Classification of cell types using a microfluidic device for mechanical and electrical measurement on single cells

Abstract

This paper presents a microfluidic system for cell type classification using mechanical and electrical measurements on single cells. Cells are aspirated continuously through a constriction channel with cell elongations and impedance profiles measured simultaneously. The cell transit time through the constriction channel and the impedance amplitude ratio are quantified as cell's mechanical and electrical property indicators. The microfluidic device and measurement system were used to characterize osteoblasts (n=206) and osteocytes (n=217), revealing that osteoblasts, compared with osteocytes, have a larger cell elongation length (64.51 ± 14.98 μm vs. 39.78 ± 7.16 μm), a longer transit time (1.84 ± 1.48 s vs. 0.94 ± 1.07 s), and a higher impedance amplitude ratio (1.198 ± 0.071 vs. 1.099 ± 0.038). Pattern recognition using the neural network was applied to cell type classification, resulting in classification success rates of 69.8% (transit time alone), 85.3% (impedance amplitude ratio alone), and 93.7% (both transit time and impedance amplitude ratio as input to neural network) for osteoblasts and osteocytes. The system was also applied to test EMT6 (n=747) and EMT6/AR1.0 cells (n=770, EMT6 treated by doxorubicin) that have a comparable size distribution (cell elongation length: 51.47 ± 11.33 μm vs. 50.09 ± 9.70 μm). The effects of cell size on transit time and impedance amplitude ratio were investigated. Cell classification success rates were 51.3% (cell elongation alone), 57.5% (transit time alone), 59.6% (impedance amplitude ratio alone), and 70.2% (both transit time and impedance amplitude ratio). These preliminary results suggest that biomechanical and bioelectrical parameters, when used in combination, could provide a higher cell classification success rate than using electrical or mechanical parameter alone.

Constriction Channel Based Single-Cell Mechanical Property Characterization

“…For diseases with blood cells or tumors, there are heterogeneous cell types and it is highly doubtful that biomechanical markers alone can provide a sound evaluation. Currently, the constriction channel design was integrated with impedance spectroscopy to enable both electrical and mechanical property characterization of single cells [61][62][63]. Further studies may consider integrating the constriction channel design with other functional components to further enable the measurement of multiple parameters of single cells, providing a comprehensive evaluation of biological cells.…”

A Mechanical Biomarker of Cell State in Medicine

“…Data collection following magnetic actuation over an array of cells is still limited by the slow response to the applied low-magnitude forces. Parallel mechanical measurement with micropipette aspiration is also possible using microfluidic approaches, 65,66 in which many parallel microchannels could be used to aspirate multiple cells with the same pressure differential. An advantage of this approach (as well as the other approaches in this section) is that mathematical analysis and extraction of physical parameters has already been established in the biophysical community for single-probe versions and should be transferrable.…”

“…Like the other static approaches, it will still be important to address the limited throughput for cells imaged in one field of view, and refreshing the system with new cells leads to similar disadvantages as described for cell transit analyzers. Importantly, for all of these techniques, multiparameter data sets can be obtained by extracting time-dependent responses (or adding electrophysiological data 66 ), but this increased information content comes at the cost of decreased throughput.…”

Recent advances in microfluidic techniques for single-cell biophysical characterization

“…Due to these merits, constriction channels have been used to measure the deformability of RBCs, 22,23,[39][40][41][42][43][44] leukocytes 45 and cancer cells. 46,47 Due to the human capillary-like environment and the physiological relevance of RBC deformability, RBCs are mostly studied in the majority of existing constriction channel-based devices. The first demonstration of microfluidic constriction channels for RBC deformability characterization was reported in 2003.…”