Induction of Endotoxin Tolerance Delays Acute Rejection in a Hindlimb Transplantation Model in Rats.

BACKGROUND: Acute rejection is seen in 85 percent of composite vascular allogeneic transplants despite long-term immunosuppression. Recently, it was reported that the induction of endotoxin tolerance prolonged heart allograft survival in mice. However, it produced side effects in all the animals secondary to the inflammatory reaction. Galactomannan has shown endotoxin tolerance without this side effect in vitro. The authors hypothesized that galactomannan-induced endotoxin tolerance delays acute rejection in vascular allogeneic transplantation without the side effects produced by lipopolysaccharide. METHODS: Twenty-four rat hindlimb transplants were divided into four groups according to the preconditioning received: control, lipopolysaccharide (0.16 ml/kg), galactomannan 72 hours before (galactomannan-72) (8 ml/kg), and galactomannan 24 hours before (galactomannan-24) (8 ml/kg). Median acute rejection time, weight loss, and diarrheal episodes were monitored. Blood samples were collected at 0, 7, 21, 30, 45, and 60 days. Plasma cytokines (i.e., tumor necrosis factor alpha, interferon gamma), peripheral chimerism, and lymphocyte percentages were analyzed. RESULTS: Median allograft survival was 40 days (range, 40 to 44 days) in the control group, 68 days (range, 61 to 71 days) in the lipopolysaccharide group, and 70 days (range, 69 to 73 days) in both galactomannan groups (p = 0.001). Weight loss was higher in the lipopolysaccharide group (p < 0.001), as was the 83.3 percent rate of diarrheal episodes (control, 0 percent, p = 0.015; galactomannan-72, 0 percent, p = 0.015; and galactomannan-24, 16.7 percent, p = 0.02). Preconditioned rats had higher peripheral blood chimerism (lipopolysaccharide, 2.30 ± 0.13 percent; galactomannan-72, 2.63 ±1.46 percent; and galactomannan-24, 2.47 ± 0.19 percent) compared to the control group (2.06 ± 0.36 percent) (lipopolysaccharide, p = 0.04; galactomannan-72, p = 0.002; and galactomannan-24, p = 0.002). CONCLUSIONS: Induction of endotoxin tolerance delays acute rejection in the rat hindlimb transplantation model. Galactomannan preconditioning has no lipopolysaccharide side effects and was equally effective in delaying acute rejection. CLINICAL RELEVANCE STATEMENT: The contributions of this experimental work are very incipient. Although the use of galactomannan in clinical practice requires more studies to assess its safety, there is no doubt that immunomodulation may be one of the responses that solve the problem of long-term immunosuppression.

Aggravation of fibrin deposition and microthrombus formation within the graft during kidney transplantation.

In kidney transplantation, microthrombi and fibrin deposition may lead to local perfusion disorders and subsequently poor initial graft function. Microthrombi are often regarded as donor-derived. However, the incidence, time of development, and potential difference between living donor kidneys (LDK) and deceased donor kidneys(DDK), remains unclear. Two open-needle biopsies, taken at preimplantation and after reperfusion, were obtained from 17 LDK and 28 DDK transplanted between 2005 and 2008. Paraffin-embedded sections were immunohistochemically stained with anti-fibrinogen antibody. Fibrin deposition intensity in peritubular capillaries(PTC) and glomeruli was categorized as negative, weak, moderate or strong and the number of microthrombi/mm2 was quantified. Reperfusion biopsies showed more fibrin deposition (20% to 100% moderate/strong, p < 0.001) and more microthrombi/mm2 (0.97 ± 1.12 vs. 0.28 ± 0.53, p < 0.01) than preimplantation biopsies. In addition, more microthrombi/mm2 (0.38 ± 0.61 vs. 0.09 ± 0.22, p = 0.02) and stronger fibrin intensity in glomeruli (28% vs. 0%, p < 0.01) and PTC (14% vs. 0%, p = 0.02) were observed in preimplantation DDK than LDK biopsies. After reperfusion, microthrombi/mm2 were comparable (p = 0.23) for LDK (0.09 ± 0.22 to 0.76 ± 0.49, p = 0.03) and DDK (0.38 ± 0.61 to 0.90 ± 1.11, p = 0.07). Upon reperfusion, there is an aggravation of microthrombus formation and fibrin deposition within the graft. The prominent increase of microthrombi in LDK indicates that they are not merely donor-derived.

