Department of Cariology and Endodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210008, China; Central Laboratory of Stomatology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, Jiangsu, 210008, China.
Department of Periodontology, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210008, China.
Acta Biomater. 2021 Nov;135:593-605. doi: 10.1016/j.actbio.2021.08.009. Epub 2021 Aug 12.
Modestly removing the excessive reactive oxygen species (ROS) plays a crucial role in regulating the microenvironment of periodontitis and provides favorable conditions for osteogenesis. However, the current strategy for scavenging ROS is not controllable, substantially limiting the outcomes in periodontitis. Herein, we introduced a controllable ROS-scavenging nanoplatform by encasing N-acetylcysteine (NAC, (a well-known ROS scavenger) into tailor-made ROS-cleavable amphiphilic polymer nanoparticles (PEG-ss-PCL NPs) as an intracellular delivery carrier. The existing ROS in the inflammatory microenvironment facilitated polymer degradation via breakage of thioketal bonds, and then led to encapsulated NAC release. NAC eliminated all ROS induced by lipopolysaccharide (LPS), while PssL-NAC adjusted the ROS level slightly higher than that of the control group. The percentage of apoptotic cells cultured with NAC and PssL-NAC decreased observably compared with that of cells cultured with 10 µg/ml LPS. The microenvironment regulated by PssL-NAC was highly suitable for osteogenic differentiation based on PCR and Western blot results, which showed higher expression levels of BMP2, Runx2, and PKA. Analysis of ALP activity and Alizarin red S staining showed consistent results. Additionally, the injection of PssL-NAC into the periodontitis area could alleviate the tissue destruction induced by ligation of the maxillary second molar. PssL-NAC showed a better ability to decrease osteoclast activity and inflammation, consequently improving the restoration of destroyed tissue. Our study suggests that ROS-responsive polymer nanoparticles loaded with NAC (PssL-NAC) can be new promising materials for the treatment of periodontitis. STATEMENT OF SIGNIFICANCE: More and more studies indicate that periodontal tissue damage is closely related to the high reactive oxygen species (ROS) environment. Excessive ROS will aggravate periodontal tissue damage and is not conducive to tissue repair. However, as an essential signal molecule in human physiological activities, ROS absence is also useless for tissue repair. In this study, we proposed to improve ROS imbalance in the environment of periodontitis as a strategy to promote periodontal regeneration and successfully synthesized a smart drug-releasing nanoplatform that can respond to ROS. Besides, we validated its ability to regulate the ROS environment and promote osteogenesis through experimental data in vivo and in vitro.
适度清除过多的活性氧 (ROS) 在调节牙周炎微环境中起着至关重要的作用，为成骨提供了有利条件。然而，目前清除 ROS 的策略不可控，极大地限制了牙周炎的治疗效果。在此，我们通过将 N-乙酰半胱氨酸 (NAC，一种众所周知的 ROS 清除剂) 封装到定制的 ROS 可裂解两亲聚合物纳米颗粒 (PEG-ss-PCL NPs) 中，作为一种细胞内递送载体，引入了一种可控的 ROS 清除纳米平台。炎症微环境中存在的 ROS 通过断裂硫代缩醛键促进聚合物降解，然后导致封装的 NAC 释放。NAC 消除了脂多糖 (LPS) 诱导的所有 ROS，而 PssL-NAC 将 ROS 水平略微调整至高于对照组。与用 10 µg/ml LPS 培养的细胞相比，用 NAC 和 PssL-NAC 培养的细胞中凋亡细胞的比例明显降低。根据 PCR 和 Western blot 结果，PssL-NAC 调节的微环境非常适合成骨分化，BMP2、Runx2 和 PKA 的表达水平更高。碱性磷酸酶 (ALP) 活性和茜素红 S 染色分析结果一致。此外，将 PssL-NAC 注射到牙周炎区域可以减轻上颌第二磨牙结扎引起的组织破坏。PssL-NAC 显示出降低破骨细胞活性和炎症的更好能力，从而改善受损组织的恢复。我们的研究表明，负载 NAC 的 ROS 响应性聚合物纳米颗粒 (PssL-NAC) 可为治疗牙周炎提供新的有前途的材料。
