Optimization of Ex Vivo Machine Perfusion and Transplantation of Vascularized Composite Allografts.

BACKGROUND: Machine perfusion is gaining interest as an efficient method of tissue preservation of Vascularized Composite Allografts (VCA). The aim of this study was to develop a protocol for ex vivo subnormothermic oxygenated machine perfusion (SNMP) on rodent hindlimbs and to validate our protocol in a heterotopic hindlimb transplant model. METHODS: In this optimization study we compared three different solutions during 6 h of SNMP (n = 4 per group). Ten control limbs were stored in a preservation solution on Static Cold Storage [SCS]). During SNMP we monitored arterial flowrate, lactate levels, and edema. After SNMP, muscle biopsies were taken for histology examination, and energy charge analysis. We validated the best perfusion protocol in a heterotopic limb transplantation model with 30-d follow up (n = 13). As controls, we transplanted untreated limbs (n = 5) and hindlimbs preserved with either 6 or 24 h of SCS (n = 4 and n = 5). RESULTS: During SNMP, arterial outflow increased, and lactate clearance decreased in all groups. Total edema was significantly lower in the HBOC-201 group compared to the BSA group (P = 0.005), 4.9 (4.3-6.1) versus 48.8 (39.1-53.2) percentage, but not to the BSA + PEG group (P = 0.19). Energy charge levels of SCS controls decreased 4-fold compared to limbs perfused with acellular oxygen carrier HBOC-201, 0.10 (0.07-0.17) versus 0.46 (0.42-0.49) respectively (P = 0.002). CONCLUSIONS: Six hours ex vivo SNMP of rodent hindlimbs using an acellular oxygen carrier HBOC-201 results in superior tissue preservation compared to conventional SCS.

Genitourinary vascularized composite allotransplantation: a review of penile transplantation.

PURPOSE OF REVIEW: Vascularized composite allotransplantation (VCA) has developed over the past 20 years, resulting in promising new reconstructive prospects for extensive soft tissue defects. More than 200 VCAs have been performed worldwide, including five genitourinary (GU)VCAs and here we review the most recent literature in this field. RECENT FINDINGS: Developments in GUVCA are continuously evolving to improve patient outcomes and suggest ethical equivalency to solid organ transplant. Recent treatment options have focused on preventing GUVCA complications by acknowledging the immunogenic tissue composition of the penis to treat rejection episodes and implementing stem cell transplant to recognized the GUVCA as self. Utilizing modern, postoperative, treatments can minimize complications and although the ethical dilemma remains, the morality of performing a GUVCA has diminished. The ethical focus relic's on standardization of patient safety. SUMMARY: GUVCA has become an established reconstructive surgical option. The prospect of VCA's future insinuates systemization between multidisciplinary VCA programs and the United Network for Organ Sharing in efforts to endorse ethical standardization. Over the last five years, the unprecedented outcomes have shown purpose to GUVCA that initiates an obligation to help those with severe genitourinary tissue defects. Progress in immunobiology continues to evolve optimal immunosuppression drug regimens and tolerance induction protocols, highlighting potential new immunologic pathways for graft acceptance.

Train Climbing-A new old trend in adolescents: Treatment of high voltage injuries and planning of a pilot project to raise awareness.

INTRODUCTION: An increasing number of high voltage electric burn injuries in a typically younger patient collective of train surfers and climbers at our level I center for burns was recognized. The purpose of this study was a retrospective data evaluation and as a consequence the implementation of an awareness program against train surfing. MATERIAL AND METHODS: In a retrospective analysis of prospectively collected data, 17 patients with high voltage injuries, who had been treated at our unit between January 2022 and January 2023, were identified. Of these patients seven were treated for injuries due to train surfing or climbing and therefore included in this study. The patients were assessed clinically for total burn surface area (TBSA), degree of burn, associated Injuries, hospital length of stay, number and type of surgeries (fasciotomy, minor/major amputations, defect coverage split skin graft or flaps). RESULTS: A total of seven males formed the basis of this report with an average age of 17.7 years (range 14-21 years). The highest ABSI (Abbreviated Burn Severity Index) score was 12, leading to the death of the 21-year-old patient who had 80% TBSA as well as multiple comorbidities including severe brain damage. The mean duration of stay at the intensive care unit (ICU) was 24.8 days and the mortality rate was 14.29%. CONCLUSION: This study highlighted the severity of injuries, with a mean TBSA of 41.42% and a mortality rate of 14.29% among the study population. Train climbing and surfing patients presented with severe injuries and fatal long-term consequences. A pilot project involving several stakeholders was initiated in order to raise awareness of the dangers of electric arcs and the risk involved.

Exploring Iodide and Hydrogen Sulfide as ROS Scavengers to Delay Acute Rejection in MHC-Defined Vascularized Composite Allografts.

