gms | German Medical Science

Objectives/Interrogation: Static cold storage (SCS) is currently the standard of care for the preservation of vascularized composite tissue allografts. This approach not only limits the time available to perform the procedure, but also has detrimental effects on the muscle microcirculation, resulting in extensive damage particularly during the reperfusion phase. Continuous machine perfusion may have the potential to change the current practice. However, ideal perfusion parameters including the perfusate and the temperature are currently unknown. In this study, we aimed to test competing perfusion modalities on a cost effective VCA model established to study neuromuscular regeneration.

Methods: Sixty male Lewis rats were distributed into 8 groups according Table 1. Amputated limbs in groups 6, 7, and 8 were perfused using custom-made mini ex-situ perfusion system for 6 hours. All transplantations were performed between Lewis rats (isograft) eliminating the confounding effects of potential immune rejection. Evaluations were performed at the completion of sciatic nerve regeneration in 3 months after the transplantation. Extensor digitorum longus (EDL) muscle force was used as the primary outcome measure in this study. Metabolomic results including 5 energy pathways and nerve axon counts are currently pending.

Results and Conclusions: Among perfusion groups and SCS, near-normothermic pulsatile perfusion using diluted blood and plasma exchange provided the best outcome after 6 hours of perfusion. Maximum twitch and titanic force measurements in this group showed no statistically significant difference compared to immediately transplanted limbs with 75 minutes of ischemia (p>0.05), while other groups had significantly lower values (p<0.05) on both parameters. Interestingly, cold preserved allografts (static G5, and dynamic pulsatile G6) demonstrated very low CMAP amplitude indicating axonal loss, despite relatively preserved twitch and titanic forces.

In conclusion,

1.

Pulsatile perfusion at hypothermic temperatures using HTK is superior to SCS in protecting limb allografts after 6 hours of perfusion.

2.

Pulsatile perfusion at near normothermic temperatures is superior to all other modalities only if combined with continuous plasma exchange.

3.

ypothermic temperatures appear to affect the nerve structure more than the muscle.