A critical review of vascular endothelial growth factor (VEGF) analysis in peripheral blood: is the current literature meaningful?

Vascular endothelial growth factor (VEGF) is a potent angiogenic growth factor with a key role in many physiological and pathological processes. Investigation into the implications of circulating levels of this cytokine is progressing at an exponential rate. However, there are important inconsistencies between reports ranging from method of sample collection, processing, software manipulation and data interpretation and controversy as to whether plasma, serum or whole blood will provide the best prognostic information. Different techniques of centrifugation and temperature on sample handling and the impact of in vitro collection of blood on subsequent VEGF results have not been fully appreciated. We provide a critical review of the literature, report the results of our further investigations, suggest a uniform protocol for handling blood samples and highlight previously unsuspected problems in data interpretation.