Clues From Strange New Antigens: How Skin Responds to Nonself.

Sentinel flaps reflect key inflammatory aspects of human face transplant rejection.

Facial transplantation offers transformative solutions for patients with severe facial disfigurements. Minimizing ischemia time is critical for preserving tissue viability, and prioritizing facial allograft recovery during multi-organ procurement aims to optimize outcomes. This study evaluates whether prioritizing face allograft procurement affects the outcomes of non-vascularized composite allotransplantation (non-VCA) organ transplants. This retrospective study analyzed four VCA donor recoveries and face transplants at our center. Perioperative data, including operation times, blood pressure, oxygenation, urine output, and blood product administration, were recorded. Donor data were verified using the United Network for Organ Sharing database, institutional records, and data from LiveOnNY and Gift of Life Organ Procurement Organizations to assess recipient and graft survival. Twenty-one allografts (VCAs and organs) were transplanted into 16 patients. One-year patient survival was 92% (11/12) among non-VCA recipients. One patient died during surgery, and two patients died more than three years post-transplant from unrelated causes. Three non-VCA graft failures occurred within the first year, resulting in an 87% graft survival rate. The median ischemia time for face transplants was 3 hours and 18 minutes. Preoperative planning, including cadaveric rehearsals, computerized surgical plans, and 3D-printed cutting guides, contributed to stable perioperative parameters and reduced blood loss. This study suggests that prioritizing facial allograft procurement is feasible and does not appear to compromise non-VCA organ transplant outcomes. Further multicenter studies are needed to validate these findings and further refine protocols.

A novel variation of the mixed lymphocyte reaction for measuring T cell responses to skin-specific antigens of pigs.

As the field of vascularized composite allograft (VCA) has matured, chronic rejection (CR) has emerged as the major cause of late graft loss, albeit occurring at a lower frequency than in many solid organ transplants. VCAs differ from conventional solid organ transplants in that they have multiple tissue targets and CR types. Exposure to environmental, physical, or thermal trauma has been shown to start or worsen both acute and CR in VCA recipients. This overview will cover the clinical presentation of CR in human and animal models, how that differs between VCA components such as skin, vessels, and adnexa, followed by a description of the pathologic presentation of CR, the resulting working pathologic classification of CR, and finally, a discussion of the pathophysiology and potential treatment or monitoring directions of CR in VCAs. These studies provide some exciting avenues where current and future research should be targeted to improve diagnosis and prognosis and find new treatment approaches, which include targeting complement and checkpoint inhibitors. The mechanisms of vasculopathy in disease states outside the field of transplantation, such as pulmonary arterial hypertension, are included, which may provide novel perspectives on CR in transplant recipients. Finally, we propose working points to summarize the current understanding of CR in VCAs and provide directions for future investigations, prevention, and possible treatment.

In vascularized composite allograft (VCA) for upper limb reconstruction, upper arm-level or transhumeral transplantations are performed less frequently than forearm and hand transplantations. Transplantation is technically more feasible at this proximal level, largely owing to the use of macrovascular anastomoses. Despite these challenges, the outlook for arm allotransplantation remains encouraging, and this protocol provides a standardized technique for harvesting a vascularized upper arm composite allograft, ensuring both optimal outcomes and minimal tissue trauma. In the case of upper arm transplant, the technique varies according to the level of transplantation: supracondylar, transhumeral at a proximal arm level, or through the shoulder with the donor humeral head. A circumferential skin incision at mid-arm, or depending on the level at the origin of the upper limb, is made. A skin flap, such as a deltoid flap, can be harvested from the donor for skin closure at proximal levels. Dissection of the cephalic vein and deeper the brachial or axillary artery and veins is required. Then, the surgeon must identify the nerves depending on the level (terminal branches of brachial plexus or anteromedial and anterolateral cords for proximal transplantation) and transect the biceps, brachialis, and triceps muscles. The coracobrachialis and the deltoid muscles mayalso be dissected depending on the amputation level. Finally, the surgeon must make a transhumeral osteotomy or, if needed, harvest the donor humeral head for shoulder reconstruction. In this case, a peroneus longus graft for the suspension ligamentoplasty can also be harvested. The goal of this protocol is to standardize the procedure of harvesting and preparing an upper arm allotransplant.

