Nerve Allograft Transplantation Research Articles

Long-term follow-up of three different nerve repair strategies (repair, autografting and allografting) in one-stage replantation to treat upper extremity amputation.

To examine the efficacy of three different nerve repair methods for one-stage replantation to treat complete upper extremity amputation and long-term postoperative functional recovery. Twenty-five patients underwent direct nerve anastomosis (Group A), for patients with nerve defects greater than 3 cm, nerve autograft transplantation be used (Group B), or patients with nerve defects less than 3 cm, nerve allograft transplantation be used (Group C) based on the severity of injury. The Disabilities of the Arm, Shoulder, and Hand (DASH) score (higher score means poorer function-less than 25 means good effect) and visual analogue scale (VAS) scores for pain at rest and under exertion were measured. Sensation recovery time and grip function were recorded. The mean follow-up time was 78 ± 29 months. Group A had the lowest DASH score, while Group C had the highest DASH score. DASH score differed significantly between the three groups (P < 0.001). Sensation was not restored in two patients in Group B and two patients in Group C, and there were significant between-group differences in sensation recovery (P = 0.001). Group C had the lowest VAS score, while Group A had the highest, and there were significant differences between groups (P = 0.044). Only one patient in Group C recovered grip function. Direct nerve anastomosis should be performed whenever possible in replantation surgery for complete upper extremity amputation, as the nerve function recovery after direct nerve anastomosis is better than that after nerve autograft transplantation or nerve allograft transplantation. Two-stage nerve autograft transplantation can be performed in patients who do not achieve functional recovery long after nerve allograft transplantation.

Reconstruction of Critical Nerve Defects Using Allogenic Nerve Tissue: A Review of Current Approaches.

Regardless of the nerve defect length, nerve injury is a debilitating condition for the affected patient that results in loss of sensory and motor function. These functional impairments can have a profound impact on the patient’s quality of life. Surgical approaches for the treatment of short segment nerve defects are well-established. Autologous nerve transplantation, considered the gold standard, and the use of artificial nerve grafts are safe and successful procedures for short segment nerve defect reconstruction. Long segment nerve defects which extend 3.0 cm or more are more problematic for repair. Methods for reconstruction of long defects are limited. Artificial nerve grafts often fail to regenerate and autologous nerve grafts are limited in length and number. Cadaveric processed/unprocessed nerve allografts are a promising alternative in nerve surgery. This review gives a systematic overview on pre-clinical and clinical approaches in nerve allograft transplantation.

The effect of full dose composite tissue allotransplantation immunosuppression on allograft motor nerve regeneration in a rat sciatic nerve model.

The purpose of this study was to identify which triple immunosuppressive protocols, currently used for vascularized composite allotransplantation in the clinic, will have the best effect on motor function recovery following nerve allograft reconstruction. Eighty-eight Lewis rats underwent a 1-cm sciatic nerve allograft transplantation and skin graft from 44 Brown-Norway rats. Group I received 0.9% isotonic saline (control); Group II, 2 mg/kg FK506; Group III, 1 mg/kg FK506 with 15 mg/kg mycophenolate mofetil (MMF); and Group IV, 2 mg/kg FK506 with 30 mg/kg MMF and prednisone. Each group consisted of 11 rats. After 12 weeks, motor function recovery was evaluated with isometric tetanic force, muscle mass, ankle contracture angle, electrophysiology, and nerve histomorphometry. Adequacy of immunosuppression was monitored with the transplanted skin graft. All data are expressed as a percentage of the contralateral side. Isometric tetanic force showed significantly better functional recovery in all groups treated with immunosuppression compared to control. Within the immunosuppression groups no significant difference was found: 42.1 ± 6.4% (Group I), 56.1 ± 12.4% (Group II), 58.4 ± 10.7% (Group III), and 61.3 ± 11.2% (Group IV). Group IV was superior to all other groups regarding ankle contracture (P < .05) and electrophysiology (P < .001). Skin graft rejection occurred in 41 and 0% (Groups III and IV, respectively). FK506 significantly enhanced motor recovery after allograft reconstruction. This effect was comparable between combination treatment (low-dose FK506 and MMF) and triple therapy (high-dose FK506 and MMF plus prednisolone). However, triple therapy was more effective in suppressing skin rejection.

