Hyperbaric sub-normothermic perfusion maintains tissue composites ex-vivo beyond the limits of cold ischemia.

Sharon D Lawson, MD, Lin Wang, MD, Anton Fries, MD, Michael Davis, MD. USA ISR

Aims:  To evaluate the ability of a novel hyperbaric oxygen warm ex vivo perfusion device to extend ex vivo viability of composite tissues in a swine model of vascularized composite auto-transplantation.

Methods: The Institutional Animal Care and Use Committee approved this protocol. Fourteen Yorkshire swine were used, four as model development. Five control flaps were flushed with Wisconsin Solution (WS) and maintained at 4ºC for three hours. Five experimental flaps were cannulated intra-arterially and perfused for five hours with hyper-oxygenated WS (mean PaO2 = 93.3 kPa) at 20ºC in a hyperbaric chamber at 3 atm (303 kPa). Flaps were then transplanted heterotopically into the animals necks. Animals were evaluated clinically and biochemically.  Additionally, flaps were assessed histologically at completion of the experiment 14 days after auto-transplantation.

Results: All flaps remained viable at the 14 day point except for two which encountered early failure secondary to technical or positioning complications.  Experimental flaps were subjectively clinically better integrated than controls.  Histological evaluation showed evidence of necrosis in all controls but flaps placed on hyperbaric ex vivo perfusion support showed no histologic evidence of ischemic injury or necrosis.  

Conclusions:  Hyperbaric subnormothermic perfusion extends the viability of tissue composites ex-vivo significantly beyond normal ischemic tolerance in a swine autotransplantation model.  Ischemic injury is mitigated as well as cold preservation induced injury.  This technology has potential utility in the field of solid organ and vascularised composite allotransplantation, and could expand the donor pool dramatically. Furthermore, ex vivo normalization of tissue physiology may reduce antigen presentation and acute rejection phenomena in allotransplantation. This is a present field of study in our lab.

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