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In the past 20 years, the number of patients in the United States who died while waiting for a human donor liver totaled >52 000. The median national wait-time for patients with acute liver failure and the most urgent liver transplant listing was 7 days in 2018. The need for a clinical 'bridge' to allotransplantation is clear. Current options for supporting patients with acute liver failure include artificial liver support devices, extracorporeal liver perfusion, and hepatocyte transplantation, all of which have shown mixed results with regard to survival benefit and are largely experimental. Progress in the transplantation of genetically-engineered pig liver grafts in nonhuman primates has grown steadily, with survival of the pig graft extended to almost 1 month in 2017. Further advances may justify consideration of a pig liver transplant as a clinical bridge to allotransplantation. We provide a brief history of pig liver xenotransplantation, summarize the most recent progress in pig-to-nonhuman primate liver transplantation models, and suggest criteria that may be considered for patient selection for a clinical trial of bridging by genetically-engineered pig liver xenotransplantation to liver allotransplantation.

Increased lymphangiogenesis and lymph node metastasis, the important prognostic indicators of aggressive hepatobiliary malignancies such as hepatocellular cancer and cholangiocarcinoma, are associated with poor patient outcome. The liver produces 25% to 50% of total lymphatic fluid in the body and has a dense network of lymphatic vessels. The lymphatic system plays critical roles in fluid homeostasis and inflammation and immune response. Yet, lymphatic vessel alterations and function are grossly understudied in the context of liver pathology. Expansion of the lymphatic network has been documented in clinical samples of liver cancer; and although largely overlooked in the liver, tumor-induced lymphangiogenesis is an important player, increasing tumor metastasis in several cancers. This review aims to provide a detailed perspective on the current knowledge of alterations in the hepatic lymphatic system during liver malignancies, as well as various molecular signaling mechanisms and growth factors that may provide future targets for therapeutic intervention. In addition, the review also addresses current mechanisms and bottlenecks for effective therapeutic targeting of tumor-associated lymphangiogenesis.

Background Positive crossmatch (XM+) combined liver–kidney transplantation due to preformed donor-specific human leukocyte antigen antibodies has produced mixed results. We sought to understand the role of delayed kidney transplant approach in XM+ combined liver–kidney transplantations. Methods XM+ combined liver–kidney transplantations were retrospectively reviewed. T- and B-cell XM, complement-dependent cytotoxic crossmatch, and flow cytometric crossmatch were performed prospectively. Results Of 183 combined liver-kidney transplantations performed (2002–2019), 114 (62%) were with “delayed” kidney transplant approach and 19 (19 of 183, 10%) were XM+. Of 19 XM+ combined liver–kidney transplantations, kidney transplant was “delayed” in 14 by an average of 47 hours (range 24–64 hours) from liver transplant. There was a significant reduction in both class I (mean pre–liver transplant mean fluorescence intensity (MFI) 26,230 versus mean post–liver transplant and pre–delayed kidney transplant MFI 3,272, P = .01) and total MFI (mean pre–liver transplant MFI 27,233 vs mean post liver transplant and predelayed kidney transplant MFI 11,469, P = .01). However, there was no significant change in the MFI of class II donor-specific antibodies (mean pre–liver transplant MFI 17,899 versus post-liver transplant and pre–delayed kidney transplant MFI 14,341, P = .19). None of XM+ delayed kidney transplants had delayed graft function, and there was no antibody-mediated rejection. One-year patient survival for the XM+ combined liver–kidney transplantation with delayed kidney transplant approach was 92.9%, which is comparable to patient survival of XM– combined liver–kidney transplantation. Whereas patient survival in recipients before “delayed” approach (“simultaneous”; n = 5) was 40% when liver–kidney transplants were performed simultaneously (P = .06). Conclusion In sensitized combined liver-kidney transplantation recipients, the “delayed” kidney transplant approach is associated with a significant reduction in total and class I donor-specific antibodies after liver transplant before kidney transplant, enabling therapeutic interventions such as plasmapheresis, if needed, providing optimal outcomes similar to crossmatch recipients.

PURPOSE OF REVIEW To review the impact of delayed kidney transplantation approach in combined (simultaneous) liver-kidney transplantation (CLKT). RECENT FINDINGS CLKT offers a life-saving procedure for patients with both end-stage liver disease and chronic kidney disease or prolonged acute kidney injury. It is the most common multiorgan transplant procedure in the US accounting for 9-10% of all liver transplants performed. The number of CLKT has also been increasing in other countries with a better understanding of hepato-renal syndrome. US is the only country which implemented a national allocation policy for CLKT in 2017. Due to the different physiological needs of liver and kidney allografts immediately after transplantation, delayed kidney transplantation approach in CLKT has been introduced for the first time by the Indiana Group, naming it as 'the Indiana Approach'. Over the years, many other groups in the US and in Europe published better outcomes in CLKT using the delayed kidney transplantation approach with the support of hypothermic machine perfusion. SUMMARY Several groups have shown that delayed kidney transplantation in CLKT is a safe procedure with better outcomes in graft(s) and patient survival.

Background Incisional hernia (IH) is a well-known complication of orthotopic liver transplantation. Despite wide recognition of the impact of this problem, the incidence remains imprecisely known. Methods The MEDLINE, EMBASE, Cochrane Central Register of Clinical Trials and Cochrane Database of Systematic Reviews databases were searched from their inception to November 2017 for abstracts documenting IH after orthotropic liver transplantation (OLT). The primary endpoint of this study was incidence of IH, secondary endpoints were time to hernia and recurrence. Three reviewers independently graded abstracts for inclusion in this review. Heterogeneity in combining data was assumed prior to pooling. Random-effects meta-analyses were performed to estimate percentages and 95% CIs. Results After a review of 77 abstracts, 18 studies were graded as relevant. The methodological quality of studies was assessed with a minimum Oxford Centre for Evidence-Based Medicine level of 2B. These represent a cohort of 981 patients with IH after OLT reported in the literature. A meta-analysis of studies meeting inclusion criteria shows mean incidence of 15.1% (CI 12.1%-18.2%). Aggregate recurrence rate reported in the literature is 12.4% (CI 4.3%-20.5%). Overall reported time to IH after OLT was 42.9 months. Conclusions Although reported incidences of IH after OLT vary widely across studies, an overall incidence of 15.1% is reported. This is a relatively late complication after transplantation. Recurrence of hernia after initial repair is 12.4% within this patient population.

