Use of Engineered Nervous Tissue Constructs to Repair Extensive Nerve Injury

描述（由申请人提供）：使用工程神经组织构建体修复广泛的神经损伤在美国每年约有360，000人遭受周围神经损伤，这是终身残疾的主要来源。 虽然修复主要周围神经损伤的主要策略是用自体神经移植物桥接损伤，但产生足够长度和数量的神经已经提出了重大挑战。 外周神经移植修复（即自体神经移植）中所谓的“黄金标准”受到供体神经的耗时采集和由采集手术引起的并发症的限制。 此外，目前用于神经移植修复的大多数替代方法（例如，合成管）在它们可以跨越以促进修复的长度上受到限制，并且通常用于小于2或3cm的间隙。 在这里，我们建议利用一种新的组织工程技术，以创造可移植的神经组织结构的主要周围神经修复。 这个过程的关键是使用一个专门设计的微步进电机系统，以产生连续的机械张力的轴突跨越两个群体的神经元在培养。 作为我们的中心假设，我们提出，工程活神经组织结构将促进主要周围神经损伤后的恢复，通过提供一个活的标记通路，引导宿主轴突从近端神经残端穿过大的神经病变，以重新支配靶组织。 除了提供一条通过损伤间隙的通路外，我们还提出，来自该结构的轴突将生长到近端和远端神经残端中。 在这个建议的第一部分，我们将修复急性广泛的急性神经损伤的动物模型，使用我们的新的活的工程神经组织结构。 在本研究的第二部分，我们将尝试在啮齿动物臂丛神经损伤的主要重建，跨越前肢从椎骨到爪子使用我们的活神经组织结构。 我们将直接比较接受含有伸长的背根神经节细胞培养物的神经组织构建体的动物与接受常规自体神经重建（反向自体移植物）、仅用合成管修复（材料基质对照）、无修复（无治疗对照）、免疫抑制对照（接受每日环孢素A注射）和物理康复对照的组的结果。 在本研究的第三部分，我们将评估我们的神经组织构建的免疫原性。 我们将调查的假设，即缺乏MHC I表达在我们延长DRG神经元的主要原因，免疫排斥反应不发生在移植宿主。 如果成功的话，我们的新型组织工程神经结构可以通过提供实验室生长的“现成”活神经来彻底改变主要神经重建的方法，这些活神经可以移植到广泛的周围神经损伤患者身上。 公共卫生相关性：在这项研究中，我们建议使用一种全新的组织工程技术来创建神经结构，用于修复动物模型中的广泛神经损伤。 如果成功的话，我们的研究结果可以通过提供实验室生长的“现成”活神经来为移植做好准备，从而使患有毁灭性神经损伤的患者受益。

DESCRIPTION (provided by applicant): Use of Engineered Nervous Tissue Constructs to Repair Extensive Nerve Injury Each year approximately 360,000 people in the United States suffer a peripheral nerve injury, which is a leading source of lifelong disability. While a primary strategy to repair major peripheral nerve injury is to bridge the damage with autologous nerve grafts, producing nerves of sufficient length and number has posed a significant challenge. The so called "gold standard" in peripheral nerve graft repair (i.e. the autologous nerve graft) is limited by the time consuming harvesting of donor nerves and complications arising from the harvesting surgery. In addition, most alternative methods currently used for nerve graft repair (e.g., synthetic tubes) are limited in the length that they can span to promote repair and are typically used for gaps of less than 2 or 3 cm. Here, we propose to utilize a novel tissue engineering technique to create transplantable nervous tissue constructs for major peripheral nerve repair. The key of this procedure is to use a specially designed microstepper motor system to produce continuous mechanical tension on axons spanning two populations of neurons in culture. As our central hypothesis, we propose that engineered living nervous tissue constructs will promote recovery after major peripheral nerve injury by providing a living labeled pathway to guide host axons from the proximal nerve stump across large nerve lesions to reinnervate the target tissue. In addition to providing a pathway through the injured gap, we also propose that axons from the construct will grow into both the proximal and distal nerve stumps. In the first part of this proposal, we will repair acute extensive acute nerve injury in an animal model using our novel living engineered nervous tissue constructs. In the second part of this study, we will attempt major reconstruction of brachial plexus injury in rodents, spanning the forelimb from the vertebrae to the paw using our living nervous tissue constructs. We will directly compare the outcome of animals receiving the nervous tissue construct containing the elongated dorsal root ganglion cell cultures with groups receiving conventional autologous nerve reconstruction (reverse autologous graft), repair with a synthetic tube alone (material substrate control), no repair (no treatment control), immunosuppression control (receiving daily cyclosporine A injection) and physical rehabilitation control. In the third part of this study, we will assess the immunogenicity of our nervous tissue construct. We will investigate the hypothesis that the lack of MHC I expression in our elongated DRG neurons is the main reason that immunorejection does not occur in transplanted hosts. If successful, our novel tissue engineered nerve construct could revolutionize methods for major nerve reconstruction by providing laboratory grown 'off-the-shelf' living nerves ready for transplant in patients with extensive peripheral nerve injuries. PUBLIC HEALTH RELEVANCE: In this study we propose to use a fundamentally novel tissue engineering technique to create nerve constructs for repair of extensive nerve injury in an animal model. If successful, our findings could benefit patients with devastating nerve injuries by providing laboratory grown 'off-the-shelf' living nerves ready for transplant.