Cryopreservation in tissue banking

Abstract

Successful cryopreservation of cells and tissues ensures genetic stability and preserved function of a banked sample throughout storage. It also provides valuable time for quality and suitability assessments to ensure the best possible patient outcomes. This flexibility lends significant support to the increased adoption of tissue therapies and the development of new protocols and procedures. This chapter considers the design and execution of current cryopreservation protocols, outlining the causes, both physical and biological, of potentially lethal cryo-injuries and how these can be reduced to clinically acceptable levels during freezing and thawing. The appropriate preparation of freshly harvested samples is discussed, including the selection of, and pre-treatment with, effective cryoprotectant compounds and the necessary use of controlled cooling and warming rates. The implications of possible differences between post-thaw survival of low volume samples, typically preserved for quality control functions, and their large volume counterparts is also considered. As well as dealing with cell suspensions the discussion includes current approaches towards the cryopreservation of larger samples, ranging from spheroids, organoids and bioartificial materials to entire, natural organs. The risk to both samples and personnel due to contaminants that inevitably accumulate in liquid nitrogen storage vessels over long banking times is detailed. Finally, alternatives to the use of liquid nitrogen in the management of the entire cryochain due to its safety, sterility and usability issues and difficulties appear necessary and are proposed.