The necessity for standardization of glioma stem cell culture: a systematic review

BACKGROUND: The cancer stem cell hypothesis is an old idea which has been revived in recent years for many cancers, including gliomas. However, this concept has become controversial due to a series of studies with conflicting results. METHODS: A systematic literature search was conducted in PubMed and the Web of Science database to analyze studies using serum-free medium and its components in glioma stem cells, glioma stem-like cells, glioma-initiating cells, or glioma neurosphere cultures. All the studies reviewed were published between 1970 and 2019. We found that no standardized culture method was used, and the data were incomparable due to differing culture conditions and the use of media with different components. CONCLUSIONS: Here, we review the most commonly used serum-free media and added components for glioma stem cell culture while highlighting the function of each component used in the media. We emphasize the necessity for standardization of glioma stem cell culture and propose a standard culture medium to prevent bias in glioma stem cell research.