Synergistic value of fibrinolysis and hypothermic aerobic preservation with oxygen in the protection of livers from non-heart-beating donors: an experimental model

The Benefits of Fibrinolysis Combined with Venous Systemic Oxygen Persufflation (VSOP) in a Rat Model of Donation after Circulatory Death and Orthotopic Liver Transplantation

Organ shortage has led to the increasing utilization of livers retrieved from donors after circulatory death (DCD). These pre-damaged organs are susceptible to further warm ischemia and exhibit minimal tolerance for cold storage. The aim was thus to examine the effects of fibrinolysis combined with Venous Systemic Oxygen Persufflation (VSOP) on the preservation of DCD livers in vivo. Livers of male Lewis rats were explanted after 45 min of warm ischemia, cold-stored for 18 h, and transplanted into a recipient animal. Livers were left untreated or underwent either VSOP or fibrinolysis via Streptokinase (SK) or received combined SK and VSOP. Combined treatment exhibited improved microvascular flow at 168 h (p = 0.0009) and elevated microperfusion velocity at 24 h post-transplantation (p = 0.0007). Combination treatment demonstrated increased portal venous flow (PVF) at 3 and 24 h post-transplantation (p = 0.0004, p < 0.0001), although SK and VSOP analogously achieved increases at 24 h (p = 0.0036, p = 0.0051). Enzyme release was decreased for combination treatment (p = 0.0002, p = 0.0223) and lactate dehydrogenase (LDH) measurements were lower at 24 h post-transplantation (p = 0.0287). Further supporting findings have been obtained in terms of serum cytokine levels and in the alterations of endothelial injury markers. The combination treatment of SK + VSOP might provide improved organ integrity and viability and may therefore warrant further investigation as a potential therapeutic approach in the clinical setting of DCD.

Protective effect of streptokinase on rat liver ischemia reperfusion injury

AIM: To study the protective effect of strep-tokinase on rat liver ischemia reperfusion injury.

METHODS: Thirty-six Wistar rats were divided randomly into control group and 2 experiment groups (12 in each group). Livers from the control group were perfused with 10 mL Ringer's solution through the portal vein and stored at 4 ℃ for 24 h. Livers from the experiment group were perfused with Ringer's solution containing 7500 IU streptokinase with or without hypothermal oxygen stored at 4 ℃ for 24 h. All cold storage livers were followed by in vitro perfusion at 37 ℃ for 45 min, and stored at 4 ℃. Changes in ALT, GLDH, and activity of PNP, 5'nucleotidase and bile secretion were detected.

RESULTS: The activity of ALT, GLDH and PNP was significantly lower in the experiment groups than in the control group(P < 0.05). Bile secretion(3.7 ± 0.7 µL/g at 45 min, 9.1 ± 0.7 µL/g at 45 min vs 1.1 ± 0.9 µL/g at 45 min, P < 0.05) and 5'nucleotidase activity were significantly increased in the experiment groups compared with the control group.

CONCLUSION: Streptokinase can improve rat liver microcirculation and ischemia reperfusion injury.

Optimising post-conditioning time of marginal donor livers

BACKGROUND

Due to the discrepancy between organ donors and receptors, the use of marginal livers (e.g., non-heart-beating-donor grafts) for transplantation purpose increased. The potential of a short-term aerobic machine perfusion (post-conditioning) for "less than optimal" grafts after cold storage (CS) was recently demonstrated. In our study, the optimal time course of post-conditioning (PC) is to be evaluated.

MATERIALS AND METHODS

Livers from male Wistar rats were withdrawn 30 min after cardiac arrest and flushed with histidine tryptophan ketoglutarate (HTK) solution. Then they were stored in HTK at 4 degrees C for 18 h. After 16 h, some livers were put on PC by cold perfusion with HTK for 0.5, 1, 2 or 3 h. Afterwards, the viability of the organs was estimated by warm reperfusion (2 h) in vitro.

RESULTS

After 1 h of PC, a significant increase in bile production and a decrease in enzyme release could be detected in comparison to CS. The adenosine triphosphate content of the PC livers after 1 h of treatment was significant higher than in CS organs. No markers for apoptosis could be detected after 1 h PC.

CONCLUSION

It can be concluded that a PC of 1 h after cold storage can ameliorate the organ viability of marginal livers. The extension or abbreviation of PC time seems to have no further beneficial effects.

Wound healing in the biliary tree of liver allografts

An increasing need for liver transplantation requires evaluation and triage of organs harvested from "extended criteria" donors. Although there is currently no widely accepted definition, most would agree that "extended criteria" includes organs donated by individuals that are old (>65 years), obese, infected with HBV or HCV, non-heart beating (NHBD), or had an unstable blood pressure before harvesting or the organ experienced a long cold ischemic time. These organs carry a statistical risk of dysfunction early after transplantation, but in the majority of recipients, hepatic parenchymal function recovers. Later, however, a small but significant percentage of extended criteria donors develop biliary strictures within several months after transplantation. The strictures occur primarily because of preservation injury that leads to "ischemic cholangitis" or deep wounding of the bile duct wall. Subsequent partial wound healing and wound contraction, but failed restitution of the biliary epithelial cell (BEC) lining, result in biliary tract strictures that cause progressive biliary fibrosis, increased morbidity, and decreased organ half-life. Better understanding of the pathophysiologic mechanisms that lead to biliary strictures in extended criteria donors provides an ideal proving ground for regenerative medicine; it also can provide insights into other diseases, such as extrahepatic biliary atresia and primary sclerosing cholangitis, that likely share certain pathogenic mechanisms. Possible points of therapeutic intervention include limiting cold and warm ischemic times, donor and/or donor organ treatment, ex vivo, to minimize the ischemic/preservation injury, maximize blood flow after transplantation, promote BEC wound healing, and limit myofibroblasts activation and proliferation in the bile duct wall. The pathobiology of biliary wound healing and therapeutic potential of interleukin-6 (IL-6) are highlighted.