In periodontal tissue engineering, periodontal ligament stem cells derived from patients with periodontitis (P-PDLSCs) are among the most promising and accessible stem cells for repairing disrupted alveolar bone and other connective tissues around the teeth. However, the inflammatory environment influences the osteogenic differentiation ability of P-PDLSCs. We examined low-intensity pulsed ultrasound (LIPUS) in P-PDLSCs in vitro and in rats with experimental periodontitis to determine whether LIPUS can enhance the osteogenic differentiation of stem cells. P-PDLSCs were harvested and isolated from the periodontal tissues around the teeth of periodontitis patients, and healthy PDLSCs (H-PDLSCs) were obtained from tissues around healthy teeth. After validation by flow cytometry analysis, the P-PDLSCs were cultured in osteogenic medium either pretreated with the endoplasmic reticulum stress (ERS) inhibitor 4-phenyl butyric acid (4-PBA) or not pretreated and then treated with or without LIPUS (90 mW/cm2, 1.5 MHz) for 30 min per day. Cell viability, ERS marker expression, and osteogenic potential were determined between the different treatment groups. LPS-induced H-PDLSCs were used to mimic the inflammatory environment. In addition, we established a model of experimental periodontitis in rats and used LIPUS and 4-PBA as treatment methods. Then, the maxillary bone was collected, and micro-CT and histology staining methods were used to detect the absorption of alveolar bone. Our data showed that the P-PDLSCs derived from periodontitis tissues were in a more pronounced ERS state than were the H-PDLSCs, which resulted in the former being associated with increased inflammation and decreased osteogenic ability. LIPUS can alleviate ERS and inflammation while increasing the bone formation capacity of P-PDLSCs in vivo and in vitro. LIPUS may be an effective method to enhance the outcome of periodontal tissue engineering treatments of periodontitis by suppressing inflammation and increasing the osteogenic differentiation of P-PDLSCs through the unfolded protein response pathway, and more detailed studies are needed in the future.

中文翻译：

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低强度脉冲超声通过未折叠的蛋白质反应在炎性条件下上调牙周膜干细胞的成骨作用。

在牙周组织工程中，源自牙周炎患者的牙周膜干细胞（P-PDLSC）是修复受损的牙槽骨和牙齿周围其他结缔组织的最有前途和可及的干细胞之一。然而，炎性环境影响P-PDLSC的成骨分化能力。我们在体外和实验性牙周炎大鼠中检查了P-PDLSCs中的低强度脉冲超声（LIPUS），以确定LIPUS是否可以增强干细胞的成骨分化。从牙周炎患者牙齿周围的牙周组织中收集并分离出P-PDLSC，并从健康牙齿周围的组织中获得健康的PDLSC（H-PDLSC）。通过流式细胞仪分析验证后，将P-PDLSC在成骨培养基中培养，要么用内质网应激（ERS）抑制剂4-苯基丁酸（4-PBA）预处理，要么未经预处理，然后用或不用LIPUS（90 mW / cm2，1.5 MHz）处理每天30分钟。确定了不同治疗组之间的细胞活力，ERS标记物表达和成骨潜能。LPS诱导的H-PDLSC用于模拟炎症环境。此外，我们建立了大鼠实验性牙周炎模型，并使用LIPUS和4-PBA作为治疗方法。然后，收集上颌骨，并用显微CT和组织学染色方法检测牙槽骨的吸收。我们的数据表明，与H-PDLSC相比，源自牙周炎组织的P-PDLSC处于更明显的ERS状态，这导致前者与炎症增加和成骨能力降低有关。LIPUS可以减轻ERS和炎症，同时在体内和体外增加P-PDLSCs的骨形成能力。LIPUS可能通过抑制炎症反应和通过展开的蛋白质反应途径增加P-PDLSC的成骨分化来增强牙周组织的牙周组织工程治疗效果，是一种有效的方法，未来还需要更详细的研究。