腺病毒介导的血红素氧合酶-1基因治疗对同种移植物慢性排斥反应损伤的保护作用

目的探讨腺病毒介导的血红素氧合酶-1（AdHO-1）基因治疗对同种移植物慢性排斥反应损伤的保护作用及其机制。方法选用血管移植和肾脏移植两种慢性排斥反应模型,对同种血管移植物和肾脏移植物进行体外AdHO-1基因转染,分析慢性排斥反应发生时移植物的结构和功能变化、目的基因和蛋白的表达以及免疫系统的相应反应。结果AdHO-1基因治疗缓解了慢性排斥反应对同种肾脏移植物的损伤,但弱于对血管移植物的保护效应;空载病毒加剧了同种肾脏移植物的损伤;AdHO-1基因治疗可减少慢性排斥反应发生时移植物内巨噬细胞和CD4^＋细胞的浸润。结论AdHO-1基因治疗可能通过保护移植物、下调免疫反应、诱导免疫偏移等作用减轻同种移植物的慢性排斥反应损伤。     

同种带瓣主动脉和肺动脉移植免疫排斥反应的研究

目的 探讨同种带瓣管道移植对宿主免疫状态的影响以及排斥反应对移植物的作用。方法 应用同种异体带瓣主动脉或肺动脉重建右室流出道,并随机分为Ａ组（移植组）,Ｂ组（免疫抑制组）和Ｃ组（对照组）。分别在术后１,２,３,４周收集外周血标本,应用流式细胞仪测定Ｂ细胞及Ｔ淋巴细胞亚群的变化,应用酶联法测定血清中ＩＬ－２含量。结果 移植１周后外周血中Ｔ淋巴细胞数明显增高,ＣＤ＾＋４阳性率,ＣＤ＾＋４／ＣＤ＾＋８比     

小肠移植术后的组织学变化及CsA对其影响

由于环孢素 A 的应用使小肠移植取得了长足进步,但小肠移植的排异和移植物抗宿主病仍是小肠移植的二大难题,本文复习了大鼠、犬和猪小肠移植术后普通组织学,免疫组织化学的变化,有助于实验及临床中从组织学诊断小肠移植的排异和移植物抗宿主病。     

同种组织瓣移植后免疫排斥反应及其对策

同种瓣具有优良的抗血栓、抗感染性能及良好的血流动力学效果 ,且移植技术日趋成熟 ,使用方便 ,广泛应用于临床 ,治疗先天性心脏病及瓣膜病。但同种瓣移植后远期易钙化毁损 ,再次移植率高。同种瓣移植后免疫排斥反应及探讨相应的治疗措施是多年来研究的热点 ,现就此问题作一综述。一、同种组织瓣的免疫原性在同种不同个体间进行组织移植后会引起不同程度的免疫排斥反应 ,其强度由供受体间的组织不相容性程度决定。决定人同种移植物与受体是否相容的抗原是人类白细胞抗原(HLA) ,按编码产物的结构、表达方式、组织分布与功能可分为 3类 :HL…     

外源基因在低温保存后同种带瓣大动脉中的表达

目的观察外源性基因在低温保存不同时间后的同种带瓣大动脉中的表达。方法将30只幼兔的同种带瓣大动脉分为5组,分别在4℃营养液中（M199）保存2、6、12、24、72h。保存后将每组中的5个同种带瓣大动脉浸入300μl含重组腺病毒(Ad5CMVLacZ)的DMEM液中,而另1个则浸入300μl不含重组腺病毒的DMEM液中,均在室温下放置30min,然后分别移植于15只成兔受体的两侧颈动脉。术后5d取出移植物,进行组织化学染色。结果所有转染重组腺病毒的同种带瓣大动脉均有不同程度的基因表达,Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ组阳性细胞平均表达量分别42.6±8.5、38.2±12.7、34.5±10.2、31.6±9.6、36.4±13.2;组间转基因细胞表达量差异无显著性（P＞0.05）。对照组均为阴性。结论对低温保存不同时间后的同种带瓣大动脉进行转基因是可行的。     

Tregs对同种异体牙移植免疫排斥反应的抑制作用

目的 探讨Tregs对同种异体牙移植术后免疫排斥反应的抑制作用,提供一种免疫移植方法.方法 免疫抑制剂Tregs给予白鼠尾巴静脉注射1周,建立白鼠同种异体牙移植模型,术后观察移植牙存活、排异发生率及程度.结果同种异体牙均诱发免疫排斥反应,但Tregs注射后免疫排斥反应的时间缓慢,组织切片存活时间显著延长（P＜0.01）.结论 使用免疫抑制剂是预防同种异体牙移植免疫排斥反应的有效方案,可以使同种异体牙移植免疫排斥反应延迟,存活时间延长.     

