The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform
John Brassil - One of the best experts on this subject based on the ideXlab platform.
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islet isolation from juvenile porcine pancreas after 24 h hypothermic machine perfusion preservation
Cell Transplantation, 2010Co-Authors: Michael J Taylor, Simona C Baicu, Elizabeth D Greene, Alma Vazquez, John BrassilAbstract:Pancreas procurement for islet isolation and transplantation is limited by concerns for the detrimental effects of postmortem ischemia. Hypothermic machine perfusion (HMP) preservation technology has had a major impact in circumventing ischemic injury in clinical kidney transplantation and is applied here to the preservation and procurement of viable islets after hypothermic perfusion preservation of porcine pancreata because pigs are now considered the donor species of choice for xenogeneic islet transplantation. Pancreases were surgically removed from young (<6 months) domestic Yorkshire pigs (25–32 kg), either before or after 30 min of warm ischemia time (WIT), and cannulated for perfusion. Each pancreas was assigned to one of six preservation treatment groups: fresh controls—processed immediately (cold ischemia <1 h) (G1, n = 7); static cold storage—flushed with cold UW-Viaspan and stored in UW-Viaspan at 2–4°C for 24 h with no prior WIT (G2, n = 9); HMP perfused on a LifePort® machine at 4–6°C and lo...
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twenty four hour hypothermic machine perfusion preservation of porcine pancreas facilitates processing for islet isolation
Joint Conference of the Cell Transplant Society (CTS) International Pancreas and Islet Transplant Association (IPITA) and International Xenotransplant, 2008Co-Authors: Michael J Taylor, Simona C Baicu, Elizabeth D Greene, Alma Vazquez, Brian Leman, John BrassilAbstract:Procurement of donor pancreata for islet isolation and transplantation is not yet widely practiced due to concerns about the impact of postmortem ischemia on functional islet yields. Perfusion/preservation technology may help to circumvent ischemic injury as applied in this study of porcine pancreata prior to islet isolation. Pancreata harvested from adult pigs were assigned to 1 of 3 preservation treatment groups: G1, fresh controls, processed immediately with minimum cold ischemia (<1 hour); G2, static cold storage, flushed with cold UW-Viaspan and stored at 2°–4°C for 24 hours; and G3, hypothermic machine perfusion (HMP) on a pulsatile LifePort machine Organ Recovery Systems, Inc., Des Plaines, Ill, United States with KPS1 solution at 4–7°C and low pressure (10 mm Hg) for 24 hours. Islet isolation was then accomplished using conventional methods. Product release criteria were used to assess islet yield and function. Islet yield was markedly different between the treatment groups. There was a statistically significant increased yield in the HMP group over static cold storage in UW-Viaspan (P < .05). Functionally, the islets from each experimental group were equivalent and not significantly different from fresh controls (G1). Dithizone staining of islets showed consistently more uniform digestion of pancreata from G3 compared with G1 and G2, with greater separation of the tissue and fewer entrapped islets. HMP for 24 hours was well tolerated, leading to moderate edema but no loss of function of the harvested islets. The edema appeared to aid in enzymatic digestion, producing a greater yield and purity of islets compared with pancreata subjected to 24 hours of static cold storage.
Maria E Mamprin - One of the best experts on this subject based on the ideXlab platform.
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cold storage of liver microorgans in Viaspan and bg35 solutions study of ammonia metabolism during normothermic reoxygenation
Annals of Hepatology, 2014Co-Authors: Maria Dolores Pizarro, Maria Gabriela Mediavilla, Florencia Berardi, Claudio Tiribelli, Joaquin V Rodriguez, Maria E MamprinAbstract:Introduction. This work focuses on ammonia metabolism of Liver Microorgans (LMOs) after cold preservation in a normothermic reoxygenation system (NRS). We have previously reported the development of a novel preservation solution, Bes-Gluconate-PEG 35 kDa (BG35) that showed the same efficacy as Viaspan® to protect LMOs against cold preservation injury. The objective of this work was to study mRNA levels and activities of two key Urea Cycle enzymes, Carbamyl Phosphate Synthetase I (CPSI) and Ornithine Transcarbamylase (OTC), after preservation of LMOs in BG35 and Viaspan® and the ability of these tissue slices to detoxify an ammonia overload in a NRS model. Material and methods. After 48 h of cold storage (0°C in BG35 or Viaspan®) LMOs were rewarmed in KHR containing an ammonium chloride overload (1 mM). We determined ammonium detoxification capacity (ADC), urea synthesis and enzyme activities and relative mRNA levels for CPSI and OTC. Results. At the end of reoxygenation LMOs cold preserved in BG35 have ADC and urea synthesis similar to controls. Viaspan® group demonstrated a lower capacity to detoxify ammonia and to synthesize urea than fresh LMOs during the whole reoxygenation period which correlated with the lower mRNA levels and activities for CPSI and OTC observed for this group. Conclusion. We demonstrate that our preservation conditions (48 hours, BG35 solution, anoxia, 0oC) did not affect ammonia metabolism of cold preserved LMOs maintaining the physiological and biochemical liver functions tested, which allows their future use as biological component of a BAL system.
