Peripheral nerve allograft: an assessment of regeneration across pretreated nerve allografts

Regeneration across lyophilized and irradiated peripheral nerve allografts was assessed using electrical and histological parameters. Regeneration did occur across these pretreated nerve allografts and was intermediate between that regeneration which occurred across a fresh, untreated nerve allograft and that which occurred across the control autograft.     

Peripheral nerve allograft: cellular and humoral immune responses of mice

Despite numerous experimental and clinical studies, no method has been established for achieving successful peripheral nerve allografts. One reason is that few studies concerning the immune response of the host have been conducted with nerve allografts. We therefore investigated the immune response of fresh nerve allografts with respect to both cellular and humoral immunological reactions. Using immunologically established strains of inbred mice, we performed the mixed lymphocyte culture (MLC) reaction and the cell-mediated lymphocytolysis reaction to test the cellular immune reaction and the complement-dependent cytotoxicity test to the humoral immune reaction. We observed that peripheral nerve tissues were strongly immunogenic; there was increased MLC reactivity to the allo-MHC antigen of the donor, specific cytotoxic T-cell activity, and production of specific antibody in the serum. For satisfactory nerve regeneration and transplantation, it is essential to suppress this immune response.     

人类去细胞同种异体神经移植物化学萃取方法的研究

目的：新鲜同种异体神经免疫排斥反应的标靶是细胞、髓鞘。发展新的化学处理方法,清除人类周围神经中的细胞和髓鞘 ,萃取粗大和长段的去细胞神经移植物。方法：切取年轻男性遗体捐献者的长段尺神经,以triton X-100和脱氧胆酸钠溶液按一定浓度和程序进行化学处理。萃取神经及新鲜神经行HE染色、髓鞘染色及纤维素染色,以观察细胞、髓鞘及神经基底膜;免疫组织化学染色以显示许旺细胞基底板层;行半薄切片及超薄切片透射电镜检查,观察超微结构。结果：去细胞神经的延展性及神经外膜的韧弹性良好。细胞和髓鞘被彻底清除,神经基底膜被保留;许旺细胞基底板层保留完好;去细胞神经为一种没有细胞髓鞘及其碎片的空的神经基质管。结论：Triton X-100及脱氧胆酸钠化学处理方法,可有效清除人类周围神经中的细胞及髓鞘,萃取粗大和长段的去细胞神经;该神经移植物保持了网管柱状组织结构,保留了许旺细胞基底板层及板层素。     

Sensory recovery following decellularized nerve allograft transplantation for digital nerve repair

Abstract

This study reported preliminary clinical experience of using decelluarised nerve allograft material for repair of digital nerve defect in five hand injury patients. From October 2009 to July 2010, five patients with traumatic nerve defect were treated with nerve repair using AxoGen® nerve allograft (AxoGen Inc, Alachua, FL) in California Hospital Medical Center. All patients were followed at least for 12 months, and sensory recovery and signs of infection or rejection were documented by a hand therapist. Average two-point discrimination was 6 mm, and average Semmes-Weinstein Monofilaments test was 4.31. No wound infections or signs of rejections were observed at wound site. All patients reported sensory improvement during the follow-up period after operation. It is believed that decellularised nerve allografts may provide a readily available option for repair of segmental nerve defect.     

The surgeon's role and responsibility in facial tissue allograft transplantation

Facial composite tissue allograft (CTA) transplantation represents a novel frontier in the reconstruction of the human form. The face plays a central role in human interactions, with significant social ramifications resulting from facial disfigurement. The surgeon performing facial tissue transplantation bears additional responsibilities unique to plastic and reconstructive procedures. Reconstruction by facial tissue transplantation may immensely improve quality of life, provided the process of patient selection is conspicuous and appropriate and allograft rejection is prevented. However, facial CTA transplantation represents an elective procedure to reconstruct a non-life-threatening defect. Given the potential for organ failure, opportunistic infection, and malignancy resulting from long-term immunosuppression, the surgeon must carefully weigh the balance of risk to benefit for the individual patient. Pioneering surgeons developing this procedure must thoroughly evaluate its impact as it relates to clinical and social issues.     

Tracheal allograft transplantation in rats: the role of different immunosuppressants on preservation of respiratory epithelium

BACKGROUND: Bronchiolitis obliterans is the most significant complication adversely affecting the survival of lung allograft recipients. Injury and loss of epithelium are associated with obliteration of the airway lumen. The aim of this study was to examine the effects of various immunosuppressants on airway epithelium. METHODS: Tracheae from Brown Norway donors were heterotopically transplanted into the greater omentum of Lewis (allografts) or Brown Norway (isografts) animals. Recipients were treated for 28 days with FK778 (20 mg/kg), tacrolimus (4 mg/kg), or sirolimus (2 mg/kg). Tracheal segments were evaluated for the degree of luminal occlusion as well as the type and percent of luminal epithelial cell coverage. RESULTS: All agents inhibited peritracheal infiltration and luminal obliteration. Tacrolimus- more than sirolimus-treated recipients showed partial preservation of the luminal epithelial coverage, whereas animals that received FK778 showed no respiratory epithelium. The epithelial loss was accompanied by the appearance of fibrous tissue, which replaced the mucosa. CONCLUSIONS: Tacrolimus as well as sirolimus effectively prevented the development of obliterative airway disease whereas tacrolimus and, to a lesser degree, sirolimus preserved epithelial cells as a source of protective cytokines. With FK778 significant airway obliteration was suppressed despite complete epithelial loss. Thus, FK778-treated animals displayed an epithelial-independent inhibitory effect on myofibroblast proliferation.     