Surgical Angiogenesis of Decellularized Nerve Allografts Improves Early Functional Recovery in a Rat Sciatic Nerve Defect Model.

BACKGROUND: Surgical angiogenesis applied to nerve grafts has been suggested to enhance nerve regeneration after nerve injury. The authors hypothesized that surgical angiogenesis to decellularized nerve allografts would improve functional recovery in a rat sciatic nerve defect model. METHODS: Sixty Lewis rats were divided in three groups of 20 animals each. Unilateral sciatic nerve defects were repaired with (1) autografts, (2) decellularized allografts, and (3) decellularized allografts wrapped with a superficial inferior epigastric artery fascial flap to add surgical angiogenesis. Twelve and 16 weeks after surgery, nerve regeneration was assessed using functional, electrophysiologic, histologic, and immunofluorescence analyses. Ultrasonography was used during the survival period to noninvasively evaluate muscle atrophy and reinnervation by measuring cross-sectional muscle area. RESULTS: Surgical angiogenesis of allografts demonstrated significantly improved isometric tetanic force recovery at 12 weeks, compared to allograft alone, which normalized between groups at 16 weeks. Cross-sectional muscle areas showed no differences between groups. Electrophysiology showed superiority of autografts at both time points. No differences were found in histologic analysis, besides a significantly inferior N ratio in allografts at 12 weeks. Immunofluorescent expression of CD34, indicating vascularity, was significantly enhanced in the superficial inferior epigastric artery fascial group compared to allografts at 12 weeks, with highest expression at 16 weeks compared to all groups. CONCLUSION: Surgical angiogenesis with an adipofascial flap to the nerve allograft increases vascularity in the nerve graft, with subsequent improvement of early muscle force recovery, comparable to autografts.

The Transition to Microsurgical Technique for Hepatic Artery Reconstruction in Pediatric Liver Transplantation.

BACKGROUND: Hepatic artery thrombosis represents a potentially fatal complication following liver transplantation. Rates of hepatic artery thrombosis are significantly higher in children, with mortality reported up to 80 percent. Microsurgical anastomosis has been shown to decrease the rate of hepatic artery thrombosis and now represents the standard of care at the authors' institution. In this article, the authors present the largest study of its type directly comparing rates of hepatic artery thrombosis with and without microsurgical reconstruction of the hepatic artery. METHODS: All pediatric patients who underwent primary orthotopic liver transplantation between 1989 and 2018 were included. Patients were divided into two cohorts: standard anastomosis with loupes, and microsurgical anastomosis under the operating microscope. The authors' primary outcome was the rate of hepatic artery thrombosis. Secondary outcomes were graft survival, patient survival, retransplantation rate, requirement for intraoperative blood products, and length of stay. RESULTS: Two hundred thirty-one children met criteria for inclusion. One hundred eighty cases were performed with loupe magnification and 51 cases were performed under the microscope. The hepatic artery thrombosis rate was lower, but not significantly so (p = 0.114), in the microsurgical group [n = 1 (2.0 percent)] compared with the standard cohort [n = 15 (8.3 percent)]. Survival analysis revealed a significant increase in graft survival with microsurgical anastomosis (p = 0.020), but not patient survival (p = 0.196). The retransplantation rate was significantly lower with microsurgical anastomosis (p = 0.021). CONCLUSIONS: Microsurgical anastomosis was associated with a clinically important decrease in hepatic artery thrombosis compared with standard loupe anastomosis. The graft survival rate was significantly higher in the microsurgical cohort, with a reduced retransplantation rate at 1 year. On this basis, the authors recommend microsurgical hepatic artery anastomosis in cases of pediatric liver transplantation. . CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Early critical cortical infarction by anti-angiotensin II type 1 receptor antibody: A case report and literature review.

