Abstract/Summary

In this issue of Blood, Welsh and colleagues determine how platelet thrombi limit the loss of plasma-borne proteins from the microvasculature. 1 The concept that platelets prevent leakage from blood vessels following a penetrating injury will come as little surprise to most readers, but exactly how platelets physically contribute to this process is not well understood. Such injuries result in the loss of blood cells and plasma into the surrounding tissues, and both forms of loss must be halted quickly. Platelets are believed to form the first line of defense in such situations, forming a thrombus that is capable of plugging the hole and supplying molecules that contribute to localized inflammation and wound healing.