Validation of blood collection procedures for the determination of circulating vascular endothelial growth factor (VEGF) in different blood compartments.
Level 4 - case-series / case-control
Comparative laboratory validation study in a single cohort of human subjects
What was done
Authors evaluated blood collection and processing methods for measuring vascular endothelial growth factor (VEGF) across different compartments in 30 subjects. They tested serum clotting durations (comparing centrifugation within 10 minutes against 2 to 4 hours), lysed whole blood, and multiple plasma preparations including Edinburgh anticoagulant mixture (EDTA, PGE1, theophylline), CTAD (citrate, theophylline, adenosine, dipyridamole), and sodium citrate. In vitro platelet activation was assessed by measuring platelet factor 4 (PF4). Both markers were quantified using commercial ELISAs.
What was found
Serum VEGF release increased with clotting time, plateauing between 2 and 4 hours. At 2 hours, VEGF increased by a median of 327% (range: 118% to 4,515%) compared with samples centrifuged within 10 minutes. VEGF levels were equivalent and PF4 was very low or undetectable in Edinburgh and CTAD plasma, whereas sodium citrate plasma showed significantly higher levels of both markers. VEGF in CTAD plasma did not correlate with leukocyte or platelet counts. Serum VEGF correlated significantly with platelet count but not with leukocyte count.
Why it matters
Unstandardized pre-analytical handling and ex vivo platelet degranulation largely explain conflicting results in circulating VEGF literature. Using CTAD plasma for circulating levels and standardized 2-hour clotting for serum enables reproducible quantification across clinical studies.
Limits
The abstract describes a small cohort (n = 30) without detailing participant health status or demographic characteristics. Absolute numerical concentrations for VEGF and PF4 across fractions are not reported in the abstract.
Cited by
- context Cancer presence can lead to elevated circulating VEGF levels in blood tests, which can be measured to monitor tumor progression or active metastasis.