Seventy-two-hour preservation of the canine pancreas by the two-layer (Euro-Collins' solution/perfluorochemical) cold storage method

A 72-hr preservation of canine pancreas by a 2-layer (Euro-Collins'/Perfluorochemical) cold storage method was tested in the canine model of segmental pancreas autotransplantation. The functional recovery of the grafts by this method (group 1) was determined by daily fasting blood glucose concentration and intravenous glucose tolerance test at 2 weeks after autotransplantation and compared with simple cold storage with Euro-Collins' solution (group 2) and control (no preservation) (group 3). Maintenance of normoglycemia for at least 5 days after transplantation was considered a successful preservation. The functional success rates after 72-hr preservation were 100%, 0%, and 100% for groups 1, 2, and 3, respectively. The mean K values of group 1 after 72-hr preservation was 1.78 +/- 0.42 compared with 2.05 +/- 0.32 for group 3 at 2 weeks after transplantation. Biopsies of grafts of group 2 after 72-hr preservation showed remarkable autolytic changes in exocrine and endocrine tissues. In contrast, biopsies of grafts of group 1 after 72-hr preservation showed almost normal architecture in both tissues. In addition, biopsies of 72-hr preserved grafts of group 1 at 4 weeks after after autotransplantation showed almost normal pancreas architecture with minimal fibrotic changes in the exocrine tissue. This study demonstrated the possibility of 72-hr preservation of the pancreas for transplantation.     

Pancreas oxygenation is limited during preservation with the two-layer method

BACKGROUND: The two-layer method (TLM) for pancreas preservation reportedly improves islet yield and transplantation outcome relative to previous methods. Increased ATP concentrations support the hypothesis that these improvements are related to better oxygenation from the perfluorocarbon solution. However, there are limited direct measurements of oxygen partial pressure, (pO(2)) in pancreata preserved with the TLM. Theory predicts that only a small fraction of a human pancreas can be oxygenated externally. In this report we examine pancreas oxygenation with the TLM using theory and direct pO(2) measurements. METHODS: pO(2) profiles in cylindrical pancreata were calculated at various temperatures with a diffusion-reaction model. The pO(2) was measured using fiber optic sensors in the core of porcine pancreatic tissue preserved with the TLM in media saturated with 100% oxygen. RESULTS: The model predicts that at 8 degrees C, even in the absence of an external pO(2) gradient, oxygen penetration depth is about 1 mm and insensitive to pancreas diameter, while the oxygenated volume fraction is about 15% for a 2.5-cm-diameter pancreas. Experimental measurements verified that pO(2) is virtually zero in the core of a 1-cm-thick pancreatic piece preserved with the TLM. Penetration of solution around the sensor may be responsible for the observed lag and for the previously reported nonzero pO(2) measurements. Reoxygenation of heat-treated tissue took several hours. CONCLUSIONS: The TLM can oxygenate only a small volume fraction of a human pancreas. Pancreas oxygenation through the native vasculature should be explored to further improve yield of viable islets.     

Characterization of islet-infiltrating immunocytes after pancreas preservation by two-layer (UW/perfluorochemical) cold storage method

Clinical islet transplantation offers the prospect of good blood glycemic control without major surgical risks. Nevertheless, long-term function of the transplanted islets is seldom appreciated because rejection is followed by the graft failure. Although it has been implicated that islets have high immunogenicity, characterization of the islet-infiltrating immunocytes, such as leukocytes and macrophages, has not been extensively studied. Rat islets were isolated by the collagenase digestion method and separated by handpicking under the microscope. The islets were further dispersed into individual cells for flow cytometric analysis. Monoclonal antibodies directed toward T cells, B cells, and macrophages as well as ICAM-1, and MHC class I and II were used to enumerate cells. Pancreatic islets contained 6.3 +/- 2.9% immunocytes; T cells (39.6 +/- 4.2%), B cells (44.7 +/- 5.8%), and macrophages (1.7 +/- 0.6%). MHC class I was expressed on 85.6 +/- 2.8%, MHC class II on 36.8 +/- 2.9%, and ICAM-1 on 39.9 +/- 7.0%. The results of islets from preserved pancreas also showed the same tendency. As these islet-infiltrating immunocytes within the grafts may contribute to the rejection, one potential strategy to prevent early graft loss might start to eliminate or inactivate the islet-infiltrating immunocytes.     