小肠移植中排斥反应的诊断方法

研究器官移植排斥反应的经典方法之一是寻找宿主细胞对移植物的浸润.然而在小肠移植的试验研究中,在使用免疫抑制剂维持移植肠稳定时,它仍有相当数量的宿主细胞浸润.这种浸润是细胞生理性再循环至移植肠的肠相关淋巴组织中,而并非免疫刺激引起的浸润.本研究目的是确定小肠移植中生理性宿主细胞浸润的程度,并且将其与同种移植时的浸润相比     

不同方法处理的同种异体骨移植免疫学比较

为比较不同处理的同种异体骨移植的免疫反应，作者用新鲜骨、自消化抗原去除骨、骨基质明胶和脱钙骨基质分别植入小鼠肌肉，行免疫学和组织碱性磷酸酶检测。结果：同种异体新鲜骨引发宿主抗体水平最高，在体外明显刺激淋巴细胞增殖；而后三种移植物引发的宿主抗体水平较低，在体外抑制淋巴细胞增殖。结论：免疫排异抑制移植物成骨，骨诱导活性物质抑制免疫反应。     

大鼠T细胞疫苗的制备及其抗移植皮肤排斥作用的实验研究

目的 探讨T细胞疫苗(TCV)的制备方法及其抗移植皮肤排斥反应的作用.方法 制备针对特定SD大鼠的供体特异性T细胞疫苗,将其免疫受体Wistar大鼠;然后取免疫前和每次免疫后第五天的受体Wistar的淋巴细胞(反应细胞)与供体SD的淋巴细胞(刺激)进行体外单向混合淋巴细胞反应(MLR),以MTT法检测细胞免疫增值反应情况,比较疫苗接种后诱导淋巴细胞反应受抑制的情况:再将SD大鼠皮肤移植到TCV免疫后的Wistar大鼠,观察皮肤移植反应并统计移植物存活的时间.排斥反应的移植物行病理检查.结果 TCV组受体淋巴细胞反应程度比接种前显著减弱(P＜0.05);特异性TCV组皮肤移植物存活时间较非特异性TCV组及对照组延长(P＜0.05).移植皮肤排斥反应病理表现更轻.结论 TCV经腹腔接种可以诱导出针对同种抗原特异性免疫耐受,TCV能够延长同种异体移植皮肤的存活时间,有一定抗移植排斥反应作用.     

深低温保存后同种带瓣大动脉的转基因研究

目的：观察外源性基因在深低温保存不同时间后的同种带瓣大动脉中的表达。方法：新西兰成年白兔15只作受体，幼兔15只作供体，各随机分为5组，从每只供体处可得到带瓣主动脉，带瓣肺动脉各1条，即每组可得到6条瓣大动脉，Ⅰ-Ⅴ组中的6条动脉分别在液氮深低温条件下保存7，14，30，90，180d，每组保存期满后，快速复温，各组中5条同种带瓣大动脉浸入300ul含重组腺病毒（Ad5CMVLacZ)的DMEM液中；1条浸入300μl不含重组腺病毒的DMEM中作对照组，均在室温下放置30min后分别移植于受体的,两侧颈动脉。各组均在移植术后5d取出移植物，进行组化染色。结果：所有转染重组腺病毒的同种带瓣大动脉均有不同程度的基因表达，对照组均为阴性，组间转基因细胞表达量差异无统计学意义（P＞0．05）。结论：对深低温保存不同时间后的同种带瓣大动脉进行转基因治疗是可行的。     

Some histological features of canine cardiac transplants

The cellular reaction in cardiac homografts was observed mainly in the perivascular areas and in the subepicardial and subendocardial layers. All the valvular structures were involved by the cellular infiltration, but the aortic and pulmonary cusp changes were less severe. Although the vascular changes seemed to be severe, yet, for unknown reasons, some vascular segments and consequently some myocardial areas were spared. The intermittent immunosuppressive therapy (azathioprine) seemed to have influenced the pathological changes; it did not completely prevent the rejection process, suggesting that better control of the host-versus-graft reaction could be obtained by continuous immunosuppression.     

Calcification of homograft valves in the pulmonary circulation -- is it device or donation related?

