The Significance of Vascular Alterations in Acute and Chronic Rejection for Vascularized Composite Allotransplantation.

Vascularized composite allotransplantation (VCA) has emerged as a useful reconstructive option for patients suffering from major tissue defects and functional deficits. While the technical feasibility has been optimized and more than 130 VCAs have been performed during the last two decades, hurdles such as acute and chronic allograft rejection, graft deterioration, and eventual functional impairment need to be addressed. Recently, chronic graft rejection and progressive failure have been linked to vascular alterations observed in the allografts. Graft vasculopathy (GV) may play a pivotal role in long-term graft deterioration. The understanding of the underlying pathophysiological processes and their initial triggers is of utmost importance in the prevention, attenuation, and therapy of GV. While there are reports on the etiology and development of GV in solid organ transplantation, there are limited data with respect to chronic rejection and GV in the realm of VCA. Nevertheless, recent reports from long-term VCA recipients suggest that GV could truly jeopardize allografts in the follow-up evaluation. Chronic rejection and GV include different entities and might have different pathways in distinct organs. Herein, we reviewed the current literature on vascular changes during both acute and chronic allograft rejection, with a focus on their clinical and translational significance for VCA

Delayed enzymatic debridement in severe burns: Proof of concept

Introduction Enzymatic debridement (ED) is a novel powerful therapy for debridement of severe burns. Standard ED is usually performed within 72 h after injury following a presoaking phase. Little evidence exists on the effectiveness of ED later than 72 h after trauma. In this retrospective study, we compared outcomes of burn patients treated within versus later than 72 h after injury. Patients and Methods 110 patients with severe burns treated with ED between 2016 and 2020 were evaluated. Patients treated later than 72 h after trauma were identified and matched to a control group treated within 72 h. Matching criteria included age, area treated with ED, and localization of ED. Exclusion criteria were abbreviated burn severity index (ABSI) greater than 12 and death within the first 10 days after burn injury. Primary outcomes were time to full epithelialization and number of secondary surgical interventions. Results 16 patients (11 female, 5 male) matched the inclusion criteria and were assigned to the late treatment group. Mean age was 54.0 ± 19.0 years, the = and mean ABSI score 6.3 ± 3.2. 16 matched patients were assigned to the early ED group. Secondary surgical procedures were performed in 62.5% of cases in both groups with a mean of 1.7 (late treatment) vs. 2.2 (control; p = 0.29) secondary procedures in each group, respectively. No significant difference between groups regarding time to complete epithelialization (28.2 days vs. 27.3 days, p = 0.45) was observed. Infection rate was higher (18.8% vs. 6.3%, p = 0.28) in the delayed group. Conclusion Delayed ED is a feasible procedure as part of personalized care in burn surgery. In our retrospective study, we could not identify r safety issues except a slightly higher infection rate. This may however be attributed to delayed initiation of burn treatment itself

Sensitization and desensitization of burn patients as potential candidates for vascularized composite allotransplantation

Sensitization describes the acquired ability of the immune system to react to foreign human leukocyte antigens (HLA) by producing antibodies and developing memory cells. In the field of transplantation, recipient preformed HLA antibodies due to previous sensitization have been identified - beneath ABO incompatibility - as a major factor for acute graft rejection. Several reasons for sensitization have largely been studied, such as previous blood transfusions, pregnancies or former transplants. Recent studies indicate that the use of assist devices (e.g. ECMO) or cadaveric skin allotransplantation providing temporary coverage in burn patients may lead to additional sensitization. As vascularized composite allotransplantation (VCA) has become a rapidly advancing therapeutic option for reconstruction of complex tissue defects in burns, it seems even more important to become familiar with immunological principles and to be cautiously aware of both sources of sensitization and therapeutic concepts in burns avoiding sensitization. This may also include emergency VCAs in burn patients as potential strategy for early definitive reconstruction avoiding procedures triggering HLA antibody formation. We hereby provide an overview on current evidence in the field of pre- and peritrans-plant sensitization, followed by posttransplant strategies of desensitization and their potential impact on future treatments of burn patients. (C) 2015 Elsevier Ltd and ISBI. All rights reserved.Peer reviewe

