Open AccessPost‐collection,pre‐measurement variables affecting VEGF levels in urine biospecimens
Author(s) -
Hayward Robert M.,
Kirk Melissa J.,
Sproull Mary,
Scott Tamalee,
Smith Sharon,
CooleyZgela Theresa,
Crouse Nancy S.,
Citrin Deborah E.,
Camphausen Kevin
Publication year - 2007
Publication title -
journal of cellular and molecular medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.44
H-Index - 130
eISSN - 1582-4934
pISSN - 1582-1838
DOI - 10.1111/j.1582-4934.2007.00135.x
Subject(s) - urine , urinary system , vascular endothelial growth factor , angiogenesis , urology , medicine , immunoassay , vegf receptors , pathology , andrology , immunology , antibody
Angiogenesis, the development and recruitment of new blood vessels, plays an important role in tumour growth and metastasis.Vascular endothelial growth factor (VEGF) is an important stimulator of angiogenesis.Circulating and urinary VEGF levels have been suggested as clinically useful predictors of tumour behaviour, and investigations into these associations are ongoing.Despite recent interest in measuring VEGF levels in patients, little is known about the factors that influence VEGF levels in biospecimens. To begin to address this question, urine samples were collected from patients with solid tumours undergoing radiotherapy and healthy volunteers.Four factors were examined for their effects on VEGF concentrations as measured by chemiluminescent immunoassay: time from sample collection to freezing, number of specimen freeze–thaw cycles, specimen storage tube type and the inclusion or exclusion of urinary sediment. The results of this study indicate that time to freeze up to 4 hrs, number of freeze–thaw cycles between one and five, and different types of polypropylene tubes did not have statistically significant effects on measured urinary VEGF levels. Urinary sediment had higher VEGF levels than supernatant in five of six samples from healthy patients.It is not clear whether there is an active agent in the sediment causing this increase or if the sediment particles themselves are affecting the accuracy of the assay.Therefore, we recommend centrifuging urine, isolating the supernatant, and freezing the sample in polypropylene microcentrifuge tubes or cryogenic vials within 4 hrs of collection.In addition, we recommend the use of samples within five freeze–thaw cycles.