ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.We demonstrated that hepatic stellate cells (HSCs) isolated from rat livers exposed to warm ischemia are significantly contractile when compared with HSCs from intact rat livers. This suggests that ischemia-reperfusion (IR)-induced impairment of sinusoidal microcirculation results, at least in part, from contraction of HSCs.Methods.Rho-associated coiled-coil forming protein serine/threonine kinase (ROCK) is one of the key regulators of HSCs motility. Therefore we investigated whether Y-27632, a p160ROCK-specific inhibitor, has beneficial effects on warm IR injury in an in vivo rat partial liver IR model and a rat orthotopic liver transplantation model.Results.After reperfusion following 90 min of warm ischemia, livers in untreated control rats had persistent congestion and impaired mitochondrial respiration, as demonstrated by increasing deoxy-hemoglobin and reduced cytochrome oxidase contents in the hepatic tissues using in vivo near-infrared spectroscopy. Serum levels of transaminase and endothelin (ET)-1 in these rats were markedly increased 1 hr after reperfusion. In contrast, when Y-27632 (3–30 mg/kg) was administered orally, hepatic tissue contents of deoxy-hemoglobin and cytochrome oxidase rapidly normalized. In such animals, the elevation of serum transaminase levels, but not that of ET-1 levels, was significantly suppressed. This is consistent with in vitro data demonstrating that Y-27632 causes HSCs to undergo relaxation even in the presence of ET-1. Moreover, in a rat orthotopic liver transplantation model, Y-27632 pretreatment dramatically improved the survival of recipients with liver grafts subjected to 45 min of warm ischemia.Conclusions.Y-27632 attenuates IR-induced hepatic microcirculation disruption by inhibiting contraction of HSCs.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.The Th1 response has been shown to play a role in acute allograft rejection, whereas the Th2 response has been implicated in the protection of allografts. Unlike allografts, the pattern of cytokines in response to solid-organ xenografts has been the subject of limited studies. We investigated intragraft cytokine expression in a concordant cardiac xenograft model (rat-to-mouse) to test if a particular cytokine profile predominates.Methods.Intra-abdominal cardiac transplantation was performed using C57BL/10 mice as recipients of PVG.R8 rat hearts. Syngeneic grafts (C57BL/10-to-C75BL/10) served as controls. Cardiac grafts harvested on various days posttransplantation were analyzed for histology and intragraft cytokine expression using reverse-transcriptase polymerase chain reaction.Results.The grafts in this model were rejected with a mean survival time of 7±1 days and showed extensive evidence of acute vascular rejection, consisting of global distortion of myocardial architecture, fewer cellular infiltrates, interstitial hemorrhage with myocyte necrosis thrombosis, and vasculitis with neutrophils and lymphocytes infiltrating vessel walls. Cardiac xenografts predominantly expressed Th2 cytokines, interleukin (IL)-4, IL-10, and transforming growth factor-&bgr; with various kinetics. IL-10 was detectable on day 1 and reached its peak level of expression on day 6 posttransplantation. IL-4 showed minimal and undetectable expression on days 1 and 3 and significant expression on day 6 posttransplantation. Transforming growth factor-&bgr; was expressed moderately on all days examined. The expression of interferon (IFN)-&ggr;, a Th1 cytokine, was specific to xenografts and showed a gradual increase from days 3 to 6 posttransplantation. In marked contrast, IL-2 showed complete lack of expression.Conclusions.Our data demonstrate predominant expression of Th2 cytokines and IFN-&ggr; in cardiac xenografts undergoing acute vascular rejection. The Th2 cytokines may promote acute vascular rejection by regulating the humoral response, and IFN-&ggr; may delay, but not prevent, this response.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.The role of glycine has not been investigated in lung ischemia-reperfusion injury after cold preservation. Furthermore, the role of apoptosis after reperfusion following cold preservation has not been fully understood.Methods.Lewis rats were divided into three groups (n=6 each). In the GLY(−) and GLY(+) groups, isolated lungs were preserved for 15 hr at 4°C after a pulmonary artery (PA) flush using our previously developed preservation solution (ET-K; extracellular-type trehalose containing Kyoto), with or without the addition of glycine (5 mM). In the Fresh group, isolated lungs were reperfused immediately after a PA flush with ET-K. They were reperfused for 60 min with an ex vivo perfusion model. Pulmonary function, oxidative stress, apoptosis, and tumor necrosis factor (TNF)-&agr; expression were assessed after reperfusion.Results.Shunt fraction and peak inspiratory pressure after reperfusion in the GLY(−) group were significantly higher than those in the GLY(+) and Fresh groups. Oxidative damage and apoptosis in the alveolar epithelial cells of the GLY(−) group, assessed by immunohistochemical staining and quantification of 8-hydroxy-2′-deoxyguanosine and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling method, were significantly higher than those of the GLY(+) and Fresh groups. There were correlations among shunt fraction, oxidative damage, and apoptosis. There was no expression of TNF-&agr; messenger RNA in all groups evaluated by the reverse transcription-polymerase chain reaction.Conclusions.Glycine attenuates ischemia/reperfusion injury after cold preservation by reducing oxidative damage and suppressing apoptosis independent of TNF-&agr; in this model. The suppression of apoptosis might ameliorate lung function after reperfusion.