Pig endothelial protein C receptor is functionally compatible with the human protein C pathway

Area of Science:

• Biochemistry
• Molecular Biology
• Xenotransplantation Research

Background:

• Endothelial protein C receptor (EPCR) regulates coagulation and inflammation.
• Interspecies incompatibilities between pig thrombomodulin (TBM) and human thrombin pose challenges in organ xenotransplantation.
• The interaction between pig EPCR (pEPCR) and human TBM is unknown.

Purpose of the Study:

• To clone and express pEPCR.
• To evaluate the function of pEPCR within the human protein C pathway in vitro.
• To assess potential molecular barriers between pEPCR and human TBM.

Main Methods:

• Pig EPCR cDNA was synthesized from pig lung RNA via RT-PCR.
• COS-7 cells were transfected with combinations of human and pig TBM and EPCR.
• TBM cofactor activity was measured using human thrombin and human protein C.

Main Results:

• Pig EPCR shares 72.3% sequence identity with human EPCR, with conserved critical residues.
• Co-transfection with human TBM and either human EPCR or pEPCR significantly increased protein C activation.
• pEPCR enhanced human TBM cofactor activity by 3-fold in vitro.

Conclusions:

• Pig EPCR is largely compatible with the human TBM/thrombin complex in vitro.
• pEPCR effectively promotes human protein C activation.
• Endogenous pEPCR is expected to enhance the efficacy of transgenic human TBM in xenograft models.