EVIDENCE OF THE EXISTENCE OF A SOLUBLE MEDIATOR OF COLD PRESERVATION INJURY

A study was designed to determine whether soluble mediators of injury are released during cold preservation. A first set of livers consistin g of three groups was stored in cold Euro-Collins solution. These were a control group stored for 10 min (group 1), an experimental group st ored for 16 hr (group 2), and an ''antiprotease'' group to which a coc ktail of antiproteases had been added, which was also stored for 16 hr (group 3). The preservation solution in these livers was washed out a t the end of preservation, and this effluent was concentrated and infu sed into a second set of livers that were all cold-stored for 4 hr. Th en, the second-set livers were either perfused-fixed at 4-degrees-C wi th universal fixative or reperfused at 37-degrees-C for 180 min in the isolated perfused rat liver (IPRL). Morphometric assessment of sinuso idal lining cells (SLC) on light and electron microscopy showed an inc reased degree of microcirculatory injury in livers preserved with conc entrates from livers of the experimental group. On light microscopy, o nly 2.2+/-0.4% (mean+/-SD) of the SLC had a normal flattened morpholog y compared with 11.9+/-2.0% in the control group, and 10.7+/-2.3%, of the SLC appeared completely detached from the underlying hepatocytes c ompared with 2.6+/-0.8% in the control group, the differences being st atistically significant (P<0.05). This injury was prevented by the add ition of antiproteases to EC solution. Similar results were obtained i n the IPRL model, in which a number of typical changes related to cold preservation injury were noted in livers preserved with concentrates from the experimental group. Compared with controls, livers preserved with concentrates from the experimental group had early and significan t alterations in markers of microcirculatory injury, including a reduc tion in portal flow and an increase in creatinine kinase-BB isoenzyme release, followed by an increase in perfusate transaminases, 1,DH, and a decrease in bile production. Again the injuries were largely preven ted by the addition of antiproteases. There were no differences among groups in the degree of white cell and platelet adherence during reper fusion. Experiments using UW solution showed similar results, indicati ng that the soluble mediator(s) is not specific for a particular prese rvation solution. These observations are consistent with the hypothesi s that soluble mediators are produced during the hypothermic period, a nd are responsible for a significant part of cold preservation injury, and that proteolytic reactions are involved in this type of injury.