Clot retraction facilitates clot lysis

Abstract

Platelet facilitation of clot lysis was studied using the dilute clot lysis assay, a standardized assay for fibrinolysis shown to correlate with the development of postoperative deep vein thrombosis. Clots prepared from dilute platelet poor plasma showed prolonged clot lysis when compared with clots prepared in a similar fashion from dilute platelet rich plasma. Since in the presence of platelets clot retraction or contraction occurred, we evaluated a possible direct contribution of retraction to clot lysis. Dilute platelet poor plasma clots were compacted by centrifugation, to a similar extent as that achieved during clot retraction in dilute platelet rich plasma. These clots now lysed at a rate that approached that seen with dilute platelet rich plasma clots. Using an alternate alternate approach, dilute platelet rich plasma clots were treated with cytochalasin B to prevent clot retraction. Such clots now showed prolonged lysis similar to that seen with dilute platelet poor plasma. The prolonged lysis of cytochalasin B treated dilute platelet rich plasma clots was corrected by artificial compaction of the clots. The results suggest that clot retraction markedly facilitates clot lysis, and shows that a major role of platelets to facilitate clot lysis is the effect of these cells to cause clot retraction.

Blood clot contraction differentially modulates internal and external fibrinolysis

“…The rate of internal fibrinolysis did not depend on clot permeability because t-PA and plasminogen already reside within the clot [9]. Clot contraction enhanced internal fibrinolysis, consistent with previous studies (although none of them involved analysis of clots formed with whole blood) [74], probably because the redistribution [31] enables individual plasmin molecules to move between fibers more efficiently [15,66]. In support of this concept, it has been observed through changes in optical density that lysis appears to occur along a front that stretches across the surface of the clot.…”

Increased fibrinolytic activity in patients undergoing cardiopulmonary bypass operation

“…In the one patient in whom they were measured, FDP levels increased with increasing clot lysis. Observations of platelet activation and consumption during CPB [4,13,17] could be due to mechanical stress and exposure to artificial surfaces in the oxygenator and the pump rather than DIC.…”

“…Clot lysis times were perfomed essentially as described by Carroll et a1 [13]. Native whole blood was diluted 1 : 10 with the buffer described by Fearnley et a1 [ 161, and aliquots were centrifuged to prepare latelet-rich and platelet-poor plasma.…”

“…We report the results of a study that assessed the fibrinolytic activity in the blood of patients before, during, and after CPB, by the use of a new method, the clot lysis assay [13], in addition to plasminogen and fibrinogen level determinations.…”

Dimensional evaluation of blood clot gap distances within intrabony defects following grafting and EDTA root surface treatment—experimental study in dogs

“…Clots formed by the blood of severely thrombocytopenic subjects or prepared from platelet poor plasma of normal subjects was found to fail in retraction, whereas clots containing normal platelets retract drastically to about 10% of their original volume. 28,29 Clot retraction results from the interaction of a static, nonmotile fibrin mesh and dynamic, actively motile blood platelet membrane glycoproteins. Platelet pseudopodia emerge radially and cover a considerable distance from platelet masses while attaching to fibrin fibers.…”