How Fresh Are Your PBMC?
When ordering human or animal blood cells for research, many scientists subscribe to the adage fresh is best. But just how viable and functional are those “fresh” PBMC you ordered after sitting out of the body for 24 hours or more?The term freshness is often used when referring to the quality of donor blood samples. However, freshness is not the measure with which you should judge sample quality. Instead, focus on the measures that matter to the outcomes of your experiments: viability and functionality.We set out to put this freshness myth to rest using human PBMC
from our lab. We received PBMC from two donors just hours after collection and evenly divided each sample into two groups. One group sat at room temperature for 24 hours to simulate one-day shipping conditions before being isolated and cryopreserved. The other group was isolated and cryopreserved within 3 hours of arrival to our lab.We measured post-thaw cell viability and recall response of our cryopreserved samples using flow cytometry and a recall antigen assay testing cytokine secretion.
1. We received fresh PBMC from two normal donors the same day as collection. Each sample was split into two halves. One half sat at room temperature (20–25°C) for 24 hours (to simulate same-day shipping conditions) before being isolated and cryopreserved. The other half was isolated and cryopreserved the same day as collection using standard methods.
2. Viability was measured for all cell types in each batch using flow cytometry.
3. The proportion of cell types present (T cells
, B cells
and NK cells
) was determined by flow cytometric analysis of cells stained with fluorescently tagged antibodies from Thermo Fisher Scientific.
4. All batches were tested for cytokine secretion using our recall antigen assay.