Enhancement of Myoblast Chemotactic Migration

描述（由申请人提供）： 遗传缺陷是几种退行性肌肉疾病如杜氏肌营养不良症（DMD）的基础，但尚未发现这些疾病的有效疗法。一种方法是基于细胞的疗法，其中将正常成肌细胞或基因修饰的患者成肌细胞注射到患病肌肉中，目的是植入足以补偿蛋白质缺陷。 然而，这种方法几乎没有取得成功，这是由于移植物存活率差和大量肌肉注射的不切实际的要求等问题。最近，已经证明通过小鼠尾静脉或动脉注射全身递送肌肉前体细胞导致再生肌肉组织的低水平供体细胞植入。血管迁移和外渗的前体细胞，从而发生，并可能提供一个有用的途径，改善细胞为基础的治疗这些毁灭性的疾病。所提出的工作的具体目的是1）鉴定成肌细胞中表达的参与与活化的内皮细胞的附着并促进跨内皮细胞迁移的分子，2）如果可能的话，通过甘氨酸诱导已知调节免疫系统细胞的附着和外渗的分子的表达来提高成肌细胞跨内皮迁移的效率。方法：研究小鼠骨骼肌成肌细胞，以确定已知在白细胞外渗中起作用的蛋白质的表达水平。炎性细胞因子将用于诱导成肌细胞表达与趋化运动相关的蛋白质。体外跨内皮细胞迁移试验将用于评估特定趋化因子、受体和细胞粘附分子在该过程中的作用以及炎性细胞因子刺激对成肌细胞迁移的影响。将正常成肌细胞和由细胞因子诱导的成肌细胞注射到mdx小鼠（DMD模型）的尾静脉中，所述小鼠经历肌肉再生并外渗到评估的组织中。结果将进一步我们的机制，促进供体成肌细胞到患病肌肉的全身植入的理解，可以显着推进肌源性前体细胞用于治疗肌营养不良症的治疗用途。

DESCRIPTION (provided by applicant): Genetic defects underlying several degenerative muscle diseases such as Duchenne muscular dystrophy (DMD) are known, yet effective therapies for these disorders have not been found. One approach has been cell-based therapy in which normal myoblasts or genetically modified patient myoblasts are injected into diseased muscle with the intent that engraftment would be sufficient to compensate for protein deficiencies. Little success has been achieved with this approach however due to problems such as poor graft survival and impractical requirements for numerous muscle injections. Recently, systemic delivery of muscle precursor cells via tail vein or arterial injection in mice has been demonstrated resulting in low-level donor cell engraftment of regenerating muscle tissue. Vascular migration and extravasation of precursor cells thus occurs and could provide a useful route for improved cell-based therapy for these devastating diseases. The specific aims of the proposed work are to 1) Identify molecules expressed in myoblasts that are involved in the attachment to activated endothelial cells and promote trans-endothelial cell migration, 2) Improve the efficiency of myoblast trans-endothelial migration, if possible, by cytokine-induced expression of molecules known to regulate attachment and extravasation of immune system cells. Methods: Murine skeletal muscle myoblasts will be studied to determine expression levels of proteins known to function in leukocyte extravasation. Inflammatory cytokines will be used to induce myoblast expression of proteins relevant to chemotactic movement. In vitro trans-endothelial cell migration assays will be used to assess the role of specific chemokines, receptors and cell adhesion molecules in this process and the influence of inflammatory cytokine stimulation on myoblast migration. Normal myoblasts and those induced by cytokines will be injected into tail veins of mdx mice (model for DMD) undergoing muscle regeneration and extravasation into tissues assessed. Results will further our understanding of the mechanisms that promote systemic engraftment of donor myoblasts into diseased muscle could significantly advance the therapeutic use of myogenic precursor cells for the treatment of muscular dystrophy.