建立豚鼠至大鼠异种肝移植模型的实验研究

目的 建立豚鼠至大鼠异种肝移植动脉化动物模型。方法 利用血管套技术和显微外科技术进行了30例豚鼠至大鼠肝移植。观察受者存活时间和移植肝组织学及超微结构变化。结果移植大鼠存活时间平均为（98.00±26.38）min,肝细胞发生弥漫性水样变性,中央静脉和小叶间静脉淤血。肝细胞内糖原颗粒消失,细胞器水肿。结论 成功地建立了非协调性异种肝移植动脉化模型。能观察移植肝的超急性排斥反应变化。     

非协调性异种肝移植动物模型的建立

目的:建立豚鼠至大鼠异种肝移植的动物模型 。方法:利用血管套技术和显微外科技术进行了23例豚鼠至大鼠肝移植。观察存活时间、谷丙转氨酶（ALT）和移植肝病理变化、荧光染色 。结果:移植大鼠存活时间平均为135.10±46.12分钟,肝细胞发生弥漫性水样变性,IgG和IgM沉积于血管内皮细胞和肝血窦 。结论:豚鼠至大鼠异种移植模型存活时间有限,移植肝发生了超急性排斥反应。     

非协调性异种肝移植中移植肝超急性排斥反应的病理形态学表现

目的:了解豚鼠至大鼠异种肝移植动物模型中移植肝病理学表现。方法:利用血管套技术和显微外科技术进行了20例豚鼠至大鼠肝移植。观察了受体存活时间和移植肝HE染色情况、电子显微镜下表现和荧光染色表现。用TUNEL法检测了移植肝细胞凋亡情况。结果:受体存活时间平均为(135.10±46.12)min,组织学表现为肝小叶结构存在,但肝细胞发生弥漫性水样变性,中央静脉和小叶间静脉淤血;电子显微镜下见肝细胞内糖原颗粒消失,细胞器水肿,近血窦处肝细胞膜破坏;IgM和IgG染色主要位于肝脏血管内皮细胞表面和肝血窦内。细胞凋亡指数为(0.80±0.31)％。结论:首次建立了豚鼠至大鼠异种肝移植模型,观察了超急性排斥反应。     

受体血清“封闭”供肝预防异种肝移植超急性排斥反应

目的 探讨受体血清“封闭”供肝对异种肝移植超急性排斥反应(hyperacute rejection,HAR)的预防作用.方法 取豚鼠和SD大鼠各20只,分别作为供体和受体,供受体随机配对;移植前采集受体大鼠近交系其他个体血清,45℃水浴灭活补体备用;实验组(n=10)术前用0.1％受体血清(recipient serum,RS)的Ringer液“封闭”供肝,对照组(n=10)仅用Ringer液灌洗供肝;采用改良“双套管法”行豚鼠、SD大鼠原位肝移植,观察供肝植入后形态学改变、受体存活时间、术后1h存活率,HE染色法检测移植肝微血栓、出血和肝细胞水肿等病理损害积分;检测血清丙氨酸转氨酶(ALT)评价肝功能.结果 两组大鼠供体异种肝移植时间和无肝期比较,差异无统计学意义(P＞0.05);对照组受体大鼠供肝充盈缓慢,灌注不均,实验组供肝充盈迅速,灌注较均匀;实验组受体大鼠术后存活时间和术后1h存活率较对照组均明显增加(P＜0.01),移植肝微血栓、间质出血(积分)较对照组明显减轻(P＜0.01),肝细胞水肿无明显差异(P＞0.05);血清丙氨酸转氨酶(ALT)较对照组明显下降(P＜0.05).结论 受体血清“封闭”供肝对异种肝移植HAR具有一定的抑制作用,是预防器官移植HAR的潜在方法之一.     

