补体在猪到猴异种心脏移植中的作用及机理

目的 探讨补体在异种大动物猪到猴心脏移植排斥反应中的作用及机理.方法 以梅山猪为供者,中国猕猴为受者,行异种腹腔异位心脏移植.随机将受者分为3组.A组(5只):为空白对照组,受者心脏移植后不作任何处理.B组(5只):为照射预处理组,受者于心脏移植前28 d、即1.5个月龄时接受60Coγ3 Gy全身剂量照射,其余同A组.C组(8只):为照射+胸腺注射预处理组,心脏移植前21 d,将供者的脾细胞(按照5×107个/只的数量)注入受者的两侧胸腺内,其余同B组.观察心脏移植术后各组移植心的存活时间;猪对猴单向混合淋巴细胞培养的刺激效应;采用双抗体夹心法检测补体C3和CD46的血清浓度;通过流式细胞术检测受者外周血细胞表面IgM、IgG阳性细胞百分比水平.结果 A、B、C三组移植心的存活时间分别为:(36.6±5.8)h、(65.6±6.5)h和(91.1±22.8)h,C组移植心的存活时间明显延长,与A组比较,P＜0.01,与B组比较,P＜0.05.C组在猪对猴单向混合淋巴细胞反应中的刺激效应较A、B组明显下降(P＜0.01).B、C组移植前补体水平(C3)无明显变化,但随着IgM、IgG水平的上升,发生排斥反应时C3和CD46水平显著降低.C组猕猴特异性抗猪抗体IgM及IgG的上升速度均较A、B组明显延缓.结论 对受者进行异种胸腺注射联合全身照射预处理在抑制T淋巴细胞免疫及体液免疫方面有重要作用,但无法抑制异种排斥反应中补体的激活,补体通过经典途径参与了延迟性异种排斥反应的发生.     

中华眼镜蛇蛇毒因子在豚鼠—大鼠异种心脏移植中的作用

目的 应用中眼镜蛇蛇毒因子（CVF）消耗补体,观察豚鼠心脏在移植入Wistar大鼠腹腔内后对超急性排斥反应的变化。方法 按0．2μg/g体重CVF大鼠腹腔内分两次间隔6小时注射,18小时后进行心脏移植。脾切除及腹腔内注射环磷酰胺（Cy）均在移植前一天进行。设计分为四组：A组为对照组,不用任何药物;B组仅用CVF;C组应用CVF＋Cy＋脾切除;D组Cy＋脾切除。Cy的用量为60mg/kg体重腹腔内注射。检测各组受体的供心存活时间,并在供心停跳后取出行光镜、电镜检查。结果 A、B、C、D各组供心存活时间分别为15－3120分钟。供心存活时间的统计学分析：A组与B、C两组比较P值＜0．01,A组与D组比较,B组与C组比较P值＞0．05,B组与D组比较,C组与D组比较P值＜0．01。光镜、电镜结果提示：B、C组与A、D组有明显不同。结论 CVF能明显抑制补体活性,减轻或延缓超急性排斥反应的发生,使供体器官存活时间延长。CVF具有异种器官移植的基础研究和临床开发意义。     

清除补体避免猪到猕猴异种心脏移植超急性排斥反应的实验研究

目的 观察纯化的眼镜蛇毒因子(CVF)对猪到狱猴异种心脏移植超急性排斥反应的影响。方法 以幼猪为供者，施行猪到狱猴腹腔内异位心脏移植，实验组(n＝4)使用CVF完全清除受者体内补体，对照组(n＝5)不使用CVF，两个组术后均采用环抱素A、甲泼尼龙和环磷酰胺抑制排斥反应，通过检测血清C3、C4水平及总补体活性验证CVF的效果，移植心停跳时切取移植心进行病理检查。结果 在使用CVF后，实验组血清C3降为0，总补体活性CH50值也几乎为0，末发现明显毒副反应，移植猪心存活时间平均为lld，最长达13d，病理学提示均发生了延迟性异种排斥反应；对照组3个移植心在移植后60min内发生超急性排斥反应，另2个分别存活22h及6d。结论 纯化的CVF有良好的清除补体的作用，且末见明显副作用；使用CVF可克服猪到狱猴异种心脏移植超急性排斥反应的发生。     