RATIONALE: Anti-angiotensin II type 1 receptor antibodies (AT1R-Abs) have been demonstrated to increase the risk of antibody-mediated rejection. We report a case of AT1R-Ab mediated rejection which caused early critical cortical infarction. PATIENT CONCERNS: A 52-year-old man with end-stage kidney disease underwent preemptive kidney transplantation (KT) from his wife. He had no immunologic risk except ABO incompatibility. Proper desensitization treatment were applied prior to KT. On postoperative day 1, he showed stable clinical course with adequate urine output, but there was no decrease in serum creatinine level and imaging studies showed hypoperfusion in the transplanted kidney. DIAGNOSES: Allograft biopsy revealed total cortical infarction with severe necrotizing vasculitis, but the medullary area was preserved. Serum AT1R-Ab concentration was elevated from 10.9 U/mL before KT to 19.1 U/mL on 7 days after KT. INTERVENTIONS: He was treated with plasmapheresis, intravenous immunoglobulin, rituximab, high-dose methylprednisolone, and bortezomib. OUTCOMES: The treatment showed a partial response, and he was discharged with 7.3 mg/dL creatinine level. At 4 months, his creatinine plateaued at 5.5 mg/dL and AT1R-Ab decreased to 3.6 U/mL. LESSONS: This case highlights the risk of early active antibody-mediated rejection by preformed AT1R-Ab, suggesting its ability to exhibit atypical histopathologic findings, such as total cortical infarction.

Splenic Artery Transposition for Arterial Reconstruction in Living Donor Liver Transplantation.

PURPOSE: In living donor liver transplantation, poor compatibility of the recipient hepatic artery remains a technical challenge. Here, we analyzed our 14 years of experience with extra-anatomic hepatic artery reconstruction. METHODS: Between July 2004 and December 2018, there were 1063 liver transplantations at our center. All patients with an extra-anatomic hepatic artery reconstruction were identified. The gastroduodenal artery and the transposed splenic artery were the primary options for extra-anatomic arterial reconstruction. Patient characteristics, operative data, and post-transplant outcome were reviewed retrospectively. RESULTS: There were 22 patients with extra-anatomic hepatic artery reconstruction, 6 with gastroduodenal artery, and 16 with splenic artery. There were 2 major complications: 1 patient underwent early reoperation due to bleeding from the splenic artery trunk and another had an iatrogenic injury to the transposed splenic artery during conversion hepaticojejunostomy. Both were treated successfully with surgery. One patient died perioperatively due to sepsis. The 1- and 3-year graft survival rates of these 16 patients were 93.7% and 87.5%. CONCLUSION: If the hepatic arteries are not suitable for anastomosis, then we consider the gastroduodenal artery and the splenic artery to be the conduits of choice for extra-anatomic arterial reconstruction. The transposed splenic artery is very consistent, easily accessible, and offers adequate length and diameter for successful arterial anastomosis.

Liver transplantation in patients with portal vein thrombosis: A strategic road map throughout management.

BACKGROUND: Liver transplantation in the setting of portal vein thrombosis is an intricate issue that occasionally necessitates extraordinary procedures for portal flow restoration. However, to date, there is no consensus on a persistent management strategy, particularly with extensive forms. This work aims to introduce our experience-based surgical management algorithm for portal vein thrombosis during liver transplantation and to clarify some of the debatable circumstances associated with this problematic issue. METHODS: Between 2006 and 2019, 494 adults underwent liver transplantation at our institute. Ninety patients had preoperative portal vein thrombosis, and 79 patients underwent living donor liver transplantation. Our algorithm trichotomized the management plan into 3 pathways based on portal vein thrombosis grade. The surgical procedures implemented included thrombectomy, interposition vein grafts, jump grafts from the superior mesenteric vein, jump grafts from a collateral and renoportal anastomosis in 56, 13, 11, 4, and 2 patients, respectively. Four patients with mural thrombi did not require any special intervention. RESULTS: Thirteen patients experienced posttransplant portal vein complications. They all proved to have a patent portal vein by the end of follow-up regardless of the management modality. No significant survival difference was observed between cohorts with versus without portal vein thrombosis. The early graft loss rate was significantly higher with advanced grades (P = .048) as well as technically demanding procedures (P = .032). CONCLUSION: A stepwise broad-minded strategy should always be adopted when approaching advanced portal vein thrombosis during liver transplantation. An industrious preoperative evaluation should always be carried out to locate the ideal reliable source for portal flow restoration.

