An ultra-rapid cryo-technique for complex organisms.

The soil nematode Caenorhabditis elegans is an excellent research model in cell biology, human disease and developmental studies. In this study, a novel cryopreservation technique based on a rapid cooling procedure, previously established for juveniles, was applied to adult-worms. Here we demonstrated that adults of C. elegans, a complex metazoan organism, survive to a rapid cooling and storage in liquid nitrogen (-196 °C) with a very high survival percentage (85%). The procedure relies on a Low CryoProtectant Technique (LCPT) and Ultra Rapid Cooling (URC). The high cooling rate is achieved through the reduction of sample volumes and the effectiveness of a nylon carrier. Our technique complies with the requirements for vitrification to occur. The main distinctive characters of this cryopreservation technique compared to other methods, e.g. Slow Freezing and Vitrification, are presented. Our results show that this cryopreservation method is valid for both unicellular and multicellular organisms; it is suitable for short or long time storage in liquid-nitrogen. This technique promises to be a unique and simpler method for cryostorage of cells, organisms and tissues.