Nerve Allotransplantation for Traumatic Nerve Injury

描述（由申请人提供）：周围神经损伤可导致严重和永久性功能缺陷。同种异体神经移植物提供了无限的神经移植材料来源，临床上用于重建严重的，否则无法修复的创伤性神经损伤。FK 506可增强神经再生，是预防同种异体移植排斥反应的首选免疫抑制剂，但可能导致患者严重发病。这项建议的长期目标是制定策略，以防止神经同种异体移植排斥反应，同时最大限度地减少免疫抑制的副作用，从而提高安全性和扩大周围神经同种异体移植的临床适应症。在几种动物模型中，共刺激阻断诱导的供体特异性免疫无反应性已被证明允许通过同种异体移植物进行神经再生，同时保持一般免疫活性。同样，同种异体神经移植物可以冷保存以降低抗原性，并接种宿主雪旺细胞以促进神经再生。更好地了解神经同种异体移植物的反应，冷保存的影响，和雪旺细胞迁移到神经移植物提供了一个基础的策略，以尽量减少对宿主免疫抑制的要求。用修饰的宿主雪旺细胞补充同种异体神经移植物可以增强通过同种异体神经移植物的再生。这些方法将扩大神经同种异体移植的适应症，包括目前使用自体神经移植的不太严重的损伤。在目的1a中，使用CD 4+和CD 8+敲除和MHC II类缺陷小鼠表征外周神经同种异体移植物中同种异体抗原呈递的直接和间接途径的相对贡献。目的1b利用STAT 4和STAT 6基因敲除小鼠研究冷保存同种异体神经移植物对这些通路的影响。在目标2a中，在同时阻断CD 28/B7和CD 40共刺激通路后，评价通过同种异体神经移植物的再生。在目标2b中，将同种异体神经移植物冷藏以优化共刺激阻断的功效，从而允许同种异体移植物接受。在目的3a中，Thy 1-CFP/S100-GFP小鼠用于表征当重新填充冷保存的神经同种异体移植物时的许旺细胞迁移、分化和成熟。在目标3b中，将神经同种异体移植物冷保存7周，然后接种培养的过表达GDNF的自体施万细胞，以允许在没有任何免疫抑制的情况下通过神经同种异体移植物再生。在目标3c中，在长猪同种异体移植物模型中评价了相同的结构，该模型与临床上遇到的长神经缺损非常相似，并将允许转移至神经损伤患者。

DESCRIPTION (provided by applicant): Injury to peripheral nerves can result in significant and permanent functional deficits. Nerve allografts offer a limitless source of nerve graft material that is used clinically to reconstruct severe otherwise irreparable traumatic nerve injuries. FK506 enhances nerve regeneration and is the immunosuppressant of choice for preventing allograft rejection, but can cause significant patient morbidity. The long-term objective of this proposal is to develop strategies to prevent nerve allograft rejection while minimizing the side effects of immunosuppression, thereby improving safety and broadening the clinical indications for peripheral nerve allotransplantation. Donor-specific immune unresponsiveness induced by costimulation blockade has been shown to permit nerve regeneration through allografts in several animal models while maintaining general immunocompetence. Similarly nerve allografts can be cold preserved to decrease antigenicity and seeded with host Schwann cells to facilitate nerve regeneration. A better understanding of the nerve allograft response, the effects of cold preservation, and Schwann cell migration into nerve grafts provides a basis for strategies to minimize requirements for host immunosuppression. Supplementation of nerve allografts with modified host Schwann cells may enhance regeneration through nerve allografts. These approaches will expand the indications for nerve allotransplantation to include less severe injuries where nerve autografts are currently used. In aim 1 a the relative contributions of the direct and indirect pathways of alloantigen presentation in peripheral nerve allografts are characterized using CD4+ and CD8+ knockout and MHC class ll-deficient mice. Aim 1b studies the effects of cold preservation of nerve allografts on these pathways using STAT4 and STAT6 gene knockout mice. In aim 2a, regeneration through nerve allografts is evaluated following simultaneous blockade of CD28/B7 and CD40 costimulatory pathways. In aim 2b, nerve allografts are cold preserved to optimize the efficacy of costimulatory blockade to permit allograft acceptance. In aim 3a, Thy1-CFP/S100-GFP mice are used to characterize Schwann cell migration, differentiation, and maturation when repopulating a cold preserved nerve allograft. In aim 3b, nerve allografts are cold preserved for 7 weeks and then seeded with cultured autologous Schwann cells that overexpress GDNF to permit regeneration through nerve allografts without any immunosuppression. In aim 3c this same construct is evaluated in a long swine allograft model that closely resembles the long nerve defects encountered clinically and will allow translation to the nerve-injured patient.