SDF-1诱导椎间盘干细胞niche内多能干细胞迁移的效应机制及其纳米微粒原位诱导组织再生作用的研究

原位诱导组织再生可用于促进椎间盘自我修复，但难在无血管的椎间盘中原位募集干细胞，椎间盘自我修复机制的进一步明确有助于解决难题。我们的前期研究显示，干细胞迁移因子SDF-1表达量随椎间盘退变而显著增高，内植后能延缓动物体内的髓核退变。最新研究发现，纤维环外层附着处及毗邻软骨膜内存在干细胞niche，富集多能干细胞（ISN-SCs），且不受无血管的限制而向髓核内迁移。但是，ISN-SCs受SDF-1诱导而迁移的效应机制及其在椎间盘内的生物学作用仍不明确。本项目拟在前期工作基础上，鉴定哺乳动物ISN-SCs的普遍存在性及干细胞特性，构建SDF-1白蛋白纳米微粒，运用细胞迁移、离体椎间盘器官和椎间盘退变模型等技术，阐明SDF-1诱导ISN-SCs迁移的效应机制，明确ISN-SCs在椎间盘内的生物学作用，和SDF-1纳米微粒的原位诱导组织再生作用，揭示椎间盘自我修复机制，为研发新型复合药物奠定基础。

Situ induced tissue regeneration can promote intervertebral disc (IVD) self-repair, and does not depend on exogenous stem cells, but it is difficult in recruitment endogenous stem cells in situ in the IVD, which is absence of blood vessels. However, self-regeneration mechanism of the IVD to further clarify will help solve this problem. Our previous studies have shown that SDF-1, an important stem cell migration factor, express significantly higher in degenerative IVD than normal group, and SDF-1 implanting can relieve the degeneration of nucleus pulposus in rat tail degeneration model. Resent researches found a potential stem cell niche in a region close to the IVD in both humans and a variety of animals including mice, rabbits, and pigs. This niche is located in the regions adjacent to the disc, such as the perichondrium and the annulus fibrosus ligament anchoring site. Rat stem cells in this niche (ISN-SCs) were successfully isolated and it was confirmed that the ISN-SCs met the minimal criteria for the definition of multipotent mesenchymal stromal cells, and had a multipotent differentiation potential. In particular, ISN-SCs showed a greater potential for osteogenesis and chondrogenesis. Studies also indicated that cellular migration had taken place from the stem cell niche areas into the mature cartilaginous tissues of the IVD. However, the ubiquity and mesenchymal stem cell characteristics of mammalian ISN-SCs are needed to be identified. Furthermore, the effect mechanism of SDF-1 inducing stem cells migration in IVD stem cell niche, and the biological effects of ISN-SCs in the IVD are both unclear. On the basis of our previous works, our study is divided as followed: (1) A variety of mammalian ISN-SCs are isolated and identified; (2) SDF-1 bovine serum albumin nanoparticles are constructed; (3) Study on effect mechanism of SDF-1 inducing ISN-SCs migration from the stem cell niche into the IVD in vitro, using transwell culture system and disc organ culture model; and (4) Effect of SDF-1 nanoparticles for in situ disc tissue regeneration in animal IVD degeneration model. The results of this study will help to clear the effect mechanism of SDF-1 inducing ISN-SCs migration, and the biological effects of ISN-SCs in the IVD, reveal the self-regenerating mechanism of the IVD, and lay the foundation for new drugs for in situ IVD tissue regeneration.