Abstract
Cryoprotectant agents (CPA) that can suppress generating ice crystals during the freezing process are essential for cell cryopreservation. On the other hand, a CPA should ideally be avoided due to their cytotoxicity and potential side effects. We previously reported a novel cryopreservation method without a CPA by ultrarapid cooling. In the method, cells were ejected as tiny droplets by inkjet cell printing. The droplets were deposited on the liquid nitrogen-cooled substrate and were vitrified, that enables cell cryopreservation. While, these droplets can devitrify easily due to CPA-free and low thermal volume of the droplets. In this study, we fabricated an aluminum career and a silicon cover to inhibit devitrification of the droplets. The experimental results indicated that the glass substrate with the career and the cover was kept under the glass-transition temperature for a several seconds. The efficacy of the career and the cover was also evaluated on mouse fibroblast 3T3 cells. The cells transferred to the cryotube and stored for one week with the career and the cover had higher viability than the ones without them. These results indicate that the career and the cover were able to inhibit devitrification of the cells frozen by our method.
