COVID-19 Infection and Acute Pancreas Transplant Graft Thrombosis.

The coronavirus disease 2019 (COVID-19) pandemic created an unprecedented challenge for healthcare, and the world continues to struggle in recovering from its aftermath. COVID-19 has been clearly linked to hypercoagulable states and can lead to end-organ ischemia, morbidity, and mortality. Immunosuppressed solid organ transplant recipients represent a highly vulnerable population for the increased risk of complications and mortality. Early venous or arterial thrombosis with acute graft loss after whole pancreas transplantation is well-described, but late thrombosis is rare. We herein report a case of acute, late pancreas graft thrombosis at 13 years post pancreas-after-kidney (PAK) transplantation coinciding with an acute COVID-19 infection in a previously double-vaccinated recipient.

Successful Liver Transplantation After Neurologically Determined Death Donation Following Sodium Nitrite Poisoning.

Sodium nitrite poisoning has been reported with increasing frequency since 2017 and popularized on social media as an effective means to commit suicide. Though accidental, non-intentional consumption has been reported, it is uncommon. Sodium nitrite is a colorless, odorless, yellowish-white crystalline material that resembles table salt, is easily ingested for self-harm, and is readily accessible through purchase from online portals at low cost. The chemical is used industrially as a curing agent for meat, fish, and cheese, as it inhibits Clostridium botulinum and prevents botulism. We herein report a successful case of liver transplantation from an organ donor who suffered brain death after intentional sodium nitrite consumption. Despite conflicting evidence on sodium nitrite's toxic versus protective effects on the liver, our transplant recipient showed normal graft function in the four months following liver transplantation. It would have been helpful and reassuring to have had access to similar positive case reports when deciding to use such a donor.

A predictive computational platform for optimizing the design of bioartificial pancreas devices.

The delivery of encapsulated islets or stem cell-derived insulin-producing cells (i.e., bioartificial pancreas devices) may achieve a functional cure for type 1 diabetes, but their efficacy is limited by mass transport constraints. Modeling such constraints is thus desirable, but previous efforts invoke simplifications which limit the utility of their insights. Herein, we present a computational platform for investigating the therapeutic capacity of generic and user-programmable bioartificial pancreas devices, which accounts for highly influential stochastic properties including the size distribution and random localization of the cells. We first apply the platform in a study which finds that endogenous islet size distribution variance significantly influences device potency. Then we pursue optimizations, determining ideal device structures and estimates of the curative cell dose. Finally, we propose a new, device-specific islet equivalence conversion table, and develop a surrogate machine learning model, hosted on a web application, to rapidly produce these coefficients for user-defined devices.

The IGFBP3/TMEM219 pathway regulates beta cell homeostasis.

Loss of pancreatic beta cells is a central feature of type 1 (T1D) and type 2 (T2D) diabetes, but a therapeutic strategy to preserve beta cell mass remains to be established. Here we show that the death receptor TMEM219 is expressed on pancreatic beta cells and that signaling through its ligand insulin-like growth factor binding protein 3 (IGFBP3) leads to beta cell loss and dysfunction. Increased peripheral IGFBP3 was observed in established and at-risk T1D/T2D patients and was confirmed in T1D/T2D preclinical models, suggesting that dysfunctional IGFBP3/TMEM219 signaling is associated with abnormalities in beta cells homeostasis. In vitro and in vivo short-term IGFBP3/TMEM219 inhibition and TMEM219 genetic ablation preserved beta cells and prevented/delayed diabetes onset, while long-term IGFBP3/TMEM219 blockade allowed for beta cell expansion. Interestingly, in several patients' cohorts restoration of appropriate IGFBP3 levels was associated with improved beta cell function. The IGFBP3/TMEM219 pathway is thus shown to be a physiological regulator of beta cell homeostasis and is also demonstrated to be disrupted in T1D/T2D. IGFBP3/TMEM219 targeting may therefore serve as a therapeutic option in diabetes.

Tumor necrosis factor receptor superfamily member 25 (TNFRSF25) agonists in islet transplantation: Endogenous in vivo regulatory T cell expansion promotes prolonged allograft survival.