The mechanism of action of the two-layer (Euro-Collins' solution/perfluorochemical) cold storage method in canine pancreas preservation

To clarify the mechanism of action of a two-layer [Euro-Collins' solution (EC)/perfluorochemical (PFC) ] cold storage method in the preservation of the pancreas, pancreatic viability and tissue concentrations of adenosine triphosphate (ATP) were examined in the canine model of pancreatic autotransplantation after preservation for 24 and 48 h by simple cold storage in EC (group 1), the two-layer, EC/PFC, method (group 2) and the two-layer, EC + 2, 4 dinitrophenol (DNP)/PFC, method (group 3). DNP is an uncoupler of oxidative phosphorylation. Maintenance of normoglycemia for at least 5 days after transplantation was considered a successful preservation. After preservation for 24 h, the functional success rates of groups 1, 2 and 3 were 100% (4/4), 100% (5/5) and 80% (4/5) respectively. One of five dogs in group 3 died of a cause unrelated to the pancreas. ATP tissue concentrations in group 2 were significantly higher than in group 1 (7.47 ± 0.47 gmol/g dry weight vs 1.41 ± 0.53 gmol/g dry weight, P < 0.01) and ATP tissue concentrations in group 3 were significantly lower than in group 2 (1.25 ± 0.37 gmol/g dry weight vs 7.47 ± 0.47 gmol/g dry weight, P < 0.01). It was apparent that ATP was not an essential factor for successful 24-hour preservation of the canine pancreas in EC because all the pancreatic grafts except one of five grafts in group 3 remained viable after preservation for 24 h, regardless of ATP tissue concentrations. On the other hand, after preservation for 48 h, the functional success rates for groups 1, 2 and 3 were 0% (0/4), 100% (4/4) and 0% (0/3) respectively. ATP tissue concentrations in group 2 were significantly higher than in group 1 (7.91 ± 1.21 gmol/g dry weight vs 1.21 ± 0.314tmol/g dry weight, P < 0.01) and ATP tissue concentrations in group 3 were significantly lower than in group 2 (0.61 ± 0.07 gmol/g dry weight vs 7.91 ± 1.21 µmol/g dry weight, P < 0.01). It was clear that preservation of the pancreas for 48 h was unsuccessful by simple cold storage in EC (group 1) and the two-layer method (group 2) made preservation for 48 h possible by increasing ATP tissue concentrations. However, DNP (group 3) inhibited the synthesis of ATP and the effectiveness of the two-layer method for 48-hour preservation of the pancreas. It was clear that maintenance of high ATP tissue concentrations during preservation was essential for the successful preservation of the canine pancreas in EC by the two-layer method for more than 48 h. We concluded that an adequate supply of oxygen to the pancreas during preservation by the two-layer method led to sufficient production of ATP to maintain cellular integrity and permitted the improvement of pancreatic preservation.     

Short-term storage of the ischemically damaged human pancreas by the two-layer method prior to islet isolation

A two-layer cold storage method (TLM) allows sufficient oxygen delivery to pancreata during preservation and resuscitates the viability of ischemically damaged pancreata in the canine pancreas transplant model. In this study, we applied a short-term preservation of the TLM to human pancreata after prolonged cold ischemia prior to islet isolation, and investigated the mechanisms of resuscitation of the ischemically damaged human pancreas by the TLM. Human pancreata were procured from cadaveric donors and preserved by the TLM for 3.2 +/- 0.5 h after 11.1 +/- 0.9 h of cold storage in UW (TLM group), or by cold UW alone for 11.0 +/- 0.3 h (UW group). Islet isolations of all pancreata were performed using the Edmonton protocol. Islet recovery and in vitro functional viability of isolated islets were significantly increased in the TLM group compared with the UW group. According to the criteria of the Edmonton protocol, 10/14 cases (71%) in the TLM group were transplanted to patients with type I diabetes mellitus compared with only 5/21 cases (24%) in the UW group. In the metabolic assessment of human pancreata, levels of energetic parameters (ATP, total adenylates, and energy charge) were significantly increased, and malondialdehyde (MDA) levels were significantly decreased after the TLM preservation. There was no observable change in the incidence or degree of mitochondrial injury after the TLM preservation. Additional short-term storage by the TLM resuscitates the ischemically damaged human pancreas by regenerating the energetic status and prevents further damage by oxidative stress, ultimately leading to improvements of islet recovery and in vitro function. Use of the TLM following prolonged storage in UW provides an excellent adjunctive protocol for treating human pancreata for the rigors of the islet isolation process.     

