A Split-Lung Ex Vivo Perfusion Model for Time- and Cost-Effective Evaluation of Therapeutic Interventions to the Human Donor Lung.

With the ongoing shortage of donor lungs, ex vivo lung perfusion (EVLP) offers the opportunity for objective assessment and potential therapeutic repair of marginal organs. There is a need for robust research on EVLP interventions to increase the number of transplantable organs. The use of human lungs, which have been declined for transplant, for these studies is preferable to animal organs and is indeed essential if clinical translation is to be achieved. However, experimental human EVLP is time-consuming and expensive, limiting the rate at which promising interventions can be assessed. A split-lung EVLP model, which allows stable perfusion and ventilation of two single lungs from the same donor, offers advantages scientifically, financially and in time to yield results. Identical parallel circuits allow one to receive an intervention and the other to act as a control, removing inter-donor variation between study groups. Continuous hemodynamic and airway parameters are recorded and blood gas, perfusate, and tissue sampling are facilitated. Pulmonary edema is assessed directly using ultrasound, and indirectly using the lung tissue wet:dry ratio. Evans blue dye leaks into the tissue and can quantify vascular endothelial permeability. The split-lung ex vivo perfusion model offers a cost-effective, reliable platform for testing therapeutic interventions with relatively small sample sizes.

MicroRNA antagonist therapy during normothermic machine perfusion of donor kidneys.

Normothermic machine perfusion (NMP) is a novel clinical approach to overcome the limitations of traditional hypothermic organ preservation. NMP can be used to assess and recondition organs prior to transplant and is the subject of clinical trials in solid organ transplantation. In addition, NMP provides an opportunity to deliver therapeutic agents directly to the organ, thus avoiding many limitations associated with systemic treatment of the recipient. We report the delivery of oligonucleotide-based therapy to human kidneys during NMP, in this case to target microRNA function (antagomir). An antagomir targeting mir-24-3p localized to the endothelium and proximal tubular epithelium. Endosomal uptake during NMP conditions facilitated antagomir co-localization with proteins involved in the RNA-induced silencing complex (RISC) and demonstrated engagement of the miRNA target. This pattern of uptake was not seen during cold perfusion. Targeting mir-24-3p action increased expression of genes controlled by this microRNA, including heme oxygenase-1 and sphingosine-1-phosphate receptor 1. The expression of genes not under the control of mir-24-3p was unchanged, indicating specificity of the antagomir effect. In summary, this is the first report of ex vivo gymnotic delivery of oligonucleotide to the human kidney and demonstrates that NMP provides the platform to bind and block detrimental microRNAs in donor kidneys prior to transplantation.

Pharmacological testing of therapeutics using normothermic machine perfusion: A pilot study of 2,4-dinitrophenol delivery to steatotic human livers.

INTRODUCTION: Normothermic machine perfusion (NMP) provides a platform for drug-delivery. However, pharmacological considerations for therapeutics delivered during NMP are scarcely reported. We aimed to demonstrate the ability of NMP as a platform for pharmacological testing, using a drug which increases metabolism (2,4-dinitrophenol; DNP) as an example therapeutic. METHODS: We performed 25 h of NMP on human livers which had been declined for transplant due to steatosis (n = 7). Three livers received a DNP bolus, three were controls, and one received a DNP infusion. RESULTS: Toxicity studies revealed DNP delivery was safe, without hepatotoxic effects. The liver surface temperature was increased in the DNP group (p = 0.046), but no livers suffered hyperthermia-the mechanism of DNP toxicity in vivo. Pharmacokinetic studies revealed DNP elimination with first-order kinetics and 7.7 h half-life (95% CI = 5.1-15.9 hrs). The clearance of DNP in bile was negligible. As expected, DNP significantly increased oxygen consumption (p = 0.023); this increase was closely correlated with perfusate DNP concentration (r2  = 0.975; p = 0.002) and the effect was lost as DNP was eliminated by the liver. A DNP infusion rate, calculated using our pharmacokinetic data, successfully maintained perfusate DNP concentration. DISCUSSION: Detailed pharmacological testing can be performed during NMP. Our therapeutic (DNP) is rapidly eliminated by the ex vivo liver, meaning the drug effect of increased metabolism is only transient. This demonstrates the importance of assessing pharmacokinetics when delivering therapeutics during NMP, especially for prolonged perfusion of organs with established roles in drug elimination. Rigorous pharmacological testing is needed to unlock the potential of NMP as a clinical drug-delivery platform.