Background Intestinal transplantation (ITx) is performed as an isolated ITx or as a part of multivisceral transplantation for intestinal failure secondary to short gut syndrome, inflammatory bowel disease, trauma, and sequelae of chronic parenteral nutrition dependence. Wound complications after ITx are very common, and abdominal wound closure cannot be immediately achieved in half of cases. Case presentation A 25-year-old man sustained an abdominal crush injury causing complete loss of his small intestine, requiring an isolated ITx in March 2016. He lost his graft because of early exfoliative rejection in November 2016. Five months after enterectomy and the immunosuppression-free period, he underwent multivisceral retransplantation in April 2017. His post-transplant course was complicated by wound healing problems that improved with treatment of his malnutrition, quantified by increasing albumin, total protein, prealbumin, weight, body mass index, and total psoas muscle area over a period of 19 months after retransplant. Conclusion To our knowledge, this is the first case described of long-term wound follow-up after a multivisceral (re)transplantation, with corresponding nutrition information and images of the wound.

Autoimmune enteropathy is a rare disease characterized by chronic watery diarrhea, weight loss, and immune-mediated injury of the enterocolic mucosa. The clinicopathologic findings of this disease are variable, and timely diagnosis is challenging. It is usually managed medically. If medical management fails, surgical intervention is considered. This is a case report of a patient with autoimmune enteropathy mimicking collagenous enterocolitis. A 55-year-old man developed intestinal failure that manifested as profuse watery diarrhea, electrolyte disturbances, and weight loss. Initially, he was diagnosed with collagenous enterocolitis based on pathologic findings. Medical interventions were started, but the patient failed to show improvement. At 13 months after the onset of the disease, he was listed for isolated intestine transplantation (IITX) for intestinal failure. A healthy donor graft became available. IITX with chimney colostomy was performed. Based on the pathologic findings of the excised native small intestine, the patient was diagnosed with severe autoimmune enteropathy. The postoperative course was uneventful. By the third postoperative week, a full diet was tolerated and parenteral nutrition (PN) was weaned to end. He was discharged on postoperative day 34. Since discharge, he has been off PN, remaining on an enteral diet. This case is the first reported IITX performed on a patient with severe autoimmune enteropathy that was both curative and lifesaving. The present case confirms that IITX promptly restores gastrointestinal absorption in medically refractory autoimmune enteropathy. This observation provides clinicians with an effective treatment option in this challenging group of patients.

Chronic alcohol consumption is linked to the development of alcohol-associated liver disease (ALD). This disease is characterized by a clinical spectrum ranging from steatosis to hepatocellular carcinoma. Several cell types are involved in ALD progression, including hepatic macrophages. Kupffer cells (KCs) are the resident macrophages of the liver involved in the progression of ALD by activating pathways that lead to the production of cytokines and chemokines. In addition, KCs are involved in the production of reactive oxygen species. Reactive oxygen species are linked to the induction of oxidative stress and inflammation in the liver. These events are activated by the bacterial endotoxin, lipopolysaccharide, that is released from the gastrointestinal tract through the portal vein to the liver. Lipopolysaccharide is recognized by receptors on KCs that are responsible for triggering several pathways that activate proinflammatory cytokines involved in alcohol-induced liver injury. In addition, KCs activate hepatic stellate cells that are involved in liver fibrosis. Novel strategies to treat ALD aim at targeting Kupffer cells. These interventions modulate Kupffer cell activation or macrophage polarization. Evidence from mouse models and early clinical studies in patients with ALD injury supports the notion that pathogenic macrophage subsets can be successfully translated into novel treatment options for patients with this disease.

Gastrointestinal complications are common after renal transplantation, and they have a wide clinical spectrum, varying from diarrhoea to post-transplant inflammatory bowel disease (IBD). Chronic immunosuppression may increase the risk of post-transplant infection and medication-related injury and may also be responsible for IBD in kidney transplant re-cipients despite immunosuppression. Differentiating the various forms of post-transplant colitis is challenging, since most have similar clinical and histological features. Drug-related colitis are the most frequently encountered colitis after kidney transplantation, particularly those related to the chronic use of mycophenolate mofetil, while de novo IBDs are quite rare. This review will explore colitis after kidney transplantation, with a particular focus on different clinical and histological features, attempting to clearly identify the right treatment, thereby improving the final outcome of patients.

The utilization of donation after circulatory death (DCD) livers has been growing over the last decade. In large-volume centers, survival outcomes have improved and are comparable to outcomes with brain death donor (DBD) liver transplantation (LT). The relatively concentrated success with DCD LT demonstrated by high-volume transplant centers has rekindled international enthusiasm. The combination of increasing expertise in DCD LT and ongoing shortage in transplantable organs has promoted expansion of the DCD donor pool with regards to donor age, body mass index and donor warm ischemia time. In this review, we focused on the practice patterns in DCD liver graft utilization in the last decade, along with the possibilities for further expansion of DCD liver graft utilization and new technologies, such as machine perfusion.

Mast cells (MCs) induce the progression of liver diseases including, but not limited to, hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), alcoholic and non-alcoholic fatty liver disease (ALD/NAFLD), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC). The effects of MCs during disease progression includes alterations in ductular reaction, steatosis, hepatic fibrosis and inflammation. In addition, there is significant crosstalk between MCs, MC mediators (histamine, tryptase, chymase) and MC-derived cytokines (transforming growth factor beta, tumor necrosis factor alpha, interleukins). Studies have been performed in rodent models, cultured cells, and human tissues to demonstrate the intracellular signaling implications of MC infiltration during liver disease. Targeting MCs may offer novel therapeutic strategies to treat liver disease. Our concise review will encompass the most recent studies involving MCs, their mediators and liver disease with the overall goal to inform the reader about the diverse role of these inflammatory immune cells in liver damage.

Background Incisional hernia repair is the most common procedure after orthotopic liver transplantation. Although enhanced recovery protocols are increasingly employed, the post–orthotopic liver transplantation patient may not benefit from all aspects of these models. The aim of the present study is to assess which perioperative interventions and patient factors affect hospital length of stay in a cohort of post–orthotopic liver transplantation patients undergoing incisional hernia repair. Methods We conducted a retrospective review of a series of adult patients undergoing incisional hernia repair after orthotopic liver transplantation. The primary endpoint was length of stay. Results were stratified by demographic, intraoperative, and postoperative variables. Results Eleven percent (172/1523) of patients who received orthotopic liver transplantation during the study period underwent subsequent incisional hernia repair. Median length of stay was 5 days (range 2–50). The strongest predictor of length of stay was postoperative renal function. Despite liberal intraoperative administration of volume (median 642 mL/h) and brisk intraoperative urine output (median 72 mL/h), postoperative acute kidney injury occurred in 48% of patients. Those that developed acute kidney injury received less intraoperative volume (6 vs 8.5 mL/kg/h; P = .031) and the severity of postoperative renal injury was inversely related to the amount intraoperative volume given. Conclusions In patients undergoing incisional hernia repair after orthotopic liver transplantation, postoperative renal function is frequently impaired. Although many aspects of current ERAS protocols may be applied to post-transplant patients, restrictive intraoperative fluid administration strategies should be employed with caution given a high propensity for the development of post-operative acute kidney injury in this complex population., Highlights • Eleven percent (172/1523) of patients who received OLT during the years 2005 to 2016 underwent subsequent IHR. • The strongest predictor of length of stay in this population was postoperative renal function. • Despite liberal intraoperative administration of volume (median 642 mL/h; 7 mL/kg/h) and brisk intraoperative urine output (median 72 mL/h), postoperative acute kidney injury (AKI) occurred in 48% of patients. • Those that developed AKI received less intraoperative volume (6 vs 8.5 mL/kg/h; P = .031) and the severity of postoperative renal injury was inversely related to intraoperative volume