Heregulin-1β Promotes the Synergistic Effect Between Allogenic Skin-Derived Precursor Differentiated Schwann Cells (SKP-SC) and Acellular Nerve Allograft (ANA) in Peripheral Nerve Regeneration Through Inhibiting Mir-21

Previous studies in our lab found that heregulin-1β with SKP-SCs (neurons and Schwann cells differentiated from SKPs) / ANA (acellular nerve allograft) transplantation represented a powerful therapeutic approach, and facilitates the efficacy of ANA in peripheral nerve injury. In this study, our purpose is to explore the mechanism between them. Firstly we transplanted ANA + SKP-SC + heregulin-1β into rats with right sciatic nerve injury and then detected the miR-21 and SOX2 (SRY-like HMG box 2) levels. Then we transfected miR-21 inhibitor in SCs (Schwann cells) which induced in hypoxic condition before harvesting. Then we detected expression of miR-21 and SOX2 using real time-PCR and western blot assay. Results in vivo showed that the expression of miR-21 in rats was inhibited after transplantation of ANA + SKP-SC + heregulin-1β with induced SOX2 accordingly. Then we found miR-21 was increased time dependently in hypoxic SCs with decreased SOX2 accordingly. After miR-21 inhibitor transfection, miR-21 level was reduced and SOX2 was up-regulated. Meanwhile it was also showed that the miR-21 inhibitor induced the hypoxic SCs growth, decreased the apoptosis with cell cycle changing. In conclusion miR-21 and its target gene SOX2 played important role in peripheral nerve injury. Heregulin-1β may increase the synergistic effect between SKP-SC and ANA through inhibiting miR-21 in vivo.

Identification of Circulating miRNAs in a Mouse Model of Nerve Allograft Transplantation under FK506 Immunosuppression by Illumina Small RNA Deep Sequencing

Background. This study aimed to establish the expression profile of circulating microRNAs (miRNAs) during nerve allotransplantation in the presence and absence of FK506 immunosuppression. Methods. A 1 cm BALB/c donor sciatic nerve graft was transplanted into the sciatic nerve gaps created in recipient C57BL/6 mice with or without daily FK506 immunosuppression [1 mg/(kg·d)]. At 3, 7, and 14 d after nerve allotransplantation, serum samples were collected for miRNA expression analysis by Illumina small RNA deep sequencing. Results. Sequence analysis showed that the dominant size of circulating small RNAs after nerve allotransplantation was 22 nucleotides, followed by 23-nucleotide sequences. Nine upregulated circulating miRNAs (let-7e-5p, miR-101a-3p, miR-151-5p, miR-181a-5p, miR-204-5p, miR-340-5p, miR-381-3p, miR-411-5p, miR-9-5p, and miR-219-2-3p) were identified at 3 d, but none was identified at 7 or 14 d. Among them, miR-9-5p had the highest fold-change of >50-fold, followed by miR-340-5p with 38.8-fold. The presence of these nine miRNAs was not significant at 7 and 14 d after nerve allotransplantation with or without immunosuppression, showing that these miRNAs are not ideal biomarkers for monitoring rejection of deep-buried nerve allografts, a response usually observed later. Conclusions. We identified nine upregulated circulating miRNAs, which may have a biological function, particularly during the early stages after nerve allotransplantation under FK506 immunosuppression.

Sensory recovery following decellularized nerve allograft transplantation for digital nerve repair

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.

Nerve allograft transplantation for functional restoration of the upper extremity: case series