Novel delivery of cellular therapy to reduce ischemia reperfusion injury in kidney transplantation.

Ex vivo normothermic machine perfusion (NMP) of donor kidneys prior to transplantation provides a platform for direct delivery of cellular therapeutics to optimize organ quality prior to transplantation. Multipotent Adult Progenitor Cells (MAPC® ) possess potent immunomodulatory properties that could minimize ischemia reperfusion injury. We investigated the potential capability of MAPC cells in kidney NMP. Pairs (5) of human kidneys, from the same donor, were simultaneously perfused for 7 hours. Kidneys were randomly allocated to receive MAPC treatment or control. Serial samples of perfusate, urine, and tissue biopsies were taken for comparison. MAPC-treated kidneys demonstrated improved urine output (P = .009), decreased expression of injury biomarker NGAL (P = .012), improved microvascular perfusion on contrast-enhanced ultrasound (cortex P = .019, medulla P = .001), downregulation of interleukin (IL)-1ß (P = .050), and upregulation of IL-10 (P < .047) and Indolamine-2, 3-dioxygenase (P = .050). A chemotaxis model demonstrated decreased neutrophil recruitment when stimulated with perfusate from MAPC-treated kidneys (P < .001). Immunofluorescence revealed prelabeled MAPC cells in the perivascular space of kidneys during NMP. We report the first successful delivery of cellular therapy to a human kidney during NMP. Kidneys treated with MAPC cells demonstrate improvement in clinically relevant parameters and injury biomarkers. This novel method of cell therapy delivery provides an exciting opportunity to recondition organs prior to transplantation.

Hypothermic machine perfusion is superior to static cold storage in deceased donor kidney transplantation: A meta-analysis.

BACKGROUND: There remains a lack of consensus on the optimal storage method for deceased donor kidneys. This meta-analysis compares storage with hypothermic machine perfusion (HMP) vs traditional static cold storage (SCS). METHODS: The Cochrane Kidney and Transplant Specialised Register was searched to identify (quasi-) randomized controlled trials (RCTs) to include in our meta-analysis. PRISMA guidelines were used to perform and write this review. RESULTS: There is high-certainty evidence that HMP reduces the risk of delayed graft function (DGF) when compared to SCS (2138 participants from 14 studies, RR = 0.77; 0.67-0.90, P = .0006). This benefit is significant in both donation following circulatory death (DCD; 772 patients from seven studies, RR = 0.75; 0.64-0.87, P = .0002) and donation following brainstem death (DBD) grafts (971 patients from four studies, RR = 0.78; 0.65-0.93, P = .006). The number of perfusions required to prevent one episode of DGF was 7.26 and 13.60 in DCD and DBD grafts, respectively. There is strong evidence that HMP also improves graft survival in both DBD and DCD grafts, at both 1 and 3 years. Economic analyses suggest HMP is cost-saving at 1 year compared with SCS. CONCLUSION: Hypothermic machine perfusion is superior to SCS in deceased donor renal transplantation. Direct comparisons with normothermic machine perfusion in RCTs are essential to identify optimal preservation methods in kidney transplantation.

'Please Squeeze': A novel approach to perineal guarding at the time of delivery reduced rates of obstetric anal sphincter injury in an Australian tertiary hospital.

