Most protocols for WBC isolation call for freshly collected blood. How are blood samples kept stable for off-site analysis in which it is shipped overnight? Through freezing?
We are trying to isolate neutrophils and perform Western blot analysis to examine the potential expression of various inflammatory proteins. It is important that blood samples are stable, as the expression of inflammatory proteins can be elicited through improper blood sample handling.
Thank you for the feedback.
Your description brings up several problems. First, of course freezing lyses the cells, so that's probably not the best idea if you want to isolate the white cells later. Second, you should also think about the blood handling itself: blood cells immediately begin reacting to the obviously unnatural environment inside the blood tube -- you already mentioned that improper blood handling is likely to be a problem. You can prove to yourself how extensive a problem you may be looking at: collect parallel samples from a few subjects, process a tube immediately and compare that to collecting, shipping and processing later -- you'll know if you have a problem or not. If you already know exactly which proteins you will be testing, you can verify all of the collection and processing. However, if you are expecting to do 'biomarker discovery', you would be better off defining the best (and most reproducible!) process that you can.
As a rule of thumb, it will be better to collect and process the samples soon (if not immediately) after blood draw. This can include providing an inexpensive centrifuge for your collection site(s) so they can indeed do that for you. I would use EDTA anticoagulation, centrifuge the tubes, and harvest the buffy coat (and then store/ship the buffy coat) -- but of course that is a hands-on process that some collection sites might not be excited about. Alternative: You can collect into blood tubes specifically designed for white cell preparation (BD calls them "CPT Tubes" (see here https://tinyurl.com/ycs8khug) -- but there are other vendors.) -- and with these it's still better to centrifuge soon/immediately after collection. You might consult with a local flow cytometry lab, since they deal with these cell isolation problems routinely.
@Craig A Gelfand thank you for your insights. We are working with a clinic to obtain blood samples, so isolation steps are somewhat limited due to the nature of this environment. Is neutrophil isolation typically not performed off-site? This poses quite a limitation in potential research.
Shipping is possible -- see, for example, https://bio-protocol.org/e2103
However, I would still recommend that you demonstrate for yourself, in a controlled experiment, whether or not time is a variable that is tolerable for your specific biomarkers.
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