Decreased apoptosis in fatty livers submitted to subnormothermic machine-perfusion respect to cold storage

Abstract

Machine perfusion at subnormothermic temperature (20°C), MP20, was developed by Vairetti et al. and showed to afford a better preservation of fatty livers respect to traditional cold storage (CS) in terms of enzyme release into the perfusate, bile production, glycogen stores, energy charge and oxidative stress. Here we investigated whether it also caused decreased cell death by apoptosis. Fatty and lean Zucker rats were submitted to MP20 or CS for 6 h and reperfused normothermically for 2 h. Apoptotic cells were revealed by immunohistochemistry of activated caspase-3 and M30 (new epitope on CK18 degraded by caspase-3) and by the TUNEL assay. Portal pressure was also determined. A statistically significant reduction of hepatocyte apoptosis, but especially of sinusoidal cells was determined for fatty livers submitted to MP20 respect to CS. Portal pressure was significantly lower after MP20 respect to CS. The reduction of sinusoidal cell death by apoptosis without need for anti-apoptotic therapies appears particularly positive since apoptotic sinusoidal cells hinder microcirculation in the sinusoids and are thrombogenic. These results further confirm the potential of MP20 for preserving fatty livers that would be otherwise discarded as grafts, and thus for increasing the donor pool for liver transplantation.

Perfusion Defatting at Subnormothermic Temperatures in Steatotic Rat Livers

“…The results indicated an active lipid metabolism export despite the reduced temperature, which was not reported previously at 20°C [6;7]. However, during the 6 hours of preservation the reduction in lipid content did not reach statistical significance, and histology did not reveal consistent changes in either group.…”

“…Sub-normothermic (~20°C) machine perfusion (SNMP) preservation is an alternative that is simpler in practice [6;7]. SNMP is performed at room temperature, eliminating the need for heating/cooling, has reduced needs on oxygen and nutrition supply, and hence can be used without red blood cells, which are used in all NMP perfusion protocols with successful transplant confirmation [9].…”

“…SNMP has been reported to be effective in resuscitating DCD livers by several groups including our own [14–16]. While SNMP was also reported to be a superior preservation modality for fatty livers based on enzyme release, energy storage, oxidative stress, and apoptosis after reperfusion [6;7], whether it can be used to reduce lipid content as shown in NMP protocols has not been previously tested. In the present study, we studied lipid secretion and content in fatty rat livers when perfused using SNMP with or without the defatting cocktail previously reported [12].…”

Graft Reconditioning before Liver Transplantation

“…Similarly to HMP, the optimal preservation solution for SNTM has not yet been defined. Continuous perfusion throughout the entire preservation period successfully reduces the rate of apoptosis in the sinusoids of steatotic livers, resulting in favorable perfusion dynamics [12]. In addition, continuous SNTM demonstrated recovery of ischemically damaged rat livers, with low aminotransferases after reperfusion suggesting beneficial effects.…”

“…To overcome this situation, several ways to increase the donor pool have been suggested, with the acceptance of livers of limited quality being the predominant way of making additional organs available [9,10,11]. Subsequently, the risk associated with LT has increased as such organs are more prone to ischemia/reperfusion injury after implantation [12,13,14,15]. This can lead to severe or even extreme allograft injury, resulting in increased morbidity and mortality immediately post transplantation [16].…”