BACKGROUND: Over the last decade the incidence of obstetric anal sphincter injuries (OASIS) has been steadily increasing locally and internationally. Investigations into reducing rates, and the long-term complications, of OASIS are required. AIMS: To determine if applying a new method of perineal guarding at the time of delivery reduces the incidence of OASIS at an Australian tertiary hospital. MATERIALS AND METHODS: A retrospective audit was performed for the three  years prior to and following mandatory introduction of a new method of perineal guarding. The novel 'Please Squeeze' technique involved placement of the accoucheur's thumb and index finger just above the line of the posterior fourchette at crowning and bringing them firmly one centimetre postero-medially to reduce tension. Demographic data were extracted from the unit's obstetric database (ObstetriX). RESULTS: There were 9453 deliveries prior to, and 9805 deliveries following commencement of 'Please Squeeze', with no difference in the incidence of caesarean (30.4% vs 30.3% P = 0.87) or forceps (6.3% vs 5.8% P = 0.14) between groups. The incidence of primiparas (P = 0.005), ventouse (P < 0.001) and spontaneous vaginal deliveries (SVD) (P = 0.005) between groups. There was a clinically important 20% reduction in the incidence of OASIS across all vaginal deliveries from 3.5% to 2.8% (P = 0.006). In SVD, there was a 20% decrease in OASIS from 2.4% to 2.2% (P = 0.02), and a 14% decrease in OASIS with assisted vaginal delivery from 8% to 7.3% (P = 0.002). The incidence of episiotomy increased 16% (P < 0.001). CONCLUSIONS: The novel 'Please Squeeze' perineal guarding method contributed to a reduced incidence of OASIS in an Australian tertiary hospital.

Bladder-Drained Pancreas Transplantation: Urothelial Innate Defenses and Urinary Track Infection Susceptibility.

BACKGROUND: Pancreas transplantation restores insulin secretion in type 1 diabetes mellitus. The graft also produces exocrine secretions that can be drained enterically (enteric drainage [ED]) or via the bladder (bladder drainage [BD]). We suggest that in BD transplants, such secretions destroy bladder innate immunity, specifically host defense peptides/proteins (HDPs), which increases patient susceptibility to recurrent urinary tract infections (rUTIs). MATERIALS AND METHODS: BD and ED patient records were reviewed retrospectively for UTIs. Urine samples from ED and BD transplant recipients were analyzed for pH, the HDPs ß-defensin 2 (HBD2) and lipocalin-2, and amylase concentrations. In vitro, bacterial growth curves and antimicrobial assays were used to evaluate the effects of pH, HBD2, and HBD2 + pancreatic digestive enzymes (pancreatin) on uropathogenic Escherichia coli (UPEC) survival and growth. RESULTS: Urinalysis revealed a significant difference in pH between the BD and ED cohorts (7.2 ± 0.8 versus 6.7 ± 0.8; P = 0.012). Urinary HDPs were measured and BD, but not ED, lipocalin-2 concentrations were significantly decreased compared with those of diabetics awaiting transplant (P < 0.05). In vitro, an alkaline environment, pH 8.0, concomitant with the urine of the patient who underwent BD transplantation, significantly reduced UPEC growth (P < 0.05); addition of pancreatin to the growth medium was associated with a significant increase (P < 0.001) in growth rate. Antimicrobial data suggested significant UPEC killing in the presence of HBD2 (P < 0.01), but not in the presence of HBD2 + pancreatin (>12,500 amylase units). CONCLUSIONS: These in vivo and in vitro data suggest that BD pancreatic exocrine secretions inactivate the bladder innate defenses, which facilitate UPEC growth and underpins the increased susceptibility of patients who underwent BD pancreas transplantation to rUTIs.

Prospective comparison of obstetric anal sphincter injury incidence between an Asian and Western hospital.

INTRODUCTION AND HYPOTHESIS: Obstetric anal sphincter injury (OASIS) rates are reported to be higher in Asian women living in Western countries than in those living in Asia, but the reasons for the differences remain unclear. The objectives of this study were for a single examiner to prospectively compare OASIS rates in primiparous Asian women in an Asian and Western birth unit and determine potential birth factors that may influence the possible difference in OASIS incidence. METHODS: This was a prospective observational study based in Hong Kong, China, and Sydney, Australia, involving primiparous women > 36 weeks gestation of Asian descent undergoing vaginal delivery. A single examiner recorded basic patient demographics, observed all the deliveries at both sites, noting birthing techniques, and then examined the women, including a rectal examination, to determine OASIS incidence. RESULTS: Seventy births in Hong Kong and 66 in Sydney were studied. The incidence of OASIS was 34% in Sydney and 10% in Hong Kong (p = 0.001). Birthweight, epidural rate, body mass index, and instrumental delivery were higher in Sydney. Episiotomy rates were higher in Hong Kong (59.2% vs. 82.9%; p = 0.007). When comparing OASIS with no-OASIS, perineal length (OR = 0.36, 95% CI 0.17 to 0.76, p = 0.004) and birthweight (OR = 1.14, 95% CI 1.00 to 1.30, p = 0.039) were independent risk factors for OASIS. CONCLUSIONS: The incidence of OASIS in Asian women is significantly higher in a Western than in an Asian setting. In Asian women, perineal length and birthweight can affect the risk of OASIS at the time of vaginal delivery.

