These problems prompted for development of simpler, more efficient, and reliable vitrification methods. Recent studies demonstrated the roles of aquaporins, a family of water channel proteins selectively permeated by water, in cryopreservation of mouse oocytes, microorganisms, and on other sections. The expression of AQP3 improved the survival rate of mouse oocytes after cryopreservation. Furthermore, it has been demonstrated that the inhibition of AQP3 increases the sensitivity of prostate cancer cells to cryotherapy. The overexpression of AQY1 and AQY2 in Saccharomyces cerevisiae obtained freeze-tolerance. These observations coherently suggest that AQPs may play some roles in freeze-tolerance. Here, we attempted to engage the cryoprotective effect of AQPs in the selection of specific mammalian cells, since only cells expressing AQPs have been shown as resistant to damage caused by freezing at high cooling rate. Indeed, we successfully identified a freezing tolerance of mammalian cell lines with either exogenous or endogenous AQP expression. Furthermore, combined with bioinformatics, we demonstrated the possibility of selecting specific types of cells differentiated from embryonic stem cells when the cells express AQPs in the process of each differentiation stage, which can be applied to regenerative medicine. We also showed that co-transfection of a gene of interest with AQP results in efficient Niltubacin accumulation of cells expressing the gene product, upon multiple cycles of freezing/thawing, suggesting that this protocol would be a potential alternative for establishment of stable cell lines to perform functional assays or drug screening protocols. Here we present a novel and efficient method for selecting or concentrating mammalian cells based on our findings that cells expressing AQPs acquired tolerance to ultra-quick freezing by evading cell membrane damages. During freezing/thawing, cells are exposed to a variety of stresses, such as changes in temperature, changes in water content, ice crystal formation, and changes in solute concentration. At low cooling rates, ice crystal formation remains extracellular whereas, at high cooling rates, extensive intracellular super-cooling and the formation of intracellular ice crystals occur, causing cellular injury to the plasma membrane. Consistently, CHO cells survive after freezing at low cooling rates but died at high cooling rates or ultra-quick freezing. Thus, the finding that the expression of AQP rescues cells from membrane damage and significantly improves cell survival rate after ultra-quick freezing is remarkable. The freezing tolerance of cells depends on membrane water permeability and the dynamics of water molecules inside and outside of cells. AQPmediated facilitated diffusion of water molecules is temperature independent, whereas the simple diffusion of water though a lipid bilayer depends on temperature, implying that the difference in water permeability becomes more obvious at lower temperatures.