A Hyperbaric Warm Perfusion System Preserves Tissue Composites Ex vivo and Delays the Onset of Acute Rejection.

BACKGROUND:  Ischemia-reperfusion injury (IRI) precipitates acute rejection of vascularized composite allografts (VCA). Hyperbaric preservation of tissues ex vivo, between harvest and revascularization, may reduce IRI and mitigate acute rejection of VCA.

METHODS:  A porcine heterotopic musculocutaneous gracilis flap model was used. In phase 1, control autografts ( n  = 5) were infused with University of Wisconsin Solution (UWS) and stored at 4°C for 3 hours. Intervention autografts ( n  = 5) were placed in a hyperbaric oxygen organ preservation system for 5 hours and infused with hyperoxygenated UWS at 20°C and 3 atm. Grafts were replanted into the animals' necks. In phase 2, similarly treated control ( n  = 8) and intervention grafts ( n  = 8) were allotransplanted into the necks of animals separated by a typed and standardized genetic mismatch. No systemic immunosuppression was given. Systemic markers of IRI, and clinical and histopathological assessments of necrosis and rejection were performed.

RESULTS:  Autotransplanted tissue composites preserved in the hyperbaric chamber showed histopathological evidence of less muscle necrosis at 3 hours ( p  = 0.05). Despite a longer period of ischemia, no evidence was found of a difference in systemic markers of IRI following revascularization in these groups. Allotransplanted tissues supported ex vivo within the hyperbaric perfusion device experienced acute rejection significantly later than corresponding controls.

CONCLUSIONS:  Hyperbaric warm perfusion preserves musculocutaneous tissue composites ex vivo for longer than standard cold preservation in this model. This translates into a delay in acute rejection of allotransplanted tissue composites.