PURPOSE OF REVIEW: To review the impact of a new technology, 3D-bioprinting, in xenotransplantation research. RECENT FINDINGS: Genetically-engineered pigs, beginning with human (h) CD55-transgenic and Gal-knockout pigs, have improved the outcomes of xenotransplantation research. Today, there are >30 different genetically-engineered pigs either expressing human gene(s) or lacking pig gene(s). CRIPSR/cas9 technology has facilitated the production of multigene pigs (up to 9-genes in a single pig) which lack multiple pig xenoantigens, and express human transgenes, such as hCD46, hCD55, hThrombomodulin, hCD39, etc. Although recent studies in nonhuman primates (NHPs) have demonstrated prolonged survival after life-supporting pig kidney, heart, and islet xenotransplantation, researchers have difficulty determining the best genetic combination to test in NHPs due to a potential >100,000 genetic combinations. 3D-bioprinting of genetically-engineered pig cells (i) is superior to 2D in vitro testing, (ii) enables organ-specific testing, (iii) helps to understand differences in immunogenicity between organs, and (iv) is faster and cheaper than testing in NHPs. Moreover, 3D-bioprinted cells can be continuously perfused in a bioreactor, controlling for all variables, except the studied variable. SUMMARY: 3D-bioprinting can help in the study of the impact of specific genes (human or pig) in xenotransplantation in a rapid, inexpensive, and reliable way.

BACKGROUND Serum sodium (Na) is considered to reflect the severity of liver cirrhosis. In the last few years, much effort has been made to integrate this association into prognostic models after liver transplantation. The aim of this study was to investigate the associations between peritransplant Na and neurological complications, as well as short-term survival, after liver transplantation. MATERIAL AND METHODS A total of 306 liver transplantations between 2012 and 2015 were evaluated. Pre- and posttransplant sodium concentrations were investigated with regard to 3-month survival and incidence of posttransplant neurological complications, along with other factors present in the operative side of the recipient and donor. RESULTS The 3-month survival rate was 94%. Neither hyponatremia (130 mEq/L) nor hypernatremia (145 mEq/L) at pretransplantion predicted 3-month survival. A large amount of intraoperative blood transfusion and a large delta Na showed a significant association with poor outcomes at 3 months. On multivariate analysis, the requirement of blood transfusion and warm ischemia time remained independent prognostic factors for 3-month mortality. Hyponatremia and a large delta Na tended to lead to the frequent development of neurological complications. These complications, secondary to rapid Na correction, were concerning and potentially led to a prolonged hospital stay and early mortality. CONCLUSIONS Rapid change in the sodium level might be caused by large amounts of blood transfusion products. This leads to a diminished short-term survival, as well as a higher rate of neurological complications.

Use of donation after circulatory death (DCD) donor livers for transplantation has remained cautious in the United States. The aim of this study was to demonstrate the expansion of a DCD liver transplantation (LT) program with the use of extended criteria donor (ECD) DCD livers. After institutional review board approval, 135 consecutive DCD LTs were retrospectively studied. ECD DCD livers were defined as those with 1 of the following factors: donor age >50 years, donor body mass index >35 kg/m2 , donor functional warm ischemia time >30 minutes, and donor liver macrosteatosis >30%. An optimization protocol was introduced in July 2011 to improve outcomes of DCD LT, which included thrombolytic donor flush and efforts to minimize ischemia times. The impact of this protocol on outcomes was evaluated in terms of graft loss, ischemic cholangiopathy (IC), and change in DCD LT volume. Of 135 consecutive DCD LTs, 62 were ECD DCDs. In total, 24 ECD DCD LTs were performed before (era 1) and 38 after the institution of optimization protocol (era 2), accounting for an increase in the use of ECD DCD livers from 39% to 52%. Overall outcomes of ECD DCD LT improved in era 2, with a significantly lower incidence of IC (5% versus 17% in era 1; P = 0.03) and better 1-year graft survival (93% versus 75% in era 1; P = 0.07). Survival outcomes for ECD DCD LT in era 2 were comparable to matched deceased donor LT. With the expansion of the DCD donor pool, the number of DCD LTs performed at our center gradually increased in era 2 to account for >20% of the center's LT volume. In conclusion, with the optimization of perioperative conditions, ECD DCD livers can be successfully transplanted to expand the donor pool for LT.

BACKGROUND & AIMS: Human non-alcoholic fatty liver disease (NAFLD) is characterized at early stages by hepatic steatosis, which may progress to nonalcoholic steatohepatitis (NASH) when the liver displays microvesicular steatosis, lobular inflammation, and pericellular fibrosis. The secretin (SCT)/secretin receptor (SCTR) axis promotes biliary senescence and liver fibrosis in cholestatic models through downregulation of miR-125b signaling. We aim to evaluate the effect of disrupting biliary SCT/SCTR/miR-125b signaling on hepatic steatosis, biliary senescence and liver fibrosis in NAFLD/NASH. APPROACH & RESULTS: In vivo, 4 wk male WT, Sct(-/-) and Sctr(-/-) mice were fed a control diet (CD) or high-fat diet (HFD) for 16 wks. The expression of SCT/SCTR/miR-125b axis was measured in human NAFLD/NASH liver samples and HFD mouse livers by immunohistochemistry (IHC) and qPCR. Biliary/hepatocyte senescence, ductular reaction and liver angiogenesis were evaluated in mouse liver and human NAFLD/NASH liver samples. miR-125b target lipogenesis genes in hepatocytes were screened and validated by custom RT(2) Profiler PCR array and luciferase assay. Biliary SCT/SCTR expression was increased in human NAFLD/NASH samples and in livers of HFD mice, whereas the expression of miR-125b was decreased. Biliary/hepatocyte senescence, ductular reaction, and liver angiogenesis were observed in human NAFLD/NASH samples as well as HFD mice, which were decreased in Sct(-/-) and Sctr(-/-) HFD mice. Elovl1 is a lipogenesis gene targeted by miR-125b, and its expression was also decreased in HFD mouse hepatocytes following Sct or Sctr knockout. Bile acid profile in fecal samples have the greatest changes between WT mice and Sct(-/-)/Sctr(-/-) mice. CONCLUSION: The biliary SCT/SCTR/miR-125b axis promotes liver steatosis by upregulating lipid biosynthesis gene Elovl1. Targeting the biliary SCT/SCTR/miR-125b axis may be key for ameliorating phenotypes of human NAFLD/NASH.