Peripheral Donor-specific Antibodies Are Associated With Histology and Cellular Subtypes in Protocol Liver Biopsies of Pediatric Recipients.

BACKGROUND: The cellular infiltrate in protocol liver biopsies (PB) following pediatric liver transplantation remains mostly uncharacterized, yet there is increasing concern about the role of inflammation and fibrosis in long-term liver allografts. We aimed to define cell types in PB and to analyze their relationship with donor-specific antibodies (DSA) and histological phenotype. METHODS: PB were performed at least 1 year after transplantation. We identified 4 phenotypes: normal, fibrosis, inflammation, inflammation with fibrosis. Cell types were counted after immunostaining for CD3, CD4, CD8, CD68, CD20, MUM1, and FoxP3. RESULTS: Forty-four patients underwent 1 PB between 2000 and 2015. Eleven percent (5/44) of PB displayed normal histology, 13.6% (6/44) fibrosis, 34.1% (15/44) inflammation, and 40.9% (18/44) inflammation and fibrosis. The main cell types in the portal tracts and lobules were CD3+ and CD68+ cells. Frequency of de novo DSA was 63% (27/44). The presence of CD8+ cells in the lobules was associated with fibrosis. Inflammation and fibrosis in PB were associated with the presence of circulating de novo DSA, number of de novo DSA, and C1q binding activity when compared to other phenotypes. CONCLUSIONS: T cells (CD3+) and macrophages (CD68+) were the most prevalent cell-types in PB. In the presence of inflammation, portal tracts were enriched in CD3+, CD20+ but displayed fewer CD68+. This coincided with the presence and number of de novo DSA. How these cellular and humoral actors interact is unclear, but peripheral DSA may be a marker of immune cellular activity in the seemingly quiescent allograft.

Normothermic Machine Perfusion Combined with Bone Marrow Mesenchymal Stem Cells Improves the Oxidative Stress Response and Mitochondrial Function in Rat Donation After Circulatory Death Livers.

There is a need to improve the quality of donor liver from donation after circulatory death (DCD). The purpose of this study was to investigate the effects and mechanism of normothermic machine perfusion (NMP) combined with bone marrow mesenchymal stem cells (BMMSCs) on the oxidative stress and mitochondrial function in DCD livers. DCD livers were obtained, a rat NMP system was established, and BMMSCs were extracted and identified. The DCD livers were grouped by their preservation method: Normal, static cold storage (SCS), NMP (P), and NMP combined with BMMSCs (PB), and the preservation time was up to 8 h. An IAR20 cell oxidative stress injury model was established in vitro by simulating DCD oxidative stress injury and coculturing with BMMSCs for 6 h. Compared with SCS group, after 6 h in vitro, the PB and P groups had significantly improved liver function and liver histological damage, reduced hepatocyte apoptosis and oxidative stress, improved hepatocyte mitochondrial damage, and increased mitochondrial membrane potential. These indicators were significantly better in the PB group than in the P group. BMMSCs significantly inhibited reactive oxygen species release from the IAR20 cell oxidative stress model in vitro, ameliorated mitochondrial damage, and increased mitochondrial membrane potential level. BMMSCs also downregulated the JUN N-terminal kinase-nuclear factor kappa B (JNK-NF-κB) signaling pathway significantly in the IAR20 cell oxidative stress model and promoted AMP-activated protein kinase (AMPK) activation. We verified that NMP combined with BMMSCs also played the same role in the PB group. NMP combined with BMMSCs could improve liver quality by relieving oxidative stress injury and improving mitochondrial function in rat DCD livers. The mechanism of protective role might involve inhibiting the JNK-NF-κB pathway to reduce oxidative stress and promote AMPK activation, thereby reducing mitochondrial damage and increase mitochondrial function.

