Invisible animal use
Scientists have been doing cell culture in the lab since the 1950s. In recent years, many new cell culture models have been developed, such as the generation of induced pluripotent stem cells, culturing of organoids and the development of organ-on-a-chip devices. These advanced models more accurately represent the human body compared to standard 2D cell culture on plastic, and are therefore, promising alternatives to animal studies.
However, these models are often not completely animal-free as many of them still rely on the use of animal-derived products such as foetal calf serum and basement membrane extracts (also known under the trade names Matrigel, Geltrex or Cultrex).
Foetal calf serum (FCS)
FCS is a serum that is added to cell culture media to promote the growth of cells in the lab. FCS is a by-product from the meat industry, whereby blood is drawn from bovine foetuses via a cardiac puncture. Approximately 500 mL of FCS can be obtained from one calf. Apart from ethical and sustainability concerns regarding the manufacturing and collection process, there are also multiple scientific concerns associated with the use of FCS. For more detailed information about the manufacturing process of FCS, please check out the following article from Thermo Fisher.
Basement membrane extract (BME)
BME is the golden standard for culturing organoids and is also used for other 3D cell culture applications. Moreover, BME is one of the most used coatings for culturing induced pluripotent stem cells. BME is manufactured by injecting Engelbreth-Holm-Swarm tumour cells into mice. These mice have been specifically bred for the production of BME. When the tumours have reached a sufficient size, the mice are euthanised, and the tumour material is harvested. These tumours grow up to a size of 4 grams, which corresponds to 15-20% of its bodyweight. Approximately 5 mL of BME can be obtained from one mouse. Based on the available information, these mice undergo severe suffering. For more information about how BME is produced, please check out the scientific articles by Kibbey et al. and Kleinman et al.. Besides these ethical concerns, there are also many scientific concerns associated with BME.
Invisible animal use
The animals required for the production of FCS and BME are generally not included in official statistics on the number of animals used for scientific purposes. This type of animal use thereby often remains invisible. Therefore, the 3Rs Centre Utrecht (3RCU) has inventorised the amounts of FCS and BME purchased within Utrecht University and the University Medical Centre (UMC) Utrecht between 2015 and 2023. These figures have been published in the annual report 2024 of the Animal Welfare Body Utrecht. On average, 795 litre of FCS and 9.8 litre of BME is used annually at Utrecht University and UMC Utrecht, which corresponds to approximately 1600 calves and 2000 mice.
These numbers are based on the received orders of FCS and BME products at Utrecht University and UMC Utrecht. For BME, we included the trade names Matrigel, Geltrex and Cultrex. For FCS, we included all FCS-related products, excluding fetuin and bovine serum albumin (BSA).
The 3RCU facilitates researchers in their efforts to replace FCS and BME from their workflows. For example, we organize the Gels and Sera Working Group. Furthermore, the FCS-free Database and BME-free Database can help researchers in finding a suitable alternative for FCS and BME, respectively, for their specific application.