牙周炎是侵犯牙龈和牙周支持组织的慢性炎症性破坏性疾病，导致牙齿松动甚至脱落。由于牙周组织炎性环境的存在或加重，新生组织面临着被二次吸收破坏的危险。防御素具有高度的抗菌活性，是维持牙周健康重要的抗微生物肽之一。本课题拟以质粒为载体，以BD-3基因修饰犬PDLCs，检测其抗菌活性，并以此构建PDL细胞片层，自体回植修复犬实验牙周炎模型。通过大体观察、组织学、免疫荧光等技术手段，观察BD-3基因修饰牙周膜细胞片层修复牙周炎组织缺损后的愈合情况、牙周软硬组织生成情况，观察牙周重建并检测分化相关因子（BSP,OCN,S100A4,POSTN）的表达情况，研究新生牙周组织对炎性环境的反应，探讨BD-3修饰后的组织工程化牙周组织抗感染能力及其可能机制，为牙周炎组织缺损修复提供实验依据，为今后移植物术后抗感染提供参考，并为基因治疗牙周病提供新思路，对于临床应用具有重要意义和广泛前景。

Periodontitis is a bacterially induced chronic inflammatory disease that is the major cause for absorption of alveolar bone and eventual loss of teeth in the adult population. The newborn tissues are proneto be re-attacked in microbial and bacerial-rich environments such as petiodontitis.Defensins are a family of antimicrobial peptides and vital contributors to host immune response.Unlike other antimicrobial peptides, beta-defenisn-3 (BD-3) exhibits effective antibacterial ability in biological fluids.On the other hand, BD-3 has been shown to promote wound closure in infected diabetic wounds. In the present study, We aim to evaluate if BD-3 enginnered periodontal ligament cell sheet could reconstruct the physiological architecture of a periodontal ligament-cementum complex, inincluding cementum and the formation of new periodontal ligaments, as.well as Sharpey_s fibers attached to the new cementum-like layer, in beegle dogs with periodontally tissue defects, thereby providing a practical approach for the tissue regeneration of infectious diseases.