非协调性异种肝移植动物模型的建立:动脉化模型与静脉化模型的比较

目的 建立豚鼠至大鼠非协调性异种肝移植动物模型,并对动脉化模型和静脉化模型进行比较.方法 共进行异种肝移植40次,其中20对为动脉化组,20对为静脉化组.比较两组存活时间、受体血中肝脏酶的变化,移植肝组织学改变和荧光抗体染色.结果 动脉化组存活时间为(92.95±28.52) min,静脉化组为(135.10±46.12) min.两组移植肝组织学变化基本相似,肝细胞水样变形、血管和血窦淤血;荧光染色见IgM和IgG沉积于血管内皮细胞和肝血窦.结论 在没有克服超急性排斥反应之前,豚鼠至大鼠异种肝移植静脉化模型比动脉化模型更简单实用.     

豚鼠至大鼠异种肝移植手术操作要点及体会

目的 建立稳定的豚鼠至大鼠的异种肝移植模型.方法 在传统"二袖套"法基础上进行改良,并分预实验和正式试验两组进行手术时间和手术成功率的比较.结果 实验通过改良型二袖套法进行肝移植手术80对,预实验手术25对,成功率68%,正式手术35对,成功率89%,显著高于预实验(P<0.05),而手术时间明显低于预实验(P<0.05).结论 改进的异种肝移植术操作简便,随着手术者经验的提高可明显提高手术成功率,可作为异种肝移植实验可靠的动物模型制作.     

猪急性缺血性肝衰模型的建立和辅助性异位部分肝移植的作用

目的: 探讨急性缺血性肝衰模型的制备、辅助性异位部分肝移植的作用. 方法: 用家猪配对开展辅助性异位部分肝移植.分三组,A组:受体肝脏和肝动脉保持原状,其门静脉缩窄;供肝植入受体右肝下,仅建立门静脉血供,不建立动脉血供.B组:受体肝动脉结扎,其他手术内容与A组相同.C组:受体肝动脉结扎,供肝动脉和门静脉血供均建立,其他手术内容与A组相同.监测各组受体存活情况,肝功能和肝脏血流情况,病理及供肝胆汁分泌情况. 结果: A组、C组受体3 d以上成活率显著高于B组.A组、C组手术前后胆红素无显著改变,B组术后胆红素显著高于术前,术后第二天B组胆红素显著高于A组、C组.C组供肝胆汁分泌和血供良好,肝细胞存活并有活跃的代偿性增生;A组、B组供肝无或仅有少量胆汁分泌,肝细胞大片坏死. 结论: 受体肝动脉结扎、门静脉缩窄足以造成急性肝衰模型;保留受体肝脏动脉血供、减少门静脉血供对受体肝脏功能无严重影响;辅助性异位部分肝移植能取得良好的效果,足以纠正急性肝衰.     

中华眼镜蛇毒结合免疫抑制剂控制异种移植排斥反应

目的:探讨协调性和非协调性异种移植免疫排斥不同机理,寻找中华眼镜蛇毒结合免疫抑制药物的最佳治疗方案。方法:采用改良的Heron颈部套袖法分别建立小鼠对大鼠,豚鼠对大鼠异种异位心脏移植模型,受体大鼠各分为4组:1组仅行异种移植不给药;2组联合应用中华眼镜蛇蛇毒因子、环磷酰胺、FK506;3组将2组中华眼镜蛇毒剂量加倍;4组在2组用药组合基础上再加用前列腺素E1。结果:给药组移植供心存活时间明显延长,尤其在小鼠对大鼠模型给予PGE1后(小鼠4组6.92d)及豚鼠对大鼠模型蛇毒因子剂量加倍后(豚鼠3组27.33h)。两类模型给药后CH50,异种抗体IgM明显降低,并逐渐出现急性血管排斥反应改变。结论:异种移植后的超急性排斥反应和急性血管排斥反应存在着密切的相互关联,是统一的排斥过程中具有不同特点的两个阶段。中华眼镜蛇毒联合多种免疫抑制药物可控制异种排斥,尤其对非协调性异种移植有更大的作用。     

