Stabilised decellularised vascular grafts in an ovine carotid model

Background: There is an urgent clinical need for an alternative vascular graft, especially for smaller artery applications such as in below-knee and coronary artery bypass. Currently available synthetic grafts have unacceptably low patency rates, while autologous saphenous vein grafts are not feasible in one third of patients. Decellularised vascular grafts have been investigated as alternative conduits, but this chemical treatment results in degradation of the extracellular matrix. Chemical stabilization of elastin with penta-galloyl glucose (PGG) combined with collagen stabilisation during covalent heparinisation was previously investigated by our group in a small animal model and shown to be effective and safe. The current study describes their evaluation in a large animal (ovine) model. Methods: Porcine mammary arteries were harvested, decellularised according to an established protocol involving rinsing with sodium hydroxide, alcohol (ETOH), treatment with DNAse/RNAse enzymes, immersion in PGG and subsequently surface modified with covalently bound heparin. Samples of the grafts were also tested for radial and suture retention strength. The prepared grafts were implanted as interposition grafts into the carotid arteries of 6 sheep, using industry standard 6mm expanded polytetrafluoroethylene (ePTFE) on the contralateral side of each animal as control. In-situ patency was determined by ultrasound and angiography at two months, following which the grafts were explanted for macro- and microscopic analysis. Results: In-vitro evaluation: Grafts showed significant levels of bound heparin (14.56 mg/g vs 0.69mg/g in untreated tissue) and demonstrated similar mechanical properties to those of human carotid arteries. Survival: Five out of six sheep survived the full 2-month implant period, while the remaining animal developed sepsis shortly after implantation and was euthanized on day 4. Patency: None of the decellularised grafts were patent at explant, as assessed by ultrasound, angiography and macroscopic examination. Two of the five control (ePTFE) grafts were patent. Microscopic analysis: An inflammatory cell infiltrate with vascularised granulation tissue was found encasing the decellularised xenografts with little or no sign of endothelial cell infiltration. Signs of early occlusion, likely due to technical factors, was noted at the sites of anastomosis. Conclusion: Although demonstrating similar mechanical properties to human carotid arteries, and promising results in the small animal model, the stabilised decellularised vascular grafts failed to achieve endothelialisation or patency in this sheep carotid model. Significant calibre mismatch between the test graft and the native artery is thought to be the primary factor in the failure of these grafts, highlighting the potential difficulty in acquiring grafts of an appropriate size from animal sources

Body surface gastric mapping to determine gastric motility patterns associated with delayed gastric emptying after pancreaticoduodenectomy. Gastric Electric Mapping after Pancreatoduodenectomy study protocol

Introduction Delayed gastric emptying (DGE) is frequent after pancreaticoduodenectomy (PD). Although often associated with postoperative pancreatic fistula, the precise pathogenesis in patients with no underlying complications remains unclear. There is evidence to suggest that, after surgery, aberrant electrical pathways are formed in the stomach which could contribute to the development of DGE.Gastric Alimetry is a novel technology which measures the electrical activity of the stomach non-invasively using an array of electrodes applied to the skin of the abdomen. This technique, termed body surface gastric mapping (BSGM), has been validated in normal controls and in patients with functional dyspepsia syndromes. This study will investigate the efficacy and feasibility of using BSGM to assess gastric motility in patients who undergo PD.Methods and analysis This prospective cohort study will be conducted at a single large volume hepatobiliary unit in the UK. 50 patients who are planned to undergo PD will be included. BSGM measurement will be performed at four timepoints viz: preoperatively, day 4 postoperatively, at discharge and 6 months postoperatively. Key parameters of BSGM measurement, including wave amplitude, frequency and directional vector, will be measured at each timepoint and compared between different patient subgroups. Symptoms will be self-reported by patients during the recording using an iPad application designed for this purpose. Quality of life and patient experience will be assessed using standardised questionnaires at the end of the follow-up period.Ethics and dissemination The protocol has been approved by the research ethics committees of Newcastle University and the Health Research Authority (HRA) of the UK (ethical approval IRAS ID 305302). Findings will be published in peer-reviewed journals and presented at national and international conferences.Trial registration number This study will automatically be registered with the ISRCTN registry by the HRA as part of the ethics approval process

Lactate-Mediated Acidification of Tumor Microenvironment Induces Apoptosis of LiverResident NK Cells in Colorectal Liver Metastasis

Colorectal cancer is the third most common malignancy worldwide, with 1.3 million new cases annually. Metastasis to the liver is a leading cause of mortality in these patients. In human liver,metastatic cancer cells must evade populations of liver-resident natural killer (NK) cells with potent cytotoxic capabilities. Here, we investigated how these tumors evade liver NK-cell surveillance. Tissue biopsies were obtained from patients undergoing resection of colorectal liver metastasis (CRLM, n ¼ 18), from the tumor, adjacent tissue, and distal resection margin. The number and phenotype of liver-resident NK cells,at each site,we reanalyzed by flow cytometry. Tumor conditioned media (TCM) was generated for cytokine and metabolite quantification and used to treat healthy liver resident NK cells, isolated from donor liver perfusate during transplantation. Liver-resident NK cells were significantly depleted from CRLM tumors. Healthy liver-resident NK cells exposed to TCM underwent apoptosis in vitro,associated with elevated lactate. Tumor-infiltrating liver-resident NK cells showed signs of mitochondrial stress,which was recapitulated in vitro by treating liver-resident NK cells with lactic acid. Lactic acid induced apoptosis by decreasing the intracellular pH of NK cells,resulting in mitochondrial dysfunction that could be prevented by blocking mitochondrial ROS accumulation. CRLM tumors produced lactate, thus decreasing the pH of the tumor microenvironment. Liver-resident NK cells migrating toward the tumor were unable to regulate intracellular pH resulting in mitochondrial stress and apoptosis. Targeting CRLM metabolism provides a promising therapeutic approach to restoring local NK-cell activity and preventing tumor growth

A scoring system for predicting malignancy in intraductal papillary mucinous neoplasms of the pancreas: a multicenter EUROPEAN validation

A preoperative estimate of the risk of malignancy for intraductal papillary mucinous neoplasms (IPMN) is important. The present study carries out an external validation of the Shin score in a European multicenter cohort.Methods An observational multicenter European study from 2010 to 2015. All consecutive patients undergoing surgery for IPMN at 35 hospitals with histological-confirmed IPMN were included.Results A total of 567 patients were included. The score was significantly associated with the presence of malignancy (p < 0.001). In all, 64% of the patients with benign IPMN had a Shin score < 3 and 57% of those with a diagnosis of malignancy had a score >= 3. The relative risk (RR) with a Shin score of 3 was 1.37 (95% CI: 1.07-1.77), with a sensitivity of 57.1% and specificity of 64.4%.Conclusion Patients with a Shin score <= 1 should undergo surveillance, while patients with a score = 4 should undergo surgery. Treatment of patients with Shin scores of 2 or 3 should be individualized because these scores cannot accurately predict malignancy of IPMNs. This score should not be the only criterion and should be applied in accordance with agreed clinical guidelines