Vascularized composite allografts (VCA) face ischemic challenges due to their limited availability. Reperfusion following ischemia triggers oxidative stress and immune reactions, and scavenger molecules could mitigate ischemia-reperfusion injuries and, therefore, immune rejection. We compared two scavengers in a myocutaneous flap VCA model. In total, 18 myocutaneous flap transplants were performed in Major histocompatibility complex (MHC)-defined miniature swine. In the MATCH group (n = 9), donors and recipients had minor antigen mismatch, while the animals were fully mismatched in the MISMATCH group (n = 9). Grafts were pretreated with saline, sodium iodide (NaI), or hydrogen sulfide (H2S), stored at 4 °C for 3 h, and then transplanted. Flaps were monitored until clinical rejection without immunosuppression. In the MATCH group, flap survival did not significantly differ between the saline and hydrogen sulfide treatments (p = 0.483) but was reduced with the sodium iodide treatment (p = 0.007). In the MISMATCH group, survival was similar between the saline and hydrogen sulfide treatments (p = 0.483) but decreased with the sodium iodide treatment (p = 0.007). Rhabdomyolysis markers showed lower but non-significant levels in the experimental subgroups for both the MATCH and MISMATCH animals. This study provides insightful data for the field of antioxidant-based approaches in VCA and transplantation.

Erratum: 4072 Optimizing ex-vivo perfusion in Vascularized Composite Allotransplantation using Hyperosmolar solution and Electric Stimulation: Preliminary Results - ERRATUM.

[This corrects the article DOI: 10.1017/cts.2020.87.].

In Vivo Activity of Genetically Modified Cells Preseeded in Rat Vascularized Composite Allografts.

OBJECTIVE: Transplantation of the hand or face, known as vascularized composite allotransplantation (VCA), has revolutionized reconstructive surgery. Notwithstanding, there are still several areas of improvement to mitigate immune rejection while sparing systemic adverse effects. The goal of this study was to evaluate the engraftment and viability of a genetically modified cell population pre-engrafted into a VCA transplant, to potentially act as a local biosensor to report and modify the graft in vivo. A rat fibroblast cell line genetically modified to secrete Gaussia-Luciferase (gLuc), which served as a constitutive biomarker of cells, was incorporated into a VCA to study the viability of biosensor cells in a syngeneic rat heterotopic partial hindlimb transplantation model. RESULTS: Five perfusions were first performed as engineering runs to have a stable limb perfusion protocol, followed by 3 perfusions to analyze the cell engraftment during machine perfusion, and finally 4 perfusions to study in vivo persistence of the cell biosensors. Blood samples were collected to monitor gLuc secretion during perfusion and postoperatively. A time-dependent increase in gLuc secretion in the limb perfusion outflow during machine perfusion indirectly verified the presence of biosensors within the graft. After the ex vivo perfusion, VCA hindlimbs were analyzed for near infrared fluorescence emission that showed a presence of dyed engineered cells in all areas of the limbs. Postoperatively, gLuc was detectable 4 to 5 days after transplantation (W = 16, P = .02857). This study demonstrated that engineered cells could be successfully preimplanted into VCAs-an important step toward development of an in vivo biosensor platform to use in modulating acute VCA outcomes.

Local FK506 implants in non-human primates to prevent early acute rejection in vascularized composite allografts.

BACKGROUND: Previous vascularized composite allograft (VCA) studies from our laboratory have shown that topical FK506 delivery in non-human primates (NHPs) was limited by inadequate dermal penetration and rejection persisted. Herein, we report the first utilization of FK506 via subcutaneously implanted discs to mitigate VCA rejection in NHPs. METHODS: Full major histocompatibility complex (MHC)-mismatched NHP pairs underwent partial-face VCA and FK506 disc implantation along the suture line. All allotransplants were maintained post-operatively for two months on the FK506 discs, methylprednisolone, mycophenolate mofetil, and supplemented with intramuscular FK506 if necessary. Group 1 (n=4) was used for optimization of the implant, while Group 2 (n=3) underwent delayed bone marrow transplantation (DBMT) after two months. VCA skin biopsies and peripheral blood samples were obtained for serial assessment of rejection and mixed chimerism by histopathology and flow cytometry respectively. RESULTS: In Group 1, two technical failures occurred. Of the remaining two NHPs, one developed supratherapeutic levels of FK506 (50-120 ng/mL) and had to be euthanized on postoperative day (POD) 12. Reformulation of the implant resulted in stable FK506 levels (20-30 ng/mL) up to POD12 when further intramuscular (IM) FK506 injections were necessitated. In Group 2, two NHPs survived to undergo conditioning and one successfully developed chimerism at 2-3 weeks post-DBMT (96-97% granulocytes and 7-11% lymphocytes of recipient-origin). However, all three NHPs had to be terminated from study at POD64, 77 and 86 due to underlying post-transplant lymphoproliferative disorder. All VCAs remained rejection-free up to study endpoint otherwise. CONCLUSIONS: This study shows preliminary results of local FK506 implants in potentially mitigating VCA acute rejection for tolerance protocols based on mixed chimerism approach.