One of the most feared complications in liver transplantation is hepatic arterial thrombosis (HAT). The incidence of HAT in liver transplantation varies from 1.2% and 8%. One of the risk factors for this complication is anatomical complexity of hepatic arterial system. The focus of this short communication is to show our approach in dealing with aberrant left hepatic artery in settings of liver transplantation. This is a single center experience. Between January 2016 and June 2019, we procured and transplanted 357 adult liver allografts. Of these, there were 34 (9.5%) livers with aberrant left hepatic artery. All of them have been reconstructed on bench table. There was no incidence of HAT in the entire cohort with ALHA. The one-year graft survival for this patient cohort was 93.1%. Our surgical approach resulted in a low incidence of HAT of 1% with excellent graft survival.

BACKGROUND AND AIMS: Nonalcoholic fatty liver disease (NAFLD) is simple steatosis but can develop into nonalcoholic steatohepatitis (NASH), characterized by liver inflammation, fibrosis, and microvesicular steatosis. Mast cells (MCs) infiltrate the liver during cholestasis and promote ductular reaction (DR), biliary senescence, and liver fibrosis. We aimed to determine the effects of MC depletion during NAFLD/NASH. APPROACH AND RESULTS: Wild-type (WT) and Kit(W-sh) (MC-deficient) mice were fed a control diet (CD) or a Western diet (WD) for 16 weeks; select WT and Kit(W-sh) WD mice received tail vein injections of MCs 2 times per week for 2 weeks prior to sacrifice. Human samples were collected from normal, NAFLD, or NASH mice. Cholangiocytes from WT WD mice and human NASH have increased insulin-like growth factor 1 expression that promotes MC migration/activation. Enhanced MC presence was noted in WT WD mice and human NASH, along with increased DR. WT WD mice had significantly increased steatosis, DR/biliary senescence, inflammation, liver fibrosis, and angiogenesis compared to WT CD mice, which was significantly reduced in Kit(W-sh) WD mice. Loss of MCs prominently reduced microvesicular steatosis in zone 1 hepatocytes. MC injection promoted WD-induced biliary and liver damage and specifically up-regulated microvesicular steatosis in zone 1 hepatocytes. Aldehyde dehydrogenase 1 family, member A3 (ALDH1A3) expression is reduced in WT WD mice and human NASH but increased in Kit(W-sh) WD mice. MicroRNA 144-3 prime (miR-144-3p) expression was increased in WT WD mice and human NASH but reduced in Kit(W-sh) WD mice and was found to target ALDH1A3. CONCLUSIONS: MCs promote WD-induced biliary and liver damage and may promote microvesicular steatosis development during NAFLD progression to NASH through miR-144-3p/ALDH1A3 signaling. Inhibition of MC activation may be a therapeutic option for NAFLD/NASH treatment. (HEPATOLOGY 2021;74:164–182).

Background: Early allograft disfunction (EAD) can be used as a tool to asses function of the liver after transplantation. Currently, most accepted EAD definition can be defined using a number of criteria including but not limited to total bilirubin > 10 mg/dL on post-operative day 7, INR > 1.6 on post-operative day 7, and ALT or AST > 2000 IU/L within the first post-operative 7 days. EAD is associated with mortality and morbidity after liver transplantation which leads to decreased recipient survival rates. It is considered a precursor step in the pathway to eventual graft loss. Methods: We have performed a literature review to understand what risk factors increase, including donor and recipient demographics as well as recipients’ MELD (Model for End Stage Liver Disease) scores, which predicts patients’ disease severity. We also compared the incidence of EAD between our center and the literature. Results: We found that incidence of EAD was between 23-40% (Table 2). It is higher when livers from donation after circulatory death (DCD) donors were used, as expected. Reference (year) Number of patients Incidence of EAD Ekser et al (2019) n = 2008 29% Olthoff et al (2010) n = 300 23% Wadei et al (2015) n = 1325 27% Lee et al (2014) n = 205 39.5% (DCD donors) Risk factors that can result in an increase occurrence of EAD were; (i) donor age, (ii) liver stenosis, (iii) expanding criteria for donor livers, (iv) prolonged warm ischemia time (WIT) and (v) cold ischemia time (CIT). Histologically, hepatocellular damage that is shown as coagulative necrosis can be seen immediately after reperfusion. Conclusions: During our literature review, potential strategies have been discovered to help prevent EAD including pharmacological treatment using glucose, antioxidants, anti-inflammatories, and apoptotic drugs. Although none of them significantly prevented the occurrence of EAD, it was clear that there are many tools that can be used to attempt to prevent EAD in order to offer a better outcome in patients undergoing liver transplantation.

Background: At the time of kidney transplantation (KT), induction immunosuppression is used to reduce the incidence of early rejection and avoid the use of chronic corticosteroids in maintenance immunosuppression. There is currently no standard of care for induction immunosuppression in the pediatric recipient, instead it is based on institutional preference. In this study, we compare our current induction immunosuppression, rabbit anti-thymocyte globulin (rATG), to our previous induction immunosuppression, Daclizumab in patients under the age of 11. Methods: From 07/2004 to 08/2019, 79 patients under the age of 11 have received a KT. 7 patients were excluded from analysis due to Basiliximab induction (n=3), graft loss within 10 days (n=3) and patient death (n=1). 72 patients were analyzed, of which 39 patients (54%) with rATG induction were compared to 33 patients (46%) with daclizumab induction. All patients were maintained on steroid-free immunosuppression regimen after transplant. More than 20 variables were followed, along with rejection, graft failure, and any prevalence of post-transplant lymphoproliferative disorder (PTLD) was recorded (Figure 1). Results: Patients demographics were similar in both groups. Graft survival was good and statistically similar up to 5 years. In both groups, serum creatinine levels were similar up to 1 year follow up. Although CMV infection was similar in both groups, BK viremia and BK virus in the urine were more frequent in rATG group. Post-transplant lymphoproliferative disorder was significantly higher in the Daclizumab group (p=0.022), but less acute rejection was observed in the Daclizumab group (Figure 1). Potential Impact: Our study suggests that rATG is a safe and effective induction agent in pediatric kidney transplant recipients under the age of 11. Recipients have excellent patient and graft survival. It is associated with strong kidney function and low PTLD. Screening for BK virus in the urine is essential with rATG induction. Table 1: Induction Agent Daclizumab rATG p value Demographics Number 33 39 N.S. Sex 15M, 18F 27M, 12F 0.042 Age (years) 5.5 ± 2.7 6.1 ± 2.7 N.S. Height (m) 1.02 ± 0.23 1.06 ± .21 N.S. Weight (kg) 18.75 ± 9.93 19.08 ± 6.42 N.S. Outcomes Cr 1 month (mg/dL) 0.56 ± .31 0.45 ± .17 0.056 Cr 6 months (mg/dL) 0.54 ± .22 0.52 ± .18 N.S. Cr 1 year (mg/dL) 0.63 ± .27 0.59 ± .17 N.S. eGFR 1 month (ml/min/1.73m2) 84.81 ± 27.95 107.08 ± 30.09 0.0019 eGFR 6 months (ml/min/1.73m2) 85.04 ± 27.60 92.48 ± 28.07 N.S. eGFR 1 year (ml/min/1.73m2) 74.31 ± 26.8 79.3 ± 22.01 N.S. Rejection 6 months 1 (3.03%) 8 (20.51%) 0.0188 Rejection 1 year 2 (6.06%) 8 (20.51%) 0.0682 Graft Survival 1 year 100% (33/33) 100% (39/39) N.S. Graft Survival 3 years 96.97% (32/33) 100% (25/25) N.S. Graft Survival 5 years 96.88 (31/32) 100% (22/22) N.S. Cases of PTLD 5 (18.18%) 0 (0%) 0.022 Chronic steroid use 2 (6.06%) 2 (5.13%) N.S. BK Urine only 1 year 0% (0/33)* 10.26% (4/39) 0.0439 BK Viremia 1 year 3.03% (1/33)* 17.95% (7/39) 0.0356 CMV Viremia 1 year 0% (0/33) 5.13% (2/39) N.S. N.S.= Not statistically significant. *BK screening was not routine during time of daclizumab induction