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Tilapia islet xenograft rejection is characterized by infiltration with macrophages (M&phgr;s), eosinophils (E&phgr;s), and T lymphocytes. The presence of these cells indicates they contribute to rejection; therefore, an attempt was made to assess their role through host immunomodulation.Methods.Tilapia islet cells were transplanted under the kidney capsule of streptozotocin diabetic Balb/c mice, which were then treated with one of several immunomodulatory regimes targeting M&phgr;s, E&phgr;s, or T cells. M&phgr;s were depleted using either silica or liposome-entrapped Cl2MDP. E&phgr; migration was blocked using monoclonal antibodies (mAbs) targeting interleukin (IL)-4 or IL-5. T-cell function was altered with mAbs targeting CD3, CD4, or CD8. Finally, T helper (Th)1 and Th2 activity was altered by depleting essential Th1 or Th2 cytokines with mAbs or by promoting a Th1 response with the injection of exogenous IL-12. The effects of antibody-mediated immunomodulation on graft survival were initially screened by cotransplanting alginate-encapsulated, mAb-secreting hybridoma cells into the peritoneal cavity at the time of islet transplantation. Significant prolongation was then confirmed using purified antibodies injected at the time of islet transplantation. Rejected grafts were examined histologically, and immunohistochemistry was used to assess the cellular infiltrates for each of the treatment groups.Results.Modulation of M&phgr;s and E&phgr;s alone did not significantly delay functional rejection of tilapia islet grafts (maximal mean graft survival time [mGST]=7.1±1.7 and 9.4±3.4, respectively) compared with untreated controls (mGST=8.2±1.0). Treatment of transplanted animals with antibodies against CD3 or CD4 significantly promoted graft survival (maximal mGST=16.3±5.8 and 34.0±11.6, respectively), whereas targeting CD8 and Th1 and Th2 cytokines showed no prolonging effect (maximal mGST=7.8±2.9 and 9.5±4.3, respectively).Conclusion.Our results indicate that rejection in the tilapia-to-mouse model follows a pattern similar to other models of discordant islet cell xenotransplantation.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Long-term xenograft survival can be achieved in hamster hearts transplanted into rats treated with cobra venom factor (CVF) and cyclosporine A (CsA). This phenomenon of “accommodation” is associated with expression of protective genes such as bcl-2, bcl-XL, and heme-oxygenase-1. We examined whether accommodation could be induced in hamster-to-rat lung xenografts and whether the pattern of protective genes is similar to cardiac xenografts.Methods.We used hamster-to-rat cardiac and lung xenotransplantation models. Cardiac xenotransplants were treated with CVF+CsA and compared with untreated controls. Lung xenotransplants were treated with either CVF+CsA or FK506 and cyclophosphamide (Cp) and compared with untreated controls. All recipients were killed by 21 days after transplantation. We examined graft survival and protein expression of protective genes, and we performed histologic and immunohistologic analyses.Results.Rejection occurred rapidly in untreated rats. CVF+CsA or FK506+Cp treatment significantly influenced graft survival. Eight of 12 CVF+CsA-treated heart transplants survived 21 days. Seven of 16 CVF+CsA-treated lung grafts and five of 12 FK506+Cp-treated lung xenografts survived 21 days. We observed significant protein expression of bcl-2, bcl-XL, and heme-oxygenase-1 in cardiac xenografts treated with CVF+CsA at 2, 14, and 21 days after transplantation, compared with normal hamster hearts. We also observed significant expression of these proteins in lung xenografts treated with either CVF+CsA or FK506+Cp at 21 days after transplantation, compared with normal lungs.Conclusions.Accommodation may be a general phenomenon for all organs, mediated through protective genes. Induction of accommodation does not require disruption of the complement system.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.The testis is an immunoprivileged organ, and at 37°C, the intratesticular microenvironment supports the survival of allogeneic islets. The objective of this study was to determine whether the immunoprotection afforded by the intratesticular environment is potent enough to prevent the rejection of xenogeneic porcine islets in a large-animal model.Methods.A bilateral cryptorchid condition was surgically created in sexually mature beagle dogs. Porcine islets were prepared from neonatal pigs by collagenase digestion and 9 days of culture, after which they were injected into each of the cryptorchid testes. Control dogs received liver subcapsular space transplants of porcine islets and autologous islets. After 100 days, the testes and relevant portions of liver were studied immunohistochemically for the presence of islet tissue.Results.The testicular interstitial space of all dogs contained abundant islet tissue. No evidence of lymphocytic infiltration or inflammation was observed. In contrast, porcine islets transplanted to the liver subcapsular space do not survive, although autologous islets engraft well in that position. This occurs even though the recipient’s serum contains preformed cytotoxic antibodies to porcine islets that persist after transplantation.Conclusions.These results demonstrate that the microenvironment existing within the surgically repositioned intra-abdominal testis supports the survival of xenogeneic tissue. The survival of xenogeneic tissue in the absence of immunosuppression in this large-animal model raises the possibility that xenogeneic porcine islet tissue will also survive in humans if transplanted into a similar environment.