Normal ranges of angiogenesis regulatory proteins in human platelets.
Platelets sequester angiogenesis regulatory proteins early in tumor growth, which suggests a new avenue for monitoring disease. To date, there are no clinically relevant reference ranges for markers of early angiogenesis. We introduce a new ELISA-based method for accurate and reproducible measurement of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), platelet factor 4 (PF4), thrombospondin-1 (TSP-1), fibroblast growth factor, basic (bFGF), and endostatin in platelets. To facilitate clinical applicability, the platelet levels in isolated samples were determined utilizing a new actin ELISA method. Platelets from healthy donors at single and repetitive time points were used for the assessment of normal ranges of these proteins. The physiological levels in platelets were: VEGF (0.74 +/- 0.37 pg/10(6) platelets); PDGF (23 +/- 6 pg/10(6)); PF4 (12 +/- 5 ng/10(6)); TSP-1 (31 +/- 12 ng/10(6)); bFGF (0.44 +/- 0.15 pg/10(6)); and endostatin (5.6 +/- 3.0 pg/10(6)). There was an excellent correlation (R(2) = 0.7) between the platelet levels calculated with the actin ELISA and complete blood count. The levels of the platelets were higher than those in platelet-poor plasma by factors of: VEGF (215-fold); PDGF (914-fold); PF-4 (516-fold); TSP-1 (813-fold); and bFGF (17-fold). The endostatin levels were nearly equivalent. The biovariability of the platelet proteins in eight healthy subjects over a 5-week period was found to be minimal. We describe accurate and direct measurements of the concentrations of VEGF, bFGF, PDGF, TSP-1, endostatin, and PF4 in platelets of healthy human subjects. In contrast to the highly variable levels in plasma and serum, the platelet-derived measurements were accurate and reproducible with minimal biovariability.
Peterson
Jon E
JE
Department of Research and Development, Ortho Clinical Diagnostics, Rochester, New York, USA. jpeters4444@aol.com
Zurakowski
David
D
Italiano
Joseph E
JE
Michel
Lea V
LV
Fox
Lucius
L
Klement
Giannoula L
GL
Folkman
Judah
J
D000328:Adult; D042501:Angiogenic Proteins / Q000032:analysis* / Q000592:standards; D001792:Blood Platelets / Q000737:chemistry*; D043169:Endostatins / Q000032:analysis / Q000592:standards; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000032:analysis / Q000592:standards; D006801:Humans; D008297:Male; D008875:Middle Aged; D010978:Platelet Factor 4 / Q000032:analysis / Q000592:standards; D010982:Platelet-Derived Growth Factor / Q000032:analysis / Q000592:standards; D012016:Reference Values; D019700:Thrombospondin 1 / Q000032:analysis / Q000592:standards; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis / Q000592:standards
D042501:Angiogenic Proteins; D043169:Endostatins; D010982:Platelet-Derived Growth Factor; D019700:Thrombospondin 1; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D010978:Platelet Factor 4