Normothermic Ex Vivo Liver Perfusion Prevents Intrahepatic Platelet Sequestration After Liver Transplantation.

BACKGROUND: The detrimental role of platelets in sinusoidal endothelial cell (SEC) injury during liver transplantation (LT) has been previously addressed after static cold storage (SCS), however, it is currently unknown after normothermic ex vivo liver perfusion (NEVLP). METHODS: Pig LT was performed with livers from heart-beating donors or donation after circulatory death (DCD) donors subjected to SCS or NEVLP (n = 5/group). RESULTS: All pigs except for 1 (DCD-SCS-group) survived 4 days. The heart-beating donor- and DCD-NEVLP-groups showed significantly lower aspartate transaminase-levels compared with the SCS-groups 3 hours post-LT (P = 0.006), on postoperative day (POD) 2 (P = 0.005), POD3 (P = 0.007), and on POD4 (P = 0.012). Post-LT total platelet count recovered faster in the NEVLP than in the SCS-groups at 12 hours (P = 0.023) and 24 hours (P = 0.0038). Intrahepatic sequestration of platelets was significantly higher in the SCS-groups 3 hours postreperfusion and correlated with severity of SEC injury. In both SCS-groups, levels of tumor growth factor-ß were higher 3 hours post-LT, on POD1 and on POD3. Moreover, platelet factor 4 levels and platelet-derived extracellular vesicles were increased in the SCS-groups. Hyaluronic acid levels were significantly higher in the SCS-groups, indicating a higher grade of endothelial cell dysfunction. Platelet inhibition achieved by pretreatment with clopidogrel (n = 3) partly reversed the detrimental effects on SEC injury and therefore provided further evidence of the important role of platelets in ischemia/reperfusion injury and SEC injury. CONCLUSIONS: Normothermic perfusion of liver grafts before transplantation effectively reduced platelet aggregation and SEC injury, which translated into an improved posttransplant organ function.

The Association Between Cytomegalovirus Infection and Cardiac Allograft Vasculopathy in the Era of Antiviral Valganciclovir Prophylaxis.

BACKGROUND: Previous studies on the association between cytomegalovirus (CMV) infection and cardiac allograft vasculopathy (CAV) were conducted on patients transplanted in the prevalganciclovir prophylaxis era. The aim of our study is to evaluate this relation in heart transplantation (HTx) recipients treated according to current prophylactic and immunosuppressive regimens. METHODS: This single-center retrospective study included all consecutive adult patients that underwent HTx between January 1, 2000, and May 31, 2018. Clinically relevant CMV infection was defined as either plasma CMV DNAemia ≥ 1000 IU/mL with/without clinical symptoms or <1000 IU/mL with symptoms. The primary endpoint was first manifestation of CAV diagnosed by coronary angiography. For statistical analysis, the cause-specific hazard regression model was applied, with clinically relevant CMV infection and any CMV infection as time-dependent variables. RESULTS: In total, 260 patients were included in the analysis. The median (interquartile range) follow-up was 7.88 (4.21-12.04) years. During the follow-up, clinically relevant CMV infection was diagnosed in 96 (37%) patients and CAV in 149 (57%) patients. In the multivariate regression analysis, independent predictors of CAV were: number of rejection episodes (cause-specific hazard ratio [95% confidence interval]: 1.18 [1.04-1.34], P = 0.01), hypertension (1.61 [1.11-2.34], P = 0.01), treatment with mycophenolate mofetil (0.68 [0.47-0.97], P = 0.03). No significant association was observed between CMV infection and CAV, except for patients who experienced a breakthrough CMV infection (n = 24) during prophylaxis (1.94 [1.11-3.40], P = 0.02). CONCLUSIONS: In the era of contemporary immunosuppression and valganciclovir prophylaxis, a significant effect of CMV infection on the risk of CAV was seen only among HTx recipients with CMV breakthrough infection.

Bronchial-arterial-circulation-sparing Lung Preservation: A New Organ Protection Approach for Lung Transplantation.

