Safely minimizing the risks associated with vascularized composite allotransplantation VCA is crucial for functional restoration of wounded warriors. Our overarching goal is enabling functional and aesthetic restoration to patients with severe, unreconstructable vascularized composite tissue defects by safe VCA protocols with minimal side effects. Our specific aims are 1 Establishing the efficacy of a low-dose IL-2 protocol at enabling minimization of immunosuppression to sirolimus monotherapy in recipients of VCA. 2 Exploring correlations between cellular and molecular immunoassays performed in specimens from VCA recipients and their donors with clinical observations of stability and rejection. In future trials, these assays can be developed into tools that prospectively predict rejection and tolerance in VCA, and 3 Implementing next-generation methods to supplement and potentially overcome limitations of established methods such as histology and ultrasound biomicroscopy UBM.We are enrolling 5 subjects for VCA. 3 months after VCA, once recipient and allograft are stable, we will administer an IL-2 based protocol intended to enable minimization of immunosuppression to sirolimus monotherapy.