Lei, Y. & Schaffer, D.V. Proc. Natl. Acad. Sci. USA 10.1073/pnas.1309408110 (18 November 2013).

Several potential applications of human pluripotent stem cells (hPSCs), whether in screens, for toxicity testing or in the clinic, are likely to require very large numbers of cells. Scalable culture methods for these cells are therefore desirable. Lei and Schaffer describe a simple three-dimensional (3D) culture method based on a thermoreversible hydrogel for long-term culture of hPSCs. The cells can be seeded at low temperature when the gel is liquid, cultured at 37 °C as suspended aggregates in the solidified 3D environment and then harvested again with a simple temperature switch. Upon optimization of multiple experimental conditions, this fully defined system permits stable and unprecedented expansion of hPSCs.