The various physiological profiles comprising vascularized composite allografts (VCAs) pose unique challenges to preservation. Minimizing ischemia, reperfusion injury, and rejection remains a primary focus of graft pretreatments (PTs). Currently, the gold standard PT consists of flushing the graft and placing it in static cold storage in the University of Wisconsin solution. With this method, graft viability is limited to 4 to 6 hours. Prolonging this time limit will increase donor allocation radius, access to care, and positive patient outcomes. We aimed to evaluate novel PTs that could potentially enhance and lengthen VCA viability. Following PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines, we conducted a comprehensive literature search of EMBASE, Cochrane, and PubMed. Studies had to be published prior to June 15, 2022. PTs had to target cell physiology, rather than immunogenicity. We extracted data including study design, PT details, evaluation metrics, and outcomes. We identified 13 studies, categorized into 3 groups: solution-based alterations to the gold standard, ex vivo perfusion, and other novel techniques. The incorporation of hydrogen sulfide and Perfadex as solutions in the gold standard protocol demonstrated a 6-day delay in rejection and limited reperfusion injury markers, respectively. In an ex vivo perfusion study, after 24 hours of PT and 12 hours posttransplant, VCA muscle contractility remained close to normal. The gold standard PT did not demonstrate the same success. However, graft weight gain, up to 50% of baseline among the reviewed articles, is a prominent adverse effect of perfusion. Another technique, cryopreservation, displayed 90% graft failure by venous thrombosis, despite high free graft viability following 2 weeks of storage. This study of PT modalities found a variety of encouraging preservation techniques for grafts with high levels of tissue diversity. Ex vivo perfusion dominated PT innovation with promising results in preserving the viability and functionality of muscle, which is central to the restoration of movement. Future studies are necessary to evaluate long-term graft outcomes and to optimize PT protocols for extended preservation times to ensure clinical relevance.

There are 18 million living military veterans in the United States, yet this population has not been the focus of educational campaigns to increase donation awareness and willingness to donate organs. This study examined whether willingness to donate organs varies by veteran-inclusive and vascularized composite allograft (VCA)-inclusive messaging. A total of 549 US veterans nondonors were randomized to four education groups: (1) general donation messaging, no veterans or VCA, (2) veteran-inclusive donation messaging, no VCA, (3) veteran- and VCA-inclusive donation messaging, or (4) no donation messaging (Control). Willingness to donate traditional and VCA organs was assessed pre-intervention, post-intervention, and at 3-weeks. Generalized Estimating Equations (GEE) models showed significant group X time interaction effects for traditional (Wald χ2 = 91.3, p<0.001) and VCA (Wald χ2 = 36.3, p<0.001) donation willingness. For traditional donation willingness, improvements were higher in veteran-inclusive messaging groups than the Control group (p<0.01). There was no difference between veteran-inclusive and non-veteran groups, nor between VCA-inclusive and non-VCA video groups. For VCA donation willingness, significant increases were observed in the veteran-inclusive plus VCA messaging group compared to messaging without veterans or VCA and Control groups (p<0.03). At follow-up, the education groups had more veterans who registered as donors, compared to the Control group (p = 0.02). Veteran-inclusive donation messaging may not be necessary to increase willingness to donate traditional organs, although it offers some advantages for increasing VCA donation willingness.

B-cell infiltration distinguishes mucosal from skin patterns of rejection in facial vascularized composite allografts.

Long-term Posttransplant-Related Bone Volumetric Changes in Eight Face Transplant Recipients – a Single Center Retrospective Case Series

