Targeting Therapeutic Molecules to Dystrophic Muscle via the Immune System

描述(由申请人提供)：治疗Duchenne肌营养不良症的药理学方法的一个主要挑战是在正确的时间将正确的分子定位到正确的位置。即使治疗分子的系统性给药对疾病组织有有益的影响，靶外效应也可能产生负面后果，影响特定治疗剂的临床使用。我们提出了一种创新的策略，利用身体自身的能力，在病理最明显的部位和时间向病变组织运送分子。我们将使用骨髓细胞(BMC)表达由激活的巨噬细胞中高表达的启动子(CD11b)驱动的治疗分子(LIF)的转基因，并将这些细胞移植到患有肌肉营养不良的小鼠体内。由于MDX小鼠肌营养不良的发病和严重程度反映了高表达CD11b的髓系细胞对肌肉的侵袭，我们预计LIF的治疗将跟踪疾病的发生和严重程度。因此，我们希望实现针对疾病组织的治疗分子的靶向递送，以最大限度地减少负面的、非靶向的影响。如果成功，我们的发现可能为肌营养不良症的治疗提供一种全新的途径。在我们拟议的研究中，我们将探索使用骨髓来源的髓系细胞作为载体，将治疗货物运送到营养不良的肌肉，目的有两个。目的1.转基因骨髓细胞移植能为营养不良肌肉提供靶向治疗分子的机制吗？我们将从三个转基因供体系中每一个移植骨髓细胞，这些转基因供体系在分化的白细胞中表达的LIF转基因水平从8到131倍不等。接受MDX的小鼠将接受病理减少、巨噬细胞从溶细胞表型转变为促再生表型以及肌肉功能改善的评估。我们还将分析负面的、偏离目标的影响的发生。目的2.受体小鼠的非清髓性条件作用能否允许转基因供体髓系细胞充分植入，从而在不产生负面、非靶点效应的情况下，从病理中解救出来？在目标2中，我们将测试在骨髓移植前使用非清髓性调节的药理学方法是否会产生足够的靶向LIF转基因到肌肉和减轻肌肉病理而不会招致负面的、非靶点的影响。

DESCRIPTION (provided by applicant): A major challenge for pharmacological approaches to treating Duchenne muscular dystrophy is targeting the right molecule to the right place at the right time. Even when systemic delivery of a therapeutic molecule has beneficial effects on diseased tissue, off-target effects can produce negative consequences that detract from the clinical use of a particular therapeutic agent. We propose an innovative strategy to exploit the body's own ability to deliver molecules to diseased tissue at sites and times when pathology is most pronounced. We will use bone marrow cells (BMCs) that express a transgene for a therapeutic molecule (LIF) that is driven by a promoter (CD11b) that is highly expressed in activated macrophages and transplant those cells into mice that have muscular dystrophy. Because the onset and severity of muscular dystrophy in mdx mice mirrors the invasion of muscle with myeloid cells that express high levels of CD11b, we anticipate that delivery of therapeutic LIF will track the occurrence and severity of the disease. Thus, we hope to achieve targeted delivery of a therapeutic molecule specifically to diseased tissue "on demand," to minimize negative, off-target effects. If successful, our findings could provide a wholly-new avenue for the treatment of muscular dystrophy. In our proposed investigation, we will explore the use of bone-marrow-derived myeloid cells as vectors for delivery of therapeutic cargo to dystrophic muscle in two aims. Aim 1. Can transplantation of genetically-modified BMCs provide a mechanism to target therapeutic molecules to dystrophic muscle? We will transplant BMCs from each of three transgenic, donor lines that display LIF transgene expression that ranges from 8- to 131- fold wild-type levels in differentiated leukocytes. Recipient, mdx mice will be assessed for reductions in pathology, shifts in macrophages from a cytolytic to a pro-regenerative phenotype and improved muscle function. We will also assay for the occurrence of negative, off-target effects. Aim 2. Can non-myeloablative conditioning of recipient mice allow sufficient engraftment of transgenic, donor myeloid cells to provide a rescue from pathology, without negative, off-target effects? In Aim 2, we will test whether the use of pharmacological approaches to non-myeloablative conditioning prior to bone marrow transplantation will yield sufficient targeting of the LIF transgene to muscle and attenuation of muscle pathology without incurring negative, off-target effects.