Dissemination of a novel organ perfusion technique: ex vivo normothermic perfusion of deceased donor kidneys.

Ex vivo normothermic perfusion (EVNP) technology is a promising means of organ preservation, assessment, and preconditioning prior to kidney transplantation, which has been pioneered by a single group. We describe the challenges of setting up clinical EVNP programs in 2 new centers, as well as early patient outcomes. Governance, training, and logistical pathways are described. In order to demonstrate safety and proficiency in this new technique, early patient outcomes are also described. Patient outcomes included the incidence of primary nonfunction, delayed graft function, graft and patient survival at 1 year. Contralateral kidneys undergoing static cold storage alone were used as a comparator group. Between March 2016 and July 2017, EVNP was performed on 14 kidneys from 12 donors (11 kidneys in center 1, 3 kidneys in center 2). Of the 14 kidneys that underwent EVNP, 12 organs were implanted into 10 recipients. Two pairs of kidneys were implanted as dual grafts and 1 kidney was implanted simultaneously with a pancreas. The remaining 7 kidneys were transplanted as single allografts. Seven pairs of kidneys were available for paired analysis comparing EVNP versus static cold storage. Graft and patient outcomes were comparable between the 2 preservation techniques. The introduction of a clinical EVNP service requires a careful multimodal approach, drawing on the expertise of specialists in transplantation, hematology, and microbiology. Both new clinical EVNP programs demonstrated proficiency and safety when a structured dissemination process was followed.

Vascular measures of atherosclerosis in detrusor overactivity and controls.

AIM: The mechanisms leading to the development of detrusor overactivity (DO) are still relatively poorly understood, however, animal studies suggest that atherosclerosis and reduced blood flow to the bladder may be one etiological pathway. Thus, the aim of this study was to evaluate signs of atherosclerosis in a large cohort of women with detrusor overactivity, using two precise measures of atherosclerotic vascular impairment, Ankle Brachial Index (ABI), and Brachial-ankle Pulse Wave Velocity (baPWV). METHODS: A prospective cohort study measuring ABI and baPWV of women with DO and controls was conducted. The ABI and baPWV were measured using an automated oscillometric blood pressure machine, to evaluate the degree of atherosclerosis in patients with DO and controls. Associations between ABI and baPWV and important confounding variables were assessed by a linear regression model. RESULTS: Ninety-eight women with DO, and 98 controls without any symptoms of DO were studied. Multivariate analysis showed an increase in left baPWV of approximately 96 cm/s units of velocity (95%CI 20.65-172.05, P = 0.01) is predicted significantly by the presence or absence of detrusor overactivity (as well by independent factors of age, diastolic blood pressure and body mass index). A similar effect was seen for right baPWV. CONCLUSIONS: On linear regression modeling, the presence of DO was a strong predictor for an increased PWV when controlling for age, BMI and diastolic blood pressure (DBP), thus supporting the hypothesis that atherosclerosis may contribute to the etiology of DO.

The urinary microbiome in patients with refractory urge incontinence and recurrent urinary tract infection.

