Noninvasive Monitoring of Allograft Rejection Using a Novel Epidermal Sampling Technique

Despite promising short- and long-term results to date in vascularized composite allotransplantation (VCA), acute rejection remains the most common major complication in recipients. Currently, diagnosis of acute rejection relies on clinical inspection correlated with histopathological analysis. However, disagreement exists regarding the value of full-thickness skin and mucosal biopsies and histopathology remains semiquantitative, subject to sampling bias, and prone to intra- and inter-observer variabilities. Additionally, biopsies may cause infection, scarring, and/or potentially incite rejection through immune activation after injury. Noninvasive methods to diagnose rejection represent a critical unmet need for the emerging field of VCA. Here, we propose a novel technique utilizing skin stripping of the epidermis and subsequent molecular analysis to detect known markers of acute rejection. Using a small animal VCA model, we sought to validate our epidermal sampling technique as a noninvasive diagnostic test for acute rejection.