Porcine Extrahepatic Vascular Endothelial Asialoglycoprotein Receptor 1 Mediates Xenogeneic Platelet Phagocytosis In Vitro and in Human-to-Pig Ex Vivo Xenoperfusion. Issue 4 (April 2015)

• Record Type: Journal Article
• Authors: Bongoni, Anjan K.; Kiermeir, David; Denoyelle, Julie; Jenni, Hansjörg; Burlak, Christopher; Seebach, Jörg D.; Vögelin, Esther; Constantinescu, Mihai A.; Rieben, Robert
• Is Part Of: Transplantation. Volume 99:Issue 4(2015)
• Publication Date: 2015-04
• Subjects: Transplantation of organs, tissues, etc -- Periodicals; Transplantation immunology -- Periodicals; 617.95
• DOI: 10.1097/TP.0000000000000553
• Languages: English
• ISSNs: 0041-1337

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>Background</title> <p>Asialoglycoprotein receptor-1 (ASGR1) mediates capture and phagocytosis of platelets in pig-to-primate liver xenotransplantation. However, thrombocytopenia is also observed in xenotransplantation or xenoperfusion of other porcine organs than liver. We therefore assessed ASGR1 expression as well as ASGR1-mediated xenogeneic platelet phagocytosis in vitro and ex vivo on porcine aortic, femoral arterial, and liver sinusoidal endothelial cells (PAEC/PFAEC/PLSEC).</p> </sec> <sec> <title>Methods</title> <p>Porcine forelimbs were perfused with whole, heparinized human or autologous pig blood. Platelets were counted at regular intervals. Pig limb muscle and liver, as well as PAEC/PFAEC/PLSEC, were characterized for ASGR1 expression. In vitro, PAEC cultured on microcarrier beads and incubated with non-anticoagulated human blood were used to study binding of human platelets and platelet-white blood cell aggregation. Carboxyfluorescein diacetate succinimidyl ester–labeled human platelets were exposed to PAEC/PFAEC/PLSEC and analyzed for ASGR1-mediated phagocytosis.</p> </sec> <sec> <title>Results</title> <p>Human platelet numbers decreased from 102 ± 33 at beginning to 13 ± 6 × 10<sup>3</sup>/μL (<italic>P</italic> < 0.0001) after 10 minutes of perfusion, whereas no significant decrease of platelets was seen during autologous perfusions (171 ± 26 to 122 ± 95 × 10<sup>3</sup>/μL). The PAEC, PFAEC, and PLSEC all showed similar ASGR1 expression. In vitro, no correlation was found between reduction in platelet count and platelet-white blood cell aggregation. Phagocytosis of human carboxyfluorescein diacetate succinimidyl ester–labeled platelets by PAEC/PFAEC/PLSEC peaked at 15 minutes and was inhibited (<italic>P</italic> < 0.05 to <italic>P</italic> < 0.0001) by rabbit anti-ASGR1 antibody and asialofetuin.</p> </sec> <sec> <title>Conclusions</title> <p>The ASGR1 expressed on aortic and limb arterial pig vascular endothelium plays a role in binding and phagocytosis of human platelets. Therefore, ASGR1 may represent a novel therapeutic target to overcome thrombocytopenia associated with vascularized pig-to-primate xenotransplantation.</p> </sec> </abstract>