Evaluation of Vascular Repair by Tissue-Engineered Human Acellular Vessels or ePTFE Grafts in a Porcine Model of Limb Ischemia and Reperfusion.

BACKGROUND: This study evaluated performance of a tissue-engineered Human Acellular Vessel (HAV) in a porcine model of acute vascular injury and ischemia. The HAV is an engineered blood vessel comprised of human vascular extracellular matrix proteins. Limb reperfusion and vascular outcomes of the HAV were compared to those from synthetic expanded polytetrafluoroethylene (ePTFE) grafts.

METHODS: Thirty-six pigs were randomly assigned to four treatment groups, receiving either the HAV or a PTFE graft following a hind limb ischemia period of either 0- or 6-hours. All grafts were 3 cm-long interposition 6 mm diameter grafts implanted within the right iliac artery. Animals were not immunosuppressed and followed for up to 28 days after surgery. Assessments performed pre- and post-operatively included evaluation of graft patency, hind limb function, and biochemical markers of tissue ischemia or reperfusion injury. Histological analysis was performed on explants to assess host cell responses.

RESULTS: Post-operative gait assessment and biochemical analysis confirmed that ischemia and reperfusion injury were caused by 6-hour ischemia, regardless of vascular graft type. Hind limb function and tissue damage biomarkers improved in all groups post-operatively. Final patency rates at post-operative day (POD) 28 were higher for HAV than for ePTFE graft in both the 0-hour (HAV: 85.7%; ePTFE: 66.7%) and 6-hour (HAV: 100%; ePTFE: 75%) ischemia groups but these differences were not statistically significant. Histological analyses identified some intimal hyperplasia and host reactivity to the xenogeneic HAV and also to the synthetic ePTFE graft. Positive host integration and vascular cell infiltration was identified in HAV but not ePTFE explants.

CONCLUSIONS: Based on the functional performance and the histologic profile of explanted HAVs, this study supports further investigation to evaluate long-term performance of the HAV when used to repair traumatic vascular injuries.