Regulatory T cells (Tregs) modulate alloimmune responses and may facilitate minimization or withdrawal of immunosuppression posttransplant. Current approaches, however, rely on complex ex vivo Treg expansion protocols. Herein, we explore endogenous in vivo Treg expansion through antibody-mediated agonistic stimulation of the tumor necrosis factor receptor superfamily member 25 (TNFRSF25) pathway and its potential to prolong graft survival in a mouse model of islet allotransplantation. C57BL/6 male mice were treated with a single dose of TNFRSF25 agonistic antibodies (4C12 or mPTX-35) or IgG control. Diabetes was induced using streptozotocin. Four days later, flow cytometry was completed to corroborate Treg expansion, and 500 islets (CBA/J male mice) were transplanted. Glycemia was assessed thrice weekly until rejection/endpoint. Early intra-graft Treg infiltration was assessed 36 h posttransplant. TNFRSF25 antibodies enabled pronounced Treg expansion and treated mice had significantly prolonged graft survival compared with controls (p < .001). Additionally, the degree of Treg expansion significantly correlated with graft survival (p < .001). Immunohistochemistry demonstrated marked Treg infiltration in long-term surviving grafts; intra-graft Treg infiltration occurred early posttransplant. In conclusion, a single dose of TNFRSF25 antibodies enabled in vivo Treg expansion, which promotes prolonged graft survival. TNFRSF25-mediated in vivo Treg expansion could contribute to achieving lasting immunological tolerance in organ transplantation.

Total pancreatectomy with islet cell autotransplantation in a 2-year-old child with hereditary pancreatitis due to a PRSS1 mutation.

Acute recurrent and chronic pancreatitis in children carries high morbidity and burden. Compared to adults, ~75% of the cases of chronic pancreatitis in children are associated with underlying genetic mutations. The decision to intervene and the optimal timing poses unique challenges. Total pancreatectomy and islet cell autotransplantation (TPIAT) provides definitive therapy to relieve pain and improve quality of life while minimizing the risk of pancreatogenic diabetes. Substantial clinical data are available for adults; however, information on clinical outcomes in children remains scarce, particularly for very young children. Herein, we present an unusual, complex case of a 2-year-old child that underwent a successful TPIAT due to hereditary pancreatitis with an underlying mutation in PRSS1 gene, complicated by unremitting pancreatic ascites, hemorrhage, and sepsis. This is the youngest case to be reported in the literature. We provide a comprehensive report of the course and procedures implemented in this patient to guide other teams when considering these extraordinary measures in similar cases.

Glucose-dependent partitioning of arginine to the urea cycle protects ß-cells from inflammation.

Chronic inflammation is linked to diverse disease processes, but the intrinsic mechanisms that determine cellular sensitivity to inflammation are incompletely understood. Here, we show the contribution of glucose metabolism to inflammation-induced changes in the survival of pancreatic islet ß-cells. Using metabolomic, biochemical and functional analyses, we investigate the protective versus non-protective effects of glucose in the presence of pro-inflammatory cytokines. When protective, glucose metabolism augments anaplerotic input into the TCA cycle via pyruvate carboxylase (PC) activity, leading to increased aspartate levels. This metabolic mechanism supports the argininosuccinate shunt, which fuels ureagenesis from arginine and conversely diminishes arginine utilization for production of nitric oxide (NO), a chief mediator of inflammatory cytotoxicity. Activation of the PC-urea cycle axis is sufficient to suppress NO synthesis and shield cells from death in the context of inflammation and other stress paradigms. Overall, these studies uncover a previously unappreciated link between glucose metabolism and arginine-utilizing pathways via PC-directed ureagenesis as a protective mechanism.

Human Induced Pluripotent Stem Cells in the Curative Treatment of Diabetes and Potential Impediments Ahead.

