic the in vivo environment for each cell type. For example:
Beyond choosing a coating that's compatible with a specific type of stem cell, investigators need to optimize coatings depending on the application and the desired cell fate. In addition to Matrigel Matrix, Corning offers extensively tested natural and synthetic forms of Fibronectin, Vitronectin, several variants of Laminins, and Collagen, plus pre-coated tissue culture products.
Some cells do best with a coating made from a mixture of ECM proteins, and investigators should optimize the overall concentration of protein as well as the ratios of ECM proteins in a mixture.
The cost of stem cell coatings is also a key consideration. For products intended to be offered to patients, it's important to find ways to drive down the cost of final therapeutic products. Optimizing protein concentration will help ensure coatings are not using costly proteins at unnecessarily high concentrations.
For guidance on choosing and optimizing coatings for stem cells, see Corning's Cell Culture Surfaces Product Selection Guide and other cell culture surface resources.
While Matrigel provides excellent results with pluripotent stem cells, it is an animal-derived product. Many companies and labs aim to eliminate animal products entirely from production, especially for therapeutic products.
According to Wilson — based on conversations with regulatory authorities — manufacturers can use animal-derived products in stem cell production as long as the final product is tested for relevant contaminants. For example, if using a mouse-derived substrate, the product must be tested for mouse adventitious virus. However, this testing is expensive, and batches may need to be discarded due to unexpected contamination. For some cell-based therapies, therefore, using a xeno-free or fully synthetic coating may help simplify the regulatory process.
Xeno-free products available for stem cells include human proteins, such as Corning rLaminin-521 (human), as well as synthetic products, like Corning Synthemax®. Synthemax, a fully synthetic Vitronectin-based peptide substrate, is extensively tested to support the production of multiple types of stem cells, including PSCs.
For some products, the use of animal-free substrates may not be feasible or may be too costly. Going through an optimization and testing process will help clarify this decision.
With decades of experience in supporting stem cell research, Corning is ready to help your organization navigate the complexities of stem cell bioproduction. Visit Corning's stem cell and cell culture surface resource pages to explore what's possible, or get in touch with our experts today.
