Change in expression of αGal and functional molecules on vascular endothelial cells of pig organs after in vivo administration of endo-β-galactosidase C (Endo Gal C)
Introduction It is well known that αGal antigen-antibody reaction plays a major role in hyperacute and acute vascular (delayed xenograft) rejection after pig-to-human xenotransplantation. We have not yet succeeded in control of anti-αGal antibodies in recipients and αGal antigens in pig organs. We have recently reported a useful tool of removing αGal epitopes: endo-β-galactosidase C which can effectively digest αGal antigens in pig cells. The purpose of this study is to examine the effect of intravenous infusion with Endo Gal C on the expression of αGal and functional molecules in pig vascular endothelial cells.
Materials and methods Twelve units of recombinant Endo Gal C were intravenously administered into pigs (15 kg). Frozen tissues which were collected from heart, liver and kidney after Endo Gal C treatment were analyzed by immunohistochemical study. The expression of αGal epitopes was examined using FITC-labeled GS-IB4 lectin. We also investigated the expression of von Willebrand Factor (vWF), endothelial NO synthetase (eNOS) and inducible NO synthetase (iNOS).
Results Endo Gal C-administered pig organs showed the negative staining of GS-IB4 lectin in vascular endothelial cells, while the staining was strongly positive in control kidney as well as heart and liver. We detected the same pattern and degree of vWF and eNOS expression on vascular endothelial cells in Endo Gal C-administered pig kidney as in control kidney. On the other hand, no expression of iNOS was observed in control and Endo Gal C-administered kidney.
Conclusions In vivo administration of Endo Gal C (0.8 U/kg) could almost completely digest αGal antigens expressed on vascular endothelial cells of pig organs. Moreover, Endo Gal C did not show definitive adverse effects in vascular endothelial cells functionally. We are now examining other structural and functional molecules such as vimentin, thrombomodulin, and complement regulating molecules in experimental xeno- and allo-graft as well as in Endo Gal C-treated organs.