氧化铈纳米颗粒表面重塑诱导组织工程骨血管化及其作用机制研究

The practical application of tissue engineering bone (TEB) is challenged by tissue necrosis and fibrosis due to the insufficient blood vessel distribution and diffusion. Vascular endothelial cell is the core cell for TEB vascularization. The proliferation and migration of vascular endothelial cell have significant effect on the formation of new blood vessels. Recently, we found that surface remodeling of ceria nanoparticles (CNPs) through changing the nanoparticle crystal structure, coating the nanoparticle with polymer and conjugating the nanoparticle with functional groups could significantly promote the growth of vascular endothelial cell. Our preliminary data indicated that the proliferation rate and migration area of vascular endothelial cells cultured with surface remodeled CNPs were 70% and 160% higher than that of vascular endothelial cells cultured without CNPs. These results imply that the surface remodeled CNP is potential reagent for angiogenesis. In the proposed project, we will study on the feasibility of using surface remodeled CNPs as induction agent for TEB vascularization. Firstly, the surface remodeling system for CNPs will be intensively studied. The biochemical activities variation of CNPs caused by the surface remodeling will be discussed. Secondly, the mechanism for the improvement of vascular endothelial cell growth induced by surface remodeled CNPs will be clarified. Thirdly, the methods of incorporating the surface remodeled CNPs into our previous reported TEB scaffold will be explored. The feasibility of the as prepared scaffold for bone and blood vessel regeneration will be evaluated and optimized in vitro. Fourthly, the angiogenesis induction strategies based on the surface remodeled CNPs will be studied and their feasiblity of blood vessel formation will be evaluated in vivo. The proposed project is aimed at exploring a new strategy for TEB vascularization.

因再生血管分布密度和浸润深度不够而导致组织坏死或纤维化是组织工程骨（TEB）面临的严峻挑战，血管内皮细胞是TEB血管再生的核心细胞，其增殖和迁移对TEB血管再生有关键影响。我们前期发现，通过改变晶体结构、包覆聚合物和嫁接功能基团等手段对氧化铈纳米颗粒（CNPs）进行表面重塑后，该纳米颗粒可使血管内皮细胞的增殖及迁移速度提高70%和160%，这提示表面重塑后的CNPs是潜在的血管再生诱导剂。本项目拟探索CNPs表面重塑及其诱导TEB体内原位血管再生的可行性，内容包括：构建CNPs表面重塑体系，分析表面重塑对其生化活性的影响；探索CNPs表面重塑对血管内皮细胞生长行为的影响，阐明其具体作用机制；建立表面重塑后的CNPs同TEB支架复合的方法，体外优化其骨和血管再生诱导性能；制定基于CNPs的TEB体内原位血管再生诱导策略，并在体内进行实验验证。项目的成功实施可为TEB血管化研究提供一种新思路。

因再生血管分布密度和浸润深度不够而导致组织坏死或纤维化是组织工程骨（TEB）面临的严峻挑战。针对该问题，项目拟利用氧化铈纳米颗粒（CNPs）的促血管再生功能促进组织工程骨血管化，主要研究内容包括：构建CNPs 表面重塑体系，分析表面重塑对其生化活性的影响；探索CNPs 表面重塑对血管内皮细胞生长行为的影响，阐明其具体作用机制；建立表面重塑后的CNPs 同TEB 支架复合的方法，体外优化其骨和血管再生诱导性能；制定基于CNPs 的TEB 体内原位血管再生诱导策略，并在体内进行实验验证。经过4年时间的系统研究，项目组有如下发现：（1）同传统加热法相比，采用微波加热合成的CNPs其SOD活性更高，对细胞的保护作用也更强；（2）将CNPs复合到组织工程骨支架表面可激活间充质干细胞钙通道，使HIF-1α的稳定性提高，并由此导致VEGF表达增加，最终导致TEB中再生血管分布密度增加；（3）CNPs可激活破骨细胞，使其分化进程加快，同时其存活时间缩短，由此使骨代谢速度在短期内加快，最终促进骨生长；（4）CNPs可诱导间充质干细胞成软骨分化及肥大化，并可通过软骨内成骨机制促进TEB骨再生。（5）CNPs降解产物Ce3+可促进破骨细胞分化。