TNF-α和IL-10在非协调性异种肝移植中的作用探讨

目的 探讨细胞因子TNF－α和IL－10在异种肝移植中的作用。方法 建立豚鼠到大鼠原位肝移植模型，用RT－PCR方法检测移植肝内TNF－αmRNA和IL－10 mRNA的表达，并通过应用FK506改变上述细胞因子mRNA的表达探讨其不同作用。结果 非协调性异种肝移植后移植肝内有TNF－αmRNA和IL－10mRNA的表达，FK506可以上调IL－10 mRNA的表达并下调TNF－αmRNA的表达，并减轻受体超急性排斥反应的程度。结论 细胞因子在异种肝移植的免疫排斥反应中有重要作用，抗炎和促炎因子的平衡对排斥反应有缓和作用。     

器官组织移植

协调性异种心脏移植排斥反应病理变化的动态研究；保存液中加入硝酸甘油提高离体犬肺的保存效果；羟基磷灰石纳米粒子肝动脉灌注对兔、VX2肝种植瘤生长和bax／bc1-2蛋白表达的影彬胡军；调节性T细胞和共刺激通路阻断剂抑制大鼠肝移植急性排斥反应的研究；肝移植治疗急性肝功能衰竭的临床疗效分析.     

Characterization of a pig-to-goat orthotopic lung xenotransplantation model to study beyond hyperacute rejection.

BACKGROUND: A pig-to-goat orthotopic lung xenograft model was developed to test whether depletion of goat xenoreactive antibodies against pig red blood cells would prolong pig lung xenograft survival. METHODS: Adult goats with anti-pig xenoreactive antibodies underwent left pneumonectomy followed by orthotopic transplantation of pig left lung (group 1) or immunodepletion of their xenoreactive antibodies by extracorporeal right pig lung perfusion before transplantation without (group 2) or with (group 3) complete clampage of the right pulmonary artery. In group 4, goat left lungs were orthotopically transplanted into pigs and served as negative controls (pig serum does not have anti-goat xenoreactive antibodies). Each study group included 5 animals. Immunosuppression in surviving recipients included cyclosporine and azathioprine. RESULTS: Group 1 recipients died 7 +/- 3 hours after xenograft reimplantation of severe pulmonary hypertension and dysfunction and vasogenic shock, with little evidence of histologic xenograft injury. Group 2 xenografts had a stable circulatory and respiratory function on reperfusion and survived 9 +/- 4 days. Group 3 animals also tolerated complete occlusion of the right pulmonary artery, and xenografts assured the total respiratory support for 4 +/- 1 days. After immunodepletion, goat serum showed no detectable titers of xenoreactive antibodies, which began to reappear by postoperative day 2, where xenografts showed histologic stigmata of acute (humoral and cellular-mediated) rejection that evolved to a complete xenograft necrose at death. Group 4 xenografts showed scattered features of acute rejection 5 +/- 1 days after the operation. CONCLUSIONS: Pig left lung xenografts can provide prolonged and complete respiratory support after depletion of goat xenoreactive antibodies, but they ultimately necrose once recipient xenoreactive antibodies return to pretransplantation values.     

Preconditioning with the prostacyclin analog epoprostenol and cobra venom factor prevents reperfusion injury and hyperacute rejection in discordant liver xenotransplantation

Abstract: Liver xenografts transplanted from guinea pig to rat suffer from inadequate organ reperfusion and initial dysfunction, despite sufficient complement depletion using cobra venom factor (CVF). Reperfusion injury is prevented when complement depleted donors are treated with the prostacyclin analog epoprostenol. Histological analysis suggests that epoprostenol preconditioning prevents post-reperfusion spasms of the intrahepatic branches of the portal vein and strongly reduces appearance of hepatocyte apoptosis shortly after transplantation. Cobra-venom-treated rats show breakdown of glucose metabolism and die in acute hypoglycaemia, whereas the additional application of epoprostenol restores gluconeogenesis. Consequently, recipient survival after epoprostenol and CVF treatment is significantly improved compared with animals receiving CVF only (5.1 ± 2.6 h vs. 17.9 ± 5.1 h). These data demonstrate that initial dysfunction of discordant liver grafts in the guinea-pig-to-rat species combination, can be overcome by the application of epoprostenol combined with CVF. Using this pharmacologic regimen, the discordant guinea-pig-to-rat model appears useful to study further questions concerning functional and immunological compatibility of a discordant liver xenograft.     