INTRODUCTION AND HYPOTHESIS: Urinary urge incontinence is a chronic, debilitating condition that is difficult to treat. Patients refractory to standard antimuscarinic therapy often experience recurrent urinary tract infections (rUTIs). The microbiota of these refractory patients with rUTI remains unexplored. METHODS: A midstream urine (MSU) sample was collected from patients with refractory urge incontinence and coexistent rUTI during acute symptomatic episodes. Culture-based diagnosis was performed using routine microbiological methods. Culture-independent profiling was performed using bacterial 16S RNA profiling. E. coli strain typing was performed by amplicon pyrosequencing of the fimH gene. RESULTS: Over 2 years, 39 patients with refractory urge incontinence and coexistent rUTI were studied, yielding 9 severely affected cases. These 9 patients were carefully monitored for a further 2 years, resulting in the collection of 102 MSU samples, 70 of which were diagnosed as UTI (median of 8 UTIs/woman). Culture-independent analysis of 38 of these samples revealed the existence of a diverse urinary microbiota. Strain typing of E. coli identified instances of rUTI caused by the same persisting strain and by new infecting strains. CONCLUSIONS: Patients with refractory urge incontinence and coexistent rUTI possess a diverse urinary microbiota, suggesting that persistent bladder colonisation might augment the pathology of their chronic condition.

Development and Evaluation of vetPAL, a Student-Led, Peer-Assisted Learning Program.

Based on an idea from a final-year student, Bristol Veterinary School introduced vetPAL, a student-led, peer-assisted learning program. The program involved fifth-year (final-year) students acting as tutors and leading sessions for fourth-year students (tutees) in clinical skills and revision (review) topics. The initiative aimed to supplement student learning while also providing tutors with opportunities to further develop a range of skills. All tutors received training and the program was evaluated using questionnaires collected from tutees and tutors after each session. Tutees' self-rated confidence increased significantly in clinical skills and for revision topics. Advantages of being taught by students rather than staff included the informal atmosphere, the tutees' willingness to ask questions, and the relatability of the tutors. The small group size and the style of learning in the revision sessions (i.e., group work, discussions, and interactivity) were additional positive aspects identified by both tutees and tutors. Benefits for tutors included developing their communication and teaching skills. The training sessions were considered key in helping tutors feel prepared to lead sessions, although the most difficult aspects were the lack of teaching experience and time management. Following the successful pilot of vetPAL, plans are in place to make the program permanent and sustainable, while incorporating necessary changes based on the evaluation and the student leader's experiences running the program. A vetPAL handbook has been created to facilitate organization of the program for future years.

Multimodal communication and audience directedness in the greeting behaviour of semi-captive African savannah elephants.

Many species communicate by combining signals into multimodal combinations. Elephants live in multi-level societies where individuals regularly separate and reunite. Upon reunion, elephants often engage in elaborate greeting rituals, where they use vocalisations and body acts produced with different body parts and of various sensory modalities (e.g., audible, tactile). However, whether these body acts represent communicative gestures and whether elephants combine vocalisations and gestures during greeting is still unknown. Here we use separation-reunion events to explore the greeting behaviour of semi-captive elephants (Loxodonta africana). We investigate whether elephants use silent-visual, audible, and tactile gestures directing them at their audience based on their state of visual attention and how they combine these gestures with vocalisations during greeting. We show that elephants select gesture modality appropriately according to their audience's visual attention, suggesting evidence of first-order intentional communicative use. We further show that elephants integrate vocalisations and gestures into different combinations and orders. The most frequent combination consists of rumble vocalisations with ear-flapping gestures, used most often between females. By showing that a species evolutionarily distant to our own primate lineage shows sensitivity to their audience's visual attention in their gesturing and combines gestures with vocalisations, our study advances our understanding of the emergence of first-order intentionality and multimodal communication across taxa.

Development of the Animal Management and Husbandry Online Placement Tool.

The workplace provides veterinary students with opportunities to develop a range of skills, making workplace learning an important part of veterinary education in many countries. Good preparation for work placements is vital to maximize learning; to this end, our group has developed a series of three computer-aided learning (CAL) packages to support students. The third of this series is the Animal Management and Husbandry Online Placement Tool (AMH OPT). Students need a sound knowledge of animal husbandry and the ability to handle the common domestic species. However, teaching these skills at university is not always practical and requires considerable resources. In the UK, the Royal College of Veterinary Surgeons (RCVS) requires students to complete 12 weeks of pre-clinical animal management and husbandry work placements or extramural studies (EMS). The aims are for students to improve their animal handling skills and awareness of husbandry systems, develop communication skills, and understand their future clients' needs. The AMH OPT is divided into several sections: Preparation, What to Expect, Working with People, Professionalism, Tips, and Frequently Asked Questions. Three stakeholder groups (university EMS coordinators, placement providers, and students) were consulted initially to guide the content and design and later to evaluate previews. Feedback from stakeholders was used in an iterative design process, resulting in a program that aims to facilitate student preparation, optimize the learning opportunities, and improve the experience for both students and placement providers. The CAL is available online and is open-access worldwide to support students during veterinary school.