眼镜蛇毒因子消耗补体对大鼠移植心急性排斥反应的抑制作用

目的研究中华眼镜蛇毒因子(CVF)消耗补体对大鼠心脏移植急性排斥反应的影响。方法以近交系BN大鼠为供者,Lewis大鼠为受者,建立腹腔异位心脏移植模型。实验分为2组,每组8只。CVF组:心脏移植术前3 d、2 d时,经受者尾静脉注射CVF 50μg／kg;术前12 h至移植心停跳时,经尾静脉注射CVF 20μg／kg,每2 d注射1次。对照组:术前、术后不给予受者任何特殊处理。术后观察移植心的存活时间,测定术后第1、3、5和6d及移植心停跳时的血清总补体活性(CH50法)、移植心C3沉积及CD3+T细胞浸润情况,并观察移植心的病理变化。结果CVF组和对照组的移植心存活时间分别为(11．69±0．72)d和(6．65±0．35)d,两组比较,差异有统计学意义(P<0．01)。CVF组移植心组织内C3沉积和CD3+T细胞浸润程度均较对照组同期明显减轻,病理损害程度也较对照组同期明显减轻。结论CVF消耗补体对大鼠心脏移植急性排斥反应起到了明显的抑制作用,从而延长移植心存活时间。     

联合药物预处理对非协调性异种心脏移植物的影响

目的　观察联合应用环孢素A(CsA)和来氟米特 (Lef)预处理对豚鼠 大鼠非协调性异种心脏移植物的影响并探讨其作用机制。方法　移植大鼠分为 4组 :A组 (CVF ,n =10 ) ;B组(CVF CsA ,n =8) ;C组 (CVF Lef,n =5 ) ;D组 (CVF CsA Lef ,n =11) ;记录移植物存活时间 ,检测移植物病理组织学 ,用免疫组织化学检测移植物CD68、CD5 7表达情况 ,TUNEL法检测移植物细胞凋亡。结果　移植物的平均存活时间 :A组为 41h、B组为 68h、C组为 5 5h、D组为 82h。各组移植物病理表现均为急性血管性排斥反应 (AVR)改变。B、C、D组移植物炎症细胞浸润数减少 ,CD68和CD5 7表达下调 ,凋亡指数较低 ,半定量测定与A组比较差异有显著性 (P <0 .0 5 ) ;D组凋亡指数最低而CD68和CD5 7表达最弱 ,与其他各组比较差异有显著性 (P <0 .0 5 )。结论　联合应用CsA和Lef预处理可明显延长非协调性异种移植物存活时间 ,减少炎症细胞浸润 ,抑制心肌细胞凋亡 ,减轻异种AVR损害。     

胸腺接种肝特异性抗原对同种肝移植排斥反应的作用

目的　研究肝特异性抗原在同种肝移植免疫反应中的作用及其意义。方法　实验大鼠随机分为 3组。Ⅰ组 :为同基因移植对照组 ,供、受者均为Wistar大鼠 ;Ⅱ组 :为异基因移植组 ,供、受者分别为SD和Wistar大鼠 ;Ⅲ组 :为异基因移植前胸腺注射组 ,供、受者分别为SD和Wistar大鼠 ,术前 1周用供者肝特异性抗原 (LSA) 10mg对受者进行胸腺注射。观察和检测术后一般状态、生存时间、病理学排斥分级及脾细胞核因子 κB活性等 ,确定各组移植后的排斥反应情况及机体的免疫状态。结果　Ⅰ组大鼠术后一般状态好 ,无排斥反应发生 ;Ⅱ组大鼠体重进行性减轻 ,术后 9～ 13d内全部死亡 ,平均存活时间 (10 .7± 0 .51)d ,排斥反应明显 ;Ⅲ组 6只大鼠 ,2只存活 2 4d ,1只存活 2 7d ,2只长期存活 ,1只于术后 15d死于胆道梗阻。术后一般状态同Ⅰ组 ,排斥分级明显低于Ⅱ组 (P <0 .0 5) ;Ⅰ组仅 5d和 7d时间段检测到较低的核因子 κB活性 ,Ⅱ组各时间段均检测到明显的核因子 κB活性 ,Ⅲ组各时间段核因子 κB活性均明显低于Ⅱ组 (P <0 .0 5)。结论　肝特异性抗原直接参与了移植肝的排斥反应 ;胸腺接种肝特异性抗原能减轻同种肝移植排斥反应的发生     

