title: The effect of Me2SO overexposure during cryopreservation on HOS TE85 and hMSC viability, growth and quality.
abstract: With the cell therapy industry continuing to grow, the ability to preserve clinical grade cells, including mesenchymal stem cells (MSCs), whilst retaining cell viability and function remains critical for the generation of off-the-shelf therapies. Cryopreservation of MSCs, using slow freezing, is an established process at lab scale. However, the cytotoxicity of cryoprotectants, like Me2SO, raises questions about the impact of prolonged cell exposure to cryoprotectant at temperatures >0 °C during processing of large cell batches for allogenic therapies prior to rapid cooling in a controlled rate freezer or in the clinic prior to administration. Here we show that exposure of human bone marrow derived MSCs to Me2SO for ≥1 h before freezing, or after thawing, degrades membrane integrity, short-term cell attachment efficiency and alters cell immunophenotype. After 2 h's exposure to Me2SO at 37 °C post-thaw, membrane integrity dropped to ∼70% and only ∼50% of cells retained the ability to adhere to tissue culture plastic. Furthermore, only 70% of the recovered MSCs retained an immunophenotype consistent with the ISCT minimal criteria after exposure. We also saw a similar loss of membrane integrity and attachment efficiency after exposing osteoblast (HOS TE85) cells to Me2SO before, and after, cryopreservation. Overall, these results show that freezing medium exposure is a critical determinant of product quality as process scale increases. Defining and reporting cell sensitivity to freezing medium exposure, both before and after cryopreservation, enables a fair judgement of how scalable a particular cryopreservation process can be, and consequently whether the therapy has commercial feasibility.
authors.affiliation: Centre for Biological Engineering, Department of Chemical Engineering, Loughborough University, Leicestershire, LE11 3TU, UK.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Morris
authors.affiliation: Centre for Biological Engineering, Department of Chemical Engineering, Loughborough University, Leicestershire, LE11 3TU, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Picken
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB2 3RA, UK.
authors.forename: Duncan M C
authors.initials: DMC
authors.lastname: Sharp
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB2 3RA, UK.
authors.forename: Nigel K H
authors.initials: NKH
authors.lastname: Slater
authors.affiliation: Aston Medical Research Institue, School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Hewitt
authors.affiliation: Centre for Biological Engineering, Department of Chemical Engineering, Loughborough University, Leicestershire, LE11 3TU, UK. Electronic address: k.coopman@lboro.ac.uk.
authors.forename: Karen
authors.initials: K
authors.lastname: Coopman
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D064987:Cell- and Tissue-Based Therapy / Q000379:methods; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D005615:Freezing; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects*
chemical_list: D003451:Cryoprotective Agents; D004121:Dimethyl Sulfoxide
keywords: Bioprocessing; Cryopreservation; Dimethylsulfoxide; HOS TE85; Human mesenchymal stem cells; Toxicity