Hello all,
I am in a bit of a dilemma where I receive blood samples from 6+ patients during the evening. I do not have the energy to process this much blood on my own during the evening, and so I store the blood samples at 4 degrees overnight until the next morning when one of my colleagues can assist with PBMC isolation. Is this a terrible way to store blood samples overnight? Is it better to store them at room temperature? I intend to use the PBMCs in future T-cell ELISpot assays.
I understand that it's best to isolate PBMCs within 8 hours, but I sometimes do not have a choice since I receive the samples so late during the day when no one is available to assist me.
Hello, Philip!
You look at this information about PMBC storage:
https://www.stemexpress.com/blog/researchers/pbmc-viability-and-recovery/
Blood Transportation & Storage
Viability and, therefore, recovery will decline. To preserve the viability of the cells when transporting overnight, a 2-8°C or 15-25°C validated shipper is recommended. The validated shipper prevents the exposure of the cargo to extremes in temperature.
However, transporting or storing the blood at 2-8°C for >24 hours can intensify granulocyte contamination in the PBMC fraction. This prolonged storage of whole blood can activate granulocytes, which affects their buoyancy profile resulting in inefficient separation and recovery of the PBMC fraction when using a density gradient.
Years ago, we were studying feto-maternal micorchimerism, looking for male cells in the circulation of mothers. Sometimes, too many samples were received to process in a workday, or too late. Our lab practice was to make sure the samples were properly mixed - no clotting - and let the samples sit overnight at room temperature. This was not a controlled experiment, but we were able to isolate cells, and prepare DNA from the overnight samples, and it did not appear to affect our results.
I do know from personal experience of isolating CD34+ cells from human cord blood samples that the cells isolated from samples stored overnight at 4oC did not expand in culture, but CD34+ cells isolated from cord blood samples stored overnight at room temperature did.
I would suggest you not refrigerate these samples and instead keep them at RT, especially if you intend to use them in T cell ELISPOT. Please see the attached reference.
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