IL-12/STAT4途径激活对同种部分肝移植排斥反应的影响

目的　探讨白细胞介素 12 /信号传导子及转录激活子 (IL 12 /STAT4)信号途径激活在同种部分肝移植排斥中的作用。方法　将供者SD大鼠与受者LEW大鼠随机分为 4组 ,每组供、受者各 40只。A组 :全肝移植组 ;B组 :部分肝移植组 ;C组 :部分肝移植 IL 12硫代修饰反义寡脱氧核苷酸 (ASPODN )治疗组 ;D组 :部分肝移植 IL 12硫代修饰正义寡脱氧核苷酸 (SPODN)对照治疗组。观察移植肝排斥病理以及受者存活时间。分别采用Western blot及EMSA检测肝移植后 0h和4d移植肝IL 12蛋白表达、STAT4蛋白表达及其DNA结合活性 ;ELISA检测受者血清IL 2、IL 10及IFN γ水平。结果　B组和D组移植肝于移植后 4d出现排斥反应 ,早于A组和C组。B组受者存活时间 (13 .5± 0 .48)d ,较A组存活时间 (2 2 .6± 0 .59)d明显缩短 (P <0 .0 0 1) ;C组存活时间 (56.8±2 .5)d ,明显长于A组和B组 (P <0 .0 0 1)。肝移植后 4d ,移植肝IL 12、STAT4蛋白表达及其DNA结合活性、受者血清IL 2、IL 10和IFN γ水平 ,B组较A组明显增高 (P <0 .0 0 1) ,C组较B组明显降低 (P <0 .0 0 1) ,D组各项指标与B组相似。结论　IL 12 /STAT 4信号途径激活可能是同种部分肝移植免疫排斥发生的重要机制     

粉防己碱和环孢素A在大鼠心脏移植中的协同作用

目的 研究粉防己碱(Tetrandrine,Tet)和低剂量环孢素A(CsA)联合使用对同种异基因大鼠移植心脏存活时间的影响.方法 分别以近交系雄性Lewis(RT11)大鼠和BN(RT1n)大鼠为供、受者,将接受心脏移植后的BN大鼠随机分为5组,术后开始连续每天腹腔注射给药.A组:给予生理盐水1 ml/d;B组:给予CsA 3.2 mg·kg-1·d-1;C组:给予Tet 40 mg·kg-1·d-1;D组:给予Tet 40 mg·kg-1·d-1和CsA 3.2 mg·kg-1·d-1;E组:给予CsA 6 mg·kg-1·d-1.观察移植心存活时间并进行病理检查,测定受者外周血CD3+CD25+ T淋巴细胞数量、体外单向混合淋巴细胞反应以及受者血清白细胞介素2(IL-2)浓度等.结果 A、B、C、D、E组大鼠的移植心平均存活分别为(7.2±0.45)d、(10.8±1.48)d、(9±1.0)d、(15.6±3.05)d和(15.2±2.28)d,D、E组移植心存活时间比A组显著延长(P＜0.05),术后6 d D组外周血CD3+CD25+ T淋巴细胞数量、单向混合淋巴细胞反应刺激指数、血清 IL-2浓度较A组显著降低(P＜0.05),D组移植心排斥反应程度最轻.结论 Tet和低剂量CsA联合应用能显著延长同种异基因大鼠移植心的存活时间,其机理可能与抑制反应性T淋巴细胞活化以及抑制外周血清IL-2产生等有关.     

白细胞介素10修饰树突状细胞诱导大鼠小肠移植免疫耐受的研究

目的　探讨白细胞介素 10 (IL 10 )修饰的供者树突状细胞 (DC)对大鼠小肠移植术后免疫耐受的诱导效果 ,为抗排斥反应治疗提供依据。方法　健康成年SD大白鼠为供者 ,Wistar大鼠为受者。受者大鼠 18只 ,随机分为 3组 ,每组均为 6只。A组 :为对照组 ,受者不经任何预处理 ,即行小肠移植术 ;B组 :小肠移植前 7d ,每只受者经尾静脉注射供者的DC ,细胞数为 2× 10 7个 ;C组 :小肠移植前 7d ,每只受者经尾静脉注射用IL 10修饰的供者DC ,细胞数为 2× 10 7个。B、C组 1周后行大鼠异位节段性小肠移植术 ,观察各组受者移植小肠存活情况。结果　A、B、C组大鼠移植小肠存活时间分别为 :(7.33± 2 .4 2 )d、(8.33± 2 .94 )d、(18.5± 5 .17)d。经统计学分析 ,A、B组之间差异无显著性 ,而C组与A、B组比较 ,差异均有显著性 (P <0 .0 1)。结论　用IL 10修饰的供者树突状细胞对受者进行预处理 ,可明显延长受者大鼠小肠移植术后存活时间。     