The successful landmark discovery of mouse and human inducible pluripotential stem cells (iPSC's) by Takahashi and Yamanaka in 2006 and 2007 has triggered a revolution in the potential generation of self-compatible cells for regenerative medicine, and further opened up a new avenue for "disease in dish" drug screening of self-target cells (Neofytou et al. 2015). The introduction of four 'Yamanaka' transcription factors through viral or other transfection of mature cells can induce pluripotency and acquired plasticity. These factors include transduction with octamer-binding transcription factor-4 (Oct-4), nanog homeobox (Nanog), sex-determining region Y-box-2 (Sox-2) and MYC protooncogene (cMyc). Such cells become iPSC's (Takahashi and Yamanaka 2006). These reprogrammed cells exhibit increased telomerase activity and have a hypomethylated gene promotor region similar to embryonic stem cells (ESC's). These milestone discoveries have generated immense hope that diseases such as diabetes could be treated and effectively cured by transplantation of self-compatible, personalized autologous stem cell transplantation of ß-cells that release physiological insulin under glycemic control (Maehr et al. 2009; Park et al. 2008) (Fig. 1). Diabetes is a profligate disease of disordered glucose metabolism resulting from an absolute or relative deficiency of insulin, the consequences of which lead to immense socio-economic societal burden. While there are many different types of diabetes, the two major types (type 1 diabetes (T1DM) and type 2 diabetes (T2DM) are caused respectively by immune-mediated destruction (T1DM) or malfunctioning (T2DM) insulin-producing ß-cells within the endocrine pancreas, the islets of Langerhans (Atkinson et al. 2011; Holman et al. 2015; You and Henneberg 2016). Almost 425 million people are affected by the global burden of diabetes, and this is predicted to increase by 48% (629 million) by 2045 (International Diabetes Federation Atlas 8th Ed 2018). Whole pancreas or islet cell transplantation offer an effective alternative to injected insulin, but both require lifelong potent immunosuppression to control both allo-and autoimmunity. Whole pancreas transplantation involves invasive complex surgery and is associated with greater morbidity and occasional mortality, while islet transplantation involves a minimally invasive intraportal hepatic infusion. Generally, whole pancreas transplantation provides greater metabolic reserve, but this may be matched by cumulative multiple islet infusions to achieve insulin independence. An additional challenge of islet transplantation is progressive loss of complete insulin independence over time, which may be multifactorial, the dominant factor however being ineffective control of autoimmunity. Both whole pancreas and islet transplantation are restricted to patients at risk of severe hypoglycemia that cannot be stabilized by alternate means, or in recipients that are already immunosuppressed in order to sustain a kidney or other solid organ transplant. The risks of chronic immunosuppression and the scarcity of human organ donors mean that both of these transplantation therapies cannot presently be extended to the broader diabetic population (Shapiro 2011; Shapiro et al. 2006). Recent progress in xenotransplantation of multiple knock-out 'humanized' pig islets could offer one potential solution, perhaps aided by clustered regularly interspaced short palindromic repeats/CRISPR associated-9 (CRISPR/Cas-9) gene editing approaches, but this remains to be proven in practice. Human stem cell derived new ß-cell products could effectively address the global supply challenge for broad application across all forms of diabetes, but recurrent autoimmunity may still remain an insurmountable challenge. Considerable progress in the generation of human stem cell derived SC-ß cells from ESC, iPS and other adult cell sources such as mesenchymal stem cells (MSCs) offer huge hope that a personalized, 'syngeneic' cell could be transplanted without risk of alloimmunity, thereby securing sufficient supply to meet future global demand (Cito et al. 2018).

The effects of kisspeptin on ß-cell function, serum metabolites and appetite in humans.

AIMS: To investigate the effect of kisspeptin on glucose-stimulated insulin secretion and appetite in humans. MATERIALS AND METHODS: In 15 healthy men (age: 25.2 ± 1.1 years; BMI: 22.3 ± 0.5 kg m-2 ), we compared the effects of 1 nmol kg-1 h-1 kisspeptin versus vehicle administration on glucose-stimulated insulin secretion, metabolites, gut hormones, appetite and food intake. In addition, we assessed the effect of kisspeptin on glucose-stimulated insulin secretion in vitro in human pancreatic islets and a human ß-cell line (EndoC-ßH1 cells). RESULTS: Kisspeptin administration to healthy men enhanced insulin secretion following an intravenous glucose load, and modulated serum metabolites. In keeping with this, kisspeptin increased glucose-stimulated insulin secretion from human islets and a human pancreatic cell line in vitro. In addition, kisspeptin administration did not alter gut hormones, appetite or food intake in healthy men. CONCLUSIONS: Collectively, these data demonstrate for the first time a beneficial role for kisspeptin in insulin secretion in humans in vivo. This has important implications for our understanding of the links between reproduction and metabolism in humans, as well as for the ongoing translational development of kisspeptin-based therapies for reproductive and potentially metabolic conditions.

Determination of Minimal Hemoglobin Level Necessary for Normothermic Porcine Ex Situ Liver Perfusion.

BACKGROUND: In current studies of ex situ liver perfusion there exists considerable variability in perfusate composition, including the type of oxygen carrier. Herein, we aim to clarify the minimal hemoglobin level necessary during normothermic porcine ex situ liver perfusion. METHODS: Livers procured from 35 to 45 kg domestic pigs were connected to our experimental ex situ circuit (n = 10). In the treatment group, perfusate was sequentially diluted hourly to predetermined hemoglobin levels. At the end of each hemoglobin dilution, perfusate samples were analyzed for liver transaminases, lactate dehydrogenase (LD), total bilirubin, and lactate levels. Liver oxygen consumption was measured. In the control group, livers were perfused continually for a duration of 24 hours at target hemoglobin levels of 30 and 20 g/L. RESULTS: Rising liver transaminases, significantly higher lactate (P < 0.001), and LD levels (P < 0.001) were noted at lower perfusate hemoglobin levels in the treatment group. Liver oxygen utilization (P < 0.001) and hepatic artery oxygen delivery (P < 0.001) were significantly lower at lower hemoglobin levels, whereas liver vessel resistance remained relatively constant. Histology demonstrated increasing parenchymal damage at lower hemoglobin levels. In control livers, higher perfusate transaminases, higher lactate, and LD levels were noted at a perfusion hemoglobin level of 20 g/L. CONCLUSIONS: Ex situ liver function decompensated during perfusion between a mean hemoglobin level of 30 to 20 g/L, as evidenced by notably rising lactate and LD levels. This study demonstrates optimal hemoglobin concentration during normothermic ex situ liver perfusion to ensure a fully metabolically functioning graft.