Vascularized composite allograft (VCA) transplantation represents a significant advancement in reconstructive surgery and offers hope to individuals who experienced congenital disorders or severe tissue injuries to restore physical appearance, function, and enhance quality of life. VCA recovery introduces complexities to conventional solid organ recovery, and there remain concerns regarding the potential impact of VCA recovery on non-VCA organs for transplant. The current retrospective study examines deceased donor characteristics and observed-to-expected (O/E) organ yield ratios for 51 VCA donors recovered in the US between July 4, 2014 and March 31, 2024, compared with a contemporary cohort of non-VCA donors recovered in 2023. Among the VCA donors, 17 donated a uterus, 15 each donated head and neck and upper limbs, 4 were abdominal wall donors, and 2 donated external male genitalia. The findings indicate that VCA donors tended to be younger (18-34 years old), predominantly White, non-Hispanic, and had no history of diabetes, along with lower weight, lower kidney donor profile index, and lower ejection fraction. The analysis revealed that VCA donors had higher observed overall organ yield than expected (O/E: 1.24, 95% CI: 1.16-1.33), with better-than-expected organ yields across VCA types. The number of deceased VCA donors in the US is still relatively small compared to the overall donor population. As the field continues to evolve and more data becomes available, further analyses need to be conducted to understand the demographics of VCA donors and the potential impact of VCA donation within the donation and transplant system.

Outcomes of Multi-Organ Donation Recipients Following Prioritized Facial Vascular Composite Allograft Procurement

Allograft vasculopathy in vascularized composite allografts (VCA) remains understudied. This review explores the vascular changes in VCA, focused on recent literature. Allograft vasculopathy in VCA generally includes progressive concentric myointimal thickening and luminal narrowing of arterial vessels through endothelial deterioration and proliferation of smooth muscle cells. Microvascular changes are also noted, with thrombosis and lumen narrowing in microvessels of the skin even in the absence of large vessel vasculopathy. Histopathologic reports of skin containing VCA rejection document arteriosclerosis in deep vessels that are not always reflected in skin punch biopsies. The first revision of the Banff VCA scoring system 2022 was developed to include vascular changes in VCA. The scoring system for chronic changes and antibody mediated rejection continues to be under development. The study of vascular changes in VCA continues to progress. Important data and advances in experimental and clinical VCA have been reported and continue to take place. Challenges ahead include capture of clinical data that will evolve beyond transient report forms and approaching on the problem of graft failure well grounded in sound scientific methodology.

Enhanced VCA Storage: A Pilot Study Demonstrating Supercooling in Orthotopic Rodent Hindlimb Transplantation

Warm ischemia time (WIT) and ischemia-reperfusion injury are limiting factors for vascularized composite allograft (VCA) transplantation. Subnormothermic machine perfusion (SNMP) has demonstrated the potential to extend WIT in organ transplantation. This study evaluates the effect of SNMP on VCA viability after prolonged WIT. Rat hindlimbs underwent WIT for 30, 45, 60, 120, 150, or 210 min, followed by 3-h SNMP. Monitoring of perfusion parameters and outflow determined the maximum WIT compatible with limb viability after SNMP. Thereafter, 2 groups were assessed: a control group with inbred transplantation (Txp) after 120 min of WIT and an experimental group that underwent WIT + SNMP + Txp. Graft appearance, blood gas, cytokine levels, and histology were assessed for 21 d. Based on potassium levels, the limit of WIT compatible with limb viability after SNMP is 120 min. Before this limit, SNMP reduces potassium and lactate levels of WIT grafts to the same level as fresh grafts. In vivo, the control group presented 80% graft necrosis, whereas the experimental group showed no necrosis, had better healing ( P = 0.0004), and reduced histological muscle injury ( P = 0.012). Results of blood analysis revealed lower lactate, potassium levels, and calcium levels ( P = 0.048) in the experimental group. Both groups presented an increase in interleukin (IL)-10 and IL-1b/IL-1F2 with a return to baseline after 7 to 14 d. Our study establishes the limit of WIT compatible with VCA viability and demonstrates the effectiveness of SNMP in restoring a graft after WIT ex vivo and in vivo, locally and systemically.