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52 hypothermic preservation of rat liver microorgans lmos in Viaspan and bg35 bes gluconate peg35 solutions study of ammonia metabolism during rewarming to evaluate their possible use as biological component of a bal system
Cryobiology, 2012Co-Authors: Florencia Berardi, Maria Gabriela Mediavilla, Claudio Tiribelli, D Pizarro, Angel L Scandizzi, J Rodri V Guez, Maria E MamprinAbstract:Bioartificial livers (BAL) were designed as a bridge to maintain patients with liver failure until they recover or receive a liver transplant. In these devices, the patient’s blood or plasma is circulated extra-corporeally through a bioreactor that houses a metabolically active component, as isolated hepatic cells or cultured cells. In this work, we tested LMOs from rat liver. LMOs are tissue slices that retain the microarchitecture of the liver lobe and its physiological characteristics. The use of LMOs is also attractive because it obviates the stages of cell isolation and cultivation. So, our group has set up a technique to manually obtain LMOs and constructed a flat-based BAL model suitable to use fresh LMOs. Moreover, we have developed a novel preservation solution, BG35, with similar efficacy than Viaspan ® to protect LMOs against cold preservation injury. This would allow having the biological component viable, functional and ready to be used when is needed for our BAL. Ammonia accumulates in the blood of patients with liver failure, causing metabolic and neurological disturbances, being crucial that any cell or tissue to be employed in a BAL can perform this task. Since the Urea Cycle is the major pathway of ammonia removal, the objective of this work was to study gene expression and activity of Carbamoyl Phosphate Synthetase I (CPSI) and Ornithine Transcarbamylase (OTC), two key enzymes, after LMOs preservation in BG35 and Viaspan ® (0 °C, 48 h). We have assayed in vitro the LMOs ability to detoxify an overload of ammonia in order to evaluate them for their successive application into a BAL. LMOs were manually cut (338 ± 27 μm thickness, n = 25). 50 LMOs were stored at 0 °C in 60 mL of BG35 or Viaspan ® . Freshly-cut LMOs were used as controls. After cold storage, LMOs were rewarmed (37 °C, Krebs Henseleit Rewarming solution, 120 min) in a Dubnoff metabolic shaker under 95%O 2 :5% CO 2 atmosphere. Samples were taken after 60 and 120 min. All groups showed a good maintenance of their viability. After 120 min, the amount of LDH released by LMOs cold preserved in BG35 (20.1 ± 5.6%) and Viaspan ® (23.4 ± 5.5 %) was similar to Controls (16.0 ± 4.4 %, n = 3). The preservation conditions did not affect ammonia metabolism: after 2 h of rewarming, LMOs cold preserved in BG35 and Viaspan ® could detoxify 29.3 ± 7.9% and 25.7 ± 4.9% of the initial overload, similarly than Controls (29.7 ± 10.7%, n = 6). Though there were differences in relative mRNA levels between Controls and the two preserved groups, the values of CPSI and OTC enzymatic activity were comparable in all studied groups. In summary, we have shown that our preservation conditions did not affect ammonia metabolism and cold preserved LMOs maintain the physiological and biochemical liver functions tested, which allows their use as biological component of a BAL system.
Karim Boudjema - One of the best experts on this subject based on the ideXlab platform.
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comparative evaluation of celsior solution versus Viaspan in a pig liver transplantation model
Transplantation, 2001Co-Authors: Maxime Audet, Eliane Alexandre, Ashiq Mustun, Pascale David, Mariepierre Chenardneu, Jerome Tiollier, Daniel Jaeck, Jacques Cinqualbre, Phillippe Wolf, Karim BoudjemaAbstract:Background. In a pig liver transplantation model, we compared the effects of Celsior solution (CS), an extracellular preservation solution, with Viaspan (University of Wisconsin solution, UW) on graft function and animal survival. Methods. Pig livers were flushed with either CS or UW solution and cold-stored for 12 hr (group 1) or for 8 to 10 hr (group 2). Grafts were transplanted orthotopically. Intrahepatic reduced and oxidized glutathione and adenine nucleotides were evaluated 1 hr after reperfusion. Liver function of transplanted animals was monitored for up to 6 days by serum transaminases, total bilirubin, purine nucleoside phosphorylase, and prothrombin levels. Results. In group 1, all animals died within 24 hr after reperfusion regardless of the preservation solution used. In group 2, no significant difference was seen in survival between the CS (72%) and the UW (67%) groups 6 days after transplantation, and there were no statistically significant differences in the biochemical data. There were no differences in histological evaluation of the livers at the time of death or killing of the animals between the CS and UW groups. Conclusion. Within the limits of this pilot study, CS is equivalent to UW in terms of graft function and animal survival.