Normothermic machine perfusion versus static cold storage in donation after circulatory death kidney transplantation: a randomized controlled trial.

Kidney transplantation is the optimal treatment for end-stage renal disease, but it is still severely limited by a lack of suitable organ donors. Kidneys from donation after circulatory death (DCD) donors have been used to increase transplant rates, but these organs are susceptible to cold ischemic injury in the storage period before transplantation, the clinical consequence of which is high rates of delayed graft function (DGF). Normothermic machine perfusion (NMP) is an emerging technique that circulates a warmed, oxygenated red-cell-based perfusate through the kidney to maintain near-physiological conditions. We conducted a randomized controlled trial to compare the outcome of DCD kidney transplants after conventional static cold storage (SCS) alone or SCS plus 1-h NMP. A total of 338 kidneys were randomly allocated to SCS (n = 168) or NMP (n = 170), and 277 kidneys were included in the final intention-to-treat analysis. The primary endpoint was DGF, defined as the requirement for dialysis in the first 7 d after transplant. The rate of DGF was 82 of 135 (60.7%) in NMP kidneys versus 83 of 142 (58.5%) in SCS kidneys (adjusted odds ratio (95% confidence interval) 1.13 (0.69-1.84); P = 0.624). NMP was not associated with any increase in transplant thrombosis, infectious complications or any other adverse events. A 1-h period of NMP at the end of SCS did not reduce the rate of DGF in DCD kidneys. NMP was demonstrated to be feasible, safe and suitable for clinical application. Trial registration number: ISRCTN15821205 .

Modeling the Effects of IL-1ß-mediated Inflammation During Ex Vivo Lung Perfusion Using a Split Human Donor Model.

BACKGROUND: The association between interleukin-1ß (IL-1ß) concentrations during ex vivo lung perfusion (EVLP) with donor organ quality and post-lung transplant outcome has been demonstrated in several studies. The mechanism underlying IL-1ß-mediated donor lung injury was investigated using a paired single-lung EVLP model. METHODS: Human lung pairs were dissected into individual lungs and perfused on identical separate EVLP circuits, with one lung from each pair receiving a bolus of IL-1ß. Fluorescently labeled human neutrophils isolated from a healthy volunteer were infused into both circuits and quantified in perfusate at regular timepoints. Perfusates and tissues were subsequently analyzed, with perfusates also used in functional assays. RESULTS: Neutrophil numbers were significantly lower in perfusate samples collected from the IL-1ß-stimulated lungs consistent with increased neutrophil adhesion ( P = 0.042). Stimulated lungs gained significantly more weight than controls ( P = 0.046), which correlated with soluble intercellular adhesion molecule-1 (R 2 = 0.71, P = 0.0043) and von-Willebrand factor (R 2 = 0.39, P = 0.040) in perfusate. RNA expression patterns for inflammatory genes were differentially regulated via IL-1ß. Blockade of IL-1ß significantly reduced neutrophil adhesion in vitro ( P = 0.025). CONCLUSION: These data illustrate the proinflammatory functions of IL-1ß in the context of EVLP, suggesting this pathway may be susceptible to therapeutic modulation before transplantation.

Pregnane X Receptor Activation in Liver Perfusion.