BackgroundMajor trauma to the spinal cord or upper extremity often results in severe sensory and motor disturbances from injuries to the brachial plexus and its insertion into the spinal cord. Functional restoration with nerve grafting neurotization and tendon transfers is the mainstay of treatment. Results may be incomplete due to a limited supply of autologous material for nerve grafts. The factors deemed most integral for success are early surgical intervention, reconstruction of all levels of injury, and maximization of the number of axonal conduits per nerve repair.ObjectiveTo report the second series of nerve allograft transplantation using cadaveric nerve graft and our experience with living-related nerve transplants.ParticipantsEight patients, seven men and one woman, average age 23 years (range 18–34), with multi-level brachial plexus injuries were selected for transplantation using either cadaveric allografts or living-related donors.MethodsGrafts were harvested and preserved in the University of Wisconsin Cold Storage Solution at 5°C for up to 7 days. The immunosuppressive protocol was initiated at the time of surgery and was discontinued at approximately 1 year, or when signs of regeneration were evident. Parameters for assessment included mechanism of injury, interval between injury and treatment, level(s) of deficit, post-operative return of function, pain relief, need for revision surgery, complications, and improvement in quality of life.ResultsSurgery was performed using living-related donor grafts in six patients, and cadaveric grafts in two patients. Immunosuppression was tolerated for the duration of treatment in all but one patient in whom early termination occurred due to non-compliance. There were no cases of graft rejection as of most recent follow-up. Seven patients showed signs of regeneration, demonstrated by return of sensory and motor function and/or a migrating Tinel's sign. One patient was non-compliant with the post-operative regimen and experienced minimal return of function despite a reduction in pain.ConclusionsDespite the small number of subjects, it appears that nerve allograft transplantation may be performed safely, permitting non-prioritized repair of long-segment peripheral nerve defects and maximizing the number of axonal conduits per nerve repair. For patients with long, multi-level brachial plexus injuries or combined upper and lower extremity nerve deficits, the use of nerve allograft allows a more complete repair that may translate into greater functional restoration than autografting alone.

The role of T helper cell differentiation in promoting nerve allograft survival with costimulation blockade

Peripheral nerve allografts provide a temporary scaffold for host nerve regeneration and allow for the repair of significant segmental nerve injuries. Despite this potential, nerve allograft transplantation requires temporary systemic immunosuppression. Characterization of the immunological mechanisms involved in the induction of immune hyporesponsiveness to prevent nerve allograft rejection will help provide a basis for optimizing immunomodulation regimens or manipulating donor nerve allografts to minimize or eliminate the need for global immunosuppression. The authors used C57Bl/6 mice and STAT4 and STAT6 gene BALB/c knockout mice. A nonvascularized nerve allograft was used to reconstruct a 1-cm sciatic nerve gap in the murine model. A triple costimulatory blockade of the CD40, CD28/B7, and inducible costimulatory (ICOS) pathways was used. Quantitative assessment was performed at 3 weeks with nerve histomorphometry, walking track analysis, and the enzyme-linked immunospot assay. The STAT6 -/- mice received 3 doses of costimulation-blocking antibodies and had axonal regeneration equivalent to nerve isografts, while treated STAT4 -/- mice demonstrated moderate axonal regeneration but inferior to the T helper cell Type 2-deficient animals. Enzyme-linked immunospot assay analysis demonstrated a minimal immune response in both STAT4 -/- and STAT6 -/- mice treated with a costimulatory blockade. The authors' findings suggest that Type 1 T helper cells may play a more significant role in costimulatory blockade-induced immune hyporesponsiveness in the nerve allograft model, and that Type 2 T helper differentation may represent a potential target for directed immunosuppression.

Nerve allotransplantation as it pertains to composite tissue transplantation.

Nerve allografts provide a temporary scaffold for host nerve regeneration and allow for the repair of significant segmental nerve injuries. From rodent, large animal, and nonhuman primate studies, as well as clinical experience, nerve allografts, with the use of immunosuppression, have the capacity to provide equal regeneration and function to that of an autograft. In contrast to solid organ transplantation and composite tissue transfers, nerve allograft transplantation requires only temporary immunosuppression. Furthermore, nerve allograft rejection is difficult to assess, as the nerves are surgically buried and are without an immediate functional endpoint to monitor. In this article, we review what we know about peripheral nerve allograft transplantation from three decades of experience and apply our current understanding of nerve regeneration to the emerging field of composite tissue transplantation.

Experience with nerve allograft transplantation.

Nerve allograft transplantation should be used for the repair of devastating peripheral nerve injuries that cannot be reconstructed through traditional means such as autologous nerve grafting or nerve transfer procedures. The risks of required systemic immunosuppression, although only temporary for nerve allograft recipients, preclude widespread use of this treatment modality. Translational research has led to several advancements in this field including the use of preoperative allograft cold preservation in University of Wisconsin organ preservation solution and inclusion of tacrolimus as part of the immunosuppressive regimen. Investigation of how to further diminish nerve allograft immunogenicity, speed neuroregeneration by use of agents such as tacrolimus, and promote preferential motor regeneration will further advance this field with the goal of restoring optimal function while minimizing patient morbidity.

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.