Lewis rat pancreas, but not cardiac xenografts, are resistant to anti-gal antibody mediated hyperacute rejection

BACKGROUND: The objective of this study was to evaluate the role of anti-Gal Abs and non-anti-Gal Abs in hyperacute rejection (HAR) of concordant pancreas xenografts compared with heart xenografts. In addition, we tested whether rejection of Lewis rat pancreas grafts was T-cell dependent and could be prevented by anti-T-cell treatment. METHODS: To determine the role of anti-Gal Abs in the induction of HAR, Lewis rat pancreas and heart xenografts were transplanted into alpha1,3Galactosyltransferase knockout (GT-Ko) mice treated with normal human serum (NHS) or hyperimmune serum, or into presensitized GT-Ko mice. To investigate whether rejection of pancreas xenograft was mediated by a T-cell dependent response, Lewis rat pancreas grafts were transplanted into streptozotocin (STZ)-induced diabetic GT-Ko mice treated with FK506, anti-CD4 mAbs (GK1.5), and thymectomy. Antidonor-specific IgM and IgG and anti-Gal Abs were analyzed by flow cytometry. Rejected and long-term surviving pancreas xenografts were assessed by functional (blood glucose) and histopathological examination. RESULTS: HAR of Lewis rat pancreas xenografts could not be induced by NHS (0.4 ml), whereas NHS (0.2 ml) resulted in HAR of Lewis heart xenografts. Infusion of Lewis rat-specific hyperimmune serum (0.2 ml) resulted in HAR of Lewis rat pancreas xenografts. In addition, second Lewis rat pancreas grafts were hyperacutely rejected by presensitized GT-Ko mice. Immunohistochemical staining showed a low expression of Galalpha1,3Gal antigen in the endocrine tissue compared with that in the cardiac grafts. The levels of anti-Gal Abs in pancreas xenograft transplantation did not increase in GT-Ko mice after pancreas xenograft transplantation that was significantly increased after heart transplantation. FK506 treatment induced long-term survival of Lewis pancreas xenografts (mean survival time (MST) >90 days). Anti-CD4 treatment delayed rejection of Lewis rat pancreas xenografts with MST of 34.3 days, whereas anti-CD4, in combination with thymectomy, synergistically prolonged survival of pancreas xenograft (MST=70.4 days). CONCLUSION: Pancreas xenograft is resistant to anti-Gal Abs-induced HAR but is susceptible to anti-donor specific Abs. Rejection of Lewis pancreas xenograft in STZ-induced, diabetic, GT-Ko mice is T-cell dependent.     

FK 409 ameliorates small-for-size liver graft injury by attenuation of portal hypertension and down-regulation of Egr-1 pathway

