骨靶向纳米转基因体系调控干细胞的定向迁移及其在骨质疏松治疗中的应用

Osteoporosis and the related fragility fractures are a major public health concerns worldwide, especially with the aging population. It is more serious in China due to the large population. Extensive attention has been devoted to develop drugs for the treatment of osteoporosis, but the current therapies are unsatisfied. It has been found that the stem cell nich has changed in the aged tissue, resulted in the decreased number of stem cell and its osteogenic ability. Stem cell transplantation is promising in treating the aging related disease; however, systemic infusions of MSCs in vivo do not promote an osteogenic response in bone because of the inability of MSCs to home to the bone surface. Targeted regulating stem cell migrate might provide a promising strategy. Our previous study has showed that non-viral vector mediated gene therapy processes significant advantages in safety and low cost in treating bone related disease, and it is easy to realize targeted gene delivery. This study will utilize bone targeted non-viral vector constructed by modifying liposome with alendronate, to deliver gene of Stromal cell Derived Factor-1to the bone which plays a key role in stem cell migration, in regulating migration of stem cell to bone surface and function to repair the tissue. This study will further explore the mechanism of stem cell homing and also provide a new strategy for the treatment of bone and aging related disease.

骨质疏松及其导致的骨折是世界性的最严重的老龄问题之一，目前尚无有效治疗方法。干细胞技术对衰老和损伤组织修复具很好的应用前景，但移植干细胞无法直接贴附于骨表面刺激骨生成影响了干细胞治疗技术的应用效果，通过调控干细胞的定向迁移将有望提供解决方法。前期研究中我们已发现，非病毒转基因技术在治疗骨相关疾病中具有突出的安全和成本优势，且容易实现靶向投递。本课题拟利用骨靶向非病毒转基因纳米体系，在骨组织或局部高表达调控干细胞迁移的细胞基质衍生因子(SDF-1)，招募间充质干细胞向骨表面的定向迁移，并探讨其参与骨重建和促进骨形成的作用效果。本研究将进一步揭示干细胞定向迁移及参与组织修复的机制，为骨质疏松及其导致的骨折提供一种新型治疗方法，同时将对其他骨相关疾病的治疗具有重要的意义和应用前景。

骨质疏松及其导致的骨折是世界性的最严重的老龄问题之一，目前尚无有效治疗方法。干细胞技术对衰老和损伤组织修复具很好的应用前景，但移植干细胞无法直接贴附于骨表面刺激骨生成影响了干细胞治疗技术的应用效果。本项目通过构建骨靶向纳米脂质体，携带细胞基质衍生因子(SDF-1)在骨组织高表达，招募间充质干细胞向骨表面的定向迁移并参与骨再生。靶向脂质体通过阿伦磷酸钠修饰PEG并通过薄膜分散法制备，与DNA的复合比为1:1（N/P），尺寸在100nm，表面电荷为20mV，与羟基磷灰石的复合率达到80%。通过体系优化，具有高转染效率和良好的生物相容性，转染效率达到50%。将构建的骨靶向脂质体用于介导SDF-1转染成骨细胞，转染后，成骨细胞可见SDF-1的基因和蛋白的表达，通过transwell侵袭实验可见成骨细胞分泌的SDF-1蛋白能够促进上层干细胞的迁移。将该体系通过尾静脉注射的方法用于体内可见在骨组织的富集，并能够对尾静脉移植的荧光干细胞促进向骨表面的迁移。这种骨靶向载体还可作为蛋白或者药物载体进行骨靶向给药，具有广泛的应用范围。本研究针对干细胞分化参与成骨的机制也进行了研究，发现干细胞会以不对称分裂的方式维持机体中自我更新与分化成骨的平衡，为干细胞成骨分化的机制方面增添了新的理论基础。