SATB2在炎症微环境下影响BMP9诱导根尖牙乳头干细胞成骨分化的作用研究

Periapical periodontitis can disrupt the development of permanent teeth and dentition. Eliminating inflammation and maintaining the normal development of tooth root tissue are the key to the treatment. We previously found that BMP9 is one of the key factors in the development of the tooth. As reported in our recently published studies in《Biomaterials》, we demonstrated that BMP9 plays an important role in inducing osteo/odontoblastic differentiation of stem cells of dental apical papilla (SCAPs) further to promote the regeneration of periapical tissue. However, in inflammatory microenvironment, BMP9-induced osteogenic signaling is inhibited by inflammatory cytokines, which can be restored by other synergistic factors. Our investigative team have recently found that SATB2 may function as a mediator and promote the osteogenic differentiation of BMP9-induced mesenchymal stem cells. Based on the previous findings, here we propose to establish in vitro cellular and in vivo animal models of inflammation to further study the roles of BMP9 and SATB2 in osteo/odontoblastic differentiation and dental tissue regeneration under inflammation conditions. By exploring the synergistic effect of BMP9/SATB2 as the central point in regulating periapical periodontitis response and promoting the biological function of tissue repair and its underlying molecular mechanism, we believe this project will not only expand our mechanistical understanding of osteogenesis-regulating factors in tissue regeneration, but also provide potentially novel approaches to the treatment of periapical periodontal disease of young permanent tooth. Thus, the proposed work is highly significant and has great translational potential.

年轻恒牙根尖周病危及牙及牙列的正常发育，消除炎症、促进牙齿根尖组织正常发育是治疗的关键。申请者发表于Biomaterials的论文揭示BMP9能诱导根尖牙乳头干细胞成骨分化，课题组也初步发现SATB2能促进此过程。但能否在炎症状态下将SATB2与BMP9联合应用，促进BMP9成骨分化，尚需进一步探索。为回答此假说，本项目拟首先通过构建细胞、动物模型，分析SATB2和BMP9表达及功能状态的时效关系，进一步确认SATB2促进BMP9的成骨作用；然后通过炎症模型状态下二者时效关系的分析，明确炎症状态下SATB2促进BMP9成骨分化的条件和机制；最后通过动物模型，观察SATB2协同BMP9诱导根尖牙乳头干细胞成骨分化的效应。研究将有助于阐释BMP9/SATB2信号级联调控根尖周炎症、促进组织修复的生物学功能及分子机制，有助于剖析成骨调控因子组织再生修复的原理，为年轻恒牙根尖周病的治疗提供新思路。

年轻恒牙根尖周病影响了儿童的咀嚼、发音以及牙和牙列的正常发育。基于口腔组织再生工程研究策略，促进牙齿及根尖周软硬组织的修复成为儿童牙齿疾病治疗的研究热点。项目组前期研究发现BMP9是调控组织再生的重要细胞因子，能诱导根尖乳头干细胞成骨、成牙分化，在牙齿发育和根尖周组织的修复再生过程中起着重要作用。同时，研究表明SATB2能与成骨分化相关的重要转录因子起协同作用。因此，探究SATB2能否在正常以及炎症微环境下促进BMP9诱导根尖牙乳头干细胞的成骨分化以及作用机制将为组织缺损修复带来新的思路。本项目首先检测了SATB2和BMP9的表达模式，揭示了SATB2 和 BMP9均在小鼠可再生切牙根尖牙乳头区域有表达；体外实验证明了SATB2 能够促进根尖牙乳头干细胞增殖、干性和成骨/牙分化；然后通过SATB2和BMP9共同感染根尖牙乳头干细胞发现SATB2与BMP9可能通过共同作用于RUNX2和OPN来促进诱导成骨分化过程；小鼠体内颅骨缺损实验进一步揭示了SATB2促进BMP9诱导体内骨组织的再生；随后通过构建细胞炎症模型揭示了炎症情况会部分抑制BMP9诱导根尖牙乳头干细胞成骨分化的能力，而SATB2特有的免疫调节促进了BMP9诱导间充质干细胞成骨分化功能。本项目进一步探究了SATB2与BMP9对其他类型牙源性干细胞的成骨作用，通过转录组测序以及异位成骨实验揭示了SATB2与BMP9均能通过影响成骨转录因子的表达促进多种类型牙源性干细胞的成骨作用。通过根尖周组织临床样本转录组测序分析进一步发现，hsa-miR-199a-5p 也能促进根尖牙乳头干细胞的成骨分化作用。除了致力于干细胞及信号通路研究，在支架材料方面，项目组设计制备了脱细胞牙髓基质功能化凝胶微球成功促进了牙髓再生；项目组团队自主研发并利用大鲵皮肤粘液提取物（SSAD）制备的生物材料具有良好的粘结性和止血效果；探讨了组织工程中梯度结构对生物陶瓷支架的生物力学及成骨性能的影响。本项目所获得的研究结果将有助于阐释通过组织工程策略对BMP9/SATB2信号级联调控炎症、促进组织修复的生物学功能及分子机制，有助于剖析成骨/牙调控因子促进组织再生修复的原理，为年轻恒牙牙髓及根尖周病、颅颌面骨缺损的治疗带来新的策略。

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