Tissue perfusion rate estimation with compression-based photoacoustic-ultrasound imaging.

Tissue perfusion is essential for transporting blood oxygen and nutrients. Measurement of tissue perfusion rate would have a significant impact in clinical and preclinical arenas. However, there are few techniques to image this important parameter and they typically require contrast agents. A label-free methodology based on tissue compression and imaging with a high-frequency photoacoustic-ultrasound system is introduced for estimating and visualizing tissue perfusion rates. Experiments demonstrate statistically significant differences in depth-resolved perfusion rates in a human subject with various temperature exposure conditions.

Intra-abdominal adhesions: cellular mechanisms and strategies for prevention.

Postoperative intra-abdominal adhesions represent a serious clinical problem. In this review, we have focused on recent progress in the cellular and humoral mechanisms underpinning adhesion formation, and have reviewed strategies that interfere with these pathways as a means to prevent their occurrence. Current and previous English-language literature on the pathogenesis of adhesion formation was identified. As the burden of surgical disease in the world population increases, and the frequency of reoperation increases, prevention of adhesion formation has become a pressing goal in surgical research.

The estimated number of patients with hepatocellular carcinoma selected for liver transplantation using expanded selection criteria.

Recently, several groups have introduced expanded criteria for selection of patients with hepatocellular carcinoma (HCC) prior to transplant, but the exact number of potential newly recruited patients remains unclear. This registry-based study assessed 270 patients diagnosed with HCC. The potential number of transplant candidates was based on age (< or =65 years), absence of metastases and macro-vascular invasion, and on 12 previously published, expanded selection criteria. A wide range of increase in the number of transplant candidates was observed (12-63% when compared with the number of such candidates who would have been selected solely based on the Milan criteria). The most conservative criteria were Seoul (Kwon, 2007; increase of 12%), Valencia (Silva, 2008; 16%), total tumor volume/alpha-fetoprotein (Toso, 2009; 20%) and UCSF (Yao, 2007; 20%). This data will assist Centers and policy agencies in predicting the need for resources linked to an expansion of criteria.

Clinical magnetic resonance imaging of pancreatic islet grafts after iron nanoparticle labeling.

There is a crucial need for noninvasive assessment tools after cell transplantation. This study investigates whether a magnetic resonance imaging (MRI) strategy could be clinically applied to islet transplantation. The purest fractions of seven human islet preparations were labeled with superparamagnetic iron oxide particles (SPIO, 280 microg/mL) and transplanted into four patients with type 1 diabetes. MRI studies (T2*) were performed prior to and at various time points after transplantation. Viability and in vitro and in vivo functions of labeled islets were similar to those of control islets. All patients could stop insulin after transplantation. The first patient had diffuse hypointense images on her baseline liver MRI, typical for spontaneous high iron content, and transplant-related modifications could not be observed. The other three patients had normal intensity on pretransplant images, and iron-loaded islets could be identified after transplantation as hypointense spots within the liver. In one of them, i.v. iron therapy prevented subsequent visualization of the spots because of diffuse hypointense liver background. Altogether, this study demonstrates the feasibility and safety of MRI-based islet graft monitoring in clinical practice. Iron overload (spontaneous or induced) represents the major obstacle to the technique.

Human islet function is not impaired by the sphingosine-1-phosphate receptor modulator FTY720.

Clinical islet transplantation for type 1 diabetes mellitus currently requires potent immunosuppressive drugs, which limits the procedure to the most severe forms of the disease, and many of the drugs are directly beta-cell toxic. A class of compounds called sphingosine-1-phosphate receptor modulators has been explored in transplantation and shown to be highly effective in multiple sclerosis and other autoimmune conditions. While FTY720, the first drug in this class, may not move forward initially in transplantation, this class requires detailed investigation to assess direct impact upon human beta-cell function and survival. We set out to evaluate the effects of FTY720 on human islets in vitro by investigating glucose-stimulated insulin and apoptosis; and in vivo, after transplantation into immunodeficient mice with chemically induced diabetes, by examining blood glucose levels, oral glucose tolerance tests and stimulated human C-peptide over a 50-day follow-up period. Our data showed that neither in vitro, nor in vivo human islet function was impaired by FTY720 exposure. Since FTY720 demonstrated no detrimental effects on human islet function in vitro or in vivo, emerging S1PR modulators may prove to be useful adjuncts in clinical islet transplantation through lack of diabetogenicity and potent immunological protection.