12: Nerve Allograft Transplantation for Functional Restoration of the Upper Extremity

12: Nerve Allograft Transplantation for Functional Restoration of the Upper Extremity

Survival of Long Nerve Allografts Following Donor Antigen Pretreatment: A Pilot Study

In this study, the authors evaluated whether the pretransplant portal venous administration of UV-B irradiated donor alloantigen would induce tolerance to long peripheral nerve allografts in a swine model. They completed nerve allograft transplantation between four swine of separate lineages. Regeneration across the nerve allografts was followed for 10 months postoperatively. Sequential IN VITRO assays demonstrated the successful and prolonged suppression of the recipient immune response to donor antigen following antigen inoculation. Histomorphometric analysis demonstrated successful regeneration across the long nerve allografts in the pretreated recipients, but not across allografts in unimmunosuppressed recipients. A single pretransplant antigen delivery protocol has the potential to replace chronic medicinal immunosuppressant therapy and its associated morbidities. Furthermore, tolerance to long nerve allografts has immediate applicability to clinical requirements for bridging multiple, complex, long nerve gaps.

Immunomodulation with anti-αβ T-cell receptor monoclonal antibodies in combination with cyclosporine a improves regeneration in nerve allografts

To investigate the use of nerve allografts in animals treated with a short-term combined protocol of anti-alpha/beta T-cell receptor monoclonal antibodies and Cyclosporine A (CsA) to induce tolerance and allow for nerve regeneration. An established rat sciatic nerve model was used. A total of 76 rats were used in this experiment (Lew RT1L n=44, Lewis-Brown-Norway (LBN RT1L+N, n=22), Brown-Norway (BN RT1N, n=10). Sciatic nerve (1.5 cm) deficits were created in the Lewis rats and the animals were randomized to seven treatment groups to allow for repair with isograft controls (LEW-LEW) and with both semiallogeneic (LBN-LEW) and full major histocompatability (MHC) mismatched (BN-Lew) allografts. Nerve regeneration was evaluated at 6 and 12 weeks by somatosensory evoked potentials (SSEP) and standardized pin-prick and toe-spread tests. Nerve samples were harvested at 12 weeks and stained with toluidine blue to assess the total number of myelinated axons, axon area, and myelin sheath thickness. Muscle denervation atrophy was evaluated by gastrocnemius weights. Immunocompetence was investigated through skin grafting and fluorescent activated cell sorting (FACS) analysis. Improved functional, electrophysiologic, and histomorphometric outcomes were observed in animals treated with anti-alpha/betaTCR mAbs and CsA after nerve allograft transplantation when compared to animals receiving no treatment and CsA alone. The immunomodulating protocol of combination anti-alpha/beta TCR mAbs and CsA for a 5 week period altered the rejection process, affording nerve regeneration. It may provide for an expanded source of nerve tissue to alleviate the morbidity of harvesting peripheral nerves from multiple sites for those afflicted with extensive peripheral nerve injuries.

Effect of transforming growth factor β1 on fresh nerve allograft transplantation

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20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,±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＜0.01).A、C两组的差异无统计学意义(P＞0.05),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。

Peripheral Nerve Allograft Transplantation with FK506

Two-centimeter nerve allografts were transplanted across a major histocompatibility barrier from donor ACI rats into a 0.5-cm gap in the sciatic nerve of recipient Lewis rats and immunosuppressed with FK506, 2 mg/kg per day for 3 months. One group of animals continued to receive intermittent immunosuppression with FK506, 2 mg/kg twice a week for another 2 months, whereas the second group of animals received no further immunosuppression in order to determine whether rejection of nerve allografts can still occur after immunosuppression is withdrawn, even after the axons have regenerated through the nerve graft. The sciatic function index improved from -76.3 at 3 months to -46.6 at 5 months in those animals continuing to receive intermittent immunosuppression, but only improved to -66.8 at 5 months when immunosuppression was discontinued. Similarly, somatosensory evoked potentials demonstrated an improvement in relative latency from 2.3 msec at 3 months to 0.34 msec at 5 months in animals continuing to receive intermittent immunosuppression, but only improved to 1.29 msec at 5 months when immunosuppression was discontinued. Nerve allografts continuing to receive intermittent immunosuppression showed no signs of rejection by light or electron microscopy and no significant difference compared with isografts, whereas nerve allografts whose immunosuppression had been stopped at 3 months showed mild signs of rejection, less regeneration, and a smaller number of nerve fibers.(ABSTRACT TRUNCATED AT 250 WORDS)