Can We See the Sugar Coat? Paving the Way to Xenotransplantation

Although allotransplantation is a life-saving procedure, the limited supply made it necessary to find an alternative approach, such as xenotransplantation utilising genetically modified pigs, which is a promising substitute. The endothelial glycocalyx (eGlx), composed of sugars, proteins, and lipids, resides over the luminal surface of the endothelium and plays a critical role in the outcome of organ transplantation, shaping both xenograft rejection and survival. Visualising eGlx in wild-type pig tissue utilising a variety of lectins staining and initiating a standardised protocol for future research. Tissue sections from pig kidney, liver lung and heart (n=19) were stained by fluorescence-conjugated lectins (LEL, WGA, BPA, UEA I, MAL-1, MAL-2) and analysed under confocal laser scanning microscopy (CLSM). Fluorescence peakto-peak (P-P) distances were measured to examine the binding specifics of lectins. LEL and WGA successfully stained eGlx in the renal cortex and cardiac tissue; additionally, LEL exhibited higher specificity. BPA, UEA I, MAL-1, and MAL-2 showed limited to no binding. This study paved an optimised protocol for lectin staining, demonstrating LEL and WGA to be the most potent markers to stain eGlx in xenotransplantation research. This will help to modify pig organs to be human-compatible while improving transplantation outcomes.