Advances and perspectives in vascularized composite allotransplantation preservation

Vascularized composite allotransplantation (VCA) involves transplants of the face, upper limb, trachea, penis, abdominal wall and, more recently, uterus. These grafts are unique in that they comprise numerous specialized tissues derived from several embryonic layers, each with its own specific constraints. Whereas the skin component, as an immunological barrier, is a real challenge in terms of immune tolerance, the muscle is highly sensitive to ischemia, and ischemia-reperfusion injuries can lead to antigen release and eventually rejection episodes. While the gold standard for the preservation of these grafts remains static cold storage (4 °C), the emergence of dynamic perfusion techniques in solid organ transplantation suggests their adaptation to VCAs. In this review, we outline the challenges imposed by composite tissue allotransplantation, and discuss the latest advances in VCA preservation based on machine perfusion but also on static techniques at negative temperatures. Particular attention is paid to subnormothermic perfusion preservation and supercooling techniques, developed by our team in an attempt to import these optimized techniques from solid organ preservation.