Droplet Generation, Vitrification, and Warming for Cell Cryopreservation: A Review

Cryopreservation is currently a key step in translational medicine that could provide new ideas for clinical applications in reproductive medicine, regenerative medicine, and cell therapy. With the advantages of a low concentration of cryoprotectant, fast cooling rate, and easy operation, droplet-based printing for vitrification has received wide attention in the field of cryopreservation. This review summarizes the droplet generation, vitrification, and warming method. Droplet generation techniques such as inkjet printing, microvalve printing, and acoustic printing have been applied in the field of cryopreservation. Droplet vitrification includes direct contact with liquid nitrogen vitrification and droplet solid surface vitrification. The limitations of droplet vitrification (liquid nitrogen contamination, droplet evaporation, gas film inhibition of heat transfer, frosting) and solutions are discussed. Furthermore, a comparison of the external physical field warming method with the conventional water bath method revealed that better applications can be achieved in automated rapid warming of microdroplets. The combination of droplet vitrification technology and external physical field warming technology is expected to enable high-throughput and automated cryopreservation, which has a promising future in biomedicine and regenerative medicine.

Automated summary

Cryopreservation is an important step in translational medicine, with potential applications in reproductive medicine, regenerative medicine, and cell therapy. Droplet-based printing for vitrification, which offers advantages such as low cryoprotectant concentration, fast cooling rate, and easy operation, has gained significant attention in cryopreservation. This review summarizes the techniques of droplet generation, vitrification, and warming, including inkjet printing, microvalve printing, and acoustic printing. It discusses the limitations of droplet vitrification and presents potential solutions. Additionally, it highlights the advantages of using external physical field warming for rapid and automated warming of microdroplets, and suggests that the combination of droplet vitrification and external physical field warming could pave the way for high-throughput and automated cryopreservation in biomedicine and regenerative medicine.