Fig. 4: Efficient cell trapping demonstrated by the microfluidic chip.

A This design has demonstrated high efficiency in trapping suspension K562 cells that can be treated with stimuli to monitor cellular response immediately after seeding in the channels. B This design is also compatible with adherent NIH3T3 cells. Fibroblast cells, when flushed in the channels are round and over the time will sink to the bottom of the channel to stretch which is promoted with fibronectin coating. Additionally, these cells also migrate in and out of the trap and within the channel. C A single fibroblast, that took 1 h, to stretch in the channel and after additional 1 h stretched completely for distinct visualization of the cytoplasm and nucleus. The blue-fluorescent signal is from CFP-labeled IRF7 transcription factor that resides in the cytoplasm until activation. D Highly efficient and consistent trapping of single cells in our device with over 90% channels being able to isolate cells, both adherent and suspension, at low pressures (N: Number of individual events). At higher pressures, of around 10 kPa, the cells squeezed through the middle of the PDMS pillars and were difficult to retain. Error bar represents mean ± SD. E The cell trapping experiment was repeated multiple times on three different microfluidic chips to determine the design’s reusability and reproducibility. For each individual chip, we observed more than 85 events with single-cell trapping and very few events with more than one cell in channel. Error bar represents mean ± SD. F Representative microscopic images of viable K562 cells NIH3T3 cells that were cultured in microfluidic channels. G K562 cells and NIH3T3 cells, cultured on the chip, showed high viability of over about 80% through media exchange. Error bar represents mean ± SD.