Divergent enhancement of in vitro induced coagulopathy by microparticle subtypes

Abstract

Background Aggressive fluid therapy of patients following a major trauma may result in hypothermia, acidosis and haemodilution that deteriorates even further towards a trauma-induced coagulopathy. The combination of these three factors is referred as lethal triad (LT) and a progressive course of LT is associated with a worsening or complete failure of haemodynamics and coagulative function. Within the process of coagulation, microparticles (MP) are crucial players at the interface of cellular and plasmatic coagulation. This study aimed at the characterization of coagulative effects originating from MP with different cellular origin and concentration under in vitro simulated traumatic conditions of haemodilution (HD) and LT. Methods HD was induced by replacing a blood volume of 33% by crystalloids and for LT, samples were further processed by reducing the temperature to 32 °C and lowering the pH to 6.8. MP were obtained either from platelet concentrates (platelet-derived MP, PDMP) or from cell culture (ECV304 cells for endothelial-derived MP, EDMP) by targeted stimulation. Effects of MP on coagulation depending on concentrations (1.000, 10.000 and 15.000 MP/µl blood) were characterized by flow cytometric platelet activation and by quantification of fibrin clot propagation and spontaneous clotting using Thrombodynamics® technology. Results MP originated from platelets and endothelial cell culture affected blood coagulation in a concentration-dependent manner. Particularly, high PDMP quantities significantly induced platelet activation and fibrin clot growth and size in HD conditions. In LT conditions, the highest PDMP concentration enhanced platelet activation, clot growth and size. In contrast, EDMP supplementation did not affect platelet activation, but resulted in enhanced formation of spontaneous clots, irrespective of simulated condition. With increasing EDMP concentration, the time until the onset of spontaneous clotting decreased in both HD and LT conditions. Discussion The study demonstrates the essential role of MP within the coagulation process in the simulated traumatic conditions. While PDMP affected platelets promoting clot formation likely by providing a surface enlargement, EDMP presumably affected clotting factors of the plasmatic coagulation resulting in an increased formation of spontaneous fibrin clots. Conclusion The diverse effects of in vitro generated MP from different cellular origin indicate a divergent mechanism of action exhibiting distinct functions within the coagulation process.