[1] Isolation of human platelets from plasma by centrifugation and washing

This chapter describes the process of isolating human platelets from plasma by centrifugation and washing. Through the centrifugation and washing methods, large volumes of blood can be handled readily and the platelet count in the final suspension can be adjusted to any desired number. By using these methods, platelets respond to aggregating and release-inducing agents in a manner similar to platelets in native plasma, or plasma anticoagulated with hirudin, and maintain this responsiveness for hours. The constituents of a medium can be varied or additions can be made, as required, for experimental purposes. Thrombin can be used as an agonist without the problem of the formation of large amounts of fibrin that occurs when thrombin is added to platelet-rich plasma. The morphological appearance of platelets by electron microscopy is similar to that of platelets in plasma. Because platelet suspensions are kept at 37°, experiments can readily be done at this temperature so that conditions more closely resemble an in vivo situation.