Microfluidic or miniaturized platform for (single) cell electroporation

A second approach towards an improvement of cell electroporation is the use of a microsystem. In such a microfluidic environment, the parameters of the electric field are better controlled, and so is the overall process of electroporation, down to the single cell level. Consequently, the success rate of electroporation becomes higher.

In general, the advantages brought by microfluidics can be classified in two groups. Firstly, dimensions are much smaller, in the micrometer range. The applied voltage required to reach the critical value across a cell is subsequently much lower, and can be even further decreased by the addition of microstructures in the device. The electric field can be shaped with the help of dedicated features, and for instance, constrictions or trapping sites lead to a local enhancement of the electric. Secondly, microfluidic is an ideal format to work at the single cell level; in a microfluidic system, cells can be treated individually, and this brings along the possibility of adjusting the electroporation protocol for every cell individually, as a function of the cell characteristics.

Single Cell Electroporation platform

A single cell electroporation (SCE) platform has been developed for the independent and parallel treatment of 9 cells. The chip is fabricated from glass and silicon, as illustrated below.

- Picture of a SCE microchip containing two main channels for the cell flow and monitoring the trapping of cells, as well as 9 smaller structures for cell trapping, all channels being etched in the silicon substrate. The electrodes for cell electroporation are integrated and fabricated on the glass substrate. Inset: enlarged view on two trapping sites with two cells individually trapped

Right: Enlarged view of a trapping site (SEM picture) that also brings a local enhancement of the electric field

On-chip single cell electroporation (transfection): an animation

LINK movie

Applications

Single cell electroporation and transfection has been demonstrated in the chip for 9 independent cells. For that purpose, the green fluorescent protein (GFP) is employed, as this enables to visualize that the transfection process has been successful and that the cells are still functioning properly. In a second step, this platform has been employed to engineer cells to investigate signaling pathways at the single cell level. For that purpose, a gene coding for a fusion protein between GFP and ERK1 (signaling protein) has been transfected in human mesemchymal cells, and ERK1 localization in the cell is followed optically. At the beginning of the experiment, as shown below, the protein is located in the cytoplasm of the cell. After exposure of the cells to a stimulating factor (FGF-2), ERK 1 is translocated into the nucleus of the cell, and the green fluorescence is partially shifted to the nucleus of the cell.

Literature

http://eprints.eemcs.utwente.nl/8867/

http://eprints.eemcs.utwente.nl/11790/

Contact persons

Dr. ir. Iris van Uitert, Alumni BIOS

Dr. Ana Valero (SCE microchip), Alumni BIOS

Dr. ir. Séverine Le Gac