Paper Title
Ex-Situ Regeneration of a Half Liver Under Conditions of Prolonged Machine Perfusion: Fantasy or Reality?

Abstract
INTRODUCTION Last decade, cold storage type and cryo-preservation have been increasingly replaced by normothermic and sub-normothermic machine perfusion preservation using various models of perfusion pumps. Furthermore, it has been shown that a well-chosen preservation method can not only "preserve" but also improve the morphological and functional properties of so-called "marginal" organs. The increase in the number of liver pathologies, on the one hand, and the success of liver transplantation, on the other hand, causes a high number of people awaiting liver transplantation resulting in donor livers deficiency. This circumstance, in its turn, provoked the application of the "split-transplant" method, as mean of increasing the effectiveness of liver transplantation programs. This method considers dividing a single donor liver into two or more small fragments, each of which retains an independent portal pedicle and a hepatic vein (its tributary), which might be technically implantable. MATERIAL AND METHODS We have tested a new, innovative perfusion machine developed by our research team which can provide both non-pulsatile and pulsatile supplies of the perfusion fluid (blood) to preserve whole and split livers by ex-situ perfusion model. 6 entire and 4 half livers of adult goats were preserved ex-situ during 8 and 12 hours with the pulsatile arterial and laminar portal flows (ensuring blood circulation under the most physiological conditions). Histological assessment of liver tissue slices stained with H&E was performed after the perfusion. RESULTS The microscopy showed the similar results in both entire and half organs ex-situ preservation: the level of steatosis, the degree of mononuclear portal infiltration, bile ductular proliferation, cholestasis, and venous congestion, as well as the number of hepatocellular necroses, were completely in the meet with the requirements applied toward the donor's livers. CONCLUSION The obtained data in cooperation with the data showing the possibility of long-term during 5-7 days of ex-situ machine perfusion, reported in the last 2-3 years by several reams of researchers, stipulate raising the hypothesis, that the split liver might be not only preserved but also regenerated under controlled ex-situ perfusion. Keywords - Liver Transplantation, Machine Perfusion, Organ Preservation.