小鼠移植心心肌细胞转染白细胞介素10基因减轻术后免疫排斥反应

目的观察应用质粒载体转染白细胞介素10(IL-10)基因至小鼠移植心肌细胞内的转染效率和基因的表达效率,探讨IL-10分子在移植物急性排斥反应中的意义。方法以C57BL／6小鼠为供者,Balb／c小鼠为受者,建立异位心脏移植模型。根据移植前经供心升主动脉冠脉灌注试剂的不同,将受者分为4组,每组20只。A组:灌注30μl的生理盐水;B组:灌注30μl的空白质粒;C组:灌注30μl的IL-10基因;D组:灌注30μl的腺相关病毒(AAV)增强型IL-10。移植后1、3、5和7 d切取移植心脏,进行病理学检查、移植心心肌组织中基因产物的逆转录聚合酶链反应(RT-PCR)和IL-10的免疫组织化学检测。并观察各组存活受者的一般情况和移植心存活时间。结果病理学观察显示:A、B组移植心在术后第3 d起出现了明显的排斥反应改变,而C、D组第3、5和7 d移植心排斥反应改变程度均较A、B组明显减轻。移植后第1和3 d,A、B组移植心心肌细胞中可见低水平的IL-10 mRNA基因和IL-10蛋白的表达,而第5和7 d时几乎检测不到;C、D组在各个时间段都可见明显的IL-10 mRNA基因和IL-10蛋白表达。A、B组移植心存活时间分别为(8．125±0．991)d和(7．714±0．756)d;C、D组移植心存活时间分别为(15．714±2．498)d和(17．857±1．864)d。C、D组与A、B组比较,差异有统计学意义(P<0．01)。结论质粒载体能有效地将IL-10基因转染入小鼠心肌细胞并进行表达,而采用AAV的末端反向重复序列(ITRs)可以提高质粒转染效率和IL-10表达水平。局部高表达的IL-10能减轻移植心的排斥反应,延长其存活时间。     

Activation of Complement in the Discordant Heart Xenotransplantation of Pig-to-Monkey Model and the Impact of Intrathymic Inoculation of Xenogeneic Antigen Combined With Whole-Body γ-Radiation

Objective

This study investigated changes in complement in discordant heart xenotransplantation using a pig-to-monkey model as well as the impact of intrathymic inoculation (IT) with xenogeneic antigen combined with whole-body γ-radiation (WBI).

Methods

In this experiment, pigs and monkeys selected as donors and recipients, respectively, were randomly divided into three groups: a blank group (group A), a whole-body irradiation group (group B) and an irradiation plus intrathymic injection group (group C). In every group, monkeys underwent heterotopic heart xenotransplantation.

Results

The results showed that the survival of donor hearts in group C was significantly longer than that of group A (P < .01). In mixed lymphocyte reactions, there was a significant reduction of the stimulation index in group C compared with group A. After xenotransplantation, the level of xenoreactive antibody in group C rose slower than that in group A or group B (P < .01). After rejection, the levels of CD46 and C3 declined greatly.

Conclusions

These results suggested that pretreatment with IT and WBI induced T-cell immunosuppression, restraining elicited xenoreactive antibody production of both immunoglobulin M and immunoglobulin G classes. However, it did not hinder complement activation via the classical pathway during hyperacute rejection and consequent xenograft rejection.     

