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International audience; Abdominoperineal amputation (AAP) is a gold standard procedure treating advanced abdominal and pelvic cancers. The defect resulting from this extensive surgery must be reconstructed to avoid complications, such as infection, dehiscence, delayed healing, or even death. Several approaches can be chosen depending on the patient. Muscle-based reconstructions are a reliable solution but are responsible for additional morbidity for these fragile patients. We present and discuss our experience in AAP reconstruction using gluteal-artery-based propeller perforator flaps (G-PPF) in a case series. Between January 2017 and March 2021, 20 patients received G-PPF reconstruction in two centers. Either superior gluteal artery (SGAP)- or inferior artery (IGAP)-based perforator flaps were performed depending on the best configuration. Preoperative, intraoperative, and postoperative data were collected. A total of 23 G-PPF were performed—12 SGAP and 11 IGAP flaps. Final defect coverage was achieved in 100% of cases. Eleven patients experienced at least one complication (55%), amongst whom six patients (30%) had delayed healing, and three patients (15%) had at least one flap complication. One patient underwent a new surgery at 4 months for a perineal abscess under the flap, and three patients died from disease recurrence. Gluteal-artery-based propeller perforator flaps are an effective and modern surgical procedure for AAP reconstruction. Their mechanic properties, in addition to their low morbidity, make them an optimal technique for this purpose; however, technical skills are needed, and closer surveillance with patient compliance is critical to ensure success. G-PPF should be widely used in specialized centers and considered a modern alternative to muscle-based reconstructions. © 2023 by the authors.

PURPOSE OF REVIEW: In this review, we discuss novel strategies that allow for extended preservation of vascularized composite allografts and their potential future clinical implications for the field of vascularized composite allotransplantation (VCA). RECENT FINDINGS: The current gold standard in tissue preservation – static cold preservation on ice – is insufficient to preserve VCA grafts for more than a few hours. Advancements in the field of VCA regarding matching and allocation, desensitization, and potential tolerance induction are all within reasonable reach to achieve; these are, however, constrained by limited preservation time of VCA grafts. While machine perfusion holds many advantages over static cold preservation, it does not significantly elongate the preservation time. More extreme preservation techniques, such as cryopreservation approaches, are, however, specifically difficult to apply to composite tissues as the susceptibility to ischemia and cryoprotectant agents varies greatly by tissue type. SUMMARY: In the current scope of extended preservation protocols, high subzero approaches of VCA grafts will be particularly critical enabling technologies for the implementation of tolerance protocols clinically. Ultimately, advances in both preservation techniques and tolerance induction have the potential to transform the field of VCA and eventually lead to broad application of reconstructive transplantation.

In contrast to conventional static cold preservation (0-4 degrees C), ex situ machine perfusion may provide better preservation of donor livers. Continuous perfusion of organs provides the opportunity to improve organ quality and allows ex situ viability assessment of donor livers prior to transplantation. This video article provides a step by step protocol for ex situ normothermic machine perfusion (37 degrees C) of human donor livers using a device that provides a pressure and temperature controlled pulsatile perfusion of the hepatic artery and continuous perfusion of the portal vein. The perfusion fluid is oxygenated by two hollow fiber membrane oxygenators and the temperature can be regulated between 10 degrees C and 37 degrees C. During perfusion, the metabolic activity of the liver as well as the degree of injury can be assessed by biochemical analysis of samples taken from the perfusion fluid. Machine perfusion is a very promising tool to increase the number of livers that are suitable for transplantation.

The current standard for liver preservation involves cooling of the organ on ice (0-4 °C). Although it is successful for shorter durations, this method of preservation does not allow long-term storage of the liver. The gradual loss of hepatic viability during preservation puts pressure on organ sharing and allocation, may limit the use of suboptimal grafts and necessitates rushed transplantation to achieve desirable post-transplantation outcomes. In an attempt to improve and prolong liver viability during storage, alternative preservation methods are under investigation. For instance, ex vivo machine perfusion systems aim to sustain and even improve viability by supporting hepatic function at warm temperatures, rather than simply slowing down deterioration by cooling. Here we describe a novel subzero preservation technique that combines ex vivo machine perfusion with cryoprotectants to facilitate long-term supercooled preservation. The technique improves the preservation of rat livers to prolong storage times as much as threefold, which is validated by successful long-term recipient survival after orthotopic transplantation. This protocol describes how to load rat livers with cryoprotectants to prevent both intracellular and extracellular ice formation and to protect against hypothermic injury. Cryoprotectants are loaded ex vivo using subnormothermic machine perfusion (SNMP), after which livers can be cooled to -6 °C without freezing and kept viable for up to 96 h. Cooling to a supercooled state is controlled, followed by 3 h of SNMP recovery and orthotopic liver transplantation.

Donor organ viability is closely linked to transplant success. In an attempt to overcome the ongoing organ shortage, the criteria for organ donation are progressively being extended. These suboptimal grafts are, however, more prone to preservation and reperfusion related injury and are associated with in inferior transplant outcomes. Oxygenated machine perfusion is a new method of organ preservation whereby an organ is ‘mechanically flushed’ outside the human body with an oxygenated fluid. Oxygenated machine perfusion is gaining increasing attention as an alternative method of organ preservation, as it can be used to improve and assess organ viability of marginal donor organs prior to transplantation. Moreover, the technique of machine perfusion also enables the development of more extreme methods of organ preservation such as cryopreservation (preservation below 0 degrees Celsius) and biobanking within a new areas of transplant surgery, such as vascularized tissue transplantation. This ultimately leads to more and better quality organs and vascularized tissue grafts. In this thesis I investigate the effects of oxygenated machine perfusion on both donor livers (part A) and limbs (part B) in more detail. The results of this thesis contribute to a better understanding of the effect of new methods of organ preservation on the quality of the organ to be transplanted.

The aim of this thesis was to study the role of gradual rewarming on enhancing organ quality in organs with low quality such as ECD and especially DCD during the organ preservation phase and before implantation. This thesis also addresses an improvement in gradual rewarming protocol by adding a hemoglobin-based oxygen carrier (HBOC) to the perfusion solution in the preclinical kidney and liver rodent models.