OBJECTIVE: Homograft valved conduits are used in the reconstruction of right ventricular outflow tract (RVOT), and calcification is a recognised phenomenon in these devices. The purpose of this study was to assess the effect of type (pulmonary and aortic) and mode of harvest of these cryopreserved homografts (cadaveric and beating heart) on the incidence of calcification of these conduits when used in the pulmonary circulation. METHODS: A retrospective study was carried out on 60 patients with congenital heart defects who underwent reconstruction of RVOT using cryopreserved homograft valved conduits. The homografts were harvested from two different groups of donors; beating heart donors and cadaveric donors. The period of study was from 1st January 1990 to 31st December 2000. There were 34 males and 26 females, and the median age was 75 months. The 30-day mortality was 10 (16.7%). The 50 survivors were followed-up 3-108 months (median 36 months). Twenty-four had aortic homografts and 26 pulmonary homografts. Twenty-four devices were from cadaveric donors and 26 from beating heart donors. RESULTS: There were 10 (20%) calcified devices, all aortic in origin. In a logistic regression analysis, aortic homografts were significant risk factor for calcification (P=0.0006). However, source of harvest was not significantly related to the incidence of calcification (P=0.6). CONCLUSION: Cryopreserved pulmonary homografts placed in the right side of the heart are less likely to undergo calcification. Homografts harvested from beating heart donors do not appear to reduce the incidence of calcification.     

Viability of fresh aortic valve homografts: a quantitative assessment

Accumulated evidence indicates that fresh aortic valve homografts function longer than preserved grafts. Thus it becomes important to assess the viability of fresh homografts on a quantitative basis. Recently, we have used autoradiography in addition to tissue culture to determine the viability of fresh aortic and pulmonary valve homografts. The uptake of thymidine was gradually reduced to 50% after 18 days of preservation in a balanced salt solution with antibiotics and the uptake was reduced to 21% in 63 days. We think that a nutrient medium is necessary if longer viability is to be obtained.     

Aortic valve homografts in the surgical treatment of complex cardiac malformations

From April of 1968 to March of 1983, the surgical treatment of complex congenital cardiac malformations requiring an extracardiac conduit for their correction was performed with aortic valve homografts or aortic valved homograft conduits sterilized and preserved in our hospital. Our experience concerns 93 patients in whom a total of 103 aortic valve homografts were implanted. Ages of the patients ranged from 7 months to 36 years (mean 11.6 years). The aortic valve homografts were used from the right atrium to the pulmonary arteries or right ventricle (right atrium-dependent conduit), from the venous ventricle to the pulmonary arteries (ventricle-dependent conduit), or in the pulmonary orifice and in the superior and/or inferior venae cavae. There were 25 early and nine late deaths (36.5%), none of them related to the aortic valve homograft. The clinical follow-up of the 59 survivors (1 month to 15 years, mean 4.3 years) evidenced neither dysfunction of the aortic valve homograft nor thromboembolism or hemolysis; 93% of the patients are in New York Heart Association Class I or II. Control cardiac catheterization in 53 patients evidenced a pressure gradient in only 14 ventricle-dependent conduits. In seven patients with serial control catheterizations after 5 to 10 years, the pressure gradient had not increased.     

Structural degeneration of pulmonary homografts used as aortic valve substitute underlines early graft failure.

OBJECTIVES: The limited availability of donor valves and experimental evidence that pulmonary valves can withstand systemic pressure made us use cryopreserved pulmonary homografts as aortic valve substitutes. We observed a high incidence of early reoperation because of severe graft insufficiency due to cuspal tears. The mid-term results are evaluated in this study and histological analysis of explanted homografts is performed to investigate the cause of graft failure. METHODS: From December 1991 to April 1994, 16 patients (13 male; mean age 37.3 years, range 21-59 years) underwent aortic valve replacement with a cryopreserved pulmonary homograft. The indication was endocarditis (n = 4), bioprosthesis degeneration (n = 3) or congenital aortic valve disease (n = 9). All homografts were implanted freehand in the subcoronary position. All patients were contacted for follow-up and recent echo-Doppler studies were reviewed. Six explanted homografts were examined microscopically using routine histological techniques to analyze changes in cell population, collagen and elastic fiber structure. RESULTS: Follow-up was complete in all patients. Reoperation was required in ten patients because of severe graft incompetence (mean implantation time 5.9 years, range 2.8-8.0 years). In two patients, recurrent endocarditis was the cause of graft failure. In the other eight patients the leaflets looked pliable and thin with gross tearing in one or more cusps. The histopathologic changes observed were remarkably similar in all examined grafts: the cusp tissue was almost non-cellular and the collagen fiber structure had mostly disappeared. At the site of rupture, the tissue had become thin with strongly degenerated collagen and elastic fiber structure. In the six patients with a homograft remaining in situ, echo-Doppler showed trivial to mild insufficiency in five cases and moderate to severe in one case, whereas no significant gradients were observed. CONCLUSIONS: We concluded that structural reduction of cell number and degenerative alterations in the molecular composition of the extracellular matrix in valve tissue is the main cause of early graft failure in this series. The use of cryopreserved pulmonary homografts in the systemic circulation is therefore not advised.     