Background Over the past decades, there has been a dramatic increase in obesity in the United States. Several studies have reported conflicting results for the impact of obesity on outcomes of liver transplantation (LT). This study aims to assess severe obesity's impact on LT outcomes and changes in body mass index (BMI) after transplantation.Methods All adult LT performed at Indiana University Health University Hospital between July 2001 and December 2018 were reviewed. A retrospective analysis for identified 2024 patients was conducted. BMI of recipients is subdivided into underweight, normal, overweight, class Ⅰ obesity, class Ⅱ obesity, and class Ⅲ obesity (Results Among 2024 patients in the analytic cohort, 1.9% were underweight, 24.5% were normal, 32.6% were overweight, 25% were in class Ⅰ obesity, 9.3% were in class Ⅱ obesity, and 1.1% were in class Ⅲ obesity. There was no significant difference in patient and graft survival at 10-year follow-up with respect to recipient obesity. The 1, 3, 5, and 10-year graft and patient survivals in class Ⅲ obesity group were 97.0%, 92.1%, 87.0%, and 79.8% for patient survival and 94.4%, 85.1%, 79.8%, and 72.5% for graft survival. Among 1004 patients identified in the sub-group, BMI of all groups except the underweight group declined in the first three months postoperatively. After the three months, the BMI of all groups except the class Ⅲ obesity group returned to the pre LT level by two years and reached a plateau by five years. In patients with class Ⅲ obesity, there was a significant increase in body weight after long-term follow-up.Conclusion In this study, class Ⅲ obesity is not associated with higher mortality. Obesity, including class Ⅲ obesity, should not be considered a contraindication to LT in the absence of other contraindications. Post-LT interventions are required to prevent significant weight gain in recipients with class Ⅲ obesity after transplantation.

BACKGROUND: The aging of liver transplant (LT) recipients, the weighting of the MELD score, and the increased prevalence of NASH has led to an increased number of older LT recipients with pre-LT chronic kidney disease (CKD). There are limited data on the impact of increased recipient age on postsimultaneous liver kidney (SLK) transplant outcomes among patients with CKD, leading some centers to employ subjective age cutoffs for potential SLK recipients. METHODS: We evaluated UNOS data of adult SLK recipients from 2/27/2002–12/31/2018, restricted to recipients with ≥90 days of waiting time and CKD (eGFR persistently

The role of donor-recipient body size mismatch (DRSM) on outcomes after whole liver transplantation (LT) is not clearly defined. At our center, in presence of considerable DRSM, objective assessment of the donor liver by a radiology or intraoperative evaluation by procuring surgeon was incorporated. To evaluate the impact of DRSM on graft outcomes with this approach, adult deceased donor whole liver transplants between July 2001 and December 2017 at our center were studied. DRSM was considered when the donor-recipient body surface area (BSA) ratio (DR-BSAr) was either0.69 or1.25. There were 54 (3.2%) transplants with DR-BSAr0.69 and 61 (3.6%) with DR-BSAr1.25. One-year graft survival was 85% vs. 89% vs. 89%; (p = .64) for transplants with DR-BSArs of0.69, 0.69-1.25, and1.25, respectively. Early allograft dysfunction (EAD) (28% vs. 27% vs. 37%; p = .07), post-transplant coagulopathy, bilirubinemia, and renal function were also comparable. In conclusion, with the actual measurement of the donor liver and recipient abdominal cavity, significant DRSM did not have a negative impact on early and long-term outcomes. Routine measurement of donor liver size by radiology may be incorporated in liver allocation to improve utilization.

Introduction The SCARE Guidelines were first published in 2016 and were last updated in 2018. They provide a structure for reporting surgical case reports and are used and endorsed by authors, journal editors and reviewers, in order to increase robustness and transparency in reporting surgical cases. They must be kept up to date in order to drive forwards reporting quality. As such, we have updated these guidelines via a DELPHI consensus exercise. Methods The updated guidelines were produced via a DELPHI consensus exercise. Members were invited from the previous DELPHI group, as well as editorial board member and peer reviewers of the International Journal of Surgery Case Reports. The expert group completed an online survey to indicate their agreement with proposed changes to the checklist items. Results 54 surgical experts agreed to participate and 53 (98%) completed the survey. The responses and suggested modifications were incorporated to the 2018 guideline. There was a high degree of agreement amongst the SCARE Group, with all SCARE Items receiving over 70% scores 7-9. Conclusion A DELPHI consensus exercise was completed, and an updated and improved SCARE Checklist is now presented.

Highlights • It is an editorial article. No highlights.

In deceased donor kidney transplantation (KT), a prolonged cold ischemia time (CIT) is a negative prognostic factor for KT outcome, and the efficacy of hypothermic machine perfusion (HMP) in prolonging CIT without any additional hazard is highly debated. We conducted a retrospective study on a cohort of 154 single graft deceased donor KTs, in which a delayed HMP, after a preliminary period of static cold storage (SCS), was used to prolong CIT for logistic reasons. Primary outcomes were postoperative complications as well as 1 year graft survival and function. 73 cases (47.4%) were managed with HMP and planned KT, while 81 (52.6%) with SCS and urgent KT. The median CIT in HMP group and SCS group was 29 hour:57 minutes [27-31 hour:45 minutes] and 11 hour:25 minutes [9-14 hour:30 minutes], respectively (P < .001). The period of SCS in the HMP group was significantly shorter than in the SCS group (10 vs. 11 hour:25 minutes, P = .02) as well as the prevalence of expanded criteria donors was significantly higher (43.8% vs. 18.5%, P < .01). After propensity score matching for these two baseline characteristics, the HMP and SCS groups showed comparable outcomes in terms of delayed graft function, vascular, and urologic complications, infections, and episodes of graft rejection. At 1 year follow-up, serum creatinine levels were comparable between the groups. Therefore, the use of HMP to prolong the CIT and convert KT into a planned procedure seemed to have an adequate safety profile, with outcomes comparable to KT managed as an urgent procedure and a CIT nearly three time shorter.

