title: A scale down process for the development of large volume cryopreservation.
abstract: The process of ice formation and propagation during cryopreservation impacts on the post-thaw outcome for a sample. Two processes, either network solidification or progressive solidification, can dominate the water-ice phase transition with network solidification typically present in small sample cryo-straws or cryo-vials. Progressive solidification is more often observed in larger volumes or environmental freezing. These different ice phase progressions could have a significant impact on cryopreservation in scale-up and larger volume cryo-banking protocols necessitating their study when considering cell therapy applications. This study determines the impact of these different processes on alginate encapsulated liver spheroids (ELS) as a model system during cryopreservation, and develops a method to replicate these differences in an economical manner. It was found in the current studies that progressive solidification resulted in fewer, but proportionally more viable cells 24h post-thaw compared with network solidification. The differences between the groups diminished at later time points post-thaw as cells recovered the ability to undertake cell division, with no statistically significant differences seen by either 48 h or 72 h in recovery cultures. Thus progressive solidification itself should not prove a significant hurdle in the search for successful cryopreservation in large volumes. However, some small but significant differences were noted in total viable cell recoveries and functional assessments between samples cooled with either progressive or network solidification, and these require further investigation.
authors.affiliation: Institute of Liver and Digestive Health, Royal Free Hospital Campus, UCL, London NW3 2PF, UK. Electronic address: peter.kilbride.11@ucl.ac.uk.
authors.forename: Peter
authors.initials: P
authors.lastname: Kilbride
authors.affiliation: Asymptote Ltd., St. John's Innovation Centre, Cowley Road, Cambridge CB4 0WS, UK.
authors.forename: G John
authors.initials: GJ
authors.lastname: Morris
authors.affiliation: Asymptote Ltd., St. John's Innovation Centre, Cowley Road, Cambridge CB4 0WS, UK.
authors.forename: Stuart
authors.initials: S
authors.lastname: Milne
authors.affiliation: Department of Surgery, Royal Free Hospital Campus, UCL, London NW3 2PF, UK.
authors.forename: Barry
authors.initials: B
authors.lastname: Fuller
authors.affiliation: Multi Imaging Centre, Anatomy Building, Downing Site, Cambridge University, CB2 3DY, UK.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Skepper
authors.affiliation: Institute of Liver and Digestive Health, Royal Free Hospital Campus, UCL, London NW3 2PF, UK.
authors.forename: Clare
authors.initials: C
authors.lastname: Selden
mesh_terms: D000464:Alginates / Q000737:chemistry; D002470:Cell Survival; D018914:Cells, Immobilized / Q000166:cytology; D015925:Cryopreservation / Q000191:economics / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D005615:Freezing; D020723:Glucuronic Acid / Q000737:chemistry; D056945:Hep G2 Cells; D006603:Hexuronic Acids / Q000737:chemistry; D006801:Humans; D007053:Ice / Q000032:analysis; D008099:Liver / Q000166:cytology*; D018401:Sample Size
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D007053:Ice; D020723:Glucuronic Acid
keywords: Bioartificial liver; Large volume cryopreservation; Network solidification; Progressive solidification; Undercooling