Heterotopic Implantation of Decellularized Pulmonary Artery Homografts In A Rodent Model: Technique Description and Preliminary Report

Purpose: Despite a substantial amount of literature on tissue-guided regeneration, decellularization process, repopulation time points and stem cell turnover, more in-depth study on the argument is required. Currently, there are plenty of reports involving large animals, as well as clinical studies facing cardiac repair with decellularized homografts, but no exhaustive rodent models are described. The purpose of this study was to develop such a model in rats; preliminary results are also herein reported. Material and Methods: Fresh or decellularized pulmonary homografts from wild type rats were implanted in the abdominal aorta of green fluorescent protein positive rats. Three experimental groups were build up: sham, fresh homograft recipients and decellularized homograft recipients. The homograft decellularization process was performed with three cycles of detergent-enzymatic treatment protocol. Surgical technique of pulmonary homograft implantation and postoperative ultrasonographic evaluation were also reported; gross, histology and immunohistochemistry analysis on unimplanted and postoperative homografts were also carried out. Results: The median total recipient operating time was 148 minutes, with a surgical success rate of 82%. The decellularization protocol resulted effective and showed a complete decellularization with intact extracellular matrix. At 15 days from surgery, the implanted decellularized pulmonary homografts exhibited cell repopulation in the outer media wall and partial endothelial lining in absence of rejection. Conclusions: Our technique is a feasible and reproducible model that can be fundamental for building a valid study for further exploitation on the field. Even in a short-term follow up, the decellularized pulmonary homografts showed autologous repopulation in absence of rejection.     

Replacement of the aortic valve with a pulmonary autograft: the "switch" operation.

The transfer of the patient's own pulmonary valve to the aortic position developed from our earlier work with aortic homografts. The valve shows no progressive tissue failure and offers the prospect of a permanent valve replacement for young people. Like homografts, the valves can be inserted in the subcoronary position or as a root replacement. In infants and growing children root replacement should be used to benefit from the valve's growth potential.     

Cryopreserved and fresh antibiotic-sterilized valved aortic homograft conduits in a long-term sheep model. Hemodynamic, angiographic, and histologic comparisons

There is a paucity of clinical and experimental data regarding the fate of cryopreserved valve aortic homografts. Fifteen lambs (mean age 4 months) underwent insertion of a valved aortic homograft between the right ventricle and pulmonary artery. In eight animals, the homografts were treated with antibiotics for 48 hours followed by up to 4 days of 4 degrees C storage (group A). In the other seven animals, the homografts were treated with antibiotics and cryopreserved at -196 degrees C (group B). The 12 long-term survivors were catheterized at 6 weeks and 4 months after implantation, at which time three animals from each group were killed. The remaining six animals were catheterized and killed at 9 months. There was no significant difference in transconduit gradient (p = 0.67) or resistance indexed to weight (p = 0.81) between groups A and B. The mean increase in transconduit gradient for both groups between catheterization at 6 weeks and 4 months was 73%, and weight increased by 51%. Histologic analysis focusing particularly on valve leaflet architecture and changes in the aortic wall revealed greater differences between individual animals and according to duration of implantation than differences between groups A and B. However, focal intracuspal thrombus of unknown significance was seen only in animals from group B. Although conduit valve leaflets generally remained free of calcification, calcification was prominent within the conduit wall of all animals. In conclusion, cryopreservation does not appear to adversely affect leaflet integrity and conduit function in this accelerated animal model relative to fresh homografts. This is in contrast to past clinical experience with homografts treated by freeze-drying and irradiation.     

Complications following homograft replacement of the right ventricular outflow tract

Twenty-two patients who had surgical reconstruction of the pulmonary artery and right ventricular outflow tract with a complete or partial valve-bearing aortic homograft have been followed for 1 to 5 years. The following complications were noted: (1) calcification of the homograft (10 patients; noted within the first postoperative year in 6 patients and 2 to 4 years after operation in the remaining 4); (2) pulmonary valve insufficiency (12 patients, including 8 with complete three-cusped aortic homografts); (3) residual obstruction (4 patients), primarily at the distal anastomosis; and (4) sudden, unexpected death (1 patient), which occurred 18 months after operation from rupture of the right ventricular outflow tract.Although the immediate postoperative results with aortic homografts are good, late complications are frequent. We have concluded that aortic homografts are not ideal for right ventricular outflow tract reconstruction. Further development and evaluation of a suitable valve-bearing prosthesis is necessary since the goals of reconstruction in this group of patients continue to be relief of obstruction and establishment of a functionally competent right ventricle-to-pulmonary artery conduit.