02514nas a2200385   4500000000100000000000100001008004100002260001500043653002500058653002900083653002800112653002100140653002000161653003500181653002000216653003500236100001500271700002800286700001600314700002400330700001400354700002200368700002700390700001800417700001800435700001800453700002600471700001800497700001900515245008700534856009200621490000600713520139500719022001402114       2025                            d  c2025-08-0810aanimal-free in vitro10achemically defined media10acomplex in vitro models10acryopreservation10acultivated meat10afetal bovine serum replacement10areproducibility10axeno-free and serum-free media1 aTilo Weber1 aAtena Malakpour-Permlid1 aAline Chary1 aVito D’Alessandro1 aLeah Haut1 aSebastian Seufert1 aEsther Veronika Wenzel1 aJames Hickman1 aKaren Bieback1 aJoachim Wiest1 aWilhelm Gerhard Dirks1 aSandra Coecke1 aStina Oredsson00aFetal bovine serum: how to leave it behind in the pursuit of more reliable science  uhttps://www.frontiersin.org/journals/toxicology/articles/10.3389/ftox.2025.1612903/full0 v73 aCell cultures form the backbone for scientific research and development, but also for clinical diagnostics and biotechnology. Supplying cells in vitro with growth factors, hormones, and other nutrients is achieved most often by supplementing culture media with fetal bovine serum (FBS). Despite its nearly ubiquitous use, there are major reproducibility, safety, and animal welfare issues arguing the need to replace FBS. Fortunately, numerous FBS replacements have been validated and are publicly or commercially available, making it possible to leave FBS behind. Successful serum-free, animal-component-free, and chemically defined media applications are highlighted in this review for the cultivation of stem cells and organoids, the development of organ-on-a-chip systems, the bioprinting of tissues, and the production of cultivated meat, antibodies, and vaccines, including the conduct of cytotoxicity tests and the cryopreservation of cells. Moreover, the use of fully animal-free models and methodologies is further discussed to promote their broader acceptance and adoption within the global scientific research and development community. In this regard, this review discusses novel avenues to address the scientific and practical hurdles that might limit a full transition from FBS to fully defined cell culture media and offers a brief perspective on potential future directions.  a2673-3080