Characteristics and Immunomodulating Functions of Adipose-Derived and Bone Marrow-Derived Mesenchymal Stem Cells Across Defined Human Leukocyte Antigen Barriers

BackgroundVascularized composite allotransplantation opens new possibilities in reconstructive transplantation such as hand or face transplants. Lifelong immunosuppression and its side-effects are the main drawbacks of this procedure. Mesenchymal stem cells (MSCs) have clinically useful immunomodulatory effects and may be able to reduce the burden of chronic immunosuppression. Herein, we assess and compare characteristics and immunomodulatory capacities of bone marrow- and adipose tissue-derived MSCs isolated from the same human individual across defined human leukocyte antigen (HLA) barriers.Materials and methodsSamples of omental (o.) adipose tissue, subcutaneous (s.c.) adipose tissue, and bone marrow aspirate from 10 human organ donors were retrieved and MSCs isolated. Cells were characterized by flow cytometry and differentiated in three lineages: adipogenic, osteogenic, and chondrogenic. In mixed lymphocyte reactions, the ability of adipose-derived mesenchymal stem cells (ASCs) and bone marrow-derived mesenchymal stem cells (BMSCs) to suppress the immune response was assessed and compared within individual donors. HLA mismatched or mitogen stimulations were analyzed in co-culture with different MSC concentrations. Supernatants were analyzed for cytokine contents.ResultsAll cell types, s.c.ASC, o.ASC, and BMSC demonstrated individual differentiation potential and cell surface markers. Immunomodulating effects were dependent on dose and cell passage. Proliferation of responder cells was most effectively suppressed by s.c.ASCs and combination with BMSC resulted in highly efficient immunomodulation. Immunomodulation was not cell contact-dependent and cells demonstrated a specific cytokine secretion.ConclusionWhen human ASCs and BMSCs are isolated from the same individual, both show effective immunomodulation across defined HLA barriers in vitro. We demonstrate a synergistic effect when cells from the same biologic system were combined. This cell contact-independent function underlines the potential of clinical systemic application of MSCs

Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development

An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In the plasma center, theoretical predictions on plasma current redistribution by a dynamo effect were confirmed experimentally. For core transport, the stabilizing effect of fast ion distributions on turbulent transport is shown to be important to explain the core isotope effect and improves the description of hollow low-Z impurity profiles. The L-H power threshold of hydrogen plasmas is not affected by small helium admixtures and it increases continuously from the deuterium to the hydrogen level when the hydrogen concentration is raised from 0 to 100%. One focus of recent campaigns was the search for a fusion relevant integrated plasma scenario without large edge localised modes (ELMs). Results from six different ELM-free confinement regimes are compared with respect to reactor relevance: ELM suppression by magnetic perturbation coils could be attributed to toroidally asymmetric turbulent fluctuations in the vicinity of the separatrix. Stable improved confinement mode plasma phases with a detached inner divertor were obtained using a feedback control of the plasma β. The enhanced D α H-mode regime was extended to higher heating power by feedback controlled radiative cooling with argon. The quasi-coherent exhaust regime was developed into an integrated scenario at high heating power and energy confinement, with a detached divertor and without large ELMs. Small ELMs close to the separatrix lead to peeling-ballooning stability and quasi continuous power exhaust. Helium beam density fluctuation measurements confirm that transport close to the separatrix is important to achieve the different ELM-free regimes. Based on separatrix plasma parameters and interchange-drift-Alfvén turbulence, an analytic model was derived that reproduces the experimentally found important operational boundaries of the density limit and between L- and H-mode confinement. Feedback control for the X-point radiator (XPR) position was established as an important element for divertor detachment control. Stable and detached ELM-free phases with H-mode confinement quality were obtained when the XPR was moved 10 cm above the X-point. Investigations of the plasma in the future flexible snow-flake divertor of AUG by means of first SOLPS-ITER simulations with drifts activated predict beneficial detachment properties and the activation of an additional strike point by the drifts