Influence of pancreas preservation on human islet isolation outcomes: impact of the two-layer method

BACKGROUND: Human pancreas preservation for islet transplantation holds additional challenges and considerations compared with whole pancreas transplantation. The purpose of this study was to clarify the limitations of the University of Wisconsin (UW) solution and the potentials of the two-layer method (TLM) for pancreas preservation before human islet isolation. METHODS: We retrospectively evaluated human islet isolation records between January 2001 and February 2003. One hundred forty-two human pancreata were procured from cadaveric donors and preserved by means of the UW solution (n=112) or TLM (n=30). Human islet isolations were performed using a standard protocol and assessed by islet recovery and in vitro function of islets. RESULTS: Eight to ten hours of cold ischemia in the UW solution is a critical point for successful islet isolations. It is difficult to recover a sufficient number of viable islets for transplantation from human pancreata with more than 10 hours of cold storage in the UW solution. The overall islet recovery in the TLM group was significantly higher than in the UW group. With 10 to 16 hours of cold storage, the success rates of islet isolations remained at 62% in the TLM group but decreased to 22% in the UW group. Transplanted islets in the TLM group worked well in the recipients. CONCLUSIONS: There are time limitations for using the UW solution for pancreas preservation before human islet isolation. The TLM is a potential method to prolong the optimal cold storage time for successful islet isolations.     

Clinical application of the two-layer (University of Wisconsin solution/perfluorochemical plus O2) method of pancreas preservation before transplantation

BACKGROUND: The two-layer method [University of Wisconson solution (UW)/perfluorochemical plus O2] for pancreas preservation has been demonstrated to be superior to simple UW storage alone in the canine model. For the first time, we applied the two-layer method to clinical whole-pancreas transplantation. METHODS: Pancreases were placed in the two-layer method in 10 cases and UW alone in 44 cases before transplant. The mean cold ischemic time was 16.5 hr in the two-layer group versus 18.1 hr in the UW group (P=NS). We compared the condition of graft at the time of reperfusion, and then 3 months posttransplant graft function and complications. RESULTS: At the time of reperfusion, no grafts in the two-layer group were edematous, compared with 10(23.3%) of 43 in the UW group (P=0.18). Seven (70%) of 10 grafts in the two-layer group obtained the best overall quality score, compared with 24(57.1%) of 42 in the UW group (P=0.72). Nine (90%) of 10 recipients in the two-layer group became insulin-independent during hospitalization, compared with 31(70.5%) of 44 in the UW group (P=0.26). Time to insulin independence was no different between the two groups. No pancreas grafts preserved by the two-layer method suffered acute rejection. Conclusions. The two-layer preservation method is feasible in human clinical transplantation. It was at least equivalent and may be superior to UW alone in both morphologic and functional assessment of the transplanted pancreas.     

Successful 24-hour preservation of ischemically damaged canine small intestine by the cavitary two-layer method

BACKGROUND: The purpose of this study is to examine the possibility of a long-term preservation of the ischemically damaged intestine by the cavitary two-layer method (TLM) in canine small intestinal transplantation. METHODS: The grafts were allotransplanted without preservation immediately (group 1) or after 30 minutes of warm ischemia (group 2). The ischemically damaged grafts were also allotransplanted after cold preservation for 24 hours in University of Wisconsin (UW) solution (group 3) or the cavitary TLM (group 4). Seven-day survivals, tissue adenosine triphosphate (ATP) concentrations, absorption tests, and histopathology were examined. RESULTS: seven-day survivals in groups 1, 2, 3, and 4 were 8 of 8, 6 of 8, 0 of 8, and 6 of 8, respectively. In group 4, significant recovery of ATP tissue level was seen after preservation compared with group 3, and absorption function and regeneration of the graft mucosa recovered at day 14. CONCLUSIONS: Ischemically damaged canine small intestine could be preserved for 24 hours by the cavitary TLM.     

Correlation between high adenosine triphosphate tissue concentration and good posttransplant outcome for the canine pancreas graft after preservation by the two-layer cold storage method.

