Comparison of techniques for rapid cooling of organs in a non-heart-beating porcine model

Extracorporeal membrane oxygenation for resuscitation of deceased cardiac donor livers for hepatocyte isolation. J Surg Res. 2013;183:e39-e48. [PMID: 23647801 DOI: 10.1016/j.jss.2013.03.026]

BACKGROUND

Deceased cardiac donors (DCDs) have become a useful source of organs for liver transplantation; nevertheless, there are concerns about the longevity of these grafts. The aim of this study was to evaluate the use of extracorporeal membrane oxygenation (ECMO) to resuscitate DCD porcine livers as a preclinical model using hepatocyte isolation and viability as a marker to assess whole-graft preservation.

MATERIALS AND METHODS

We randomized Landrace pigs into three groups after cardiac death and 30 min of warm ischemia: group 1, peritoneal cooling with intravascular cooling for 2 h; group 2, ECMO for 2 h; and group 3, control (conventional intravascular cooling and retrieval). We then reperfused group 1 and 2 livers for 2 h on an ex vivo reperfusion circuit and isolated hepatocytes.

RESULTS

After reperfusion, hepatocyte viability was significantly improved in the ECMO group compared to the cooling groups, as measured by trypan blue, methylthiazolyldiphenyl-tetrazolium bromide, and seeding efficiency. Glycogen and reduced glutathione content were significantly used in the ECMO group both before and after reperfusion compared with group 2. The adenosine diphosphate:adenosine triphosphate ratio showed an improved trend (lower) in the ECMO group compared with the cooling group but did not reach statistical significance either before or after reperfusion.

CONCLUSIONS

This preclinical study suggests that ECMO is a viable technique for liver preservation that gives an improved yield of hepatocytes when isolated from a DCD liver, suggesting improved liver preservation.

Peritoneal cooling may provide improved protection for uncontrolled donors after cardiac death: an exploratory porcine study

Uncontrolled donation after cardiac death (DCD) renal transplantation relies on rapid establishment of organ preservation interventions. We have developed a model of the uncontrolled DCD, comparing current in situ perfusion (ISP) techniques with additional peritoneal cooling (PC). Ten pigs were killed and subjected to a 2 h ischemia period. The ISP group modeled current DCD protocols. The PC group (PC) modeled current protocols plus PC. Two animals were used as controls and subjected to 2 h of warm ischemia. Core renal temperature and microdialysis markers of ischemia were measured. Preservation interventions began at 30 min, with rapid laparotomy and kidney recovery performed at 2 h, prior to machine perfusion viability testing. The final mean renal temperature achieved in the ISP group was 26.3 degrees C versus 16.9 degrees C in the PC group (p = 0.0001). A significant cryopreservation benefit was suggested by lower peak microdialysate lactate and glycerol levels (ISP vs. PC, p = 0.0003 and 0.0008), and the superiority of the PC group viability criteria (p = 0.0147). This pilot study has demonstrated significant temperature, ischemia protection and viability assessment benefits with the use of supplementary PC. The data suggests a need for further research to determine the potential for reductions in the rates of ischemia-related clinical phenomena for uncontrolled DCDs.

Effect of warm ischemia time and organ perfusion technique on liver microvascular preservation in a non-heart-beating rat model

BACKGROUND

Current organ shortage has led to a reconsideration of non-heart-beating cadaveric donation.

METHODS

We assessed the effectivity of dual, i.e., arterial and portal-venous versus exclusive, arterial gravity perfusion for procurement of rat livers after 30 min and 60 min of cardiac arrest, analyzing the rate and homogeneity of microvascular perfusion by in situ fluorescence microscopy.

RESULTS

After 30 min of cardiac arrest, a nearly 100% recovery of acinar perfusion with a sinusoidal density not significantly different from that of normal, nonischemic livers was achieved by dual gravity perfusion. Prolongation of cardiac arrest to 60 min caused an almost 50% deficit of acinar and sinusoidal perfusion (P<0.05) with a concomitant 2-3-fold increase of heterogeneity of hepatic microperfusion. Regardless of the warm ischemic time period, dually perfused livers exhibited significantly (P<0.05) higher rates of both acinar and sinusoidal perfusion with increased homogeneity of microcirculation when compared with exclusive arterial perfusion.

CONCLUSION

These data underline the need and benefit of dual perfusion as well as the limitation of warm ischemic tolerance to 30 min for safe liver procurement of non-heart-beating donors.