P Neuhaus - One of the best experts on this subject based on the ideXlab platform.
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24 h storage of pig livers in uw htk hydroxyethyl starch and saline solution is microdialysis an appropriate method for the continuous graft monitoring during preservation
Transplant International, 2006Co-Authors: Gero Puhl, Peter Olschewski, Wenzel Schoning, U P Neumann, Daniel Sredznizki, Anja Dankof, U Settmacher, P NeuhausAbstract:Summary Recent studies demonstrate the feasibility of microdialysis to monitor metabolism in ischemic livers. Whether these parameters correlate with markers of liver cell integrity in an experimental model using pig livers and different preservation solutions was an aim of this study. Pig livers were flushed with either 4 °C Histidine-Typtophan-Ketoglutarate solution (HTK) (Custodiol®), University of Wisconsin solution (Viaspan®), and hydroxyethyl starch, or 12 °C saline solution. After 24-h storage, the livers were rinsed with saline to measure liver enzymes and lactate from the effluate. Utilizing microdialysis, intraparenchymal lactate, pyruvate, glucose, and glycerol was monitored. Tissue biopsies were taken for histological examinations. Cold preservation resulted in a decrease of metabolic activity measured by intrahepatic glucose, lactate, and pyruvate levels, as well as lactate in the effluate, independently of the solution used. Of particular interest, glycerol levels partially reflected the extent of hepatocellular damage and liver enzyme release. Glycerol levels partially discriminated preservation of different quality and were in accordance to histological findings and liver enzyme release. Lactate, pyruvate, and glucose levels were not appropriate as markers during cold storage. Whether or not glycerol monitoring could represent an additional and rational complementation to the current practice of macroscopic, microscopic and donor evaluation has to be clarified by further studies.
Luigi Boschiero - One of the best experts on this subject based on the ideXlab platform.
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a comparative prospective study of two available solutions for kidney and liver preservation
Transplantation, 2004Co-Authors: Paola Pedotti, Massimo Cardillo, Paolo Rigotti, Giorgio Enrico Gerunda, Roberto Merenda, Umberto Cillo, G Zanus, Umberto Baccarani, Maria Luisa Berardinelli, Luigi BoschieroAbstract:BACKGROUND Viaspan (University of Wisconsin [UW]) solution is the gold standard for abdominal organ preservation. Celsior (CEL) is an extracellular-type, low-potassium, low-viscosity solution, initially used for heart and lung preservation. We have performed a prospective multicenter study to compare the role of these cold-storage solutions on kidney and liver recovery after transplantation. PATIENTS AND METHODS From March 15, 2000 to December 31, 2001, 441 (172 CEL and 269 UW) renal transplants (RT) and 175 (79 CEL and 96 UW) liver transplants (LT) were included in the study. RESULTS Perfusate volume used was significantly lower in the UW group, being 4,732 +/- 796 mL versus 5,826 + 834 mL in the CEL group (P < 0.001). In LT, median total bilirubin serum levels were significantly higher at 5 and 7 posttransplant days in the UW group (90.6 and 92.3 micromol/L, respectively) as compared with CEL (51.3 and 63.4 micromol/L, respectively). After LT, primary nonfunction (PNF) rates in the CEL and UW groups were 3.8% and 4.2% (P = NS) respectively, with 1-year graft and patient survival being 83.3% versus 85.4% (P = NS) and 89.9% versus 90.6% (P = NS). After RT, delayed graft function (DGF) rates were 23.2% and 22.7% (P = NS), respectively; PNF rates were 1.9% and 1.7% (P = NS) respectively, with 1-year graft and patient survival being 92.3% versus 94.2% (P = NS) and 99.4% versus 97.7% (P = NS). CONCLUSIONS CEL solution was shown to be as effective as UW in both liver and kidney preservation. In LT patients, biliary function recovery is significantly better in the CEL group. CEL solution represents an efficacious option in multiorgan harvesting.