Induction of anti-Forssman antibodies in the hamster-to-rat xenotransplantation model

BACKGROUND: In the hamster-to-rat heart xenotransplantation model, the serum response of the host contributes to determine whether the xenograft is accommodated or rejected. METHODS: To further characterize the serum response in this model, we compared anti-hamster antibodies found in naive LEW-1A rats, or in LEW-1A rats rejecting or accommodating a hamster heart, using a combination of cobra venom factor (CVF) and cyclosporin A (CsA) given for 10 days, and then CsA alone. RESULTS: Hamster hearts grafted into rat recipients contained IgG and IgA deposits to the same extent whether the xenograft was rejected or accommodated. Only immunoglobulins of the IgM isotype were found to be more abundant in recipients rejecting their graft. A significant part of this IgM response was directed toward the Forssman antigen, a sphingolipid present in the hamster but not in the rat. However, although anti-Forssman antibodies bind in situ to hamster tissues, this binding was not able to induce hyperacute rejection after antibody transfer. Furthermore, depletion of anti-Forssman antibodies from a rejecting serum did not modify its rejection properties. CONCLUSION: Unlike the pig-to-primate discordant xenotransplantation model, in which preexisting anti-carbohydrate antibodies are directly responsible for hyperacute rejection, in the concordant hamster-to-rat situation, the evoked IgM anti-Forssman carbohydrate antibodies do not appear to be the main cause of the vascular rejection.     

Prolongation of discordant renal xenograft survival by depletion of complement. Comparative effects of systemically administered cobra venom factor and soluble complement receptor type 1 in a guinea-pig to rat model

Abstract There is an increasing body of evidence to suggest that inhibition of complement activation may be a valuable approach to avert hyperacute rejection. In our study, the guinea-pig to rat discordant kidney xenograft model was adapted for the investigation of renal transplant function and an attempt was made to delay the hyperacute rejection using systemically administered cobra venom factor (CVF) and soluble complement receptor type 1 (sCR1). The saline-treated control recipients experienced a rapid transplant rejection with a xenograft survival averaging 10.5 ± 2.1 min. Administration of a single 60 U/kg i. v. bolus of CVF significantly prolonged renal graft survival to 20.4 ± 2.5 h, and by a single bolus of sCR1 (50 mg/kg) a prolongation of graft survival to 18.8 ± 2.3 h was achieved. The grafts functioned only over periods of 2.5 ± 0.3 and 2.3 ± 0.2 h, respectively. No complications of sCR 1 were noted. We concluded that complement inhibition by sCR 1 may be an important component in the therapeutic approach aiming at the prevention of hyperacute rejection in human organ transplantation.     

Discordant liver transplantation in the guinea pig to rat model does not lead to classical hyperacute rejection

Abstract: Discordant grafting, the best alternative for future transplantation, is hampered by hyperacute rejection (HAR). Yet, there might be a difference in susceptibility to HAR between organs. In allogeneic transplantation the liver is less sensitive to antibody mediated rejection. In order to investigate whether this might also occur in discordant xenotransplantation, we performed orthotopic liver transplantation (OLT) from Dunkin Hartley guinea pigs (GP) to Brown Norway rats. Five groups were studied. In group 1, untreated controls survived for 1.5 to 4.5 hr (n = 5). In order to investigate how long a recipient could survive without a functioning graft, animals in group 2 underwent total hepatectomy (tHx) with portal-caval shunt, resulting in survival times ranging from 2 to 7 hr (n = 5). Antibody reduction by splenectomy (Spx) on day -5 (group 3) did not increase survival time (1 to 2 hr, n = 5). Complement depletion by cobra venom factor (CVF) prolonged the survival time up to 35 hr (n = 7, group 4). One animal lived for 4 days. The combined treatment of Spx and CVF resulted in similar survival times as following CVF alone, ranging from 2 hr to 6 days (n = 6, group 5). Surprisingly, none of the grafts in either of the groups showed classical signs of hyperacute rejection, like hemorrhage, edema, or obstruction of capillaries and veins as seen in the GP to rat heart transplantation model. Also liver enzyme parameters indicated no ongoing rejection. Immunohistochemistry revealed deposits of complement factors C1q, C3, and C6 on Kupffer cells but not on endothelial cells. These results indicate that, in this particular discordant model, the liver is not affected by the classical features of HAR. The beneficial effect of CVF on recipient survival therefore may rather be due to inhibition of a lethal secondary response evoked by the graft than to inhibition of HAR.     