BACKGROUND: Compromised microvasculature resulting from disrupted bronchial arterial circulation appears to trigger chronic lung allograft dysfunction. Maintaining the microvasculature throughout the transplant process could improve the long-term health of transplanted lungs. We recently developed a bronchial-arterial-circulation-sparing (BACS) lung preservation approach and tested whether this approach would decrease microvascular damage and improve allograft function. METHODS: The lungs of Lewis rats were procured using either the BACS approach, where the bronchial and pulmonary arteries were synchronously perfused; a conventional approach, where only the pulmonary artery was perfused; or a conventional approach with a prostaglandin flush. After 4 hours of cold ischemia, physiologic function and vascular tone of the grafts were evaluated during ex vivo lung perfusion (EVLP), and microvasculature damage was assessed using 2-photon microscopy analysis. Lung function was compared after transplant among the groups. RESULTS: After 4 hours of cold ischemia, the BACS group exhibited significantly higher adenosine triphosphate levels and lower expression of phosphorylated myosin light chain, which is essential for vascular smooth muscle contraction. On EVLP, the BACS and prostaglandin groups showed lower pulmonary vascular resistance and less arterial stiffness. BACS attenuated microvasculature damage in the lung grafts when compared with conventional preservation. After transplantation, the lungs preserved with the BACS approach exhibited significantly better graft function and lower expression of phosphorylated myosin light chain. CONCLUSIONS: Our data suggest that BACS lung preservation protects the dual circulation inherent to the lungs, facilitating robust microvasculature in lung grafts after transplantation, leading to better posttransplant outcomes.

Association of Clinical Rejection Versus Rejection on Protocol Biopsy With Cardiac Allograft Vasculopathy in Pediatric Heart Transplant Recipients.

BACKGROUND: Two or more early rejections (<1 y) or any late acute rejection (>1 y) have been associated with coronary artery vasculopathy (CAV) in pediatric heart transplant (HT) recipients. We hypothesized that clinical rejection defined by concurrent new-onset heart failure or left ventricular systolic dysfunction is more strongly associated with future CAV than rejection diagnosed on protocol biopsy. METHODS: We identified all subjects <21 years old who received first HT at Boston Children's Hospital during 1986-2015 with at least 1 post-HT coronary angiogram. CAV was diagnosed using 2010 International Society for Heart and Lung Transplantation guidelines. Time to CAV diagnosis was assessed using a Cox model with occurrence of clinical rejection analyzed as a time-varying covariate. RESULTS: Of 228 study subjects, 106 remained rejection-free, 77 had rejection diagnosed only on protocol biopsy (≥2R cellular or antibody-mediated), and 45 had a clinical rejection. Subjects with rejection diagnosed only on protocol biopsy were not at higher risk of CAV (hazard ratio [HR] 1.09, 95% confidence interval [CI]: 0.54-2.09). In contrast, clinical rejection was significantly associated with risk of CAV (HR 4.84, 95% CI: 2.99-7.83). Late rejection was associated with a higher risk of CAV (HR 4.27, 95% CI: 2.42-7.51) if it was clinical rejection but not if it was diagnosed on protocol biopsy (HR 0.83, 95% CI: 0.51-1.37). CONCLUSIONS: Clinical rejection poses a far greater risk for future CAV than rejection on protocol biopsy in pediatric HT recipients. Preventing CAV should therefore become the focus of medical management after initial treatment and resolution of clinical rejection.

Ultrasound Assessment of the Superior Capsular Reconstruction With Dermal Allograft: An Evaluation of Graft Thickness and Vascularity.