ABO-incompatible liver transplantation for critically ill adult patients.

ABO incompatible (ABO-In) liver transplant remains a controversial solution to acute liver failure in adults. Adult liver recipients with acute liver failure or severely decompensated end-stage disease, intubated and/or in the intensive care unit, were grouped as ABO-In (n = 14), ABO-compatible (n = 29, ABO-C) and ABO-identical (n = 65, ABO-Id). ABO-In received quadruple immunosuppression with antibody-depleting induction agents (except two), calcineurin inhibitors, antimetabolites and steroids. No significant difference of patient and graft survivals was observed among ABO-In, ABO-C and ABO-Id: graft survivals were 64%, 62% and 67%, respectively, in 1 year and 56%, 54% and 60%, respectively, in 5 years; patient survivals 86%, 69% and 67%, respectively, in 1 year and 77%, 61% and 62%, respectively, in 5 years. Three ABO-In grafts were lost (one hyper-acute rejection and two hepatic artery thrombosis). Surgical and infectious complications were similarly distributed between groups, except the hepatic artery thrombosis, more frequent in ABO-In (2, 14%) than ABO-I (1, 1.5%, P < 0.05). In contrast to previous studies, no significant difference of patient and graft survivals could be observed among all ABO-compatibility settings. Our results suggest that ABO-incompatible transplants should be viewed as an important therapeutic option in adult patients with acute liver failure awaiting an emergency procedure.

Detection of insulin mRNA in the peripheral blood after human islet transplantion predicts deterioration of metabolic control.

Recent updates of the Edmonton trial have shown that insulin independence is progressively lost in approximately 90% of islet transplant recipients over the first 5 years. Early prediction of islet graft injury could prompt the implementation of strategies attempting to salvage the transplanted islets. We hypothesize that islet damage is associated with the release and detection of insulin mRNA in the circulating blood. Whole blood samples were prospectively taken from 19 patients with type 1 diabetes receiving 31 islet transplants, immediately prior to transplantation and at regular time-points thereafter. After RNA extraction, levels of insulin mRNA were determined by quantitative reverse tran-scriptase-polymerase chain reaction. All patients exhibited a primary peak of insulin mRNA immediately after transplantation, without correlation of duration and amplitude with graft size or outcome. Twenty-five subsequent peaks were observed during the follow-up of 17 transplantations. Fourteen secondary peaks (56%) were closely followed by events related to islet graft function. Duration and amplitude of peaks were higher when they heralded occurrence of an adverse event. Peaks of insulin mRNA can be detected and are often associated with alterations of islet graft function. These data suggest that insulin mRNA detection in the peripheral blood is a promising method for the prediction of islet graft damage.

Stem cell sources for clinical islet transplantation in type 1 diabetes: embryonic and adult stem cells.

Lifelong immunosuppressive therapy and inadequate sources of transplantable islets have led the islet transplantation benefits to less than 0.5% of type 1 diabetics. Whereas the potential risk of infection by animal endogenous viruses limits the uses of islet xeno-transplantation, deriving islets from stem cells seems to be able to overcome the current problems of islet shortages and immune compatibility. Both embryonic (derived from the inner cell mass of blastocysts) and adult stem cells (derived from adult tissues) have shown controversial results in secreting insulin in vitro and normalizing hyperglycemia in vivo. ESCs research is thought to have much greater developmental potential than adult stem cells; however it is still in the basic research phase. Existing ESC lines are not believed to be identical or ideal for generating islets or beta-cells and additional ESC lines have to be established. Research with ESCs derived from humans is controversial because it requires the destruction of a human embryo and/or therapeutic cloning, which some believe is a slippery slope to reproductive cloning. On the other hand, adult stem cells are already in some degree specialized, recipients may receive their own stem cells. They are flexible but they have shown mixed degree of availability. Adult stem cells are not pluripotent. They may not exist for all organs. They are difficult to purify and they cannot be maintained well outside the body. In order to draw the future avenues in this field, existent discrepancies between the results need to be clarified. In this study, we will review the different aspects and challenges of using embryonic or adult stem cells in clinical islet transplantation for the treatment of type 1 diabetes.