OBJECTIVE: To investigate whether low-dose nitric oxide donor FK 409 could attenuate small-for-size graft injury in liver transplantation using small-for-size grafts. SUMMARY BACKGROUND DATA: The major concern of live donor liver transplantation is small-for-size graft injury at the early phase after transplantation. Novel therapeutic strategies should be investigated. METHODS: We employed a rat orthotopic liver transplantation model using small-for-size (40%) graft. FK 409 was given at 30 minutes before graft harvesting (2 mg/kg) to the donor and immediately after reperfusion (1 mg/kg) to the recipient (FK group). Graft survival, intragraft genes expression, portal hemodynamics, and hepatic ultrastructural changes were compared between the 2 groups. RESULTS: Seven-day graft survival rates in the FK group were significantly improved compared with those of rats not receiving FK 409 (control group; 80% versus 28.6%, P = 0.018). In the FK group, portal pressure was significantly decreased within the first 60 minutes after reperfusion whereas in the control group, transient portal hypertension was observed. Intragraft expression (both mRNA and protein) of early growth response-1, endothelin-1, endothelin-1 receptor A, tumor necrosis factor-alpha, macrophage-inflammatory protein-2, and inducible nitric oxide synthase was significantly down-regulated accompanied with up-regulation of heme oxygenase-1, A20, interferon-gamma-inducible protein-10, and interleukin-10 during the first 24 hours after reperfusion. Hepatic ultrastructure, especially the integrity of sinusoids was well protected in the FK group. CONCLUSIONS: Low-dose FK 409 rescues small-for-size grafts in liver transplantation by attenuation of portal hypertension and amelioration of acute phase inflammatory response by down-regulation of Egr-1, together with prior induction of heat shock proteins.     

Heart and liver xenotransplantation under low-dose tacrolimus: graft survival after withdrawal of immunosuppression

BACKGROUND: The hamster-to-rat xenotransplantation model is a useful model to investigate the features of extended host response to long-surviving xenografts. Early xenoantibody responses are T-cell independent and resistant to tacrolimus. Treatment with the combination of mofetil mycophenolate plus FK506 avoids acute xenograft rejection completely, but after withdrawal of immunosuppression hamster grafts are rejected by a process called late xenograft rejection (LXR). METHODS: Hamster hearts and livers were transplanted into Lewis rats. Grafted rats were treated with mofetil mycophenolate (25 mg/kg/day) for 8 days and FK506 (0.2 mg/kg/day) for 31 days. Serum IgM and IgG levels were determined by flow cytometry and interferon-gamma levels by ELISA. IgM, IgG, and C3 deposits were measured in tissue by immunofluorescence, and leukocyte infiltration was measured by immunoperoxidase staining. Results. Survival of heart and liver xenografts in the rats was 48+/-4 days and 63+/-8 days, respectively. After cessation of all immunosuppression, hearts were rejected in 18+/-4 days and livers in 33+/-8 days. Production sequences of xenoantibodies in the two organs differed substantially, especially 7 days after transplantation and at the moment of rejection. Quantification of interferon-gamma levels indicated that there were no significant changes after transplantation. Histological and immunohistochemical studies showed signs of humoral mechanism of LXR in rats undergoing heart transplantation and cellular mechanism of LXR in those that received a liver transplant. Conclusions. These observations suggest that rejection in the hamster-to-rat heart xenotransplantation model is mediated by a T cell-independent B-cell response to which a T cell-dependent B-cell response is added in LXR. In the liver xenotransplantation model, our hypothesis is that LXR is mediated by a mixed cell mechanism, involving lymphocytes CD4+ CD45RC+, macrophages, and cytotoxic T lymphocytes. In summary, we have demonstrated and compared the peculiar features of LXR in two different organs.     

Pathogenesis of coxsackievirus-B5 acquired from intra-renal porcine islet cell xenografts in diabetic mice

Abstract: Background:  We previously demonstrated the ability of a human isolate of coxsackievirus-B5 (CVB5) to infect productively adult porcine islet cells (PICs) in vitro. PICs infected with CVB5 remain viable, and upon transplantation reversed diabetes in C56BL/6 mice for up to 5 days.
Methods:  In the present work, we expanded this graft-to-host xenozoonosis model by examining the long-term functionality of CVB5-infected PIC xenografts in immunosuppressed mice. And, we characterized the pathogenesis of CVB5 infection in mice resulting from directional transmission of the virus from PIC xenografts to surrounding tissues in a mouse model for immunosuppressed human PIC xenograft recipients.
Results:  Both acutely (12 h) and chronically (72 h) infected PIC xenografts functioned in vivo to reverse diabetes in mice. The efficacy of both infected and un-infected PICs was transient beyond 5 days post-inoculation and the long-term functionality of the grafts was compromised by host-to-graft rejection. CVB5-infected PIC xenografts transmitted infectious virus to immunosuppressed recipient mice resulting in extensive histopathologic changes. The virus replicated in the heart, liver, spleen, kidney, pancreas, brain and skeletal muscle in higher levels in severe-combined immunodeficient (SCID) mice that were directly inoculated with virus when compared to controls. In addition, infectious virus was recovered for up to 22 days after inoculation in SCID mice whereas it was only detected up to Day 4 PI in non-SCID mice.
Conclusions:  Immunosuppressed PIC xenograft recipients may be more susceptible to infection with CVB5 which could target the xenograft leading to disseminated infection in the host.     

