Purpose: The purpose of this study was to evaluate the accuracy of measurement of a known concentration of vascular endothelial growth factor (VEGF) using cytometric bead-based assay in microsamples (50 microL) and compare it with that obtained by enzyme-linked immunosorbent assay.
Methods: A known concentration of VEGF samples was prepared with addition of VEGF (100 pg/mL) to 1 mL of Hank balanced salt solution. This preparation was further diluted serially to 50, 25, and 12.5 pg/mL; and VEGF estimation was done on each of these samples using Luminex, a commercially available cytometric bead-based assay and enzyme-linked immunosorbent assay. The assay was replicated three times at each dilution.
Results: The mean concentrations of VEGF measured using Luminex were 97.7 +/- 6.2, 47.3 +/- 8.1, 24.9 +/- 2.2, and 14.2 +/- 1.8 pg/mL at 100, 50, 25, and 12.5 pg/mL dilutions, respectively. Similarly, the mean concentrations of VEGF measured using enzyme-linked immunosorbent assay for equivalent dilutions were 100.6 +/- 24.4, 53.8 +/- 16.8, 44.8 +/- 35.5, and 14.19 +/- 0.7 pg/mL, respectively.
Conclusion: Bead-based assay accurately measures VEGF concentration in a microsample and has better validity and reliability as compared with enzyme-linked immunosorbent assay.