Division of Bioengineering, National University of Singapore, 7 Engineering Drive 1, Singapore, 117574, Singapore.
Lab Chip. 2010 Oct 7;10(19):2605-13. doi: 10.1039/c003873c. Epub 2010 Aug 5.
In blood vessels with luminal diameter less than 300 µm, red blood cells (RBCs) which are smaller in size and more deformable than leukocytes, migrate to the axial centre of the vessel due to flow velocity gradient within the vessels. This phenomenon displaces the leukocytes to the vessel wall and is aptly termed as margination. Here, we demonstrate using microfluidics that stiffer malaria-infected RBCs (iRBCs) behave similar to leukocytes and undergo margination towards the sidewalls. This provides better understanding of the hemodynamic effects of iRBCs in microcirculation and its contribution to pathophysiological outcome relating to cytoadherence to endothelium. In this work, cell margination is mimicked for the separation of iRBCs from whole blood based on their reduced deformability. The malaria infected sample was tested in a simple long straight channel microfluidic device fabricated in polydimethylsiloxane. In this microchannel, cell margination was directed along the channel width with the iRBCs aligning near each sidewall and then subsequently removed using a 3-outlet system, thus achieving separation. Tests were conducted using ring stage and late trophozoite/schizont stage iRBCs. Device performance was quantified by analyzing the distribution of these iRBCs across the microchannel width at the outlet and also conducting flow cytometry analysis. Results indicate recovery of approximately 75% for early stage iRBCs and >90% for late stage iRBCs at the side outlets. The simple and passive system operation makes this technique ideal for on-site iRBCs enrichment in resource-limited settings, and can be applied to other blood cell diseases, e.g. sickle cell anemia and leukemia, characterized by changes in cell stiffness.
在管腔直径小于 300 µm 的血管中，由于血管内的流速梯度，比白细胞更小、更具变形性的红细胞（RBC）迁移到血管的轴向中心。这种现象将白细胞推向血管壁，恰当地称为靠边。在这里，我们使用微流控技术证明，刚性更强的感染疟原虫的红细胞（iRBC）的行为类似于白细胞，并向侧壁靠边。这有助于更好地理解 iRBC 在微循环中的血液动力学效应及其对与细胞黏附内皮相关的病理生理结果的贡献。在这项工作中，基于 iRBC 变形能力的降低，模拟细胞靠边来分离 iRBC 与全血。在简单的长直通道微流控装置中用聚二甲基硅氧烷（polydimethylsiloxane）来测试感染了疟疾的样本。在这个微通道中，细胞靠边沿着通道宽度进行，iRBC 靠近每个侧壁排列，然后使用 3 出口系统将其去除，从而实现分离。使用环状体期和晚期滋养体/裂殖体期 iRBC 进行了测试。通过分析这些 iRBC 在出口处穿过微通道宽度的分布以及进行流式细胞术分析，来量化设备性能。结果表明，早期 iRBC 的回收率约为 75%，晚期 iRBC 的回收率超过 90%。这种简单的被动系统操作使其成为资源有限环境中现场 iRBC 富集的理想技术，并且可以应用于其他血细胞疾病，例如以细胞刚性变化为特征的镰状细胞贫血和白血病。
