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BACKGROUND Though researchers have been exploring therapeutic strategies of treating serious periodontal tissue loss including the application of stem cells, tissue regeneration of the periodontal complex involving cementum, periodontium and alveolar bone has hardly been achieved. Aiming at tackling the problem of severely damaged periodontal complex, it is worth trying to make advantages of Hertwig's epithelial root sheath (HERS) cells to tissue regeneration mimicking the physiological developmental process with their ability of cementum, bone and periodontium formation. METHODS HERS cells and dental follicle cells (DFCs) were acquired from Sprague Dawley rats' molar germs and identified by immunofluorescence. Alizarin red assay, ALP staining, AKP test, real-time qPCR and western blot were conducted to confirm the osteogenic potential, epithelial-mesenchymal transition (EMT) character of harvested HERS cells and epithelial-mesenchymal interaction (EMI) with DFCs. An animal model of periodontal defect was constructed to testify the tissue regeneration ability in vivo. Micro-CT and histological examinations were interpreted to unvail the tissue repair outcomes. RESULTS HERS cells expressed strong epithelial cell markers CK14 and E-cadherin. The in vitro experiments overall showed the concretely enhanced osteogenic differentiation ability in either HERS group or HERS+DFC group. Meanwhile, the in vivo conduction of rat mandibular periodontal repair experiment showed regenerative effectiveness of periodontal complex structure in both HERS and HERS+DFC group in situ, testified by Micro-CT and histological analysis. CONCLUSIONS HERS cells show potential for periodontal tissue regeneration which suggests the future possibilities of being considered as one of the cell choices for severely damaged periodontal tissue repair. This article is protected by copyright. All rights reserved.