BioMEMS Resource Center, Center for Engineering in Medicine and Surgery, Massachusetts General Hospital, Shriners Hospital for Children, Harvard Medical School, Boston, Massachusetts, USA.
Lab Chip. 2023 Mar 28;23(7):1879-1885. doi: 10.1039/d2lc00903j.
Neutrophils are the most numerous white blood cells and are the first to arrive at sites of inflammation and infection. Thus, neutrophil behavior provides a comprehensive biomarker for antimicrobial defenses. Several microfluidic tools have been developed to test neutrophil chemotaxis, phagocytosis, extrusion of extracellular traps, Traditional tools rely on purified neutrophil samples, which require lengthy and expensive isolation procedures from large volumes of blood. In the absence of such isolation, visualizing neutrophils in blood is complicated by the overwhelming number of red blood cells (RBCs), which outnumber neutrophils by 1000 : 1. Recently, several microfluidic technologies have been designed to analyze neutrophils directly in blood, by separating neutrophils on selectin coated surfaces before the migration assay or blocking the advance of RBCs with the moving neutrophils. However, RBC contamination remains an issue, albeit with a reduced ratio, down to 1 : 1. Here, we present an RBC-debulking strategy for neutrophil assays based on microscale passive redirection filters (PRFs) that reduce RBC contamination down to as few as a 1 : 17 RBC to neutrophil ratio. We compare the performance of different PRF designs and measure changes in neutrophil chemotaxis velocity and directionality following immune stimulation of whole blood.
中性粒细胞是数量最多的白细胞，也是最先到达炎症和感染部位的细胞。因此，中性粒细胞的行为为抗菌防御提供了全面的生物标志物。已经开发了几种微流控工具来测试中性粒细胞的趋化性、吞噬作用、细胞外陷阱的挤出。传统的工具依赖于从大量血液中经过冗长且昂贵的分离程序来纯化中性粒细胞样本。在没有这种分离的情况下，由于红细胞（RBC）的数量远远超过中性粒细胞（RBC 比中性粒细胞多 1000：1），因此可视化血液中的中性粒细胞变得很复杂。最近，已经设计了几种微流控技术，可以直接在血液中分析中性粒细胞，在迁移分析之前，通过选择在选择素涂覆的表面上分离中性粒细胞，或者通过阻止 RBC 与移动的中性粒细胞一起前进来阻止 RBC 的前进。然而，RBC 污染仍然是一个问题，尽管比例有所降低，降至 1：1。在这里，我们提出了一种基于微尺度被动重定向过滤器（PRF）的中性粒细胞测定的 RBC 减容策略，可将 RBC 污染降低到仅为 1：17 的 RBC 与中性粒细胞的比例。我们比较了不同 PRF 设计的性能，并测量了全血免疫刺激后中性粒细胞趋化性速度和方向性的变化。
