Sand-mediated ice seeding enables serum-free low-cryoprotectant cryopreservation of human induced pluripotent stem cells

Human induced pluripotent stem cells (hiPSCs) possess tremendous potential for tissue regeneration and banking hiPSCs by cryopreservation for their ready availability is crucial to their widespread use. However, contemporary methods for hiPSC cryopreservation are associated with both limited cell survival and high concentration of toxic cryoprotectants and/or serum. The latter may cause spontaneous differentiation and/or introduce xenogeneic factors, which may compromise the quality of hiPSCs. Here, sand from nature is discovered to be capable of seeding ice above −10 °C, which enables cryopreservation of hiPSCs with no serum, much-reduced cryoprotectant, and high cell survival. Furthermore, the cryopreserved hiPSCs retain high pluripotency and functions judged by their pluripotency marker expression, cell cycle analysis, and capability of differentiation into the three germ layers. This unique sand-mediated cryopreservation method may greatly facilitate the convenient and ready availability of high-quality hiPSCs and probably many other types of cells/tissues for the emerging cell-based translational medicine. A novel method with sand-mediated ice seeding is developed for cryopreservation of human iPSCs. The cryopreserved human iPSCs retain high viability, pluripotency, and differentiation capacity in vitro and in vivo. The sand-based method is simple to use and cost effective, minimizes clinically concerning elements in the cryopreservation solution, and can be widely used for the cryopreservation of human iPSCs and possibly many other types of stem cells for the burgeoning cell-based medicine. [Display omitted] •Sand in nature is discovered to be excellent in seeding ice at high subzero temperatures.•The sand-mediated ice seeding enables the elimination of serum in cryopreservation solution.•The sand-mediated ice seeding enables the reduction of cryoprotectant by half.•The human iPSCs retain their intact pluripotency and differentiation capacity after cryopreservation.