The effect of Me2_{2}SO overexposure during cryopreservation on HOS TE85 and hMSC viability, growth and quality

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 Me$_{2}$SO, 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 Me$_{2}$SO 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 Me$_{2}$SO 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 Me$_{2}$SO 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.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

Cnidaria: Anthozoans in the Hot Seat

Cnidarians comprise a diverse and phylogenetically basal phylum, some of which—such as scleractinian corals (Anthozoa)—are responsible for the formation and maintenance of ecosystems. Anthozoan immunology is a relatively new field, yet has great potential to inform invertebrate immunology, medicine, as well as coral reef conservation and restoration. Here we review cnidarian innate immune mechanisms in the context of invertebrate effector responses. We focus on anthozoans and discuss the blurred boundary between immune and stress responses. We conclude by high 1ighting unique aspects of coral biology and exploring the role of immunology in coral reef conservation and restoration through climate change