Trophism and Homeostasis of Liver Sinusoidal Endothelial Graft Cells during Preservation, with and without Hypothermic Oxygenated Perfusion

SIMPLE SUMMARY: Little is known about the functions and intracellular mechanisms of the endothelial cells in liver grafts. In particular, we still know little about the effect of the most recent machine perfusion techniques currently applied to improve liver transplant outcomes. In this study we analyzed different endothelial markers of both immunohistochemical and gene expression in two different biopsies (for each donor). We observed a severe depression of endothelial trophism in liver grafts, which is restored after reperfusion. This is interesting for further studies on liver grafts, especially considering that the execution of HOPE seems to improve this functional recovery. We propose that our results may help improve the knowledge on graft tissues in order to customize the perfusion techniques prior to transplant and, therefore, improve liver transplant outcomes. ABSTRACT: The aim of the present study was to evaluate the homeostasis and trophism of liver sinusoidal endothelial cells (LSECs) in vivo in different stages of liver graft donation, in order to understand the effects of graft ischemia and perfusion on LSEC activity in liver grafts. Special attention was paid to grafts that underwent hypothermic oxygenated perfusion (HOPE). Forty-seven donors were prospectively enrolled, and two distinct biopsies were performed in each case: one allocation biopsy (at the stage of organ allocation) and one post-perfusion biopsy, performed after graft implant in the recipients. In all biopsies, immunohistochemistry and RT-PCR analyses were carried out for the endothelial markers CD34, ERG, Nestin, and VEGFR-2. We observed an increase in CD34 immunoreactivity in LSEC during the whole preservation/perfusion period (p < 0.001). Nestin and ERG expression was low in allocation biopsies, but increased in post-perfusion biopsies, in both immunohistochemistry and RT-PCR (p < 0.001). An inverse correlation was observed between ERG positivity and donor age. Our results indicate that LSEC trophism is severely depressed in liver grafts, but it is restored after reperfusion in standard conditions. The execution of HOPE seems to improve this recovery, confirming the effectiveness of this machine perfusion technique in restoring endothelial functions.