低氧预处理自体骨髓间充质干细胞修复关节软骨损伤的MRI活体示踪研究

To repair articular cartilage defects is one of the tough problems in medicine. With the development of the research on stem cells in regeneration medicine, stem cell therapy has been become the hotspot of studies. The therapeutic efficacy of it was demonstrated by clinical research. Bone marrow derived mesenchymal stem cells(MSCs) are convenient for isolating culture in vitro and capable of multi-directional differentiation. The study showed that these cells can repair various types of tissue. However, the mechanisms of stem cells to repair articular cartilage defects are not understood, and the poor survival rate and short life time of stem cells post transplant in vivo will affect the therapeutic efficacy. In our study, bone mesenchymal stem cells are obtained by isolating culture in vitro, and labeled with SPIO. Then, these cells are pretreated under hypoxia which can increase survival rate and life time after transplantation in vivo by increased paracrine mechanisms. The capable of tissue repair of these transplantation stem cells will be promoted. Then, these treated MSCs are applied to animal model, the locally distribution and differentiation process of the stem cells will be traced by MRI. The indication related to articular cartilage defects repair can be observed in real time. The study tries to elucidate the process and mechanisms of action of MSCs to articular cartilage defects and will provide the experimental data and foundation for articular cartilage defects treatment.

关节软骨损伤的修复是目前医学难题之一。随着干细胞在再生修复研究领域的不断发展，干细胞治疗已成为研究热点，其治疗效果已为临床所证实。骨髓间充质干细胞（MSCs）易于体外分离培养，具有较强的多向分化能力，研究表明其对多种组织均有一定的修复功能。然而，干细胞修复关节软骨损伤的作用机制尚未阐明，干细胞体内移植后生存率低，生存时间短等特性，影响其修复治疗效果。本研究拟体外分离培养获得原代自体MSCs，采用SPIO标记细胞后，于体外进行低氧预处理，通过增强其旁分泌机制增加移植后干细胞体内的生存率和生存时间，提高干细胞移植后的组织修复能力。然后，将处理后的MSCs注射于动物模型软骨损伤区，经MRI追踪干细胞在治疗局部的分布及分化过程，观察关节软骨修复的相关指标，阐明骨髓间充质干细胞修复关节软骨损伤的作用过程和机制，建立自体MSCs应用治疗研究模型，为找到关节软骨损伤的新型干细胞治疗手段提供研究依据和

关节软骨损伤修复是当前医学难题之一。近年来干细胞治疗在再生修复领域快速发展并在临床得到应用，为关节软骨损伤的修复提供新的方向。本研究通过体外分离培得到骨髓间充质干细胞（BMMSCs），并用SPIONs标记BMMSCs，通过细胞毒性试验获取合适的SPIONs浓度。对标记后的BMMSCs进行低氧预处理，发现细胞的标记率和细胞表型未发生变化；通过细胞凋亡、细胞周期和细胞迁移能力的试验，发现低氧预处理不会影响细的胞凋亡，同时使更多细胞维持在G0期，保持BMMSCs的干性，并且促进BMMSCs的迁移能力；并且对BMMSCs的成软骨分化能力进行检测，发现低氧预处理促进BMMSCs的成软骨分化能力。制作了关节软骨损伤的动物模型，通过关节腔注射SPIONs标记的BMMSCs，并且通过MRI进行检测细胞在体内的迁移情况和修复效果，对比病理切片染色和免疫组化，发现细胞转移至软骨损伤区分化成软骨细胞修复损伤，低氧预处理组在体内试验验证了促进BMMSCs向软骨分化的能力。