Department of Biomedical Engineering, Boston University, 44 Cummington Street, Boston, MA 02119, USA.
Lab Chip. 2011 Sep 7;11(17):2941-7. doi: 10.1039/c1lc20401g. Epub 2011 Jul 20.
Blood cells naturally auto-segregate in postcapillary venules, with the erythrocytes (red blood cells, RBCs) aggregating near the axis of flow and the nucleated cells (NCs)--which include leukocytes, progenitor cells and, in cancer patients, circulating tumor cells--marginating toward the vessel wall. We have used this principle to design a microfluidic device that extracts nucleated cells (NCs) from whole blood. Fabricated using polydimethylsiloxane (PDMS) soft lithography, the biomimetic cell extraction device consists of rectangular microchannels that are 20-400 μm wide, 11 μm deep and up to 2 cm long. The key design feature is the use of repeated expansions/contractions of triangular geometry mimicking postcapillary venules, which enhance margination and optimize the extraction. The device operates on unprocessed whole blood and is able to extract 94 ± 4.5% of NCs with 45.75 ± 2.5-fold enrichment in concentration at a rate of 5 nl s(-1). The device eliminates the need to preprocess blood via centrifugation or RBC lysis, and is ready to be implemented as the initial stage of lab-on-a-chip devices that require enriched nucleated cells. The potential downstream applications are numerous, encompassing all preclinical and clinical assays that operate on enriched NC populations and include on-chip flow cytometry (A. Y. Fu et al., Anal. Chem., 2002, 74, 2451-2457; A. Y. Fu et al., Nat. Biotechnol., 1999, 17, 1109-1111), genetic analyses (M. M. Wang et al., Nat. Biotechnol., 2005, 23, 83-87; L. C. Waters et al., Anal. Chem., 1998, 70, 5172-5176) and circulating tumor cell extraction (S. Nagrath et al., Nature, 2007, 450, 1235-1241; S. L. Stott et al., Proc. Natl. Acad. Sci. U. S. A., 2010, 18392-18397; H. K. Lin et al., Clin. Cancer Res., 2010, 16, 5011-5018).
血液细胞在毛细血管后静脉中自然自动分离，其中红细胞（RBC）聚集在流轴附近，有核细胞（NC）——包括白细胞、祖细胞，以及在癌症患者中，循环肿瘤细胞——向血管壁边缘移动。我们利用这一原理设计了一种从全血中提取有核细胞（NC）的微流控装置。该仿生细胞提取装置采用聚二甲基硅氧烷（PDMS）软光刻技术制造，由 20-400 μm 宽、11 μm 深、长达 2 cm 的矩形微通道组成。关键设计特点是使用重复扩展/收缩的三角形几何形状模拟毛细血管后静脉，从而增强边缘移动并优化提取效果。该装置可用于未经处理的全血，能够以 5 nl s(-1)的速度提取 94±4.5%的 NC，浓度富集 45.75±2.5 倍。该装置无需通过离心或红细胞裂解对血液进行预处理，可直接作为微流控芯片装置的初始阶段使用，而这些微流控芯片装置需要富含有核细胞。其潜在的下游应用众多，涵盖了所有基于富含有核细胞的群体进行的临床前和临床检测，包括芯片流式细胞术（A. Y. Fu 等人，Anal. Chem.，2002，74，2451-2457；A. Y. Fu 等人，Nat. Biotechnol.，1999，17，1109-1111）、遗传分析（M. M. Wang 等人，Nat. Biotechnol.，2005，23，83-87；L. C. Waters 等人，Anal. Chem.，1998，70，5172-5176）和循环肿瘤细胞提取（S. Nagrath 等人，Nature，2007，450，1235-1241；S. L. Stott 等人，Proc. Natl. Acad. Sci. U. S. A.，2010，18392-18397；H. K. Lin 等人，Clin. Cancer Res.，2010，16，5011-5018）。
