Microfluidic Label-Free Ferrohydrodynamic Separation of Circulating Tumor Cells

Circulating tumor cells (CTCs) have significant implications in both basic cancer research and clinical applications. To address the limited availability of viable CTCs for fundamental and clinical investigations, effective separation of extremely rare CTCs from blood is critical. Ferrohydrodynamic cell separation (FCS), a microfluidic label-free method that conducts cell sorting based on cell size difference in biocompatible ferrofluids, has thus far not been able to enrich low-concentration CTCs from cancer patients' blood because of technical challenges associated with processing clinical samples.1-3

In this study, we demonstrated the development of a laminar-flow microfluidic FCS device that was capable of enriching rare CTCs from patients' blood in a biocompatible manner with a high throughput and a high rate of recovery.4,5 Systematic optimization of the FCS devices through a validated analytical model was performed to determine optimal magnetic field and its gradient, ferrofluid properties, and cell throughput that could process clinically relevant amount of blood.6 We first validated the capability of the FCS devices by successfully separating low-concentration (100 cells/mL) cancer cells from white blood cells, with an average cell recovery rate of 92.9% and an average purity of 11.7%, at a throughput of 6 mL per hour.

Biocompatibility study on H1299 and HCC1806 cell lines showed that separated cancer cells had excellent short-term viability, normal proliferation, and unaffected key biomarker expressions. We then demonstrated the enrichment of CTCs in blood samples obtained from patients with newly diagnosed advanced non-small cell lung cancer (NSCLC). While still at its early stage of development, FCS could become a complementary tool for CTC separation for its high recovery rate and excellent biocompatibility, as well as its potential for further optimization and integration with other separation methods.

(1) Zhao, W.; Cheng, R.; Miller, J. R.; Mao, L. Adv Funct Mater 2016, 26, 3916-3932.

(2) Zhao, W.; Zhu, T.; Cheng, R.; Liu, Y.; He, J.; Qiu, H.; Wang, L.; Nagy, T.; Querec, T. D.; Unger, E. R.; Mao, L. Adv Funct Mater 2016, 26, 3990-3998.

(3) Logun, M. T.; Bisel, N. S.; Tanasse, E. A.; Zhao, W. J.; Gunasekera, B.; Mao, L. D.; Karumbaiah, L. J Mater Chem B 2016, 4, 6052-6064.

(4) Mao, L.; Schroeder, C.; Zhao, W.; US Patent, 2016 15/223515.

(5) Zhao, W.; Cheng, R.; Jenkins, B. D.; Zhu, T.; Okonkwo, N. E.; Jones, C. E.; Davis, M. B.; Kavuri, S. K.; Hao, Z.; Schroeder, C.; Mao, L. Lab on a chip 2017, 17, 3097-3111.

(6) Zhao, W.; Cheng, R.; Lim, S. H.; Miller, J. R.; Zhang, W.; Tang, W.; Xie, J.; Mao, L. Lab on a chip 2017, 17, 2243-2255.