In previous blogs, we have discussed the importance of removing fetal bovine serum from cell culture due to problems associated with the use of animal products including variability, concerns about animal origin contaminants and ethics. As reported previously, animal and blood donor derived products carry a risk of pathogen contamination and often demonstrate inconsistent performance. Removing serum is a challenge because most cells rely on serum or blood proteins to maintain health and deliver the desired productivity. However, cells can be successfully moved out of serum, or at a minimum serum can be reduced, by using products that replace the key components of serum. Insulin and transferrin supplements contain some of the key components of serum and are commonly used to remove or reduce serum in culture.

Insulin and transferrin supplements can be used with many different cell types including stem cells, primary cells, cell-based vaccine lines, and in antibody production lines like CHO, Hybridoma and HEK293. Many classic media (DMEM, RPMI and MEM) were formulated for use with serum and cannot support cells on their own because they lack the necessary factors required for cell health and productivity. The universal factors that are required in nearly all cell lines, which have been identified in the literature include insulin, transferrin and selenium. For certain cell lines Ethanolamine may also be critical and in some cases attachment factors such as fibronectin, laminin, vitronectin and growth factors may be beneficial.

To address cell needs in serum free conditions, insulin and transferrin supplements have been formulated to include selenium and sometimes ethanolamine. Each of the insulin and transferrin supplement components carry out an important role in cell culture. Insulin is a growth factor that helps cells utilize glucose and amino acids. Transferrin is a universal iron carrier that provides iron and also helps cells maintain homeostasis by helping cells regulate the amount of iron uptake. Selenium is required for proper functioning of glutathione peroxidase, thioredoxin reductase, and other antioxidant enzymes. Ethanolamine is required for phospholipid synthesis in some cell types. For recommendations on using insulin and transferrin supplements to remove serum, please see our Guest Blog “An Easy Method to Reduce or Eliminate Serum in Cell Culture.”

Depending on the formulation and manufacturer, insulin and transferrin supplements are also called ITSE, SITE, or ITS. Other differences between suppliers include whether the product is recombinant, animal-free or derived from animal tissue or from donor blood. Most of the insulin-transferrin products on the market use blood-derived proteins including bovine transferrin or plasma derived human transferrin. They can also contain insulin from porcine origin. However there are a few recombinant and completely animal-free insulin and transferrin supplements available from InVitria and Fisher Scientific. Price can also be variable and is often based on other elements of the formulation. Please see the table below for a comparison of available insulin-transferrin supplements.

Have you used insulin-transferrin supplements to remove or reduce serum in your culture? How did it work for you? Suggestions?