Monoclonality
Document monoclonality – a regulatory metric for therapeutic cell lines
What is monoclonality?
Monoclonality is term that describes a cell line that originates from a single progenitor (single cell) - and is therefore monoclonal. Cell line development and assurance of monoclonality are critical steps in the process of generating biopharmaceutical molecules, such as monoclonal antibodies. A cell line can be established following the isolation of a single viable cell robustly expressing the protein of interest. A key milestone in this process is documenting evidence of clonality to ensure the genetic reproducibility of the cell line.
Documentation of monoclonality is a regulatory metric for therapeutic cell lines and is typically image-based, whereby an image of a single cell is recorded and included in regulatory filings.
Why is monoclonality important?
As regulations for cell line development become increasingly more stringent, researchers will be required to perform single-cell cloning and provide evidence that a cell line is derived from a single cell—proof of clonality. Traditional cloning methods (e.g. limiting dilution and FACS) use statistical analysis to determine a confidence level for monoclonality. However, the documentation of monoclonality has driven the need for more robust technologies and methodologies in bioprocessing. Many researchers now routinely use imaging systems, such as the CloneSelect Imager, to verify monoclonality and monitor cell growth in cell culture media.
What is monoclonal and what is not
By using the CloneSelect Imager software to zoom in on individual, immobilized colonies, it is possible to track growth and determine whether a colony is monoclonal by reviewing the colony images at different time points. In figure below, the images of two colonies are shown. By observing growth of the two colonies and tracking the images back to Day 0, it can be determined whether or not the colony originated from one or more cells. The addition of the beads (shown in the yellow circles) to the semi-solid media serves as a location reference to confirm that the same colony is being imaged each time.
CHO-s cell growth in CloneMedia CHO Growth A semi-solid mediaCloneSelect imager was used to capture images from the 6-well plates at multiple time points. On day 0, it is clearly observed on the top row that one cell is present while on the bottom row, two cells are observed. The yellow circle show the position of a bead that serves as a location reference to confirm that the same colony is imaged over time.
Providing image evidence of monoclonality (report)
Providing image evidence of monoclonality in the cell line development process is not as simple as exporting an image of a single cell. For example, high-resolution images of the entire well should also be inspected to ensure the absence of a second cell.
With a few simple clicks, the Monoclonality Report feature on the CloneSelect™ Imager (CSI) objectively organizes the supporting image evidence needed to establish clonality into an easily shareable report, saving researchers hours typically required to do the same process manually.
Methods for monoclonality assurance
Learn more about the different methods to verify and document monoclonality.