新鲜同种异体神经移植基因治疗的实验研究

目的探讨新鲜同种异体神经移植的可能性及经基因治疗后的疗效。方法取健康成年不同窝的Wistar大鼠60只,按手术先后随机分为3组,每组各2 0只。将3组大鼠右侧的坐骨神经在梨状肌孔下0 .5cm处整齐切除2 .0cm ,切除的神经段互换移植修复神经缺损处。术中A组于局部肌肉及神经两断端注射转化生长因子β1(TGF β1)质粒,B、C组注射等量的生理盐水。术后仅C组给予环孢霉素A( 15mg/kg )喂养。于术后6周和12周进行形态学观测及再生轴突计数。结果A、C组的神经生长明显优于B组,水肿明显减轻。A、C组再生轴突数明显多于B组[A组为( 78.3±4.6)个, x±s ,下同] ;B组为( 15 .0±3 .5 )个,C组为( 76.1±4.2 )个。A、C组明显优于B组(P <0 .0 1)。A、C两组的差异无统计学意义(P >0 .0 5 ) ,两组再生轴突均已通过移植体。结论局部使用TGF β1质粒可在局部发挥免疫抑制作用,降低宿主的免疫排斥反应。     

Osteochondral allograft transplantation in the knee

Despite significant improvements for the past 20 years in the treatment of full-thickness chondral defects with the use of chondroprotective biological methods (microfracture, autologous chondrocyte transplantation, osteochondral autograft, and periosteal graft), the treatment of large osteochondral defects in young and physically active population is still challenging. Alternatives for the treatment of chondral defects exceeding 3 cm in size are limited, and among them, allografts have been used longer than any other treatment methods with the most favorable results. The success rates for osteochondral allograft transplantation have been reported as 95%, 71%, and 66% at 5, 10, and 20 years, respectively. Factors that adversely affect long-term results include advanced age, allograft transplantation to both sides of the joint, inappropriate loading, osteoarthritis, and osteonecrosis due to steroid use. Today, as a result of improvements in tissue-organ transplantation, increased availability of fresh tissue from donors, and increased demand from patients and physicians, there has been growing interest in the use of osteochondral allografts in selected patients to delay arthroplasty for chondral defects.     

Osteochondral allograft transplantation in the knee

Fresh osteochondral allograft (OCA) transplantation has over a 100-year clinical history. Many clinical and basic scientific studies have been performed with the result that allografting is now a part of the "cartilage repair paradigm" for the treatment of chondral or osteochondral lesions. In the knee joint, allografting has also been successfully used in complex joint reconstruction for the treatment of osteonecrosis, fracture malunion, and selected cases of osteoarthritis. Unlike many other cartilage repair techniques, OCA have the ability to restore mature, hyaline articular cartilage to the affected area. By virtue of their composite structure (cartilage and bone), allografts also can restore diseased or damaged bone often present in large or complex lesions. Nevertheless, OCA present unique and important difficulties in their clinical application, such as allograft tissue availability, safety issues, and immunologic response to the graft. Ongoing investigations continue to clarify the indications, surgical techniques, and clinical outcomes of fresh OCA.     

去细胞异体神经移植后T细胞亚群及细胞内细胞因子的实验研究

目的 为化学去细胞同种异体周围神经移植的临床应用提供进一步的免疫学实验依据.方法 128只BALB/C小鼠分随机分为假手术组、自体神经移植组、新鲜异体神经移植组和化学去细胞异体神经移植组,每组32只.对各实验组分别进行相应的手术.分别在术后3、7、14、28 d将各组8只小鼠脾淋巴细胞进行分离,特异性荧光标记的单克隆抗体作用后,经流式细胞仪检测T淋巴细胞亚群及细胞内细胞因子的水平及其变化趋势. 结果 在各时间点中,化学去细胞神异体经移植组CD3+、CD4+、CD8+、CD25+阳性细胞率以及IL-2、IFN-γ、TNF-α阳性细胞率与假手术组、自体神经移植组相比差异均无统计学意义(P＞0.05).而新鲜异体神经移植组与其他三组比较差异有统计学意义(P＜0.05). 结论 化学去细胞处理的同种异体神经的免疫源性等于或接近于自体神经,明显低于新鲜同种异体神经.     

丝列霉素处理的外周血单核细胞对大鼠同种异体移植心脏的影响

目的观察MMC处理的外周血单核细胞（PBMCs）对大鼠同种异体心脏移植的影响。方法BN大鼠作为供体，Lewis大鼠作为受体，体重在200～300g。PBMCs于含有MMC的细胞培养液中培养30min后于移植前1周静脉注射人受体，然后接受心脏移植，观察移植心脏的存活情况；并利用FACS检测MMC对PBMCs存活率的影响。结果MMC处理过的PBMCs诱导了细胞的凋亡；接受MMC处理过的PBMC的大鼠，移植心脏的存活时间明显得以延长。结论MMC处理的PBMCs可以延长大鼠移植心脏的存活时间，对移植心脏的延长作用可能是由于MMC诱导了细胞的凋亡引起的。     

Nerve allograft transplantation: a review

Peripheral nerves that are interrupted by trauma or surgical resection require reapproximation of their ends. When primary repair cannot be performed without undue tension, nerve grafting is required. Nerve repair with autograft is limited when there is insufficient amount of autologous nerves available for large nerve defects. This encouraged the search for alternative means of reconstruction in extensive nerve injuries. The cadaveric nerve allograft provides an unlimited graft source without the morbidities associated with autograft reconstruction; but these grafts are rapidly rejected unless appropriate recipient immunosuppression is achieved. An optimal treatment method for nerve allograft transplantation must minimize or prevent rejection while permitting nerve regeneration at the same time. In this report, the literature of nerve allograft transplantation experimental studies, strategies to prevent nerve allograft rejection, and reported clinical experiences are reviewed.