Decay-accelerating factor prevents acute humoral rejection induced by low levels of anti-alphaGal natural antibodies

BACKGROUND: Hyperacute and delayed vascular rejection due to natural antibodies (NAb) present major obstacles in pig-to-primate xenotransplantation. Although "supraphysiologic" expression of human complement regulatory proteins (CRPs) can prevent hyperacute rejection in discordant xenogenic recipients, their physiologic role in the homologous setting is undefined. We have evaluated the effect of the absence of decay-accelerating factor (DAF) on cardiac allograft rejection in the presence of different levels of antidonor antibodies (Ab). METHODS: DAF1-deficient (DAF KO; B6129F2 H-2) mice were used as heart graft donors to alpha1,3-galactosyltransferase deficient (GalT KO; B6, H-2) recipients. Heterotopic heart grafting was performed with or without presensitization. Graft survival, histology, and anti-alphaGal Ab levels were monitored. RESULTS: DAF knockout (KO) but not wild-type (WT) grafts showed hyperacute or acute humoral rejection in nonsensitized GalT KO mice with low levels of anti-alphaGal IgM NAb. However, humoral rejection of both DAF KO and DAF WT donor grafts occurred in presensitized GalT KO recipients. CONCLUSIONS: The expression of DAF prevents hyperacute rejection in mice with low titers of anti-alphaGal antibody. These studies demonstrate the physiologic role of DAF in preventing humoral rejection in the presence of low levels of NAb and have implications for transplantation of discordant vascularized xenografts.     

延长非协调性异种心脏移植存活时间的研究

目的 寻找延长非协调性异种心脏移植存活时间的方法。方法 实验分Ａ、Ｂ、Ｃ、Ｄ４组,将异种心脏（豚鼠－大鼠）移植于颈部。Ａ组：移植前受体用眼镜蛇蛇毒因子（ＣＶＦ）１５０ｕｇ．ｋｇ－１．ｄ＾－１,腹膜腔内注射（ｉ．ｐ）,每天分２次,相隔３ｄ,共４次;Ｂ组：在Ａ组的基础上,移植前１ｈ加用己酮可可碱（ＰＴＸ）５０ｍｇ／ｋｇ（ｉ．ｐ）,然后每隔６ｈ按２５ｍｇ／ｋｇ（ｉ．ｐ）至发生排斥反应为止;Ｃ组：在Ａ组的     

Pre-treatment of donor with 1-deamino-8-d-arginine vasopressin could alleviate early failure of porcine xenograft in a cobra venom factor treated canine recipient.

OBJECTIVE: Unlike cardiac or renal xenotransplants, the depletion of complement using cobra venom factor (CVF) does not improve pulmonary xenograft survival. Several cases suggest that the swine von Willebrand factor (vWF) may play a major role in presenting a different pathogenesis of pulmonary xenograft dysfunction from other organs. To evaluate the role of vWF and the complement system in mediating hyperacute vascular injury of pulmonary xenografts and elucidate pathogenesis of the injury, we performed swine-to-canine orthotropic single lung xenotransplantation after pre-treatment of 1-deamino-8-d-arginine vasopressin (DDAVP) and CVF. METHODS: We set up three groups for lung xenotransplantation: group I served as the control group; group II, recipients pre-treated with CVF; group III, donors pre-treated with DDAVP (9 mg/kg, 3 days)/recipients pre-treated with CVF (60 u/kg). Hemodynamic data, coagulation and complement system parameters, and grafted lung pathologies were examined serially for 3h after transplantation. RESULTS: DDAVP infusion reduced the vWF content in swine lung tissue in vivo (7.7+/-2.4 AU/mg vs 16.0+/-5.6 AU/mg, P < 0.0001). Infusion of CVF 24 h prior to transplantation effectively depleted the recipient's serum C3 and complement hemolytic activity below the detectable range. Regardless of the use of CVF, both groups I and II transplanted with unmodified grafts showed an immediate drop in leukocytes and platelet counts after transplantation. However, in group III, in recipients transplanted with DDAVP pre-treated swine lung, the platelet count did not decrease after transplantation (P = 0.0295). The decrease of plasma antithrombin and fibrinogen tended to be attenuated in group III. Light microscopic examination revealed extensive vascular thromboses in both capillary and larger vessels, as well as early pulmonary parenchymal damage in groups I and II, but were rarely observed in group III. CONCLUSIONS: Complement inhibition alone was not enough to alleviate intravascular thrombosis, the main pathology in pulmonary xenotransplantation. Pre-infusion of DDAVP to the donor animal was effective in preventing platelet sequestration and attenuated intravascular thrombosis. It is suggested that the strategies targeting vWF would be promising for successful pulmonary xenotransplantation.