Stability of the Human Plasma Proteome to Pre-analytical Variability as Assessed by an Aptamer-Based Approach

Variable processing and storage of
whole blood and/or plasma are
potential confounders in biomarker development and clinical assays.
The goal of the study was to investigate how pre-analytical variables
impact the human plasma proteome. Whole blood obtained from 16 apparently
healthy individuals was collected in six EDTA tubes and processed
randomly under six pre-analytical variable conditions including blood
storage at 0 °C or RT for 6 h (B6h0C or B6hRT) before processing
to plasma, plasma storage at 4 °C or RT for 24 h (P24h4C or P24hRT),
low centrifugal force at 1300 × g, (Low×g), and immediate processing to plasma under 2500 × g (control) followed by plasma storage at −80 °C.
An aptamer-based proteomic assay was performed to identify significantly
changed proteins (fold change ≥1.2, P <
0.05, and false discovery rate < 0.05) relative to the control
from a total of 1305 proteins assayed. Pre-analytical conditions Low×g and B6h0C resulted in the most plasma proteome changes
with 200 and 148 proteins significantly changed, respectively. Only
36 proteins were changed under B6hRT. Conditions P24h4C and P24hRT
yielded changes of 28 and 75 proteins, respectively. The complement
system was activated in vitro under the conditions B6hRT, P24h4C,
and P24hRT. The results suggest that particular pre-analytical variables
should be controlled for clinical measurement of specific biomarkers.