Objective To summarize patient characteristics and outcomes for the historical and current methods of long-segment tracheal replacement in humans. Materials and Methods A single reviewer screened the abstracts and full texts using Covidence for file management. Studies published in English that reported human subjects with circumferential or near-circumferential (>270 degrees) cervical tracheal replacements were included. Articles with subjects treated with primary anastomosis alone, retracted articles, abstracts, expert opinion articles, and conference presentations were excluded. Results A total of 32 articles were included in the review reporting 156 cases of long-segment tracheal replacement including synthetic (alive at 1-8 years n = 6/64), regenerative medicine (dead at 15 days-55 months n = 4, not reported n = 6), cadaveric tracheal allograft (alive at 5 months-10 years n = 32/38), aortic allograft (alive at 6-85 months n = 12/16), free tissue transfer (alive at 6-108 months n = 13/21), allotransplantation (alive at 6-24 months n = 5/8), and vascular composite allograft (VCA) (alive at 20 months n = 1/1). Conclusion Silicone and Marlex prostheses have poor long-term outcomes. The cadaveric tracheal allograft can only replace near-circumferential tracheal defects and is therefore limited to benign tracheal pathology. Inadequate structural support plagues the aortic allograft and often requires numerous invasive procedures and maintenance of an intraluminal stent. A lack of mucociliary clearance exists in all methods of tracheal replacement except cadaveric tracheal allograft and VCA and can cause fatal mucous plugging and chronic pulmonary infections. VCA and allotransplantation require long-term immunomodulation therapy.

Vascularized composite allografts (VCAs) present unique challenges in transplant medicine, owing to their complex structure and vulnerability to ischemic injury. Innovative preservation techniques are crucial for extending the viability of these grafts, from procurement to transplantation. This study addresses these challenges by integrating cryoprotectant agent (CPA) optimization, advanced thermal tracking, and stepwise CPA loading strategies within an ex vivo rodent model. CPA optimization focused on various combinations, identifying those that effectively suppress ice nucleation while mitigating cytotoxicity. Thermal dynamics were monitored using invasive thermocouples and non-invasive FLIR imaging, yielding detailed temperature profiles crucial for managing warm ischemia time and optimizing cooling rates. The efficacy of stepwise CPA loading versus conventional flush protocols demonstrated that stepwise (un)loading significantly improved arterial resistance and weight change outcomes. In summary, this study presents comprehensive advancements in VCA preservation strategies, combining CPA optimization, precise thermal monitoring, and stepwise loading techniques. These findings hold potential implications for refining transplantation protocols and improving graft viability in VCA transplantation.