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.The recurrence of autoimmunity and allograft rejection act as major barriers to the widespread use of islet transplantation as a cure for type 1 diabetes. The aim of this study was to evaluate the feasibility of immunoisolation by use of an agarose microcapsule to prevent autoimmune recurrence after islet transplantation.Methods.Highly purified islets were isolated from 6- to 8-week-old prediabetic male nonobese diabetic (NOD) mice and microencapsulated in 5% agarose hydrogel as a semipermeable membrane. Islet function was evaluated by a syngeneic islet transplantation model, in which islets were transplanted into spontaneously diabetic NOD mice.Results.The nonencapsulated islet grafts were destroyed and diabetes recurred within 2 weeks after transplantation in all 12 mice. In contrast, 13 of the 16 mice that underwent transplantation with microencapsulated islets maintained normoglycemia for more than 100 days after islet transplantation. Histologic examination of the nonencapsulated islet grafts showed massive mononuclear cellular infiltration with &bgr;-cell destruction. In contrast, the microencapsulated islets showed well-granulated &bgr; cells with no mononuclear cellular infiltration around the microcapsules or in the accompanying blood capillaries between the microcapsules.Conclusions.Agarose microcapsules were able to completely protect NOD islet isografts from autoimmune destruction in the syngeneic islet transplantation model.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Acute graft dysfunction caused by ischemia-reperfusion injury is recognized as a major source of morbidity and mortality following adult heart transplantation. The aim of this study was to determine whether treating the donor and recipient with cariporide, an inhibitor of the sodium-hydrogen exchanger, could reduce ischemia-reperfusion injury.Methods.A porcine model of donor brain death, hypothermic ischemic preservation, and orthotopic cardiac transplantation was used. Allografts in both the control group (CON, n=6) and treatment group (CAR, n=6) were arrested and stored for 4 hours in the extracellular crystalloid cardioplegia currently used in the clinical transplantation program at our institution. In addition, both the donor and recipient animals in the CAR group received a single intravenous dose of cariporide (2 mg/kg) 15 minutes before harvesting and reperfusion, respectively.Results.The initial rate of troponin I release was significantly lower in recipients of CAR hearts than in recipients of CON hearts (P=0.020). All hearts were weaned successfully from bypass. More CAR hearts were weaned successfully at the first attempt, at 1 hour post-reperfusion, than CON hearts (6 of 6 vs 3 of 6), but this did not achieve statistical significance. Left ventricular contractility (preload recruitable stroke-work relationship) and left ventricular compliance (end-diastolic pressure-volume relationship) were significantly better preserved in CAR hearts than CON hearts (bothP<0.0001).Conclusions.Myocardial injury was reduced, and contractile function was better preserved in allografts that received cariporide, compared with allografts that received conventional preservation alone.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Composite tissue allografts are unique because they provide the vascularized bone marrow with stroma, which is the supportive microenvironment. In this study, we investigated the beneficial effect of donor-derived bone marrow cells within the long-surviving recipient rats after limb transplantation.Methods.Green fluorescent protein (GFP) transgenic rats developed for paramount cell marking were donors, and wild Wistar rats were recipients. Orthotopic hind-limb transplantation was performed using a microsurgical technique. Tacrolimus (1.0 mg/kg) was intramuscularly injected for 14 days postoperatively. The skin graft from GFP+donor onto the GFP−recipient was performed as a control. Flow cytometric analyses of recipient peripheral blood and bone marrow were carried out at 4 to 6 days, 18 to 21 days, 6 weeks, and 2, 4, 6, 9, and 12 months after transplantation.Results.The rats that received tacrolimus therapy achieved prolonged composite graft acceptance more than 12 months, whereas GFP+skin grafts were rejected at 47 days under the same immunosuppressive protocol. Numerous GFP+lymphocytes and granulocytes were detected within the recipient bone marrow for the first 6 weeks post limb transplantation. These cells remained relatively stable for more than 12 months.Conclusions.The results showed that donor-derived hematopoietic stem cells engrafted in recipient bone marrow and differentiated to lymphocytes and granulocytes after limb transplantation. The vascularized bone marrow, transplanted as a part of the hind limb, could have contributed to mixed chimerism and worked as the bone-marrow source in the recipients.

ISSN:0041-1337    

出版商:OVID    

年代:2003

数据来源: OVID