A Modification of the Wu and Hoak Method for the Determination of Platelet Aggregates and Platelet Adhesion

Summary

The Wu and Hoak method for determining circulating platelet aggregates has poor reproducibility; problems have been reported with the composition of the buffer systems, haemolysis, the effects of blood collection technique and a divergence of the platelet aggregate ratio in blood for healthy donors from the theoretical value of 1. Our investigations suggest that the original technique is highly operator-dependent, especially the collection of blood and the method of counting platelets after centrifugation. We describe an improved modification of the Wu and Hoak technique; a new buffer system has been developed and the proportion of blood in the buffered EDTA and buffered EDTA- formalin solutions has been altered to obtain platelet rich plasma. The platelet aggregate ratio (PAR) by this modified method for healthy donors in two different studies was 0.97 ± 0.02 and 0.98 ± 0.01 respectively. Finally, the principle of Wu and Hoak was used to measure accurately platelet adhesion, without the role of platelet-platelet interactions (aggregation). Platelet adhesion and aggregation were then used to evaluate the thrombogenicity of various artificial surfaces, including silicone rubber and polytetra- fluoroethylene (PTFE) vascular grafts.

Keywords

Platelet aggregation - Adhesion - Artificial surfaces

• References

• 1 Wu KK, Hoak JC. A new method for the quantitative detection of platelet aggregates in patients with arterial insufficiency. Lancet 1974; 2: 924-926
• 2 Maca RD, Fry GL, Hoak JC. New method for detection and quantitation of circulating platelets aggregates. Microvasc Res 1972; 4: 453-457
• 3 Rohrer TF, Pfister B, Weber C, Imhof PR, Stucki P. Validity of the Wu-Hoak method for the quantitative determination of platelet aggregation in vivo. Blut 1978; 36: 15-20
• 4 Prazich JA, Rapaport SI, Samples JR, Engler R. Platelet Aggregate Ratios - standardization of technique and test results in patients with myocardial ischemia and patients with cerebrovascular disease. Thromb Haemostas 1977; 38: 597-605
• 5 Raper CG L. Circulating Platelet Aggregates. Thromb Haemostas 1978; 39: 537-538
• 6 Turpie AG, de Boer AC, Genton E. Platelet consumption in cardiovascular disease. Semin Thromb Hemostas 1982; 8: 161-185
• 7 Chamone DA F, Vermylen J. The induction of platelet aggregates in healthy subjects by venous occlusion. Thromb Haemostas 1977; 38: 132 (Abstr)
• 8 Dacie JV, Lewis SM. Practical Haematology. 5. Ed Churchill Livingstone; Edinburgh: 1975. p 338
• 9 Lewis SM, Stoddart CT. Effects of anticoagulants and containers (glass and plastic) on the blood count. Lab Practice 1971; 20: 787-792
• 10 Fleming AF, Woolf AJ. A spectrophotometric method for the quantitative estimation of bilirubin in liquor amnii. Clin Chim Acta 1965; 12: 67-74
• 11 Nossel HL, Yudelman I, Canfield RE, Butler Jr VP, Spanondis K, Wilner GD, Qureshi GD. Measurement of fibrinopeptide A in human blood. J Clin Invest 1974; 54: 43-54
• 12 Bowry SK. Development of in vitro blood compatibility assessment procedures and evaluation of selected biomaterials. PhD thesis University of Strathclyde; Glasgow: 1981
• 13 Haimow H, Giron F, Jacobson JW. The expanded polytetra- fluoroethylene graft. Arch Surg 1979; 114: 673-677
• 14 Born GV R. Aggregation of blood platelets by adenosine diphosphate and its reversal. Nature 1962; 194: 927-929
• 15 Wu KK, Hoak JC. Increased platelet aggregates in patients with transient ischemic attacks. Stroke 1975; 6: 521-524
• 16 Robertson RM, Robertson D, Friesinger GC, Timmons S, Hawiger J. Platelet aggregates in peripheral and coronary-sinus blood in patients with spontaneous coronary-artery spasm. Lancet 1980; 2: 829-831
• 17 Schwartz MB, Hawiger J, Timmons S, Friesinger GC. Platelet aggregates in ischemic heart disease. Thromb Haemostas 1980; 43: 185-188
• 18 Salem HH, Koutts J, Firkin BG. Circulating platelet aggregates in ischaemic heart disease and their correlation to platelet life span. Thromb Res 1980; 17: 707-711
• 19 Gjesdal K. Platelet function and plasma free fatty acids during acute myocardial infarction and severe angina pectoris. Scand J Haematol 1976; 17: 205-212
• 20 Davis JW, Phillips PE, Lewis Jr HD, Davis RF. Relationships of the platelet aggregate ratio to serum cholesterol concentration, smoking, age. Postgrad Med J 1981; 57: 150-152
• 21 Kohanna FH, Smith MH, Salzman EW. Do patients with thromboembolic disease have circulating platelet aggregates. Blood 1984; 64: 205-209