bFGF和BMP-2序贯释放对牙周组织再生的影响

Stem cell transplantation-based traditional periodontal tissue engineering is one important direction of regeneration and reconstruction of periodontal defect. However, many barriers limit its clinical application. Recruitment of enough endogenous functional cells to the defect regions and promotion of their committed differentiation at appropriate times to reestablish the destroyed periodontium becomes a new strategy for periodontal regeneration. Our previous study found that bFGF could promote the proliferation, chemotaxis and maintain the stemness of bone marrow stromal cells (BMSCs) while BMP-2 enhanced osteogenic differentiation. Therefore, the combination and sequential timed-release of bFGF and BMP-2 can comprehensively regulate stem cell function. Firstly, the controlled and sustained system can release bFGF at the early stage of wound healing to recruit stem cells to the wound area, and promote the proliferation and maintain the stemness of stem cells, as well as enhance angiogenesis and neuranagenesis. Afterwards, at the peak period of proliferation, BMP-2 will be released and enhance the osteogenic/cementogenic differentiation of stem cells, therefore to promote periodontal regeneration. In this grant, we propose to investigate the combined effects of bFGF and BMP-2 on the proliferation, chemotaxis, stemness and osteogenic differentiation of periodontal ligament stem cells. Moreover, we will construct co-delivery thermosensitive hydrogel system for the sequential timed-release of bFGF and BMP-2. Finally, rat periodontal defect will be created to explore the effects and mechanisms of bFGF and BMP-2 sequential release on the recruitment, committed differentiation and periodontal regeneration in vivo. This strategy will help to create a new insight into the clinical therapy of periodontal diseases and provide scientific foundation for the successful application of in situ tissue engineering technique in periodontal tissue regeneration.

以干细胞移植为基础的传统牙周组织工程是修复牙周缺损的重要方向，但要转化为临床应用尚存在障碍。动员足量的自身功能细胞迁移到缺损区，并适时定向分化，重建牙周组织成为新的策略。我们前期研究发现bFGF能促进细胞增殖、趋化和干性维持，BMP-2能促进成骨分化。因而采用bFGF和BMP-2联合应用并序贯释放可以实现对干细胞功能的综合调控：在创伤愈合早期释放bFGF，募集干细胞到达创伤局部，并发挥促增殖、干性维持和血管神经再生的作用；而后在细胞增殖高峰期，释放BMP-2，促进干细胞定向成骨/成牙骨质分化，可以有效促进牙周再生。据此，本项目拟通过体外实验探讨两者联合对牙周膜干细胞增殖、趋化、干性维持和成骨分化的影响；构建共载bFGF和BMP-2的温敏凝胶序贯控释体系，并通过体内实验研究两者序贯释放对干细胞动员、定向分化及牙周组织再生的协同促进效应。这一策略有望为牙周病的治疗提供新的思路和方法。

以生物活性因子和支架材料为基础的原位组织工程在重建和再生颌面部组织缺损中具有重要意义。该项目以此作为切入点，在优化组织工程、促进牙周再生及组织缺损修复方面做出贡献。基于牙周原位组织工程原理，首先，发现了序列应用bFGF与BMP-2对人PDLSCs的促成骨效果比单独应用某一种因子或者两种同时应用有更强的促成进效应。而后采用静电纺丝技术构建出具有序列递控bFGF与BMP-2功能的壳-芯纤维支架。利用bFGF对干细胞的募集归巢、促增殖作用及BMP-2较强的促骨作用，二者序列应用募集干细胞迁移至牙周缺损区，并促进MSCs增殖、迁移和成骨分化。在创区序列应用时，启动宿主修复潜能，动员自身干细胞到达创区，促进早期骨改建，调节骨的平衡和稳态，还能促进成骨相关蛋白表达，提高新生骨质量，同时改善新生牙周膜纤维的质量，并促进新生牙骨质形成。通过bFGF与BMP-2的序列递控能协同促进愈合过程中牙周/骨组织再生，为原位牙周组织工程策略进一步临床转化奠定了坚实的基础。总之，该项目为牙周病、组织创伤探讨了新的治疗策略，支架材料和生物活性因子，促进了原位牙周组织工程技术在牙周再生治疗中的应用和发展，为临床牙周病及口腔颌面部缺损的治疗奠定理论依据和实验基础。. 该项目在Advanced Science, Bioactive Materials, Acta Biomaterialia, Biomaterials Science等SCI收录杂志上发表论文21篇，均标明NSFC资助号81670993。在该项目的资助下，获得山东省科技进步二等奖等奖项，培养了泰山学者特聘专家及多名优秀研究生和博士生, 项目组成员多次参加国内外组织再生及口腔学术会议汇报成果，获得同行专家一致认可与好评。