507 - Role of the expression of human endothelial protein C receptor and thrombomodulin on GalT-KO PA
507
Role of the expression of human endothelial protein C receptor and thrombomodulin on
GalT-KO PAEC in PC activation
Claudia Maria Radu 1 , Cristiana Bulato 1 , Sabrina Gavasso 1 , Luca Spiezia 1 , Cesare Galli 4 ,
Paolo Simioni
1
, Emanuele Cozzi
2,3
1 Cardiologic,
Thoracic and Vascular Sciences, University of Padua, Padua; 2 Surgical and
Gastrointestinal Sciences, University of Padua, Padua;
3
Consortium for Research in Organ Transplantation (CORIT), Padua;
4
Istituto Sperimentale Italiano Lazzaro L. Spallanzani, AVANTEA, Cremona; Italy
Introduction: The protein C (PC) anticoagulant pathway plays a key role in the control of
haemostasis. PC activation is catalyzed on endothelium by a complex composed by thrombin,
thrombomodulin (TM) and endothelial PC receptor (EPCR). Microvascular thrombosis observed
in pig organs transplanted into primates is probably associated to the inability of EPCR and TM,
expressing on pig vascular endothelium, to activate efficiently primate circulating PC.
Aim of the study: To understand the importance of expression of both human receptors
(EPCR and TM) on GalT-KO PAEC surface reproducing
in vitro the PC
pathway.
1/2
507 - Role of the expression of human endothelial protein C receptor and thrombomodulin on GalT-KO PA
Materials and methods: Confluent cells were pre-incubated with saturating concentrations of
anti-human EPCR (5 ug/ml) or anti-human TM (20 ug/ml) or both antibodies. At the end of
incubation, human PC and thrombin were added and after 120 min at 37°C the activated PC
(APC) generated was measured using a chromogenic substrate.
Results: The pre-incubation of hEPCR-hTM-GalT-KO PAEC with anti-human EPCR or
anti-human TM results in a reduction of PC activation of 32% and 80%, respectively. In the
presence of both antibodies, the generation of APC is reduced by 97%.
Conclusions: These result confirm that TM is an essential protein for PC activation in the
presence or absence of EPCR, while the function of EPCR is to amplify the catalytic reaction
mediated by the thrombin-TM complex. The generation of genetically modified pigs that express
inhibitors of coagulation could overcome the develop of microvasculat thrombosis in
transplanted organs.
2/2