Cryopreservation: methods, equipment and critical concerns.

The technique of cryopreservation aims to maintain the biological samples in a metabolic suspension state, by which all chemical, physical and biological changes are diminished. The biology principles behind cryopreservation are widely investigated in the literature. However, little scientific interest has been focused to the current equipment used as cryogenic storages and how they affect the viability and functionality of the cells during their preservation. This review paper attempts to bridge the gap between the biology and engineering aspects of cryopreservation. The basic principles of cryobiology, the cryoinjury mechanisms, the role of cryoprotective agents, the state of the art cryopreservation methods and equipment, and concerns regarding the use of liquid nitrogen as cryogenic refrigerant are covered. Further to our knowledge there is no complete review in the literature describing the connection between the current cryogenic equipment and the physical events taking place during cryopreservation. The paper aims to provide researchers with the key knowledge of cryopreservation, not only from a biological point of view, but from a technical aspect, too, in order to contribute to the development of the cryobiology field.