Microcirculatory alterations after orthotopic pig-to-baboon heart transplantation

Bauer A, Renz V, Baschnegger H, Abicht J‐M, Beiras‐Fernandez A, Brenner P, Thein E, Schmoeckel M, Reichart B, Christ F. Microcirculatory alterations after orthotopic pig‐to‐baboon heart transplantation. Xenotransplantation 2011; 18: 232–238. © 2011 John Wiley & Sons A/S. Abstract: Background: Whilst macrohemodynamic function of porcine xenografts transplanted into baboons has been assessed perioperatively, the ability of the xenograft to maintain systemic microcirculatory perfusion has not been investigated after pig‐to‐baboon xenotransplantation so far. Methods: We investigated the sublingual microcirculation of six baboons undergoing orthotopic transplantation of hCD46‐transgenic pig hearts using orthogonal polarization spectral imaging. Microvascular measurements were performed after induction of anesthesia, in the early phase of cardiopulmonary bypass (CPB), during reperfusion of the porcine heart and 1 h after the xenograft had resumed its life‐supporting function. Microvascular blood flow was analyzed semiquantitatively and the number of visualized cell‐to‐cell interactions was counted. Results: The proportion of continuously perfused microvessels was 97 (96 to 97) % at baseline and 95 (94 to 97) % in the early phase of CPB. It decreased significantly (P < 0.05) during CPB to 89 (84 to 91), and alterations were still present (P < 0.05) when CPB was terminated and the xenograft had taken over systemic perfusion 83 (81 to 85) %. The microcirculatory changes correlated with the lactate levels (y = 18.1–0.18 x; r² = 0.55; P < 0.001), but no correlation with macrohemodynamic parameters was found. Conclusion: Microvascular blood flow is altered after orthotopic pig‐to‐baboon heart transplantation, despite systemic hemodynamic parameters being well maintained by the porcine xenograft. These changes are moderate but persist after termination of CPB. Further studies need to elucidate whether these changes are transient or add to the mortality associated with cardiac xenotransplantation.     

Intrahepatic complement activation, sinusoidal endothelial injury, and lactic acidosis are associated with initial poor function of the liver after transplantation

BACKGROUND: Changes in glucose metabolism in the liver during transplantation have been recently described using microdialysis. Here, these findings are correlated with histopathologic, immunohistochemical, and ultrastructural changes in liver. METHODS: Microdialysis catheters were inserted into 15 human livers, which were perfused with isotonic solution, and samples of perfusate were analyzed before harvest, after storage, and after reperfusion. At each stage Menghini needle biopsy samples were taken and each studied using light and electron microscopy. RESULTS: Six livers showed serum biochemical evidence of initial poor function. These livers had significantly more staining for complement fragment 4d (C4d) of both lobular and periportal hepatocytes. C4d-positive hepatocytes were also found in the liver during cold storage (3 of 15). These periportal hepatocytes also showed evidence of necrosis and were found to have intracellular neutrophils. Hepatocyte rounding in zone III, necrosis, and C4d staining in recipient were also significantly correlated with the degree of lactic acidosis during this phase. Intrahepatic lactic acidosis at all time points was significantly associated with sinusoidal endothelial cell injury after reperfusion. There were no correlations between glucose, pyruvate, and glycerol levels and histopathologic changes in the liver. DISCUSSION: In the patients studied, the degree of C4d staining correlated with initial poor function and was associated with intrahepatic lactic acidosis in the donor during cold storage and after reperfusion. Complement activity in the liver during cold storage may be after in situ activation. Intrahepatic lactic acidosis is associated with sinusoidal endothelial cell and hepatocyte injury. The role of intrahepatic neutrophils is uncertain and could possibly be in response to cell necrosis.     

