种子细胞成骨分化并形成新骨质对组织工程修复骨缺损具有重要意义，移植后因缺氧而存活困难却制约了种子细胞的应用。用释氧剂供氧被公认可解决此问题，但适宜于细胞存活与成骨分化的氧浓度范围尚未知。已往的释氧材料均有释氧时间短、释氧量不可控的缺陷，故实际应用效果不佳。为此，本课题拟用外周血间充质干细胞（PBMSCs）为种子细胞模型研究不同氧浓度对其存活与分化的影响,以得出安全有效的浓度范围。用CaO2和PLGA构建释氧时程长、释氧量可控的缓释微囊，并将其与PBMSCs共同加入基础骨组织工程材料中，经体外检测后用于移植修复大鼠股骨极限缺陷模型。本课题除了研究可控释氧微囊对PBMSCs存活与成骨分化效率外，还将通过Western Blot, RT-PCR等探讨其作用机制，通过组织学、micro-CT和生物力学检测骨再生的效果。核心目的是构建全新的可控释氧型骨组织工程材料，为有效修复大段骨缺损提供治疗策略。

The osteo-differentiation and osteogenesis of seeding cells has important significance on bone tissue engineering. However, majority of seeding cells cannot survive in the transplanted bioscaffold which mainly duo to hypoxia. Using oxygen releasing agent to supply oxygen has been accepted as a potential strategy to solve this problem. To now, the suitable and safe range of oxygen concentration for cell survival and osteo-differentiation is unknown. The existing oxygen releasing materials are not controllable which releasing oxygen only in short term. Above issues strictly limited the application of the oxygen releasing technique. Therefore, the present study planed to use the peripheral blood mesenchymal stem cells (PBMSCs) as the seeding cell model to study that the effects of different oxygen concentration on the survival and osteo-differentiation of seeding cells. Using CaO2 and PLGA to fabricate a novel oxygen generating microspheres which can release oxygen long-term and release oxygen is quantitatively controllable. Then, the microspheres and PBMSCs will be added into a basic bone tissue engineering materials for repairing critical size femur bony defect. This study is not only designed to study of controllable oxygen generating microspheres’ effects on the survival and osteo-differentiation of PBMSCs, but also to explore the mechanism of it by Western blot, RT-PCR as well as to test bone regeneration effect by histological,micro CT and biomechanical. The core objectives of this study are fabricating a novel controlled oxygen releasing material and providing an efficient strategy for the treatment of large bone defects.