PURPOSE: To assess postoperative changes in the thickness of the dermal allograft of the superior capsular reconstruction (SCR) and to evaluate the graft for the presence of intrasubstance pulsatile vessels. METHODS: A retrospective chart review was conducted to identify SCR patients who had ultrasound evaluations between May 2014 and February 2019. Data were collected and stratified based on time from surgery into 2 groups: 0 to 12 months and past the 12-month follow-up. The primary outcome measure was graft thickness at the articular margin-greater tuberosity interface (tuberosity measurement). Secondary measures included midsubstance graft thicknesses 0.5, 1.0, and 1.5 cm medial to the tuberosity measurement; status of lateral graft fixation; presence of pulsatile vessels; and American Shoulder and Elbow Society and visual analog scale scores. RESULTS: Eighteen patients were included for analysis. The tuberosity measurement at final follow-up (mean 25 months, range 12-40 months) was (mean ± standard error [95% confidence interval (CI)]) 4.4 ± 0.2 mm (95% CI 4.0-4.8). This differed significantly from the midsubstance measurements: 0.5 cm: 3.6 ± 0.2 mm (95% CI 3.3-4.0, P = .008); 1.0 cm: 3.1 ± 0.2 mm (95% CI 2.7-3.4, P < .001); and 1.5 cm: 2.9 ± 0.2 mm (95% CI 2.6-3.2, P < .001). Ten constructs (56%) showed signs of pulsatile vessels in the first 12 months and all constructs were intact. ASES scores improved from 49.3 ± 4.0 (95% CI 41.6-57.1) preoperatively to 85.1 ± 2.9 (95% CI 79.4-90.8) (P < .001), and VAS scores decreased from 5.3 ± 0.6 (95% CI 4.2-6.5) preoperatively to 0.9 ± 0.3 (95% CI 0.3-1.5) at final follow-up (P < .001). CONCLUSIONS: The SCR dermal allograft significantly thickens at its lateral aspect, presents with evidence of vasculature in most patients in the first year of implantation, and is not resorbed by the body. LEVEL OF EVIDENCE: Level IV - therapeutic case series.

Progenitor-derived human endothelial cells evade alloimmunity by CRISPR/Cas9-mediated complete ablation of MHC expression.

Tissue engineering may address organ shortages currently limiting clinical transplantation. Off-the-shelf engineered vascularized organs will likely use allogeneic endothelial cells (ECs) to construct microvessels required for graft perfusion. Vasculogenic ECs can be differentiated from committed progenitors (human endothelial colony-forming cells or HECFCs) without risk of mutation or teratoma formation associated with reprogrammed stem cells. Like other ECs, these cells can express both class I and class II major histocompatibility complex (MHC) molecules, bind donor-specific antibody (DSA), activate alloreactive T effector memory cells, and initiate rejection in the absence of donor leukocytes. CRISPR/Cas9-mediated dual ablation of ß2-microglobulin and class II transactivator (CIITA) in HECFC-derived ECs eliminates both class I and II MHC expression while retaining EC functions and vasculogenic potential. Importantly, dually ablated ECs no longer bind human DSA or activate allogeneic CD4+ effector memory T cells and are resistant to killing by CD8+ alloreactive cytotoxic T lymphocytes in vitro and in vivo. Despite absent class I MHC molecules, these ECs do not activate or elicit cytotoxic activity from allogeneic natural killer cells. These data suggest that HECFC-derived ECs lacking MHC molecule expression can be utilized for engineering vascularized grafts that evade allorejection.

Impact of Rifaximin Therapy on Ischemia/Reperfusion Injury in Liver Transplantation: A Propensity Score-Matched Analysis.

Intestinal microbiota is thought to play an important role in hepatic ischemia/reperfusion injury (IRI) after liver transplantation (LT). Rifaximin, a nonabsorbable antibiotic used to treat encephalopathy, exhibits antibacterial activity within the gut. We report the first study examining the impact of pre-LT rifaximin use on reducing hepatic IRI and inflammatory cell infiltration after LT. This retrospective single-center study included adult LT recipients from January 2013 through June 2016. Patients were divided into 2 groups based on duration of rifaximin use before LT: rifaximin group (≥28 days) and control group (none or <28 days). Patients receiving other antibiotics within 28 days of LT and re-LTs were excluded. Outcomes and messenger RNA (mRNA) expression in the graft were compared by 1:1 propensity score-matching and multivariate analyses. On 1:1 matching (n = 39/group), rifaximin patients had lower postoperative serum transaminase levels and lower early allograft dysfunction (EAD; 10.3% versus 33.3%; P = 0.014). Of the matched patients, 8 patients (n = 4/group) had postreperfusion liver biopsies (approximately 2 hours after reperfusion) available for mRNA analysis. Hepatic expression of CD86 (macrophage marker) and cathepsin G (neutrophil marker) was significantly lower in rifaximin patients than controls (P < 0.05). The multivariate analysis included 458 patients. Rifaximin treatment <28 days was identified as an independent risk factor EAD in all patients and those with high Model for End-Stage Liver Disease (MELD) score (MELD ≥35; n = 230). In conclusion, the propensity score-matched and multivariate analyses suggest a therapeutic role of rifaximin in reducing EAD. Pre-LT rifaximin administration exerted a protective function against early liver injury, potentially by suppressing inflammatory cell activation in the graft.

