Cell Therapy for the Degenerating Intervertebral Disc

 描述（由申请人提供）： 2001年至2010年期间，超过13万名现役军人被诊断出椎间盘（IVD）退变，这一时期的年发病率翻了一番多。超过68，000天的工作时间损失归因于椎间盘变性特异性诊断。军事训练和行动本身对身体的要求很高，使军人患IVD变性和相关颈部和背部疼痛的风险增加。在退伍军人中，慢性背痛占脊椎按摩治疗的70%以上，在许多情况下与他们的服务期直接相关。尽管患病率和成本飙升，但没有恢复患病IVD生理功能的特定治疗方法。 这项初步研究的目的是证实年轻的同种异体关节软骨细胞，特别是那些诱导过表达生长因子（例如，骨形态发生蛋白（BMP-7）在修复退变的IVD中是有效的。关节软骨细胞将是合适的细胞来源，因为它们已经具有与IVD细胞相似的表型，并且与天然椎间盘细胞不同，它们具有通过同种异体移植进行临床转化的更大潜力。这里将使用年轻的软骨细胞，因为大量文献支持年轻细胞通过营养因子使宿主组织恢复活力而比老年细胞具有更多再生能力的观点。我们的团队率先开发了兔IVD损伤模型，该模型非常适合评估基于细胞的治疗方法。 我们的初步数据表明，年轻的同种异体关节软骨细胞注射到受伤的兔IVD的中心存活，并减少宿主组织的炎症。在拟定的研究中，将评估具有不同特性的水凝胶作为支架，可防止注射针道泄漏并增强修复的IVD的生物力学特性。在力学上模拟天然NP的可注射植入物将更有可能在体内加载椎间盘时在细胞中诱导适当的表型。具体而言，我们的团队开发了基于透明质酸（HA）的水凝胶，有助于保持软骨细胞的表型和生长，其在体温下固化，因此是注射治疗的理想选择。我们还测试了三重互穿网络（TIN）水凝胶，可增强修复的IVD的生物力学性能。基于我们的初步研究，我们假设移植接种在水凝胶中的关节软骨细胞将重新填充IVD，从而通过提供营养因子和合成细胞外基质来减少炎症并增强生物力学性能。提出了两个具体的目标，以测试这一假设。在目标1中，我们将比较HA和TIN凝胶在兔IVD损伤模型中支持移植的关节软骨细胞存活和减少宿主炎症反应方面的作用。最能支持细胞存活并减少宿主炎症的水凝胶将进一步测试。在目的2中，我们将确定年轻的关节软骨细胞对损伤的成熟兔IVD的治疗作用。将确定软骨细胞（天然或过表达骨形态发生蛋白（BMP）-7）对宿主IVD炎症、生物力学特性和组织结构的影响。 我们预计，用软骨细胞接种在水凝胶中修复的IVD将显示出改善的生物力学性能、减少的炎症和改善的形态。这些对兔子的研究将为临床研究奠定基础，临床研究将测试移植的软骨细胞是否 有效减轻椎间盘退变及背痛，令病人受惠。

 DESCRIPTION (provided by applicant): Between 2001 and 2010, more than 130,000 active service members received diagnoses of intervertebral disc (IVD) degeneration, with annual incidence rates more than doubling over this period. Over 68,000 days of lost duty time were attributed to disc degeneration-specific diagnoses. Military training and operations are inherently physically demanding, placing military service members at increased risk for IVD degeneration and related neck and back pain. Among Veterans, chronic back pain accounts for over 70 percent of chiropractic visits and in many cases is directly connected to their period of service. Despite the prevalence and soaring costs, there is no specific treatment that restores physiological functions of the diseased IVD. The objective of this pilot study is to confirm that young allogeneic articular chondrocytes, especially those induced to overexpress growth factors (e.g., bone morphogenetic protein, BMP-7) are effective in repairing the degenerating IVD. Articular chondrocytes would be an appropriate cell source because they already have a phenotype similar to that of the IVD cells, and, unlike native disc cells, have greater potential for clinical translation through allogeneic transplantation. Young chondrocytes will be used here because a body of literature supports the notion that young cells possess more regenerative capacity than older cells by rejuvenating host tissue via trophic factors. Our team has pioneered the development of a rabbit IVD-injury model which is ideally suited to evaluating cell-based therapeutics. Our preliminary data have shown that young allogeneic articular chondrocytes injected into the center of the injured rabbit IVD survived and reduced inflammation of the host tissue. In the proposed study, hydrogels with distinct properties will be assessed as scaffold that may prevent leakage from the injection needle track and enhance biomechanical properties of the repaired IVD. The injectable implants shown to mimic the native NP in mechanics will be more likely to induce the appropriate phenotype in the cells as the disc is loaded in vivo. Specifically, our group has developed hyaluronic acid (HA)-based hydrogels conducive to preservation of chondrocyte phenotype and growth, which solidify at body temperature and are thus ideal for injection therapies. We have also tested a triple-interpenetrating-network (TIN) hydrogel that enhances biomechanical properties of the repaired IVD. Based on our preliminary studies, we hypothesize that transplanting articular chondrocytes seeded in hydrogels will repopulate the IVD thus reducing inflammation and enhancing biomechanical properties by providing trophic factors and synthesizing extracellular matrix. Two specific aims are proposed, to test this hypothesis. In Aim 1, we will compare the HA and TIN gel in supporting transplanted articular chondrocyte survival and reducing host inflammatory responses in the rabbit IVD-injury model. The hydrogel that best supports cell survival and reduces host inflammation will be further tested. In Aim 2, we will determine the therapeutic effects of young articular chondrocytes on injured mature rabbit IVDs. The effects of chondrocytes (native or overexpressing bone morphogenetic protein (BMP)-7) on the host IVD inflammation, biomechanical properties, and tissue structure will be determined. We expect that IVDs repaired with chondrocytes seeded in hydrogel will show improved biomechanical properties, decreased inflammation, and improved morphology. These studies in the rabbit will lay the groundwork for clinical studies that will test if transplanted chondrocytes are effective in reducing disc degeneration and back pain, thus benefiting patients.