Monoclonal antibodies (mAbs) are often used to diagnose and treat many diseases such as cancer. Monoclonal antibodies are produced from immune cells that are clones of a unique parent cell. The mAbs are generated by fusing B cells (isolated from an immunised mouse) with an immortal myeloma cell line. The resultant fused cells, known as hybridomas produce the antibodies. The hybridomas are screened to select a clone with the most desired antibody specificity. The products of these individual clones are monoclonal antibodies.

Isolation of single cells in monoclonal antibody production is an important step. The limiting dilution technique is one of the most common methods in this application, involving the serial dilution principle. The goal is to dilute the cell suspension to a point where only a single cell is isolated into a single microwell. In this technique, the seeding density is very crucial. If a low seeding density is used, this will increase the number of empty wells which results in a waste of time and consumables.

Conversely, if the cells are seeded at a higher density, there will be a higher chance of having multiple cells in one well, and cannot be guaranteed that the obtained clones originated from single cells as it is difficult to identify by microscope. Therefore, limiting dilution is usually performed a few times to achieve good efficiency in producing a good monoclonal cell line.

CellGem – a Novel Microfluidic-based Technique for Single Cell Isolation

Here, we describe a new method for single-cell isolation. CellGem, is a disposable chip in which single cells can be isolated, validated, and expanded to form monoclonal cell colonies using conventional micropipettes and microscopes.

CellGem is a simple, easy-to-use microfluidic chip that requires minimum reagent consumption. The chip is composed of 60 arrays of wells, with the cell capture wells up one side of the chip and the cell culture wells on the other side. Simply, the cell suspension is loaded on the chip and the cells with the desired size will fall into the capture well, while other uncaptured cells will be washed off. The chip is then flipped over to allow the captured single cells to drop into the culture well. The single cells are then cultured in these wells to form single-cell colonies before harvesting and transferring to the conventional culture ware. Due to the microfluidic system, the single cell can be cultured for a longer time with a higher viability rate.

This innovative microfluidic chip-based method for the isolation of monoclonal cell lines is cost-and
time-effective and is a better alternative approach to limiting dilution or fluorescence-activated cell
sorting (FACS) which requires specialized equipment.

Want to find out more about different single-cell isolation techniques, check out our related blog “The 7 Single Cell Isolation Techniques”

References

• AtlantisBioscience. THE 7 SINGLE CELL ISOLATION TECHNIQUES. 14 July 2022. URL: The 7 Single Cell Isolation Techniques – ATLANTIS BIOSCIENCE
• Yeh CF, Lin CH, Chang HC, Tang CY, Lai PT, Hsu CH. A Microfluidic Single-Cell Cloning (SCC) Device for the Generation of Monoclonal Cells. Cells. 2020;9(6):1482. Published 2020 Jun 18. doi:10.3390/cells9061482