外泌体转运表观遗传修饰酶GCN5持久恢复牙周炎条件下牙周膜干细胞功能的机制研究

Local transplantation of periodontal ligament stem cells (PDLSCs) durably rescues recipient PDLSCs functions and promotes alveolar bone regeneration in periodontitis condition. However, the underlying mechanisms are not fully understood. Our previous study indicates that donor cells could secrete exosomes transferring important signals to durably rescue recipient cell functions. Our further study shows that, in periodontitis condition, the histone acetyltransferase GCN5 decreased, which durably impair osteogenic differentiation potentials of PDLSCs. This is closely related to the impaired regenerative potential of alveolar bone. Moreover, the PDLSC-derived exosomes contain high level of GCN5. Therefore, we hypothesize that donor PDLSC-derived exosomes transferred GCN5 to durably rescue recipient PDLSC functions and promoted alveolar bone regeneration in periodontitis condition. The present study will conduct four parts to explore the mechanisms underlying PDLSC-transplantation based periodontal regeneration. The four parts includes the rescuing effects of donor PDLSC-derived exosomes on recipient PDLSC functions, transferring of GCN5 from donor to recipient PDLSCs, the rescuing effects of exosome-derived GCN5 on recipient PDLSC functions, the regulatory mechanisms underlying the effects of GCN5 on osteogenic differentiation of PDLSCs. This study hopefully reveals the new mechanisms underlying stem cell therapy and provides important theory and experimental evidence.

牙周膜干细胞（PDLSCs）局部移植持久恢复牙周炎条件下宿主PDLSCs功能并促进牙槽骨再生，但机制尚不清楚。我们在前期研究中发现，供体细胞能够分泌外泌体转运关键信号分子持久恢复宿主细胞功能；进一步研究显示，牙周炎条件下PDLSCs中组蛋白乙酰转移酶GCN5表达下降，持久抑制PDLSCs成骨分化功能，与牙槽骨再生能力缺陷密切相关；而供体PDLSCs来源的外泌体中含有丰富的GCN5。由此推测，供体PDLSCs分泌外泌体转运GCN5持久恢复牙周炎宿主PDLSCs成骨分化功能并促进牙槽骨再生。本研究拟从供体PDLSCs分泌外泌体恢复宿主PDLSCs功能、外泌体转运GCN5至宿主PDLSCs、外泌体来源GCN5对宿主PDLSCs功能的恢复、GCN5对PDLSCs成骨分化功能的调控四个部分探讨PDLSCs移植促进牙周再生的机理。本研究有望揭示干细胞治疗的新机制，为其临床应用提供重要理论和实验依据。

牙周膜干细胞（PDLSCs）局部移植能够提升宿主干细胞再生潜能并促进牙周组织再生，但机制尚不清楚，前期研究结果表明外泌体作为细胞间信号传递的重要媒介，可能在其中发挥重要作用。该研究根据前期设计内容开展，解析外泌体对PDLSCs功能的调控作用机制，证明内容物GCN5等在外泌体调节再生过程中的关键作用。该研究首先分离鉴定了PDLSCs等牙源性干细胞来源的外泌体，明确其关键生物学特性，并明确其对PDLSCs成骨及成血管的促进作用。在机制研究中，发现外泌体能够向受体细胞转运GCN5，通过增强线粒体转录因子A（TFAM）表达提高干细胞的氧化磷酸化水平进而提高其成骨能力；同时，外泌体能够向受体细胞转运miR-222，提高干细胞的细胞外基质分泌、聚合体形成能力、以及成血管能力。在体内实验中，发现外泌体能够促进炎性牙周缺损新骨形成及血管化，发挥促进牙周再生的功能。因此，该研究发现了外泌体中GCN5等关键内容物在调节干细胞生物学功能及再生潜能中的作用，提示多种内容物的协同作用在细胞外囊泡生物学功能中发挥关键作用，相关研究内容发表论文5篇。该研究为牙周缺损再生的临床治疗策略提供了新思路，并为调节内源干细胞功能促进再生提供实验依据。