Background We examined how extra-hepatic comorbidity burden impacts mortality in patients with cirrhosis referred for liver transplantation (LT). Methods Adults with cirrhosis evaluated for their first LT in 2012 were followed through their clinical course with last follow up in 2019. Extra-hepatic comorbidity burden was measured using the Charlson Comorbidity Index (CCI). The endpoints were 90-day transplant free survival (Cox-Proportional Hazard regression), and overall mortality (competing risk analysis). Results The study included 340 patients, mean age 56 ± 11, 63% male and MELD-Na 17.2 ± 6.6. The CCI was 0 (no comorbidities) in 44%, 1–2 in 44% and > 2 (highest decile) in 12%, with no differences based on gender but higher CCI in patients with fatty and cryptogenic liver disease. Thirty-three (10%) of 332 patients not receiving LT within 90 days died. Beyond MELD-Na, the CCI was independently associated with 90-day mortality (hazard ratio (HR), 1.32 (95% confidence interval (CI) 1.02–1.72). Ninety-day mortality was specifically increased with higher CCI category and MELD ≥18 (12% (CCI = 0), 22% (CCI = 1–2) and 33% (CCI > 2), (p = 0.002)) but not MELD-Na ≤17. At last follow-up, 69 patients were alive, 100 underwent LT and 171 died without LT. CCI was associated with increased overall mortality in the competing risk analysis (Sub-HR 1.24, 95%CI 1.1–1.4). Conclusions Extra-hepatic comorbidity burden significantly impacts short-term mortality in patients with cirrhosis and high MELD-Na. This has implications in determining urgency of LT and mortality models in cirrhosis and LT waitlisting, especially with an ageing population with increasing prevalence of fatty liver disease.

The gastrointestinal peptide, secretin (Sct) is an important homeostatic regulator of pancreatic and liver secretory function. With regard to the liver, discoveries have been made, in the last decades, indicating a key role for the secretin/secretin receptor axis during normal or cholestatic conditions. Since large cholangiocytes are the only cells to express secretin receptor in the liver, research on secretin also expanded our knowledge on biliary epithelia. In this review we examined in detail the role of the secretin/secretin receptor axis, not only on biliary secretion, but also on cholangiocyte proliferation and senescence, as well as in prompting fibrotic processes involving biliary epithelia. Relevant data on human chronic cholestatic liver diseases, such as primary biliary cholangitis or primary sclerosing cholangitis, and obtained in animal models mimicking the diseases or in correlative studies on human are also reported. The aim of this review is to provide an update on the progress regarding the interactions between secretin and the biliary epithelia in normal and pathological conditions, underlining the aspects that suggests modulation of secretin pathway as a possible therapeutic approach for chronic cholestatic human liver disease.

Xenotransplantation (i.e. cross-species transplantation) using genetically-engineered pig organs could be a limitless source to solve the shortage of organs and tissues worldwide. However, despite prolonged survival in preclinical pig-to-nonhuman primate xenotransplantation trials, interspecies coagulation dysregulation remains to be overcome in order to achieve continuous long-term success. Different platelet aggregometry methods have been previously used to study the coagulation dysregulation with wild-type and genetically-engineered pig cells, including the impact of possible treatment options. Amongst these methods, while thromboelastography and rotational thromboelastometry measures the change in viscoelasticity, optical aggregometry measures the change in opacity. Recently, impedance aggregometry has been used to measure changes in platelet aggregation in electrical conductance, providing more information to our understaning of coagulation dysregulation in xenotransplantation compared to previous methods. The present study reviews the merits and differences of the above-mentioned platelet aggregometers in xenotransplantation research.

BACKGROUND Liver transplant (LT) patients have an increased risk of postoperative respiratory failure requiring tracheostomy. This study sought to characterize objective clinical predictors of tracheostomy. MATERIAL AND METHODS The records for 2017 LT patients at a single institution were reviewed. Patients requiring tracheostomy were first compared with all other patients. A case-control subgroup analysis was conducted in which 98 tracheostomy patients were matched with 98 non-tracheostomy LT patients. For the case-control study, muscle mass was assessed using preoperative computed tomography scans. RESULTS Among 2017 LT patients, 98 required tracheostomy (5%), with a 19% complication rate. Tracheostomy patients were older and had a higher model for end-stage liver disease score, a lower body mass index (BMI), and a greater smoking history. Tracheostomy patients had a longer hospital stay (45 vs. 10 days, P

Kidney transplantation is a well-established therapy for patients with end-stage renal disease. While a significant improvement of short-term results has been achieved in the short-term, similar results were not reported in the long-term. Heme-oxygenase (HO) is the rate-limiting enzyme in heme catabolism, converting heme to iron, carbon monoxide, and biliverdin. Heme-oxygenase overexpression may be observed in all phases of transplant processes, including brain death, recipient management, and acute and chronic rejection. HO induction has been proved to provide a significant reduction of inflammatory response and a reduction of ischemia and reperfusion injury in organ transplantation, as well as providing a reduction of incidence of acute rejection. In this review, we will summarize data on HO and kidney transplantation, suggesting possible clinical applications in the near future to improve the long-term outcomes.

Combined liver-kidney transplantation is a life-saving procedure for patients with end-stage liver disease and underlying chronic kidney disease, or prolonged acute kidney injury. Due to physiologic changes secondary to portal hypertension in patients with end-stage liver disease, kidney injury is common, and combined liver-kidney transplantation accounts for 10% of all the liver transplants performed in the United States. Recently implemented policy in the United States standardizes the medical criteria for eligibility, and introduces a 'safety net' for those who are transplanted with a liver graft alone, in order to be able to receive a kidney graft later. Increasing number of combined liver-kidney transplants provides a large cohort of patients to be studied in detail for identification of factors (both donor and recipient-related) associated with better outcomes. Data regarding the safety and efficacy of delaying the kidney transplant part of the combined liver-kidney transplantation, and the immunologic benefits of the multi-organ transplantations including the liver are emerging. Here, we review the most recent analyses, and provide our opinion regarding the best practices in combined liver-kidney transplantation based on the evidence.

