Microfluidic High-Migratory Cell Collector Suppressing Artifacts Caused by Microstructures

Abstract

The small number of high-migratory cancer cells in a cell population make studies on high-migratory cancer cells difficult. For the development of migration assays for such cancer cells, several microfluidic devices have been developed. However, they measure migration that is influenced by microstructures and they collect not only high-migratory cells, but also surrounding cells. In order to find high-migratory cells in cell populations while suppressing artifacts and to collect these cells while minimizing damages, we developed a microfluidic high-migratory cell collector with the ability to sort cancer cells according to cellular migration and mechanical detachment. High-migratory cancer cells travel further from the starting line when all of the cells are seeded on the same starting line. The high-migratory cells are detached using a stretch of cell adhesive surface using a water-driven balloon actuator. Using this cell collector, we selected high-migratory HeLa cells that migrated about 100m in 12 h and collected the cells.

Keywords: balloon; high-migratory cell; microfluidic cell collector; migration assay.

Figure 1

Collection of high-migratory cells. (a) Seeding of cells in a cell culture microchamber. (b) Cell migration in the cell culture microchamber. (c) Detachment of high-migratory cells. (d) Collection of the high-migratory cells.

Figure 2

Microfluidic high-migratory cell collector. (a) Top view and (b) cross section of the microfluidic device and its specifications. (c) Seeding cancer cells in a line pattern by laminar flow. (d) Screening for high-migratory cancer cells, and detachment of the cells by the expansion of a balloon.

Figure 3

Fabrication process of a microfluidic high-migratory cell collector. (a) SU-8 patterning of the molds for a balloon and a microchamber. (b) polydimethylsiloxane (PDMS) shaping of a balloon and a cell culture microchamber. (c) PDMS replica of a balloon and a microchamber. (d) Spincoating of PDMS. (e) Bond of a thin membrane to a PDMS balloon. (f) Bond of the PDMS structure made in (e) to a PDMS cell culture microchamber.

Figure 4

Fabricated microfluidic high-migratory cell collector. (a) Overview of the device. Magnified images of (b) inlets of culture medium and cell suspension. (c) Cell culture microchamber where high-migratory cancer cells are selected. (d) Outlets of culture medium and cell suspension.

Figure 5

Cells seeded in a line pattern using the laminar flow.

Figure 6

Cellular distribution seeded by the cell patterning method using laminar flow. The distance is the length between the edge of the cell detachment zone and each seeded cell.

Figure 7

Surface profile of the expanded balloon. Error bar is accuracy of our measurement method.

Figure 8

Cell detachment using balloon expansion. (a) Adhesive cells on balloon. (b) Detachment with the expansion of the balloon for 30 min in total. (c) Cells remaining after wash-out. (d) Cell detachment ratio as a function of duration of balloon expansion (n = 3. Error bar is standard deviation.). (e) Comparison of survival rate between cells detached by either the balloon or trypsin (n = 3. Error bar is standard deviation.). (f) Comparison of relative cell proliferation rates between cells detached by either the balloon or trypsin (n = 3. Error bar is standard deviation.).

Figure 9

Screening for a high-migratory cell. (a) 0 h, (b) 3 h, (c) 6 h, (d) 9 h, and (e) 12 h, (f) the trajectory of the high-migratory cell traced every hour.

Figure 10

Detachment and collection of a high-migratory cell. (a) Initial condition. (b) The adhesive cell after the expansion of balloon for 20 min. It was detached. (c) Collection of the detached cell by flowing the cell culture medium at 500 μL/min.