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The effect of Me$_{2}$SO overexposure during cryopreservation on HOS TE85 and hMSC viability, growth and quality

Published version
Peer-reviewed

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Authors

Morris, TJ 
Picken, A 
Sharp, DMC 
Slater, NKH 
Hewitt, CJ 

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.

Description

Keywords

human mesenchymal stem cells, HOS TE85, cryopreservation, dimethylsulfoxide, bioprocessing, toxicity

Journal Title

Cryobiology

Conference Name

Journal ISSN

0011-2240
1090-2392

Volume Title

73

Publisher

Elsevier
Sponsorship
Biotechnology and Biological Sciences Research Council (BB/I016961/1)
The authors would like to acknowledge the Engineering and Physical Sciences Research Council (EPSRC; UK, EP/F500491/1) and Bioprocessing Research Industry Club (BBSRC/BRIC; UK, BB/I017602/1) for their support and funding.