BACKGROUND Patients undergoing re-transplantation often receive high doses of immunosuppression, which may lead to an immunocompromised status of the recipient. This study investigates the outcomes after intestine/multivisceral re-transplantation. MATERIAL AND METHODS Clinical outcomes of 23 patients undergoing 24 re-transplantations at a single intestine transplant center were reviewed. Bone marrow suppression was used as a surrogate marker of immunocompromised status, and was defined as platelet count

Introduction Strengthening The Reporting Of Cohort Studies in Surgery (STROCSS) guidelines were developed in 2017 in order to improve the reporting quality of observational studies in surgery and updated in 2019. In order to maintain relevance and continue upholding good reporting quality among observational studies in surgery, we aimed to update STROCSS 2019 guidelines. Methods A STROCSS 2021 steering group was formed to come up with proposals to update STROCSS 2019 guidelines. An expert panel of researchers assessed these proposals and judged whether they should become part of STROCSS 2021 guidelines or not, through a Delphi consensus exercise. Results 42 people (89%) completed the DELPHI survey and hence participated in the development of STROCSS 2021 guidelines. All items received a score between 7 and 9 by greater than 70% of the participants, indicating a high level of agreement among the DELPHI group members with the proposed changes to all the items. Conclusion We present updated STROCSS 2021 guidelines to ensure ongoing good reporting quality among observational studies in surgery., Highlights • In order to maintain relevance and continue upholding good reporting quality among observational studies in surgery, STROCSS 2019 guidelines were updated through a DELPHI consensus exercise. • 42 people participated in the development of STROCSS 2021 guidelines and there was a high level of agreement among the DELPHI group members with the proposed changes to all the items. • Updated STROCSS 2021 guideline is presented.

The positive impact of delayed kidney transplantation (KT) on patient survival for combined liver-kidney transplantation (CLKT) has already been demonstrated by our group. The purpose of this study is to identify whether the quality of the kidneys (based on kidney donor profile index [KDPI]) or the delayed approach KT contributes to improved patient survival. In total, 130 CLKTs were performed between 2002 and 2015, 69 with simultaneous KT (group S) and 61 with delayed KT (group D) (performed as a second operation with a mean cold ischemia time [CIT] of 50 ± 15 hours). All patients were categorized according to the KDPI score: 1%-33%, 34%-66%, and 67%-99%. Recipient and donor characteristics were comparable within groups S and D. Transplant outcomes were comparable within groups S and D, including liver and kidney CIT, warm ischemia time, and delayed graft function. Lower KDPI kidneys (34%) were associated with increased patient survival in both groups. The combination of delayed KT and KDPI 1%-33% resulted in 100% patient survival at 3 years. These results support that delayed KT in CLKT improves patient survival. The combination of delayed KT and low KDPI offers excellent patient survival up to 3 years. Improved outcomes in the delayed KT group including high KDPI kidneys supports expansion of the donor pool with the use of more extended criteria donor and donation after circulatory death kidneys. Liver Transplantation 24 222-232 2018 AASLD.

Fatty liver diseases, such as non-alcoholic fatty liver disease (NAFLD), are global health disparities, particularly in the United States, as a result of cultural eating habits and lifestyle. Pathological studies on NAFLD have been mostly focused on hepatocytes and other inflammatory cell types; however, the impact of other biliary epithelial cells (i.e., cholangiocytes) in the promotion of NAFLD is growing. This review article will discuss how cholestatic injury and cholangiocyte activity/ductular reaction influence NAFLD progression. Furthermore, this review will provide informative details regarding the fundamental properties of cholangiocytes and bile acid signaling that can influence NAFLD. Lastly, studies relating to the pathogenesis of NAFLD, cholangiopathies, and ductular reaction will be analyzed to help gain insight for potential therapies.

Purpose of review To review the progress in the field of xenotransplantation with special attention to most recent encouraging findings which will eventually bring xenotransplantation to the clinic in the near future. Recent findings Starting from early 2000, with the introduction of galactose-α1,3-galactose (Gal)-knockout pigs, prolonged survival especially in heart and kidney xenotransplantation was recorded. However, remaining antibody barriers to non-Gal antigens continue to be the hurdle to overcome. The production of genetically engineered pigs was difficult requiring prolonged time. However, advances in gene editing, such as zinc finger nucleases, transcription activator-like effector nucleases, and most recently clustered regularly interspaced short palindromic repeats (CRISPR) technology made the production of genetically engineered pigs easier and available to more researchers. Today, the survival of pig-to-nonhuman primate heterotopic heart, kidney, and islet xenotransplantation reached more than 900, more than 400, and more than 600 days, respectively. The availability of multiple-gene pigs (five or six genetic modifications) and/or newer costimulation blockade agents significantly contributed to this success. Now, the field is getting ready for clinical trials with an international consensus. Summary Clinical trials in cellular or solid organ xenotransplantation are getting closer with convincing preclinical data from many centers. The next decade will show us new achievements and additional barriers in clinical xenotransplantation.

The International Liver Transplantation Society (ILTS) 2019 Annual Congress was held in Toronto, Canada, in May 2019. Members of the ILTS Basic and Translational Research Committee attended all sessions of the meeting and selected the most promising, innovative, and novel research presented. A total of 900 abstracts were presented at the meeting. The percentage of abstracts presented at the ILTS Congress that contains basic or translational research continues to increase, accounting for 15% of all the abstracts in 2019, up from 10% in 2018. Here, we summarize the "what's hot what's new" in 5 main themes: liver immunobiology and tolerance, ischemia/reperfusion injury and organ preservation, bioengineering and liver regeneration, hepatic primary tumor biology, and pathophysiology of liver failure.

INTRODUCTION: Cholangiocarcinoma (CCA) is a devastating liver tumor with a poor prognosis. While less than 50% of patients with CCA may benefit from surgical resection, the rest undergoes chemotherapy with disappointing results (mean survival

Cholangiocarcinoma (CCA) is a highly aggressive malignancy that emerges from the biliary tree. There are three major classes of CCA—intrahepatic, hilar (perihilar), or distal (extrahepatic)—according to the location of tumor development. Although CCA tumors are mainly derived from biliary epithelia (i.e., cholangiocytes), CCA can be originated from other cells, such as hepatic progenitor cells and hepatocytes. This heterogeneity of CCA may be responsible for poor survival rates of patients, limited effects of chemotherapy and radiotherapy, and the lack of treatment options and novel therapies. Previous studies have identified a number of neuroendocrine mediators, such as hormones, neuropeptides, and neurotransmitters, as well as corresponding receptors. The mediator/receptor signaling pathways play a vital role in cholangiocyte proliferation, as well as CCA progression and metastases. Agonists or antagonists for candidate pathways may lead to the development of novel therapies for CCA patients. However, effects of mediators may differ between healthy or cancerous cholangiocytes, or between different subtypes of receptors. This review summarizes current understandings of neuroendocrine mediators and their functional roles in CCA.

