人体90%的柠檬酸都沉积在骨组织，参与骨微结构和力学强度的维持。基于此，我们前期研发了一系列基于柠檬酸的仿生骨材料，在动物模型中表现出极为良好的骨诱导和成骨性能。随后在细胞研究中发现：柠檬酸可上调成骨标志基因的表达，促进成骨细胞分化与矿化，并且存在时间依赖与剂量依赖效应。但柠檬酸促进成骨细胞分化的分子机制尚不清楚，国内外也未见报道。本课题拟在已构建的成骨细胞Pdha1基因敲除（柠檬酸合成下调）的小鼠与细胞模型上，观测骨与细胞的表型，利用蛋白质组学/mRNA转录组测序技术，筛查其下游差异表达蛋白，探讨柠檬酸促进成骨分化的具体分子机制；随后应用上述机制，探索诱导成骨的“最优柠檬酸浓度窗”，构建柠檬酸降解浓度可控型“双相”骨支架，在细胞和大鼠颅骨缺损模型评价其骨再生修复功能，研究成果将为成骨细胞分化调控机制的探索提供新的思路，为临床大段骨缺损的修复治疗提供新的仿生材料选择。

Ninety percent of citrate in human body is located in bone tissue, involved in maintenance of bone microstructure and mechanical strength. Inspired on it, we developed a series of biomimetic citrate-based bone scaffolds, which showed excellent osteoinduction and osteogenesis in animal models. In vitro study, citrate was found to up-regulate the expression of bone markers and promote osteoblastic differentiation and mineralization with culture stage-dependent and dose-dependent effect. However, the specific molecular mechanism of citrate to promote osteoblastic differentiation is unknown and hasn’t been reported domestic and abroad. In the current study, the bone phenotype of the PDHA1 KO mice (citrate down-regulation, targeting osteoblast) and the interested Protein/mRNA screened by Proteomics/mRNA sequencing will be detected to explore the molecular mechanism of citrate in osteogenic differentiation of osteoblasts. Then, based on the findings mentioned above, novel controllable citrate-releasing BGS (Biphasic Gradient Scaffold) will be developed to release citrate relocated in the Optimal Citrate Concentration Window for promoting osteogenesis and be evaluated in vivo and vitro. These results will offer a new idea for the regulation mechanism of osteoblastic differentiation and develop a promising biomimetic bone scaffold for Critical-Sized Bone Defects management.