Normothermic ex vivo perfusion of the limb allograft depletes donor leukocytes prior to transplantation

kinetics of donor leucocyte extravasation, cytokine secretion and cell-free DNA was charac-terised in the circulating perfusate. Results: Flow cytometry revealed increasing populations of viable leukocytes over time, reach-ing 49 billion leukocytes by 6 h. T (3.0 x 10 9 cells) and B cells (3.1 x 10 8 cells) lymphocytes, monocytes (2.7 x 10 9 cells), granulocytes (8.1 x 10 9 cells), NK (6.3 x 10 8 ) and gamma delta (8.1 x 10 8 ) cells were all identified. Regulatory T cells comprised a minor population (1.6 x 10 7 cells). There was a cumulative increase in pro-inflammatory cytokines suggesting that the donor limb has the capacity to elicit significant inflammatory responses that could contribute to leucocyte activation and diapedesis. Conclusion: EVNP not only acts as a preservation tool, but could also be utilized to immun-odeplete the VCA allograft prior to transplantation. This has clinical implications to mitigate acute rejection and prevent graft dysfunction and supports the future application of machine perfusion in graft preservation and immune modulation. (c) 2021 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by El-sevier Ltd. All rights reserved.