BACKGROUND: Liver normothermic machine perfusion (NMP) is being adopted as a method of optimizing livers before transplantation. However, there is further potential to use the NMP model as a platform for drug delivery. Pregnane X receptor (PXR) activation upregulates CYP3A expression and has been shown to be protective against ischemia-reperfusion in rodents. We introduced a PXR activator during NMP and assessed activation of its downstream targets. METHODS AND MATERIALS: Organs were perfused on a NMP circuit using an oxygenated red cell-based perfusate. A series of livers were allocated to PXR treatment and compared with a control group. Biopsies were taken at the start and end of the perfusion process to quantify CYP3A expression. Perfusion samples were taken throughout the perfusion process and used to measure biochemical variables (lactate and alanine transaminase). RESULTS: Quantification polymerase chain reaction using the delta computed tomography method on 5 livers which received Avasimibe demonstrated successful upregulation of CYP3A43 and CYP3A4 over the course of perfusion by 3.8-fold and 2.2-fold, respectively (P = .026 and P = .098, respectively; Student t test). The 4 control livers had no significant change in expression of CYP3A43 or CYP3A over the course of perfusion. CONCLUSIONS: We have demonstrated that NMP can be successfully used as a platform for drug delivery with reliable transcription activation of downstream targets. Although it remains to be seen whether PXR therapy is beneficial in humans, the model suggests that perfusion could be used clinically in the future to further optimize grafts by acting as a drug delivery system.

Methaemoglobinaemia Can Complicate Normothermic Machine Perfusion of Human Livers.

Background: Although liver normothermic machine perfusion is increasingly used clinically, there are few reports of complications or adverse events. Many centers perform liver NMP to viability test suboptimal grafts, often for prolonged periods. In addition, several researchers are investigating NMP as a drug delivery platform, which usually necessitates prolonged perfusion of otherwise non-viable liver grafts. We describe two instances of methaemoglobinaemia during NMP of suboptimal livers. Methods: The NMP of eight human livers rejected for transplantation is described. Methaemoglobinaeima developed in two; one perfused using generic Medtronic™ perfusion equipment and one using the OrganOx Metra®. Results: The first liver (53 years DBD) developed methaemoglobinaemia (metHb = 2.4%) after 13 h of NMP, increasing to metHb = 19% at 16 h. Another liver (45 years DBD) developed methaemoglobinaemia at 25 h (metHb = 2.8%), which increased to metHb = 28.2% at 38 h. Development of methaemoglobinaemia was associated with large reductions in oxygen delivery and oxygen extraction. Both livers were steatotic and showed several suboptimal features on viability testing. Delivery of methylene blue failed to reverse the methaemoglobinaemia. Compared to a matched cohort of steatotic organs, livers which developed methaemoglobinaemia showed significantly higher levels of hemolysis at 12 h (prior to development of methaemoglobinaemia). Conclusions: Methaemglobinaemia is a complication of NMP of suboptimal liver grafts, not limited to a single machine or perfusion protocol. It can occur within 13 h (a timepoint frequently surpassed when NMP is used clinically) and renders further perfusion futile. Therefore, metHb should be monitored during NMP visually and using blood gas analysis.

Use of Dextran 40 After Pancreas Transplant May Reduce Early Inflammation and Significant Bleeding Compared to a Heparin-Based Protocol.

BACKGROUND: Dextran 40 (D40) is a synthetic colloid with anticoagulant properties that is used instead of heparin after pancreas transplantation; however, there is a lack of evidence on which is more effective. Graft thrombosis and pancreatitis, which may be mediated through microthrombosis or macrothrombosis within the graft, remain significant complications after pancreas transplantation. We hypothesized that D40 reduces inflammation through its antithrombotic promicrocirculatory effects. We evaluated D40 compared to a heparin-based protocol by comparing postoperative complications and post-transplant levels of inflammation. MATERIALS AND METHODS: Data were collected retrospectively for pancreas transplant patients between December 2009 and August 2018. A total of 26 patients had been treated with the pre-dextran protocol and 37 had received D40. Postoperative complications and inflammatory markers (white cell count [WCC], C-reactive protein [CRP], and amylase) on postoperative days 1, 2, 3, and 7 were compared between groups. Potential confounders were also recorded. RESULTS: Patients in the D40 group had similar thrombosis rates but were less likely to have had graft loss as a result of thrombosis or substantial postoperative bleeding compared to the heparin-based protocol. The group who received D40 had significantly lower CRP and WCC on days 2, 3, and 7. The differences on days 3 and 7 remained when the results were adjusted for the significant confounders of cold ischemic time and donor age. CONCLUSIONS: D40 appears to be as effective as intravenous heparin at preventing graft thrombosis after pancreas transplant and to confer a reduced risk for bleeding. It may also reduce postoperative inflammatory processes, leading to reduced graft pancreatitis.