Experimental discordant hepatic xenotransplantation in the recipient with liver failure: implications for clinical bridging trials

BACKGROUND: Clinical xenotransplantation might start with bridge-to-bridge trials. Situations where hyperacute rejection is avoided would provide opportunities for the initiation of bridging trials. Patients with liver failure have a diminished capacity to initiate antibody and complement-induced injury of xenogeneic endothelium. Hyperacute rejection of a liver xenograft manifests as a coagulopathy. We examined the ability of a recipient with liver failure to hyperacutely reject a liver xenograft in the dog-to-pig model in the immediate postoperative period. STUDY DESIGN: Liver failure in pigs was induced with galactosamine. Canine livers were transplanted into pigs with liver failure and into healthy pigs. The postoperative course was monitored for 1 hour for histologic changes in the xenograft, changes in platelet counts, and whole blood clotting with Sonoclot analysis. In vitro assays with pig serum and canine hepatic sinusoidal endothelial cells were used to assess the effect of liver failure on serum cytotoxicity and xenoreactive antibody levels. RESULTS: All untreated pig recipients of liver xenografts died from a coagulopathy. Recipients with liver failure manifested no signs of coagulopathy, and had minimal change in platelet counts or Sonoclot (Sienco Inc., Morrison, CO) tracings. Liver xenograft biopsies from recipients with liver failure showed no evidence of the tissue injury that characterized the biopsies of control recipients. Serum from pigs was less cytotoxic to the canine hepatic sinusoidal endothelium after induction of liver failure. The xenoreactive antibody levels and repertoire were similar in the pig serum before and after liver failure was induced. CH50 (total complement) levels were diminished in pigs after the induction of liver failure. CONCLUSIONS: Liver xenotransplantation used in bridging trials in recipients with liver failure might not face the barrier of hyperacute rejection.     

Glutathione and ultrastructural changes in inflow occlusion of rat liver

BACKGROUND: Liver ischemia/reperfusion is frequently associated with organ injury to which reactive oxygen species contribute. The aim of our study was to evaluate cytosolic and mitochondrial glutathione levels and morphological changes in hepatocytes of rat liver in an experimental model of ischemia/reperfusion. MATERIALS AND METHODS: The experimental procedure consisted of temporary interruption of blood flow to the left lateral and medial hepatic lobes for different lengths of time and, in some cases, subsequent reperfusion. Cytosolic and mitochondrial glutathione levels were evaluated and ultrastructural analysis was carried out for all samples. RESULTS: Ischemic lobes showed ultrastructural changes in relationship with the increase in ischemia time. Total glutathione levels did not show variations in ischemic lobes and sham lobes with respect to control rats during ischemia only. Instead, during reperfusion, significant ultrastructural alterations of the hepatocytes and a significant depletion of glutatione in cytosolic and mitochondrial compartments were evident. The sham lobes also showed a significant glutathione decrement. Increased oxidized glutathione (GSSG) levels were found during ischemia both in ischemic lobes and in sham lobes. During reperfusion GSSG was found to a minor extent, in the cytosolic compartment. In mitochondria GSSG levels were also high during reperfusion. CONCLUSIONS: We conclude that depletion of glutathione contributes to impaired liver after reperfusion following ischemia but depletion of glutathione alone does not induce changes in the morphology of the hepatocytes. Glutathione depletion and a greater quantity of GSSG, even in sham lobes, may indicate a metabolic alteration which spreads to compartments that are not involved in ischemia/reperfusion.