Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY 13244, USA; BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA.
Laboratory of Analytical Chemistry, Division of Biological Standards and Quality Control, Office of Compliance and Biologics Quality, Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, USA.
Acta Biomater. 2024 Oct 1;187:253-260. doi: 10.1016/j.actbio.2024.08.043. Epub 2024 Aug 28.
Many medical devices implanted in patients to mitigate diseases and medical conditions have different types of topographic features. While appropriate textures can promote the integration of host cells and reduce scar tissue formation, some textured implants with inappropriate topographies have been associated with inflammation, bacterial colonization, or even malignant complications. To better understand how surface topography affects host immune response to colonizing bacteria, a protocol was developed to investigate phagocytosis of bacterial cells attached on polydimethylsiloxane (PDMS) surfaces with different square-shaped recessive patterns. The interaction between activated RAW 264.7 macrophages and Escherichia coli in recessive wells was visualized in 3D using multiple fluorescent markers. The results revealed that there is a threshold dimension of topography, below which phagocytosis of attached bacterial cells is significantly impeded. Specifically, under our experimental condition, up to 100-fold reduction in phagocytosis was observed in square-shaped patterns with 5 µm side length and 10 µm depth compared to the flat control and patterns with 10 µm or longer side length. The spacing between wells also showed significant effects; e.g., phagocytosis in the wells further decreased when spacing increased to 50 µm. These results are helpful for understanding how undesired topographies may contribute to bacterial colonization and thus infection and other associated complications. STATEMENT OF SIGNIFICANCE: Surface topography plays an important role in bacteria-material infections and thus the safety of implantable medical devices. Undesired topographic features can cause biofilm formation and related complications. However, how surface topography affects the capability of host immune cells to clear colonizing bacteria is not well understood. In this study, the interaction between macrophage RAW264.7 and colonizing E. coli cells on polydimethylsiloxane (PDMS) with recessive features is investigated. It was discovered that the size of recessive features and the spacing between these features have significant effects on phagocytosis of bacteria by macrophages. These new results are helpful for understanding the complex interaction among host cells, bacteria, and implanted biomaterials, which will help guide the rational design of safer medical devices.
许多植入患者体内以减轻疾病和医疗状况的医疗设备具有不同类型的地形特征。虽然适当的纹理可以促进宿主细胞的整合并减少疤痕组织的形成，但一些具有不合适地形的纹理植入物与炎症、细菌定植甚至恶性并发症有关。为了更好地了解表面形貌如何影响宿主对定植细菌的免疫反应，开发了一种方案来研究附着在聚二甲基硅氧烷 (PDMS) 表面上的具有不同方形凹陷图案的细菌细胞的吞噬作用。使用多个荧光标记物在 3D 中可视化 RAW 264.7 巨噬细胞与大肠杆菌在凹坑中的相互作用。结果表明，存在地形的阈值尺寸，低于该尺寸，附着的细菌细胞的吞噬作用会受到严重阻碍。具体来说，在我们的实验条件下，与平面对照和边长为 10 µm 或更长的图案相比，边长为 5 µm 且深度为 10 µm 的方形图案中观察到的细菌吞噬作用降低了 100 倍。凹坑之间的间距也显示出显著的影响；例如，当间距增加到 50 µm 时，吞噬作用进一步降低。这些结果有助于了解不理想的地形如何导致细菌定植，从而导致感染和其他相关并发症。
表面形貌在细菌-材料感染以及因此植入式医疗器械的安全性中起着重要作用。不理想的地形特征会导致生物膜形成和相关并发症。然而，表面形貌如何影响宿主免疫细胞清除定植细菌的能力还不是很清楚。在这项研究中，研究了具有凹陷特征的聚二甲基硅氧烷 (PDMS) 上巨噬细胞 RAW264.7 和定植大肠杆菌细胞之间的相互作用。发现凹陷特征的大小和这些特征之间的间距对巨噬细胞吞噬细菌的能力有显著影响。这些新结果有助于理解宿主细胞、细菌和植入生物材料之间的复杂相互作用，这将有助于指导更安全的医疗器械的合理设计。
