Optimization of mouse embryonic stem cell culture for organoid and chimeric mice production.

In vitro stem cell culture is demanding in terms of manpower and media supplements. In recent years, new protocols have been developed to expand pluripotent embryonic stem cells in suspension culture, which greatly simplifies cell handling and scalability. However, it is still unclear how suspension culture protocols with different supplements affect pluripotency, cell homogeneity and cell differentiation compared to established adherent culture methods. Here we tested four different culture conditions for mouse embryonic stem cells (mESC) and quantified chimerism and germ line transmission as well as in vitro differentiation into three-dimensional neuro-epithelia. We found that suspension culture supplemented with CHIR99021/LIF offers the best compromise between culturing effort, robust pluripotency and cell homogeneity. Our work provides a guideline for simplifying mESC culture and should encourage more cell biology labs to use stem cell-based organoids as model systems.