Vascularized Composite Allotransplantation (VCA) is a promising option for extensive tissue reconstruction. Successful graft outcomes in VCA surgeries require close monitoring of immunological reactions and the progression of ischemic conditions. Excessive immunosuppression may lead to chronic infections and dangerous side effects, while inadequate immunosuppression can result in acute or chronic rejection episodes, jeopardizing graft function. Monitoring the immunological status of an allograft becomes critical when exploring innovative tolerance induction protocols or transitioning patients from conventional therapies. Currently, confirming clinical rejection involves invasive biopsies, which are suboptimal for routine monitoring due to associated risks. Thus, developing non-invasive technologies capable of detecting changes in the immunological status of the graft before apparent clinical signs of inflammation and tissue damage become imperative. To address these limitations, this study proposes a low-cost, portable, flexible, miniaturized, and site-of-care (SOC) platform for multiplex sensing of predictive biomarkers (e.g., interleukin 6 (IL6), lactate) and pH to detect instances of VCA rejection before apparent clinical signs of immunogenic reactions such as inflammation and tissue damage.The sensor fabrication was performed on in-house fabricated porous laser-engraved graphene (PLEG)-electrode, utilizing the laser-induced carbonization (LIC) technique on a thin (12.5 µm) polyimide (PI) surface at optimized laser parameters (laser power-22%, speed-5.2%, and gas flow-50%). The PI sheet was laminated on a polyethylene terephthalate (PET) sheet with silicone adhesive in the middle, helping to dissipate the heat generated during the carbonization process. Compared to conventional screen-printed platforms, the PLEG electrode provides higher surface area, receptor loading, electrical conductivity, ease of surface modification, and improved sensitivity with an average resistance of 40 ± 3 Ω/cm. Subsequently, the connection pad and reference electrodes (RE) were coated with silver/silver chloride (Ag/AgCl) conductive paste for improved connection. The RE was stabilized by coating it with polyvinyl butyrate (PVB) and sodium chloride polymeric cocktail. Three working electrodes (WE) were designated as WE-1 (for IL6), WE-2 (for lactate), and WE-3 (for pH). The sensor construction was initiated with surface activation WEs in 0.50 M H2SO4 containing 0.10 M KCl as a supporting electrolyte by sweeping potential between 1.0 and -1.2 V vs. Ag/AgCl reference electrode. For IL-6 sensing, the WEs were incubated with freshly prepared 1-pyrenebutyric acid N-hydroxysuccinimide (PBASE) as a non-covalent crosslinker (10.0 mM) in dimethylformamide (DMF) for 3 hrs., followed by buffer wash (3 times) to remove any unbound crosslinker. Later, a monoclonal antibody to IL6 was immobilized using peptide bond formation between PBASE and the recognition element, passivated by incubating in Bovine serum albumin (BSA) to block non-specific binding. Upon binding, the antigen-antibody complex's formation results in a decrease in voltammetric signal of the redox signal, generating an IL6-dependent change in current. For lactate detection, an amperometric method utilizes a two-electrode electrochemical setup. The WE comprise a composite Glutaraldehyde/BSA/Lactate-Oxidase/Prussian Blue/PLEG-electrode (GA/BSA/LOx/PB/ PLEG). An Ag/AgCl-coated electrode serves as the RE, and counter electrodes (CE). For the pH sensor (PANI/PLEG), polyaniline (PANI) was electrodeposited at 0.80 V for 600 sec on an activated PLEG electrode washed with distilled water and coated with Nafion (0.25% v/v). For pH measurements, the open-circuit potential (OCP) was measured between the PANI/PLEG electrode and the RE.Post characterization, the sensor’s electrochemical measurements to detect IL6, lactate, and pH were performed in buffer, artificial interstitial fluid, porcine blood, and serum samples with portable potentiostat. Under optimal experimental conditions, the devised platform showed a sensitivity of 2.59 µA/(log10IL6), 0.021 µA/mM, and ~49.39 ± 2 mV in spiked serum for IL6, lactate, and pH, respectively. Subsequently, serum samples of porcine VCA recipients were collected on postoperative days (POD) 0, 2, and 6 and tested using the IL-6, lactate, and pH sensors, respectively. The sensors can successfully track the change in the levels of IL6 (increasing) and lactate (increasing) and the change in pH post-surgery and align with clinical observations of inflammation and ischemia post-allograft on POD6. The sensor results were also validated using commercial IL6 ELISA and lactate kits using the same samples and showed a correlation (r) of r = 0.9885 (n=3, for IL6) and r = 0.9896 (n=3, for lactate). Our results demonstrate that the developed miniaturized platform offers a portable, low-cost, robust, and multiplex sensing platform capable of quantifying predictive biomarkers post-VCA surgeries. This platform presents a promising, miniaturized, and cost-effective solution for the real-time monitoring of biomarkers in VCA models. KEYWORDS: Vascularized Composite Allotransplantation (VCA), Ischemia, Interleukin-6, Lactate, Electrochemical sensor, Porous laser engraved graphene, Multiplex sensing

Introduction: Improving public awareness about the opportunity to become a vascularized composite allograft (VCA) donor is crucial to increasing access to organs. Prior research identified a need for comprehensive and comprehensible public education materials. A 2-round Delphi panel was conducted to garner US expert consensus on the topics and language to include in public education materials via an organ procurement organization-hosted website. Methods: The round 1 survey assessed the importance of educational topics and statements (n = 19) using 5-point Likert scales. The round 2 survey asked experts to rate new and repeated educational topics (n = 27). Open-ended comment boxes elicited experts' feedback and language revisions for educational statements. Responses were analyzed using descriptive statistics and rapid qualitative analysis. Findings: Eighteen experts responded to the round 1 survey and 15 to round 2. After round 2, 20 topics had mean (M) importance greater than neutral (M > 3.00) and were retained in the educational materials. The 5 most important topics by mean Likert ratings were: consent process for donation (M = 4.73), potential recipients (M = 4.73), most common vascularized composite organs transplanted (M = 4.47), purpose (M = 4.47), and definition (M = 4.47). Seven themes emerged from experts' open-ended comments about the importance and language of educational statements. Conclusions: Delphi panel findings identified expert-endorsed topics and educational statements for public education about vascularized composite organ donation via an educational website. Future research should assess the website's impact on public knowledge of VCA donation.

Why partial heart transplantation could be regulated as organ transplantation