Beneficial effects of Pluronic F-68 and artificial oxygen carriers on the post-thaw recovery of cryopreserved plant cells.

The storage of prokaryotic and eukaryotic cells at ultra-low temperature in liquid nitrogen (-196 degrees C) is a procedure that has assumed an increasingly important role in underpinning many aspects of biotechnology. For eukaryotic cells, the transition from a cryopreserved state to physiologically normal temperatures and oxygen tensions, induces respiratory imbalances that may stimulate the production of toxic oxygen radicals causing impaired cellular functions. Novel treatments, that focus specifically on enhancing oxygen delivery to cells, are important in maximising post-thaw recovery. Recently, several approaches have been evaluated with suspension cultured plant cells as a model, yet biotechnologically-important, totipotent eukaryotic cell system. Such treatments include non-ionic surfactants, primarily Pluronic F-68, and artificial oxygen carriers, the latter based on inert perfluorochemical liquids or chemically-modifed haemoglobin, as supplements to culture medium used during the post-thaw recovery phase of cell growth. When used either alone or in combination, such novel treatments stimulate significantly the post-thaw viability and biomass production of cultured plant cells. Many of these technologies will be exploitable in cryopreservation protocols for eukaryotic cells in general.