Simultaneous and Multimodal Antigen-Binding Profiling and Isolation of Rare Cells via Quantitative Ferrohydrodynamic Cell Separation.

Simultaneous cell profiling and isolation based on cellular antigen-binding capacity plays an important role in understanding and treating diseases. However, fluorescence-activated cell sorting (FACS) and magnetic-activated cell sorting (MACS) are not able to meet this need, due to their requirement for a large quantity of target cells and the limitation stemming from bimodal separation. Here we report a microfluidic method, termed quantitative ferrohydrodynamic cell separation (qFCS), that achieved multimodal rare cell sorting and simultaneous antigen profiling at a ∼30,000 cell min-1 throughput with a 96.49% recovery rate and a 98.72% purity of recovered cells. qFCS profiles and sorts cells via cellular magnetic content of the magnetically labeled cells, which correlates to cellular antigen-binding capacity. By integrating cellular magnetophoresis and diamagnetophoresis in biocompatible ferrofluids, we demonstrate that the resulting qFCS device can accurately profile and isolate rare cells even when present at ∼1:50,000 target to background cells frequency. We show that the qFCS device could accurately profile and isolate T lymphocytes based on a low-expression CD154 antigen and allow on-device analysis of cells after processing. This method could address the need for simultaneous and multimodal rare cell isolation and profiling in disease diagnostics, prognostics, and treatment.

Magnetic Force-Based Microfluidic Techniques for Cellular and Tissue Bioengineering.

Live cell manipulation is an important biotechnological tool for cellular and tissue level bioengineering applications due to its capacity for guiding cells for separation, isolation, concentration, and patterning. Magnetic force-based cell manipulation methods offer several advantages, such as low adverse effects on cell viability and low interference with the cellular environment. Furthermore, magnetic-based operations can be readily combined with microfluidic principles by precisely allowing control over the spatiotemporal distribution of physical and chemical factors for cell manipulation. In this review, we present recent applications of magnetic force-based cell manipulation in cellular and tissue bioengineering with an emphasis on applications with microfluidic components. Following an introduction of the theoretical background of magnetic manipulation, components of magnetic force-based cell manipulation systems are described. Thereafter, different applications, including separation of certain cell fractions, enrichment of rare cells, and guidance of cells into specific macro- or micro-arrangements to mimic natural cell organization and function, are explained. Finally, we discuss the current challenges and limitations of magnetic cell manipulation technologies in microfluidic devices with an outlook on future developments in the field.

Rapid and cost-efficient enumeration of rare cancer cells from whole blood by low-loss centrifugo-magnetophoretic purification under stopped-flow conditions.

We present a substantially improved design and functionality of a centrifugo-magnetophoretic platform which integrates direct immunoseparation and cost-efficient, bright-field detection of cancer cells in whole blood. All liquid handling takes place in a disposable cartridge with geometry akin to a conventional compact disc (CD). The instrumentation required to process such a "lab-on-a-disc" cartridge can be as simple and cost-efficient as the rotor on a common optical disc drive. In a first step, target cells in a blood sample are specifically bound to paramagnetic microbeads. The sample is then placed into the disc cartridge and spun. In the second step, magnetically tagged target cells are separated by a co-rotating, essentially lateral magnetic field from the background population of abundant blood cells, and also from unbound magnetic beads. A stream of target cells centrifugally sediments through a stagnant liquid phase into a designated detection chamber. The continuous, multiforce immunoseparation proceeds very gently, i.e. the mechanical and hydrodynamic stress to the target cells is minimized to mitigate the risk of cell loss by collective entrapment in the background cells or vigorous snapping against a wall. We successfully demonstrate the extraction of MCF7 cancer cells at concentrations as low as 1 target cell per µl from a background of whole blood, with capture efficiencies of up to 88%. Its short time-to-answer is a notable characteristic of this system, with 10% of target cells collected in the first minute after their loading to the system and the remainder captured within the following 10 min. All the above-mentioned factors synergetically combine to leverage the development of a prospective point-of-care device for CTC detection.