Pediatric extremity bone sarcoma reconstruction with the vascularized fibula flap: Observational study assessing long-term functional outcomes, complications, and survival.

BACKGROUND: Limb salvage is important in pediatric patients with bone sarcomas. The vascularized fibula flap is a versatile option, combined or not with a bone allograft. The authors evaluated the functional long-term outcomes, complications, and survival of using this technique in pediatric patients. METHODS: A retrospective review of 27 pediatric patients reconstructed between 2011 and 2018 with the fibula flap after bone sarcoma resection was conducted. Long-term functional outcomes, complications, and survival were assessed. Variables analyzed were age, sex, Capanna technique, follow-up, complications, additional surgeries, time to weight bearing, length discrepancy, and sport practice. RESULTS: Twenty-seven patients with a mean age of 9.3 years were included. The mean follow-up was 44.33 months. The Capanna technique was performed in 15 patients. All extremities but one were salvaged. The overall complication rate was 74.07%. Fibula fracture and nonunion rates were 34.04% and 11.11%, respectively. Partial weight bearing was resumed at a mean of 9.07 months. About 79.17% of patients with a 12-month follow-up achieved full weight bearing. An age below 8 years was significantly associated with a lower major complication rate and a shorter time to weight bearing and full weight bearing. Major complications and additional surgeries were significantly associated with longer periods until weight bearing and full weight bearing. CONCLUSIONS: The fibula flap allows the majority of extremities to be reconstructed. However, a high rate of complications and additional surgeries should be anticipated. Full weight bearing is usually achieved within the first year, with modest functional increase afterward. Less complications and a faster functional recovery are expected in patients below the age of 8 years.

Impact of Temporary Portocaval Shunting and Initial Arterial Reperfusion in Orthotopic Liver Transplantation.

The use of a temporary portocaval shunt (TPCS) as well as the order of reperfusion (initial arterial reperfusion [IAR] versus initial portal reperfusion) in orthotopic liver transplantation (OLT) is controversial and, therefore, still under debate. The aim of this study was to evaluate outcome for the 4 possible combinations (temporary portocaval shunt with initial arterial reperfusion [A+S+], temporary portocaval shunt with initial portal reperfusion, no temporary portocaval shunt with initial arterial reperfusion, and no temporary portocaval shunt with initial portal reperfusion) in a center-based cohort study, including liver transplantations (LTs) from both donation after brain death and donation after circulatory death (DCD) donors. The primary outcome was the perioperative transfusion of red blood cells (RBCs), and the secondary outcomes were operative time and patient and graft survival. Between January 2005 and May 2017, all first OLTs performed in our institution were included in the 4 groups mentioned. With IAR and TPCS, a significantly lower perioperative transfusion of RBCs was seen (P < 0.001) as well as a higher number of recipients without any transfusion of RBCs (P < 0.001). A multivariate analysis showed laboratory Model for End-Stage Liver Disease (MELD) score (P < 0.001) and IAR (P = 0.01) to be independent determinants of the transfusion of RBCs. When comparing all groups, no statistical difference was seen in operative time or in 1-year patient and graft survival rates despite more LTs with a liver from a DCD donor in the A+S+ group (P = 0.005). In conclusion, next to a lower laboratory MELD score, the use of IAR leads to a significantly lower need for perioperative blood transfusion. There was no significant interaction between IAR and TPCS. Furthermore, the use of a TPCS and/or IAR does not lead to increased operative time and is therefore a reasonable alternative surgical strategy.