PPCA has historically been considered detrimental to donor quality in LT, but transplantation of grafts from this group of donors is now routine. Our study aims to evaluate the outcomes associated with use of donors with a history of PPCA in the pediatric population. This study is a single-center retrospective analysis of all pediatric LTs performed over an 18-year period. Donors and recipients were stratified by the presence and length of donor PPCA time. Preprocurement donor and post-transplant recipient laboratory values were collected to assess the degree of ischemic liver injury associated with each donor group. Cox regression analysis was used to compare survival. The records for 130 deceased pediatric LT donors and corresponding recipients were reviewed. There were 73 (56%) non-PPCA donors and 57 (44%) PPCA donors. Donors that experienced a PPCA event demonstrated a higher median, pretransplant peak alanine aminotransferase (ALT) level (P .001). When comparing post-transplant recipient median ALT levels, donors with any PPCA had lower median peak ALT (P = .15) and day 3 ALT (P = .43) levels than the non-PPCA group. Rates of early graft loss did not differ. The PPCA group with40 minutes of ischemia had markedly lower survival at 10 years, but this finding did not reach statistical significance. Liver grafts from donors with or without PPCA demonstrated no statistically significant differences in function or survival. A history of donor PPCA alone should not be used as an exclusionary criterion in pediatric liver transplantation.

Background and Hypothesis: Development of realistic, scaffold-free 3D organoids/tubuloids such as renal-like tissue, can serve as models for study of renal drug toxicity/screening, tissue repair, and renal disease. Previous studies utilized urine-derived epithelial cells (UDEpCs) to create viable tubuloid structures suspended in 3D Matrigel, displaying renal epithelial gene expression and functionality. Alternatively, renal proximal tubule epithelial cells (PTECs) with HUVECs were co-cultured in a monolayer to improve the model. Therefore, we hypothesized that the addition of HUVECs will help to establish and optimize growth conditions of UDEpCs in a 3D environment. Experimental design: UDEpCs were isolated and co-cultured with tdTomatoHUVECs in Matrigel with different combinations of growth media. Cell growth and endothelial cell tube formation were examined daily. PTECs and tdTomatoHUVECs were also used to make spheroids in low-binding plates. Real-time PCR analysis was performed to examine gene expression for epithelial markers (ABCC4, PAX8), an endothelial marker (PECAM1), and TGF-β in spheroids. Results: A single cell-derived colony was isolated from human urine and was double positive for CD10 and CD13, two renal PTEC markers. Co-culture of UDEpCs and tdTomato-HUVECs in Matrigel dramatically increased the growth, survival, and tubuloid formation of both cell types, for up to 12 days. Total RNA from spheroids showed a decline over time in all conditions. Gene expression was decreased in co-culture conditions, but patterns of gene expression were maintained. Conclusions and Potential Impact: Future studies will examine gene expression in Matrigel cells, further optimize conditions for growth of UDEpCs, and perform functional assays, such as brush border enzyme activity. Improved methods to develop 3D kidney organoids/tubuloids will produce more accurate models for renal function studies. Developing a functional model mimicking in vivo processes can lead to new applications for creating novel therapies and treatment strategies.

BACKGROUND Acute liver rejection (ALR), a significant complication of liver transplantation, burdens patients, healthcare payers, and the healthcare providers due to an increase in morbidity, cost, and resources. Despite clinical resolution, ALR is associated with an increased risk of graft loss. A unique protocol of delayed immunosuppression used in our institute provided a model to characterize metabolomic profiles in human ALR. MATERIAL AND METHODS Twenty liver allograft biopsies obtained 48 hours after liver transplantation in the absence of immunosuppression were studied. Hepatic metabolites were quantitated in these biopsies by liquid chromatography and mass spectroscopy (LC/MS). Metabolite profiles were compared among: 1) biopsies with reperfusion injury but no histological evidence of rejection (n=7), 2) biopsies with histological evidence of moderate or severe rejection (n=5), and 3) biopsies with histological evidence of mild rejection (n=8). RESULTS There were 133 metabolites consistently detected by LC/MS and these were prioritized using variable importance to projection (VIP) analysis, comparing moderate or severe rejection vs. no rejection or mild rejection using partial least squares discriminant statistical analysis (PLS-DA). Twenty metabolites were identified as progressively different. Further PLS-DA using these metabolites identified 3 metabolites (linoleic acid, γ-linolenic acid, and citrulline) which are associated with either cyclooxygenase or nitric oxide synthase functionality. CONCLUSIONS Hepatic metabolic aberrancies associated with cyclooxygenase and nitric oxide synthase function occur contemporaneous with ALR. Additional studies are required to better characterize the role of these metabolic pathways to enhance utility of the metabolomics approach in diagnosis and outcomes of ALR.

Corneal transplantation is the only option to cure corneal opacities. However, there is an imbalance between supply and demand of corneal tissues in the world. To solve the problem of corneal shortage, corneal xenotransplantation studies have been implemented in the past years using porcine corneas. The corneal xenografts could come from 1) wild type pigs, 2) genetically-engineered pigs, 3) decellularized porcine corneas, and 4) decellularized porcine corneas that are recellularized with human corneal cells, eventually with patients’ own cells, as in all type of xenografts. All approaches except, the former would reduce or mitigate recipient immune responses. Although several techniques in decellularization have been reported, there is still no standardized protocol for the complete decellularization of corneal tissue. Herein, we reviewed different decellularization methods for porcine corneas based on the mechanism of action, decellularization efficacy, biocompatibility, and the undesirable effects on corneal ultrastructure. We compared 9 decellularization methods including: (i) sodium dodecyl sulfate, (ii) triton x-100, (iii) hypertonic saline, (iv) human serum with electrophoresis, (v) high hydrostatic pressure, (vi) freeze-thaw, (vii) nitrogen gas, (viii) phospholipase A(2), and (ix) glycerol with chemical crosslinking methods. It appears that combined methods could be more useful to perform efficient corneal decellularization.

In pig-to-baboon organ xenotransplantation, coagulation dysfunction and inflammation have been suggested to be associated with acute humoral xenograft rejection. We have evaluated platelet counts, plasma fibrinogen, and parameters of inflammation as indicators of xenograft failure in baboons with kidney and heart grafts from genetically-engineered pigs. Blood chemistry, hematologic, immune, and inflammatory parameters were measured in recipient baboons (n = 16) with organs from α1,3-galactosyltransferase gene-knockout pigs expressing human complement- and coagulation-regulatory proteins. Thrombocytopenia and reduction of plasma fibrinogen level were observed in baboons developing graft failure, and these correlated with histopathologic findings of glomerular and interstitial thrombosis, and vasculitis in the graft. Not infrequently, in baboons with pig kidney grafts, a consumptive coagulopathy developed prior to a rise in serum creatinine. In contrast, when kidney graft survival was prolonged, no changes were observed in platelet count or fibrinogen. Indicators of the inflammatory response, particularly the serum amyloid A (SAA) assay, increased when graft failure was developing. There were no changes in cellular immune parameters, e.g., T or B cell counts or phenotypes that indicated graft failure. Therefore, in clinical xenotransplantation, noninvasive parameters (e.g., platelet count, fibrinogen level, SAA) might provide more reliable indicators of impending xenograft failure than measurements of immune parameters or even of serum creatinine.