Use of Engineered Nervous Tissue Constructs to Repair Extensive Nerve Injury

描述（由申请人提供）：使用工程神经组织结构修复广泛的神经损伤每年在美国大约有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是一个重大挑战。周围神经移植修复（即自体神经移植）的所谓“金标准”受到供体神经采集耗时和采集手术并发症的限制。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）在促进修复的长度上是有限的，并且通常用于小于2或3厘米的间隙。在这里，我们建议利用一种新的组织工程技术来创建可移植的神经组织结构，用于周围神经修复。这个过程的关键是使用一个特殊设计的微步进电机系统在培养的两个神经元群体的轴突上产生连续的机械张力。作为我们的中心假设，我们提出工程化活神经组织构建将促进周围神经损伤后的恢复，提供一个活的标记途径，引导宿主轴突从近端神经残端穿过大的神经病变，重新支配目标组织。除了通过损伤间隙提供一条通路外，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。在本提案的第一部分，我们将在动物模型中修复急性广泛急性神经损伤，使用我们的新型活工程神经组织结构。在本研究的第二部分，我们将尝试在啮齿动物中重建臂丛神经损伤，使用我们的活体神经组织结构，从椎骨到脚掌跨越前肢。我们将直接比较接受含有长背根神经节细胞培养的神经组织构建的动物与接受常规自体神经重建（反向自体移植物）、单独用合成管修复（材料底物对照）、不修复（无治疗对照）、免疫抑制控制（每日注射环孢素a）和物理康复控制的动物的结果。在本研究的第三部分，我们将评估我们的神经组织结构的免疫原性。我们将研究一种假设，即在我们细长的DRG神经元中缺乏MHC I表达是移植宿主不发生免疫排斥反应的主要原因。如果成功，我们的新型组织工程神经结构将通过提供实验室生长的“现成的”活神经，为广泛周围神经损伤的患者提供移植准备，从而彻底改变主要神经重建的方法。

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.