June 2, 2017
I hope your response to that title is “of course it still matters!”, but in case you missed it last year at ISCT 2016 we published a poster showing that after just 20 innocent exposures over 3 months, MSC viable-recovery declined 50% vs. the control at -190°C.
We kept the experiments running and at ISCT 2017 in London last month we published another poster of the same cells and study, now after 70 exposures and 13 months storage. The results were similar; the variable group (subjected to TWEs) had lower viability, lower recovery and lower proliferation than the control group that never warmed above Tg.
The “But…” is that statistically, the TWE variable group was no worse after 13 months and 70 exposures than vs. 3 months and 20 exposures. This leads us to believe that the damage from TWEs happened in less than 20 exposures. How soon? We do not know yet, but I hope to set up some new experiments with partners to determine just that.
The effects of transient warming events (TWE) are not widely known yet, but thanks to this type of research we are getting the word out.
Some further discussion: an interesting trend we saw on this new data after 13 months storage is a noticeable change in some of the antigen surface markers. Although they tend to up/down express the same on all batches, there is a difference between the -190°C control and TWE variable group this time on CD19 & CD34. The other interesting bit on the -80°C experiment group is the -80°C to -190°C variable batch (think LN2 to dry ice and back) were nearly all dead (<4% viability) whereas last year’s same variable batch had similar results to the -80°C control batch (83% viability).