2526: Non-invasive monitoring of allograft rejection using thermal imaging in a large animal model of vascularized composite allotransplantation

2526: Non-invasive monitoring of allograft rejection using thermal imaging in a large animal model of vascularized composite allotransplantation Keli Kolegraff, Amy Quan, Nicole Crane, Howard Wang, Joseph Lopez, Georg Furtmuller, Sara Alfadil, Sara Mermulla, Byoung Chol Oh, Paul Akre, Jose C. Alonso-Escalante, Jeffrey Walch, Jaimie Shores, Damon Cooney, Steven Bonawitz, Eric Elster, Gerald Brandacher, and W. P. Andrew Lee Johns Hopkins University School of Medicine, Baltimore, MD, USA; Naval Medical Research Center, Bethesda, MD, USA; Uniformed Services University of the Health Sciences and Walter Reed National Military Medical Center, Bethesda, MD, USA Background Vascularized composite allotransplantation (VCA), including hand and face transplantation, is increasingly utilized for reconstruction of disfiguring injuries. Immune rejection is a problem inherent to allotransplantation and must be recognized early to prevent graft injury/loss. Skin biopsy is required to confirm rejection however this approach may further promote rejection through tissue injury. Thermal imaging has been used to non-invasively detect inflammation and ischemia in other disease states but has not been evaluated in VCA rejection. The purpose of this study was to evaluate the utility of non-invasive thermal imaging in the detection of rejection in a swine VCAmodel. Methods Osteomyocutaneous hindlimb transplantation was performed in 9 MGH miniature swine across a full SLA mismatch. The positive rejection control group (3 pigs) did not receive any form of immunosuppression. The treated group (6 pigs) received non-myeloablative conditioning with 50cGy total body and 350cGy thymic irradiation prior to transplantation, daily tacrolimus (20–25 ng/ml) until POD 30, and IV steroids on POD 4–6. Allografts were assessed daily for erythema, edema, blistering, and ulceration. Daily infrared images were acquired using a thermal camera (FLIR E8 #63903-0303) and thermal emission intensities from graft and contralateral flank control were analyzed using Image. Results In the untreated group, erythema was observed by POD 4 and progressed to epidermolysis by POD 8 in 3/3 animals. In the treated group, rejection was observed at POD 5–7 in 6/6 animals and was reversed by POD 10 with steroids in 5/6 animals. The sixth animal developed severe rejection on POD 5 that progressed to necrosis despite steroids. Interestingly, infrared imaging did not distinguish these episodes of rejection in the early post-operative period (POD 60), there was a trend toward cooler graft temperatures even in the absence of clinical rejection. Conclusions Despite signs of inflammation, infrared imaging did not reliably detect graft rejection. The finding that grafts become cooler over time suggests there may be long-term changes in graft perfusion. This may represent chronic graft injury and is the subject of on-going studies. CONTACT Keli Kolegraff keli@jhmi.edu © 2016 Keli Kolegraff, Amy Quan, Nicole Crane, Howard Wang, Joseph Lopez, Georg Furtmuller, Sara Alfadil, Sara Mermulla, Byoung Chol Oh, Paul Akre, Jose C. Alonso-Escalante, Jeffrey Walch, Jaimie Shores, Damon Cooney, Steven Bonawitz, Eric Elster, Gerald Brandacher, and W. P. Andrew Lee. Published with license by Taylor & Francis. This is an Open Access article distributed under the terms of the Creative Commons Attribution-Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. The moral rights of the named author(s) have been asserted. VASCULARIZED COMPOSITE ALLOTRANSPLANTATION 2016, VOL. 3, NOS. 1–2, 39 http://dx.doi.org/10.1080/23723505.2016.1234260