Assessment of viability of a pancreas graft during preservation is very important to avoid transplantation of a nonfunctioning allograft. In the present report the correlation between adenosine triphosphate tissue concentration at the end of cold preservation by the two-layer method and viability a of canine pancreas graft following transplantation was studied. After preservation by an original two-layer (Euro-Collins' solution/perfluorochemical) method (group 1) and a modified two-layer (University of Wisconsin solution/PFC) method (group 2) for 24, 48, 72, 96, and 120 hr (subgroups A, B, C, D, and E), the tissue concentration of ATP was determined using high-performance liquid chromatography, and the viability of the pancreas graft was tested in the canine model of segmental pancreas autotransplantation. Maintenance of normoglycemia for at least five days after transplantation was considered to indicate a viable pancreas graft. In group 1, functional success rates were A: 5/5, (100%), B: 4/4 (100%), C: 4/4, (100%), and D: 0/4 (0%), respectively. The ATP tissue concentrations were 7.47 +/- 0.47 (n = 5), 7.91 +/- 1.21 (n = 4), 8.29 +/- 0.21 (n = 4), and 4.94 +/- 1.11 (n = 4) mumol/g dry weight in groups 1A, 1B, 1C, and 1D, respectively. There was a statistically significant difference between viable groups (groups 1A, 1B, and 1C, 7.86 +/- 0.77 mumol/g dry weight [n = 13]) and the nonviable group (group D, 4.94 +/- 1.11 mumol/g dry weight (n = 4) (P less than 0.01). On the other hand, the functional success rates were 3/3 (100%), 3/3 (100%), 3/3 (100%), 5/7 (71%), and 0/3 (0%) in groups 2A, 2B, 2C, 2D, and 2E, respectively. Two of seven dogs died of causes related to the grafts (pancreatitis and thrombosis). The ATP tissue concentrations were 8.53 +/- 1.45 (n = 3), 9.64 +/- 1.77 (n = 3), 13.81 +/- 2.09 (n = 3), and 12.49 +/- 2.52 (n = 5) mumol/g dry weight in groups 2A, 2B, and 2C and in viable grafts in group 2D, respectively, but the ATP tissue concentration of nonviable grafts in group 2D and group E were 3.51 +/- 0.81 (n = 2) and 3.98 +/- 1.34 (n = 3) mumol/g dry weight, respectively. There was a statistically significant difference between viable groups (groups 2A, 2B, 2C and viable grafts in group 2D, 11.03 +/- 2.72 mumol/g dry weight [n = 14]) and nonviable groups (group E and nonviable grafts in group 2D, 3.79 +/- 1.06 mumol/g dry weight [n = 5]) (P less than 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)     

Advantages of normothermic perfusion over cold storage in liver preservation

BACKGROUND: To minimize the ischemia-reperfusion injury that occurs to the liver with the current method of preservation and transplantation, we have used an extracorporeal circuit to preserve the liver with normothermic, oxygenated, sanguineous perfusion. In this study, we directly compared preservation by the standard method of simple cold storage in University of Wisconsin (UW) solution with preservation by perfusion. METHODS: Porcine livers were harvested from large white sows weighing between 30 and 50 kg by the standard procedure for human retrieval. The livers were preserved for 24 hr by either cold storage in UW solution (n=5) or by perfusion with oxygenated autologous blood at body temperature (n=5). The extracorporeal circuit used included a centrifugal pump, heat exchanger, and oxygenator. Both groups were then tested on the circuit for a 24 hr reperfusion phase, analyzing synthetic function, metabolic capacity, hemodynamics, markers of hepatocyte and reperfusion injury, and histology. RESULTS: Livers preserved with normothermic perfusion were significantly superior (P=0.05) to cold-stored livers in terms of bile production, factor V production, glucose metabolism, and galactose clearance. Cold-stored livers showed significantly higher levels of hepatocellular enzymes in the perfusate and were found to have significantly more damage by a blinded histological scoring system. CONCLUSIONS: Normothermic sanguineous oxygenated perfusion is a superior method of preservation compared with simple cold storage in UW solution. In addition, perfusion allows the possibility to assess viability of the graft before transplantation.     

SWH液对大鼠肝脏保存有效时间的探讨

目的通过与UW液进行比较,探讨SWH液对SD大鼠肝脏保存的有效时间.方法应用大鼠原位肝移植模型,通过高效液相色谱法（HPLC）,检测肝组织ATP、ADP、AMP,计算总腺苷酸含量（TAN）及Atkinson＇s能量转换（EC）,判断肝脏能量代谢状态;通过检测谷丙转氨酶（ALT）、谷草转氨酶（AST）、乳酸脱氢酶（LDH）含量,判定肝脏功能;观察移植术后7d动物存活率,判定SWH液对大鼠肝脏有效保存的时间.结果保存18 h组的ATP、TAN、EC恢复水平明显低于保存8 h组,相差显著,保存12 h组与保存8 h组比较相差不显著;保存18 h组的ALT、AST、LDH明显高于保存8h组,差异显著,保存12 h组与保存8 h组比较相差不显著;SWH液组移植术后7 d动物存活率有高于UW液组的趋势.结论无论使用SWH液还是UW液,SD大鼠肝脏有效保存的时间都不超过12 h.